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Qilun ZHU MSc Information Management
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Citation Studies of Publications in Superconductivity Research by China
with Comparative Studies of Some Other Countries
A study submitted in partial fulfillment of
the requirements for the degree of
Master of Science in Information Management
at
THE UNIVERSITY OF SHEFFIELD
by
Qilun ZHU
September 2008
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Abstract
Aims: This study aims to analyze citations statistics of original publications in
superconductivity research by China, and measure the impact of China in
superconductivity research with comparison to some other leading countries
of the world.
Background: Superconductivity research has been explosive since two
scientists of IBM Zurich research center discovered which is so called as
“high-temperature” superconductor in 1986. During 1986-2007, Chinese
scientists contributed thousands of original articles in superconductivity
research, and there is a general interest to quantify the contributions and
impact of China in superconductivity research.
Methodology: The methodology used for this study is citations analyses.
Data source is from ISI Web of Sciences. Web of Sciences analyzing tools
and Microsoft Excel are used for data analyses.
Results: The original articles by China in superconductivity research are
published in an extensive range of source journals and subject areas.
Citations of these articles are from a broad range of countries, much more
extensive range of source journals and subject areas. The total number of
citations of China is far less than USA and Japan, less than Germany;
however, the number of citations of China of each year has been continuously
increasing, and it has been catching up or over taken England, France and
Russia in many cases in recent years.
Conclusion: China is one of the leading countries of the world in
superconductivity research. The general impact of China in superconductivity
research is far less than the super countries of USA and Japan, and less than
Germany; however, China has been catching up or over taken England,
France and Russia in many cases with increasing impact in superconductivity
research in recent years.
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Table of Contents
Chapter 1 Introduction ................................................................................................................. 5
1.1 Aims and Objectives ............................................................................................ 5
1.2 Background ............................................................................................................. 5
1.2.1 Research Background and Original publications ..................................... 5
1.2.2 Citation Analysis and Its Related Applications ......................................... 6
1.2.3 Implications of Interest of This Study ......................................................... 7
Chapter 2 Literature Review ....................................................................................................... 8
2.1 Superconductivity Research ............................................................................. 8
2.2 Science Citation Index and Citations Analyses ......................................... 9
2.3 Citations Analyses in Mapping Superconductivity Research .............. 12
2.4 Citations Analyses in the Measure of Nations’ Contribution .............. 14
2.5 Web of Sciences, Scopus, and Google Scholar ....................................... 17
Chapter 3 Methodology ............................................................................................................. 19
3.1 Data Source: Web of Sciences ...................................................................... 19
3.2 Data Selection Criteria: 1986-2007 original articles ............................ 19
3.3 Data Analysis Criteria: non-self-citations .................................................. 20
3.4 Data Classification Scheme: JCR scheme ................................................. 21
3.5 Research Techniques and Approaches ........................................................ 21
Chapter 4 Limitations of the Research .................................................................................... 22
4.1 Limitations by Data Sources .......................................................................... 22
4.2 Limitations of Methodology of Citations Analyses .................................. 22
4.3 Limitations of Technical Analyzing Tools .................................................... 23
4.4 Limitations of Time of Study .......................................................................... 23
Chapter 5 Original Articles by China ........................................................................................ 24
5.1 Growth of Articles through the Years .......................................................... 24
5.2 English is the Primary Language .................................................................. 26
5.3 Subject Areas ....................................................................................................... 27
5.4 Source Journals ................................................................................................... 28
5.5 International Collaborations ........................................................................... 30
Chapter 6 Citation Analyses of China ...................................................................................... 33
6.1 Citations by Document Types ........................................................................ 33
6.2 Citations Growth through the Years ............................................................ 34
6.3 Citations by Different Languages ................................................................. 36
6.4 Citations from Different Countries/Territories ......................................... 37
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6.5 Citations by Institutions ................................................................................... 39
6.6 Citations by Subject Areas .............................................................................. 41
6.7 Citations by Source Journals .......................................................................... 42
Chapter 7 Comparative Studies ............................................................................................... 43
7.1 Original Publications .......................................................................................... 43
7.1.1 Publications Growth through the Years ......................................................... 43
7.1.2 Publication Source Journals ..................................................................... 46
7.1.3 Publication Subject Areas .......................................................................... 51
7.2 Citations Analyses of Different Countries .................................................. 55
7.2.1 Citations Count, Averages, Growth, and h-index ................................... 56
7.2.2 Citations Distribution in Different Countries ............................................ 62
7.2.3 Citations Source Journals ......................................................................... 66
7.2.4 Citations Subject Areas .............................................................................. 69
7.3 Key and Top Institutions .................................................................................. 72
7.3.1 Definitions and Numbers ........................................................................... 72
7.3.2 Citations of Top Institutions ....................................................................... 77
7.4 International Collaborations ........................................................................... 80
7.4.1 Original Publications .................................................................................. 80
7.4.2 Citations boosted? ...................................................................................... 85
Chapter 8 Conclusions .............................................................................................................. 87
References: ................................................................................................................................. 94
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Chapter 1 Introduction
1.1 Aims and Objectives
This study aims to analyze citations statistics of original articles by
China in superconductivity research, and measure the impact of China in
superconductivity research with comparison to some other leading
countries of the world. Other objectives include finding out key institutions
of China in superconductivity research and comparing the impact of top
institutions of different countries, investigating international collaborations
in superconductivity research and whether or not citations are boosted by
international collaborations.
1.2 Background
1.2.1 Research Background and Original publications
In 1986, Bednorz and Muller, 2 scientists at the IBM Zurich Research
Laboratory, reported discovery of new superconducting materials which
demonstrated superconductivity at much higher degree than previously
known. This finding was so important that it won the 1987 Nobel Prize in
Physics, and led to an explosive further research development in
superconductivity over the world (Royal Swedish Academy of Sciences,
1987). In 1987, Chinese scientists made a tiny breakthrough in finding
better superconductors (Zhao et al., 1987).
Since then, a lot more new contributions have been made world
widely in superconductivity research. During 1986-2007, 125 countries
contributed more than 100,000 publications in superconductivity, among
which China ranks No.6 with a total number of 7,241 publications in this
research area (Thomson Scientific, 2008c).
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1.2.2 Citation Analysis and Its Related Applications
Citation analysis has become a methodology adopted by many
bibliometric researchers in different science domains since the advent of
Science Citation Index (SCI).
SCI is now in its web edition called Web of Sciences (WOS), which
“covers more than 5,800 journals” from “more than 100 disciplines” of the
world‟s leading research, and “provides access to current and
retrospective bibliographic information, author abstracts, and cited
references” (Thomson Scientific, 2008b).
However, it has been upon the same assumptions for SCI and WOS
that Garfield and the Institute of Scientific Information (ISI) or Thomason
Scientific have founded the database services. The assumptions are that
(although arguably): there are inherent relationships between an original
cited publication and the succeeding citing publications, and in some
respect, citations indicate the impact of the original cited research on the
succeeding citing researches.
By counting and analyzing the publications which have cited the
original publications, citation analyses have been proved to be very useful
at different levels in the assessment of the extent and range of impact of
the original researches.
With regard to the research of superconductivity, there have been
already documented citation analyses which revealed the country impact
in this research area. However, there has not been any of this kind
analyses carried out and reported for China by now.
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1.2.3 Implications of Interest of This Study
In China, there have been two National Prizes in Natural Science
Research (which are the highest national government prizes) awarded to
the progresses in superconductivity research since 1986 (The Ministry of
Science and Technology of China, 2007). On the other hand, more than a
few of Chinese people including scientists have the impression that
superconductivity research in China has already advanced to such level
as very close to that of the leading countries (e.g. U.S., Japan, etc.) in the
world in some respect (Zhang, 2006).
Therefore, it might be of general interest to carry out a quantitative
research by analyzing citations statistics of original publications by China
with comparison to those of some other leading countries of the world, in
order to disclose the actual impact and contributions of China in
superconductivity research.
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Chapter 2 Literature Review
2.1 Superconductivity Research
Superconductivity was first discovered by H. Kamerlingh Onnes in
1911. What he found was that, when reached a critical temperature
(typically a few degrees above absolute zero) specific to different metals,
the electrical resistance of some metals disappeared completely in a
narrow temperature range. (Schrieffer and Tinkham, 1999)
This discovery is of tremendous significance in many respects. For
example, pilot systems have already been developed for applications
such as electrical generators and energy storage arrangements. However,
since the available superconducting materials require unpractical low
temperatures, the technical applications have been greatly limited. (Royal
Swedish Academy of Sciences, 1987) Therefore, the drive for exploring
“high temperature” superconducting materials is persistently demanding.
By now, researches have reported materials of superconductivity at
increasingly high temperatures. However, the milestone was in 1986 when
Bednorz and Müller found “superconductivity in an oxide material at a
temperature 12°C higher than previously known” (Royal Swedish
Academy of Sciences, 1987). This discovery started a new era of what is
now so called “high temperature” superconductivity research.
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2.2 Science Citation Index and Citations Analyses
Science Citation Index (SCI) was launched in 1964 by Institute for
Scientific Information (ISI), which was founded by Eugene Garfield. Now,
SCI has evolved to its web edition Web of Sciences (WOS), and ISI has
been merged into Thomson Scientific.
SCI/WOS aims to cover the core literatures, most of which are
journals, of all disciplines of science, and expand the coverage to include
other important literatures based on the ISI defined impact factors. Moed
conducted a thorough investigation of SCI/WOS coverage by discipline,
and concluded that all disciplines of natural science are covered as
“excellent” or “good” (Moed, 2005).
SCI/WOS was primarily designed for search of literatures, and citation
index was meant to augment traditional natural language indexing terms.
However, since it is built upon linkage of citations, SCI/WOS now has
often been used for citation analyses in order to assess “the contributions
made by various bodies in the scholarly system to the advancement of
scholarly knowledge” (Moed, 2005).
According to Garfield (Garfield, 1979), citations “support, provide
evidence for, illustrate, or elaborate on what the author has to say”, and
hence, “the act of citing is an expression of the importance of the material.
The total number of such expressions is about the most objective
measure there is to the material‟s importance to current research.”
However, it has always been argued what the citations actually
measure. Some researchers advocate that citations measure “quality of
research” (Cole and Cole, 1971), “authoritativeness” (Gilbert, 1977),
“intellectual influence” (Zuckerman, 1987), “popularity” (Borgman and
Furner, 2002). Others contend that what citations measure is not clear
(Cronin, 1984; MacRoberts and MacRoberts, 1989).
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MacRoberts presented a complete picture about the problems in their
critical review: “Formal Influences Not Cited”; “Biased Citing”; “Informal
Influences Not Cited”; “Self-Citing”; “Different Types of Citations”
(affirmative or negative); “Variation in Citation Rate with Type of
Publication”, “Nationality, Time Period, and Size and Type of Specialty”;
“Technical Limitations” including “Multiple authorship”, “Synonyms”,
“Homonyms”, “Clerical errors”, “Coverage of literature”, …, etc.
(MacRoberts and MacRoberts, 1989)
However, despite the debate, citations analyses have been applied to
the evaluation of research performance widely. These performance
evaluations based on citations analyses have been practiced extensively
at individual (most at internal circumstances, e.g. for making decisions
about hiring and tenure), departmental (Bradley et al., 1992; Bishop et al.,
2003) or institutional (Seng and Willett, 1995; Redman et al., 2001), and
national (Braun et al., 1994a; Braun et al., 1994b; Hicks et al., 2004)
levels. The above listed references are only a few examples.
Meanwhile, researches have also been carried out in the attempt to
validate the results of citations analyses by comparisons to peer reviews.
For instances: Lawani and Bayer presented evidences based on 872
cancer papers that highly rated papers by peers are more highly cited in
the publications. (Lawani and Bayer, 1983) Goldberger et al conducted a
study on the Research-Doctorate Programs in the United States and
identified "the clearest relationship” between ratings and citations: “faculty
in top-rated programs cited more than faculty in lower-rated programs”.
(Goldberger et al., 1995) Norris and Oppenheim demonstrated again the
high correlation between 2001 UK Research Assessment Exercise (RAE)
scores and the citations count for archaeology departments of UK
universities (Norris and Oppenheim, 2003).
On the other hand, researchers who advocate citation analyses for
research evaluation also observe the problems, and declare that “citations
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are only rough indicators” which could be used to measure the works
“among a relatively large sample of scientists” rather than “a particular
individual‟s work” (Cole, 1989).
Fortunately, while the problems of citations analyses in the evaluative
context are magnified in the circumstances of individual evaluations,
these problems could be confidently canceled out while the evaluation is
conducted at an aggregate level of the joint performance of scientists.
There are other applications of citations analyses as well, which
comprise mapping science activities, identifying trends or research fronts,
and tracing the history of research (Garfield, 1998).
Moed summarized citations analyses into five broad themes: “(1) The
assessment of the contribution made by various bodies in the scholarly
system to the advancement of scholarly knowledge; (2) Analyses of the
global scholarly system, including studies of its various characteristics
and their relationships to research performance; (3) Analyses of scholarly
fields; (4) Analyses of the science-technology interface and the economic
contributions of science; (5) Assessment of educational, social and
cultural contributions of basic research.” (Moed, 2005)
This study will involve analyses of nations‟ contributions of science in
the field of superconductivity research, and may also reflect related
scientific activities such as the international collaborations in the global
context.
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2.3 Citations Analyses in Mapping Superconductivity
Research
There are different approaches in mapping the research activities of
superconductivity by citations analyses. The following are only some
examples.
Nadel compared the citation and co-citation data of the core
explanatory theory of superconductivity (BCS theory) and the historically
identified events, and indicated the correspondence in between (Nadel,
1981).
Arunachalam and Singh analyzed publications in superconductivity
research of 1969-1970, and their citations over the following twelve years,
with the attempt to “identify the geographical origin, language, and
journal-wise distributions of the papers, the citedness and the distribution
of citations as a time series”. Their main findings included: English is the
main language for communications of superconductivity research; USA,
USSR and Japan are leading countries in the research; the highly cited
papers received most of their citations during the years shortly after
publication, and the citations declined with years (Arunachalam and Singh,
1984).
Garfield associated the key research papers identified by the high
number of citations, with the milestones of the progresses of
superconductivity research, and indicated high coincidence (Garfield,
1988). He also used citations count to identify the high impact individuals,
institutions, and journals, as well as to indicate research front in the field
of superconductivity research. (Garfield, 1990)
Chu concerned about the formal and informal structure of
communications between Chinese and non-Chinese scientists in
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superconductor research. She identified notable similarities in formal
communications: “analogous cited cores, identical publication sources,
and comparable intellectual structures of co-citation data” (Chu, 1992a);
and the lower visibility of Chinese scientists compared to their
counterparts in the informal communications (Chu, 1992b). Chu also
studied the formal communications among Chinese superconductor
researchers in a later research, based on citation statistics from Chinese
Science Citation database (Chu, 1998).
Cardona and Marx studied the impact of the works by Vitaly Ginzburg,
one of the most influential scholars in superconductivity research, with
particular attention to his most frequently cited articles and books and their
impact on recent research (Cardona and Marx, 2006).
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2.4 Citations Analyses in the Measure of Nations’
Contribution
There are also many examples where citations analyses have been
used to measure nations‟ contributions in both specific subjects and more
general science and technology. The following are only a few examples.
Arunachalam and Singh analyzed superconductivity research papers
by Israeli scientists indexed in Physics Abstracts 1971-1982, as well as
the relevant citations records, and concluded that Israel performed quality
research in the field of superconductivity, almost as good as the leading
country USA. (Arunachalam and Singh, 1985) This research, as to our
knowledge, has been the only attempt thus far to measure country
performance in superconductivity research by now.
Jain and Garg studied the patterns of publications and citations of
laser research by India during 1967-84 with data from Journal of Current
Laser Abstracts and Science Citation Index, and were convinced that
Indian performance in laser research was part of the mainstream science
(Jain and Garg, 1992).
Uzun et al explored Turkish physics publications that appeared in the
list of SCI source journals during 1982-1990, and discovered that “papers
from Turkey that appeared in the American and European journals are
cited at rates higher than the corresponding „average' papers” (Uzun et al.,
1993).
Kim measured research performance of Korean physicists with data
from SCI 1994-1998, and compared Korean-authored papers versus
internationally co-authored papers. Based on the citations count, Kim
revealed that papers with U.S. co-authors received the highest citation
rate, and there had been significant differences between the average
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citations per paper of different countries (Kim, 2001).
Sometimes researchers tend to introduce or employ specific scales in
the measurement of country performance:
Arunachalam and Doss analyzed papers indexed in three years of
Biochemistry and Biophysics Citation Index. They used the sum of Impact
Factors (IFs) of the journals in which papers had been published as a
rough measure to scale institutions‟ research contribution. They identified
great portion of papers with international co-authors, and found that
international collaboration raised the IFs value of Israeli publications
(Arunachalam and Doss, 2000).
Garg investigated publications of laser research by India and China at
conferences and in journals during 1993 and 1997, and used the following
measures to quantify the research impact: “Normalized Impact Factor”,
“Normalized impact per paper”, “Proportion of papers in high quality
journals”, “Publication Effective Index” (Garg, 2002). These measures
were used again later in Kumar and Garg‟s analyses of publications by
India and China in computer science during 1971-2000, to reflect the
research impact of these two countries in computer science (Kumar and
Garg, 2005).
There are also researches which involve comparative studies of many
nations‟ performances in science and technology.
King analyzed the publication and citations numbers of different
nations, and quantified the nations‟ impact in science and technology
during 1993-2002. He compared 31 countries which contributed
altogether more than 98% of the world‟s total number of highly cited
papers, defined as the most cited 1% papers by field and year generated
from Thomson ISI. He used indicators as: total number of publications
and citations, the share of top 1% highly cited publications, the number of
citations per paper, publications and citations per researcher, and
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sometimes combined with financial/economical indices such as GDP,
HERD (Higher Education funding of R&D), etc. Based on share of top 1%
of highly cited publications during 1997–2001, he produced a list of ranks
for different nations, among which China was at the place of 19th. Based
on the share of citations, he also identified the national strengths in
different disciplines in seven categories: clinical medicine; preclinical
medicine and health; biological sciences; environment; mathematics;
physical sciences; and engineering (King, 2004).
Guan and Ma measured China‟s impact in semiconductor research
based on the publications and citations data of 1995-2004 from ISI Web of
Sciences database. They focused on five Asian countries/regions, but
also included Germany and USA for comparative studies in a broader
extent. They counted publications and citations, adopted “the average
number of citations per article published in a country”, “the uncitedness”,
and “the percentage of highly cited papers” as measures for the impact
analyses, which revealed that Chinese scientists in semiconductor
research “have a low international visibility”. They also studied Leimkuhler
curve and Gini indices for the inequality of citations times and informatric
productivities among different countries (Guan and Ma, 2007).
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2.5 Web of Sciences, Scopus, and Google Scholar
For decades, citations analyses had solely depended on the citations
data source from Science Citations Index (SCI) or Web of Sciences
(WOS). However, Scopus from Elsevier and Google Scholar from Google
started to provide citations data since 2004. By now, there have been
many other databases with citations launched and in use, however, WOS,
Scopus and Google scholar remain the principle ones when referred to
citations databases, and some researches have already been carried out
to compare the performances of their citations data sources.
Bar-IIan et al. have proposed a set of measures to compare these
citations databases, and also tried applying these measues to the
publications of highly cited Israeli scientists for feasibility tests. The results
indicate “high similarities between the rankings of the ISI Web of Sciences
and Scopus and lower similarities between Google Scholar and the other
tools” (Bar-Ilan et al., 2007). However, Falagas, et al‟s study in biomedical
information indicates that Scopus offer about 20% more citations than
Web of Sciences (Falagas et al., 2008).
On the other hand, Scopus has been pointed out to have more
coverage in journal titles while at the meantime have its limitations of
publication years which include merely 1995 onwards. (Falagas et al.,
2008), and Google Scholar has been identified to have its different
indexing strategies of including books and proceedings, which often
attract more citations than journal articles. (Bar-Ilan et al., 2007) Meho
and Yang‟s case study in citations of library and information science
advocates that Google Scholar has its strength in the “coverage of
conference proceedings as well as international, non-English language
journals” (Meho and Yang, 2007).
With regard to database reliability, Jacso has reported with that the
citations count from WOS gives out “only the exact match”, however, with
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facilities to “allow the searchers to visually scan and check the imperfect
but close matches” (Jacso, 2006a). Bar-IIan have uncovered that citations
from Google Scholar often include both preprint and journal version of the
same paper, which contribute to duplicate count of citations (Bar-Ilan,
2008). Jacso have also reported with figures about the duplicated,
non-scholarly, and error citations in Google Scholar, which are meant to
cause the “phantom” or “inflated” citations count (Jacso, 2006b).
There is also a detailed and justified research reported by Bakkalbasi,
et al., which counted citations of articles from two different disciplines of
oncology and condensed matter physics, and of two different years of
1993 and 2003. The results revealed that: all three tools, i.e. WOS,
Scopus and Google Scholar, returned some unique citations; however,
WOS returned the most citations for condensed matter physics of both
1993 and 2003 and for oncology of 1993; while for oncology 2003,
Scopus returned the most citations, and Google Scholar returned the
most unique citations. Furthermore, it was concluded that “the question of
which tool provides the most complete set of citing literatures may depend
on the subject and publication year of a given article” (Bakkalbasi et al.,
2006).
Bakkalbasi, et al‟s conclusion is of great significance because it could
be used to well explain the inconsistency in different research results,
while it is has been well supported by the major findings with regard to the
differences of different databases reported by other researches. It could
also be served as evidence that WOS should be an appropriate data
source for this specific study, since superconductivity is a branch of
condensed matter physics, for which WOS has reported to be the most
suitable data source for citation analysis.
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Chapter 3 Methodology
3.1 Data Source: Web of Sciences
Although there are other sources with citations statistics, such as
Google Scholar, Scopus, etc., the previous research by Bakkalbasi, et al
which is metioned in Chapter 2 has implied that Web of Sciences should
be the most suitable data source for this specific study.
3.2 Data Selection Criteria: 1986-2007 original articles
1986 was the starting point of the explosive development of research
in “high temperature” superconductivity, as it has been reported in the
section of literatures review. 2007 was the last year that the complete
year-round publications are available. It is intended that the inclusion of
citations data of the complete set of 1986-2007 publications should reveal
a holistic picture of the impact of the superconductivity research of China
in the new “high temperature” era.
The following search terms are used for the complete set of
publications in superconductivity related research of China during
1986-2007 within the database of Web of Sciences.
TS=(superconduct*) AND CU=(China) Timespan=1986-2007. Databases=SCI-EXPANDED
Where superconduct* is used for key word search, * is used as
truncation to represent superconductor(s), superconducting,
superconductivity, etc; and the country is limited to China, time span is
limited to 1986-2007.
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The result reveals that 7,241 papers including articles, notes, letters,
reviews, editorial materials, meeting abstracts, corrections have been
published. Table-3.2.1 lists the relevant record count and the percentage
rate of different document types of publications.
Document Type Record Count % of 7241
ARTICLE 6977 96.35%
NOTE 135 1.86%
LETTER 53 0.73%
REVIEW 49 0.68%
EDITORIAL MATERIAL 19 0.26%
MEETING ABSTRACT 5 0.07%
CORRECTION 3 0.04%
Total: 7241 100.00%
Table-3.2.1 Document Types of Publications of China
Since this study aims to evaluate the original important contributions
by China in superconductivity research, and since articles are of the most
important original publications here above, it is decided that the
publications and citations analyses are based on articles only.
3.3 Data Analysis Criteria: non-self-citations
Citations analyses are primarily based on the number of citations
excluding self-citations. However, in the comparative studies where
h-index is used, h-index based on non-self-citations is not available. In
this case, the h-index based on the total numbers of citations is used in
order to obtain some overall understanding about the situations.
Although it is arguable that self-citations may also reflect the impact of
a publication, it is evident that this impact is limited within the authors‟
research group. Since this study aims to evaluate the impact of original
research by China in the broad extent of the academic world, it is
reasonable to exclude self-citations in citations analyses of China as well
as the comparative studies of citations of different countries. .
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3.4 Data Classification Scheme: JCR scheme
JCR classification scheme is used for subject analyses of original
publications as well as citations of publications. Since JCR is used by the
database of Journal Citation Report, which is a by-product of Web of
Since, and since this study is of citations analyses carried within WOS
database, it will be more consistent using JCR classification scheme for
data analyses.
3.5 Research Techniques and Approaches
WOS has provided excellent citations analyzing tools, i.e. analyzing
publications and citations by countries, document types, institutions,
languages, publication years, source titles, subjects, etc. It also presents
citations reports, provided with detailed results of non-self citations. These
have been used for most of our data analyses. Besides, Microsoft Excel is
used when there is the need or the WOS analyzing tools become
inefficient, e.g. to compare the data sets of different countries, to sort out
the publications by reprint authors, etc.
The following major aspects are looked while data are analyzed: trend
of growth or decrease of publications and citations over the years;
coverage of source journals of publications and citations; impact factors of
source journals; subject areas of original publications and citations, key
institutions in terms of the original publications and citations of the top
institutions of different countries; International collaborations and whether
or not they have helped to boost the number of citations.
Comparative studies of different countries are emphasized on
similarity or dissimilarity in patterns rather than bench marking, although
at some point this might seem evident and inevitable.
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Chapter 4 Limitations of the Research
This study is not complete and has inevitable limitations in terms of
data sources, methodology, technical analyzing tools, and time of study.
4.1 Limitations by Data Sources
Although Web of Sciences is supposed to provide the best data
sources for citations analyses in this study, it is not perfect. There are
some inevitable faults in the data sources sometimes, such as errors of
data entries, etc. For example, Web of Sciences analyzing tools
sometimes may provide the results with a note such as “12 records
(0.0763% of total) do not contain data in the field being analyzed”, which
is obviously a kind of faults due to the errors of data entries. It is believed
that such minor faults of data may not affect the overall results of this
study, although it is definitely better to have a data source without faults.
Besides, since this study is carried out in the middle of 2008, the
citations data for some of the 2007 original articles are less than one year,
which makes the citations analyses incomplete in this case.
4.2 Limitations of Methodology of Citations Analyses
The most distinct limitations of citations analyses with regard of this
study should be self-citations and reasons of citing. In this study,
self-citations are excluded, and self-country citations are also excluded in
the comparative studies. However, reasons of citing do affect the way how
to perceive the citations of an original article, as some original articles
might have presented incorrect theories or inaccurate experimental
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results and hence citations of such articles are only to point out the
mistakes or inaccuracies, which is on the contrary of the idea that citations
reflect the impact of the original articles on later researches. Since this
study is intended to reveal the impact of China in superconductivity
research, in which case, the impact is supposed to be perceived in the
positive way, and hence it is regretful that there is by no means to
distinguish the reasons of citing. However, for the comparative studies of
other countries, since this is the same problem for all countries under
study, it is believed that this problem won‟t affect much the relative results
of different countries.
4.3 Limitations of Technical Analyzing Tools
The main analyzing tools used for this study are Web of Sciences
analyzing tools and Microsoft Excel. The manual works on Microsoft Excel
are based on the data deprived from Web of Sciences analyzing tools.
Web of Sciences analyzing tools are not able to generate citations report
for more than 10,000 original articles, and therefore, the comparative
studies of citations analyses have to be carried out based on original
publications of 2001-2007 and with subject focus in three top areas. This
has caused inconsistency of the comparative studies, as the publications
analyses of original articles are of 1986-2007 but citations analyses are of
different years.
4.4 Limitations of Time of Study
This study has been carried out within only 2 months, and with such a
limited time, there couldn‟t be thorough and complete investigations in
every possible aspects.
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Chapter 5 Original Articles by China
In order to obtain an overview of the original articles by China, a
series of statistical analyses are presented in this chapter. Besides,
comparative studies of original articles by different countries are
presented in Chapter 7.
5.1 Growth of Articles through the Years
Table-5.1 lists the record count and percentage of different years of
the original articles in superconductivity research by China.
Publication Year Record Count % of 6977
1986 27 0.39%
1987 94 1.35%
1988 131 1.88%
1989 165 2.36%
1990 183 2.62%
1991 238 3.41%
1992 192 2.75%
1993 196 2.81%
1994 279 4.00%
1995 265 3.80%
1996 277 3.97%
1997 476 6.82%
1998 281 4.03%
1999 263 3.77%
2000 438 6.28%
2001 364 5.22%
2002 389 5.58%
2003 524 7.51%
2004 473 6.78%
2005 562 8.06%
2006 550 7.88%
2007 610 8.74%
Total: 6977 100.00%
Talbe-5.1 Articles of the Years
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It is clearly seen that there is a continuous growth in the number of
articles published through the years (Chart-5.1.1). Detailed analysis
reveals that the rapid growth started from 1999, as there were only less
than 30% articles published during the beginning half of the period, while
on the other hand there were more than 70% articles published during the
later half of the period (Chart-5.1.2).
0
100
200
300
400
500
600
700
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
Chart-5.1.1 Original Articles: growth through the years
1986, 0.39%
1987,
1.35%
1995,
3.80%
1994,
4.00%1993,
2.81%
1997,
6.82%1998,
4.03%
1999,
3.77%
2000,
6.28%
2001,
5.22%
2002,
5.58%
2003,
7.51%
2004,
6.78%
2007,
8.74%2006,
7.88%2005,
8.06%
1992,
2.75%
1988,
1.88%
1989,
2.36%
1990,
2.62%
1991,
3.41%
1986-1996:
29.34%
1996,
3.97%
Chart-5.1.2: % of Original Articles of the years
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5.2 English is the Primary Language
Analysis by languages reveals that English is the primary language
used for original articles in superconductivity research by China, as
95.71% articles are in English (Table-5.2). Further analysis by publication
years identifies a general trend of growth in English articles published
through the years (Chart-5.2).
Language Record Count % of 6977
ENGLISH 6678 95.71%
CHINESE 297 4.26%
GERMAN 1 0.01%
JAPANESE 1 0.01%
Total: 6977 100.00%
Table-5.2 Analysis by Language
0
100
200
300
400
500
600
700
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
Chart-5.2 English Articles: growth through the years
Since English is the language of science, and it is the most commonly
used language in the academic world, articles published in English
usually have greater influence than those in other languages. With
increasing number of articles published in English, China has obviously
become more visible and influential in the world wide community of
superconductivity research.
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5.3 Subject Areas
Analysis by subject areas has disclosed that all original articles by
China in superconductivity research are published in 69 subject areas.
This indicates that superconductivity research in China has covered a
broad range of subject areas.
Table-5.3 lists the focus original subject areas of the original articles
by China in superconductivity research, which are defined as that each of
these subject areas has included at least 1% original articles by China. It
is seen that there are 19 such subject areas, with the top 3 subject areas
as: applied physics, condensed matter physics, and multidisciplinary
physics, which have published most original articles. This indicates that
superconductivity research of China is very much focused in these
physics subject areas.
Subject Area Record Count % of 6977
PHYSICS, APPLIED 2890 41.42%
PHYSICS, CONDENSED MATTER 2259 32.38%
PHYSICS, MULTIDISCIPLINARY 1218 17.46%
MATERIALS SCIENCE, MULTIDISCIPLINARY 562 8.06%
ENGINEERING, ELECTRICAL & ELECTRONIC 309 4.43%
PHYSICS, MATHEMATICAL 223 3.20%
CHEMISTRY, PHYSICAL 181 2.59%
METALLURGY & METALLURGICAL ENGINEERING 155 2.22%
MULTIDISCIPLINARY SCIENCES 151 2.16%
PHYSICS, NUCLEAR 119 1.71%
PHYSICS, PARTICLES & FIELDS 116 1.66%
NUCLEAR SCIENCE & TECHNOLOGY 113 1.62%
PHYSICS, ATOMIC, MOLECULAR & CHEMICAL 112 1.61%
PHYSICS, FLUIDS & PLASMAS 106 1.52%
CHEMISTRY, MULTIDISCIPLINARY 103 1.48%
MATHEMATICS, APPLIED 92 1.32%
THERMODYNAMICS 91 1.30%
OPTICS 88 1.26%
MATHEMATICS 71 1.02%
Table-5.3 Focus Original Subject Areas of China
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5.4 Source Journals
Analysis by source journals has disclosed that all original articles by
China in superconductivity research are published in 422 source journals.
Table-5.4.1 lists the core original source journals of China, which are
defined as that each of these journals has published at least 1% original
articles by China. It is seen that there are 18 such core original source
journals, and they have published more than 2/3 of the original articles by
China in superconductivity research.
Source Title Record Count % of 6977
PHYSICA C 1339 19.20%
PHYSICAL REVIEW B 709 10.16%
SUPERCONDUCTOR SCIENCE & TECHNOLOGY 362 5.19%
SOLID STATE COMMUNICATIONS 273 3.91%
CHINESE PHYSICS LETTERS 254 3.64%
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY
184 2.64%
CHINESE PHYSICS 181 2.59%
JOURNAL OF PHYSICS-CONDENSED MATTER 176 2.52%
PHYSICS LETTERS A 173 2.48%
ACTA PHYSICA SINICA 163 2.34%
COMMUNICATIONS IN THEORETICAL PHYSICS 140 2.01%
INTERNATIONAL JOURNAL OF MODERN PHYSICS B 129 1.85%
JOURNAL OF SUPERCONDUCTIVITY 120 1.72%
JOURNAL OF APPLIED PHYSICS 119 1.71%
CHINESE SCIENCE BULLETIN 110 1.58%
APPLIED PHYSICS LETTERS 101 1.45%
PHYSICAL REVIEW LETTERS 100 1.43%
CRYOGENICS 88 1.26%
Total: 4721 67.67%
Table-5.4.1: Core Original Source Journals of China
Since Journal Impact factor is a well known indicator which implies the
general academic influence of an academic journal, it is attempted to look
at the impact factors of these core original source journals of China in
order to have a general impression about their academic influences. The
result reveals that the average journal impact factor of these journals is
2.011 (Table-5.4.2).
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Abbreviated Journal Title Impact Factor
APPL PHYS LETT 3.596
CHINESE PHYS 2.103
CHINESE PHYS LETT 0.812
CHINESE SCI BULL 0.770
COMMUN THEOR PHYS 0.676
CRYOGENICS 0.981
IEEE T APPL SUPERCON 1.551
INT J MOD PHYS B 0.647
J APPL PHYS 2.171
J PHYS-CONDENS MAT 1.886
PHYS LETT A 1.711
PHYS REV B 3.172
PHYS REV LETT 6.944
PHYSICA C 1.079
SOLID STATE COMMUN 1.535
SUPERCOND SCI TECH 2.547
AVERAGE: 2.011
Table-5.4.2 Journal Impact Factors 1
Since most articles are published in top 3 physics subject areas:
applied physics, condensed matter physics, and multidisciplinary physics,
the attempt is made to look at the average journal impact factors of these
three physics subject categories. This is for comparison between the two
average impact factors in order to reveal the relative academic influence
of the core original source journals of China.
Analysis of data of impact factors from Journal Citation Reports
reveals that the average journal impact factor of the above mentioned
three physics subject categories is 2.123 (Thomson Scientific, 2007;
Thomson Scientific, 2008a). The closeness of the two averages (2.011 vs.
2.123) may lead to the conclusion that the core original source journals of
China are at about the average level in terms of academic influence.
1 Note: Journal Impact Factors are not available for the following two journals:
ACTA PHYSICA SINICA and JOURNAL OF SUPERCONDUCTIVITY
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5.5 International Collaborations
Analysis by countries reveals that a substantial amount of original
articles by China in superconductivity research are of the results of
international collaborations, with a total number of 53 collaborative
countries which count for nearly 30% collaborative research activities with
regard of the total number of articles (Table-5.5.1).
Country/Territory Record Count % of 6977
USA 555 7.95%
JAPAN 390 5.59%
GERMANY 200 2.87%
AUSTRALIA 155 2.22%
FRANCE 86 1.23%
SOUTH KOREA 84 1.20%
ENGLAND 83 1.19%
ITALY 82 1.18%
CANADA 58 0.83%
BELGIUM 40 0.57%
RUSSIA 40 0.57%
NETHERLANDS 33 0.47%
SINGAPORE 28 0.40%
SWEDEN 23 0.33%
SWITZERLAND 20 0.29%
SPAIN 18 0.26%
BRAZIL 17 0.24%
POLAND 15 0.22%
AUSTRIA 13 0.19%
ISRAEL 11 0.16%
DENMARK 10 0.14%
NEW ZEALAND 7 0.10%
NORWAY 7 0.10%
INDIA 5 0.07%
BYELARUS 4 0.06%
PAKISTAN 4 0.06%
SLOVAKIA 4 0.06%
UKRAINE 4 0.06%
CUBA 3 0.04%
CZECH REPUBLIC 3 0.04%
FED REP GER 3 0.04%
SCOTLAND 3 0.04%
SIERRA LEONE 3 0.04%
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USSR 3 0.04%
BULGARIA 2 0.03%
BURUNDI 2 0.03%
GREECE 2 0.03%
IRELAND 2 0.03%
MALAYSIA 2 0.03%
MEXICO 2 0.03%
THAILAND 2 0.03%
TURKEY 2 0.03%
ARGENTINA 1 0.01%
ARMENIA 1 0.01%
FINLAND 1 0.01%
JORDAN 1 0.01%
MOLDOVA 1 0.01%
PORTUGAL 1 0.01%
REP OF GEORGIA 1 0.01%
ROMANIA 1 0.01%
SERBIA MONTENEG 1 0.01%
SLOVENIA 1 0.01%
UZBEKISTAN 1 0.01%
Total: 2041 29.25%
Table-5.5.1 Collaborative Countries of China
Since the reprint authors are usually responsible for the articles, and
since this study aims to evaluate the original contributions of China,
therefore, it is of obvious interest to have a look at the total number of
reprint authors of China in the international collaborations. Detailed
investigation into the database has revealed that 88% of the reprint
authors of the complete set of articles are of China, while only 12% are of
other countries (Talbe-5.5.2).
Country/Territory Record Count % of 6977
China 6147 88%
Other Country 830 12%
Total: 6977 100%
Table-5.5.2 Number of Reprint Authors in Total Number of Articles
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In Table-5.5.2, the countries of reprint authors are defined by the
authors‟ affiliations rather than nationalities. This is because the
researches are actually carried out in the authors‟ work places, and it is
fair to attribute the research results to the countries of the research
institutions.
Compare Table-5.5.1 and Table-5.5.2, it could be reasonably
concluded that China has been playing an active role in the international
collaborations in superconductivity research, and has been the main
contributor of most international collaborative researches in which it is
involved. However, there are some difficulties in estimation of the exact
percentage rate of the contributions of China because the record count in
Table-5.5.1 includes duplicate numbers as sometimes more than two
countries may work together for one research project.
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Chapter 6 Citation Analyses of China
By the time of this study, there have been 29,838 total number of
citations to the 6,977 original articles in superconductivity research by
China published during 1986-2007, among which the number of
non-self-citations is 15,735 (Thomson Scientific, 2008c). A series of
detailed citation analyses based on the non-self citations are carried out in
this chapter. In addition, the comparative studies of citation analyses of
other countries are presented in Chapter 7.
6.1 Citations by Document Types
Table-6.1 lists the citations count by different document types. It is
seen that most citations come from articles, and some are from reviews,
notes, news items and other publications. The citations of articles and
notes generally indicate the impact of original articles on the new original
researches, and those of reviews and news items usually indicate the
important interest in the original articles recognized by research peers in
the academic communities. Therefore, it is impressive that the original
articles have received 14,497 article citations and 842 review citations.
Document Type Record Count % of 15735
ARTICLE 14497 92.13%
REVIEW 842 5.35%
NOTE 222 1.41%
LETTER 88 0.56%
EDITORIAL MATERIAL 50 0.32%
CORRECTION 20 0.13%
CORRECTION, ADDITION 11 0.07%
NEWS ITEM 4 0.03%
MEETING ABSTRACT 1 0.01%
Total: 15735 100.00%
Table-6.1 Analysis by Document Types: total non-self-citations
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6.2 Citations Growth through the Years
Citations through the years have been listed in Table-6.2. It is clearly
seen that there has been continuous growth in the number of citations
through the years, with the rapid growth started from 2001 (Chart-6.2).
The continuous growth in citations numbers through the years is
partly because citations accumulate by years, and within each year,
citations include not only current articles but also previous ones which
may date back to a few years or even many more years ago. However,
the continuous and rapid growth in citations since 2001 is also partly
attributed to the continuous and rapid growth of the original articles from
1999 (Chart-5.1.1). The delay of years is because citations are always
one or two years behind the original publications. On the other hand, the
continuously increasing number of citations also indicates that the general
impact of the original articles by China in superconductivity research has
been increasing gradually.
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Publication Year Record Count % of 15735
1986 4 0.03%
1987 24 0.15%
1988 145 0.92%
1989 267 1.70%
1990 283 1.80%
1991 270 1.72%
1992 310 1.97%
1993 362 2.30%
1994 428 2.72%
1995 431 2.74%
1996 496 3.15%
1997 554 3.52%
1998 522 3.32%
1999 602 3.83%
2000 655 4.16%
2001 696 4.42%
2002 863 5.48%
2003 1073 6.82%
2004 1303 8.28%
2005 1552 9.86%
2006 1807 11.48%
2007 2162 13.74%
2008 926 5.89%
Total: 15735 100.00%
Table-6.2 Citation numbers through the years: non-slef-citations
0
500
1000
1500
2000
2500
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
Chart-6.2 Citations Growth through the years: non-self-citations
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6.3 Citations by Different Languages
The original articles by China in superconductivity are published in
only 4 different languages: English, Chinese, Germany and Japanese.
However, citations of the original articles are of 12 different languages
(Table-6.3).
Language Record Count % of 15735
ENGLISH 15231 96.80%
CHINESE 288 1.83%
RUSSIAN 169 1.07%
JAPANESE 15 0.10%
GERMAN 12 0.08%
FRENCH 8 0.05%
SPANISH 4 0.03%
PORTUGUESE 3 0.02%
UKRAINIAN 2 0.01%
CZECH 1 0.01%
KOREAN 1 0.01%
WELSH 1 0.01%
Table-6.3 Analysis by languages: total non-self-citations
There is no surprise that English is the primary language of citations
as it is the language of science and also the primary language of the
original articles. It is not unexpected either, that many citations are in
Chinese, Japanese and German because these are the languages which
are also used by the original articles. However, it is impressive that some
of the citations are in other languages which are not used by the original
articles. This indicates that the original articles by China in
superconductivity research have their impact beyond the language
barriers.
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6.4 Citations from Different Countries/Territories
Citations of the original articles in superconductivity research by
China are from a total number of 104 countries/territories all over the
world. Table-6.4 has listed the important citing countries which have
contributed at least 1% of the total number of citations.
It is seen that China itself contributed the most citations with 23.67%
of total, followed closely by USA (21.70%) and Japan (15.89%) not far
away from. However, the biggest citing group is the European countries,
as Germany, Russia, France, Italy, England, Switzerland, etc., have
added up to over 50 % citations in total.
Country/Territory Record Count % of 15735
CHINA 3725 23.67%
USA 3415 21.70%
JAPAN 2500 15.89%
GERMANY 1492 9.48%
RUSSIA 1077 6.84%
INDIA 960 6.10%
FRANCE 891 5.66%
ITALY 742 4.72%
SOUTH KOREA 735 4.67%
ENGLAND 713 4.53%
SWITZERLAND 624 3.97%
POLAND 551 3.50%
AUSTRALIA 540 3.43%
CANADA 410 2.61%
AUSTRIA 378 2.40%
SPAIN 322 2.05%
SLOVENIA 271 1.72%
BRAZIL 248 1.58%
UKRAINE 222 1.41%
SWEDEN 206 1.31%
NETHERLANDS 203 1.29%
BELGIUM 200 1.27%
ISRAEL 199 1.26%
TURKEY 173 1.10%
Table-6.4 Important Citing Countries: total non-self-citations
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Compare to the countries involved in the international collaborations
with China, the total number of citing countries is almost doubled. 50 more
countries other than the original collaborators of China, have contributed
to the citations. This indicates that the original articles by China have their
impact in a broad range of countries.
On the other hand, detailed analysis of the citations by important
collaborative countries reveals that the majority of citations come from the
collaborators of China, as they have contributed 70% of the total number
of citations (Chart-6.4). This indicates that the most distinct impact of the
original articles in superconductivity research by China is contained within
the collaborative countries of China.
Chart-6.4 Citations Distribution in different countries: total non-self-citations
The important collaborative countries are defined as that the total
number of collaborative articles by each of these countries in
collaborations with China is at least of 1% of the total number of original
articles by China.
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6.5 Citations by Institutions
Citations of the original articles in superconductivity research by
China are from 4,408 institutions around the world. Table-6.5 has listed
the important institutions each of which has contributed at least 1% of the
total number of citations. It is very impressive that there are only 48 such
institutions, with Chinese Academy of Sciences, University of Tokyo, and
Tohoku University on the top of the list.
Institution Name Record Count % of 15735
CHINESE ACAD SCI 1216 7.73%
UNIV TOKYO 571 3.63%
TOHOKU UNIV 483 3.07%
UNIV SCI & TECHNOL CHINA 416 2.64%
NAGOYA UNIV 400 2.54%
PEKING UNIV 368 2.34%
RUSSIAN ACAD SCI 365 2.32%
OSAKA UNIV 330 2.10%
TOKYO INST TECHNOL 326 2.07%
NATL TAIWAN UNIV 308 1.96%
NANJING UNIV 288 1.83%
SEOUL NATL UNIV 268 1.70%
PRINCETON UNIV 252 1.60%
UNIV CINCINNATI 252 1.60%
SUNGKYUNKWAN UNIV 251 1.60%
TATA INST FUNDAMENTAL RES 248 1.58%
INST HIGH ENERGY PHYS 245 1.56%
TOKYO METROPOLITAN UNIV 245 1.56%
UNIV HAWAII 242 1.54%
YONSEI UNIV 239 1.52%
UNIV SYDNEY 238 1.51%
NIIGATA UNIV 237 1.51%
UNIV MELBOURNE 237 1.51%
KOREA UNIV 235 1.49%
UNIV LJUBLJANA 233 1.48%
JOZEF STEFAN INST 231 1.47%
ACAD SINICA 228 1.45%
BUDKER INST NUCL PHYS 228 1.45%
TOHO UNIV 226 1.44%
UNIV MARIBOR 226 1.44%
KANAGAWA UNIV 223 1.42%
INST THEORET & EXPT PHYS 222 1.41%
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UNIV TSUKUBA 222 1.41%
OSAKA CITY UNIV 221 1.40%
H NIEWODNICZANSKI INST NUCL PHYS 218 1.39%
VIRGINIA POLYTECH INST & STATE UNIV 218 1.39%
CHIBA UNIV 214 1.36%
NARA WOMENS UNIV 214 1.36%
PANJAB UNIV 212 1.35%
KYUNGPOOK NATL UNIV 211 1.34%
TOHOKU GAKUIN UNIV 211 1.34%
TOKYO UNIV AGR & TECHNOL 208 1.32%
KYOTO UNIV 203 1.29%
CNRS 190 1.21%
ARGONNE NATL LAB 187 1.19%
UNIV ILLINOIS 184 1.17%
UNIV CAMBRIDGE 167 1.06%
RIKEN 159 1.01%
Table-6.5 Important Citing Institutions and their Number of Citations
Further analyses of the 4,408 institutions reveal that there are three
types of important institutions which have contributed the most citations:
universities, institutes and academies/national labs. Universities rank the
highest, with nearly 73% of the total number of institutions (Chart-6.5.1),
and they have contributed nearly 70% citations (Chart-6.5.2).
Univ ersity
72.90%
Academy &
Natl. Lab
10.40%
Institute
16.70%
Academy
& Natl Lab
16.40% University
69.50%
Institute
14.10%
Chart-6.5.1 Type of Institutions Chart-6.5.2 Citations of Institutions
Therefore, it could be concluded that the original articles by China in
superconductivity research have their impact in an extensive range of
institutions around the world, most of which are universities. Besides, the
impact is more distinct within the 48 important citing institutions, and most
distinct within Chinese Academy of Sciences, University of Tokyo and
Tohoku University.
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6.6 Citations by Subject Areas
Citations of the original articles in superconductivity research by
China are of 140 subject areas, which have doubled the 69 subject areas
of the original articles. This indicates that the original articles by China
have their impact in a broad range of subject areas, far beyond the
subject areas where the original articles have been published.
Table-6.6 lists the focus citations subject areas of China which are
defined as that each of these subject areas has included at least 1% of
the total number of citations. It is seen that there are 20 such subject
areas, with the top 3 subject areas of citations the same as those of
original articles. It is also seen that there are substantial overlaps in the
subject areas of Table-5.3 and Table-6.6. This indicates that the original
articles in superconductivity research by China have their most distinct
impact within the same or near-by subject areas as the original articles.
Subject Area Record Count % of 15735
PHYSICS, CONDENSED MATTER 5511 35.02%
PHYSICS, APPLIED 4713 29.95%
PHYSICS, MULTIDISCIPLINARY 2473 15.72%
MATERIALS SCIENCE, MULTIDISCIPLINARY 1628 10.35%
CHEMISTRY, PHYSICAL 950 6.04%
CHEMISTRY, MULTIDISCIPLINARY 553 3.51%
PHYSICS, PARTICLES & FIELDS 553 3.51%
PHYSICS, MATHEMATICAL 470 2.99%
ENGINEERING, ELECTRICAL & ELECTRONIC 417 2.65%
PHYSICS, NUCLEAR 402 2.55%
PHYSICS, ATOMIC, MOLECULAR & CHEMICAL 388 2.47%
CHEMISTRY, INORGANIC & NUCLEAR 349 2.22%
METALLURGY & METALLURGICAL ENGINEERING 343 2.18%
ASTRONOMY & ASTROPHYSICS 260 1.65%
CRYSTALLOGRAPHY 240 1.53%
OPTICS 220 1.40%
INSTRUMENTS & INSTRUMENTATION 216 1.37%
NUCLEAR SCIENCE & TECHNOLOGY 192 1.22%
NANOSCIENCE & NANOTECHNOLOGY 187 1.19%
MATERIALS SCIENCE, COATINGS & FILMS 169 1.07%
Table-6.6 Focus Citations Subject Areas of China
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6.7 Citations by Source Journals
Citations of the original articles in superconductivity research by
China are from 1,042 source journals. Compared to the 422 source
journals which have published the original articles, the number of citations
source journals is almost 2.5 times as that of the original source journals.
This indicates that the original articles by China in superconductivity
research have their impact in an extensive range of source journals,
which is far beyond the source journals of original articles.
Table-6.7 lists the core citations source journals of China which are
defined as that each of these journals has contributed at least 1% of the
total number of citations. It is seen that there are 12 such core citations
source journals; and they have altogether contributed nearly 50% of the
total number of citations. This indicates that the original articles in
superconductivity research by China have their most distinct impact within
these core citations source journals. By the way, it is also seen that except
Physical Review D, 11 of the 12 core citations source journals appeared in
the list of core original source journals, and these 11 journals might be
defined as key source journals of superconductivity research of China in
terms of the importance of both original articles and citations.
Source Title Record Count % of 15735
PHYSICAL REVIEW B 2378 15.11%
PHYSICA C 1716 10.91%
SUPERCONDUCTOR SCIENCE & TECHNOLOGY 675 4.29%
PHYSICAL REVIEW LETTERS 619 3.93%
JOURNAL OF PHYSICS-CONDENSED MATTER 315 2.00%
SOLID STATE COMMUNICATIONS 299 1.90%
APPLIED PHYSICS LETTERS 290 1.84%
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY
267 1.70%
JOURNAL OF APPLIED PHYSICS 266 1.69%
PHYSICAL REVIEW D 207 1.32%
INTERNATIONAL JOURNAL OF MODERN PHYSICS B 183 1.16%
PHYSICS LETTERS A 180 1.14%
Total 7395 47.00%
Table-6.7 Core Citations Source Journals of China
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Chapter 7 Comparative Studies
This study aims to investigate the overall contribution and impact of
China in superconductivity research. It is of obvious interest to compare
China with some leading countries of the world in this research field.
Search results from Web of Sciences for the period of 1986-2007
reveal that the leading countries in superconductivity research defined by
the total number of original articles indexed in WOS are as following: USA
(28340), Japan (24319), Germany (11363), France (7901), Russia (7893),
China (6977), and England (5675), etc.
However, it is not intended to bench mark the countries hereby, but
only to get an overall picture about how China has relatively performed in
comparison with other leading countries of the world in terms of both
original publications and citations.
7.1 Original Publications
7.1.1 Publications Growth through the Years
The numbers of original articles in superconductivity research
published each year by the seven countries under study during
1986-2007 are presented in Table-7.1.1. Web of Sciences uses the actual
publication date to define the publication year in the search term, in which
case, e.g. if an article in the 2007 volume of a journal was published
somehow delayed in the year of 2008, it is dated as an 2008 article; and if
an article in the 1986 volume of a journal was actually published in
advance in 1985, it is dated as an 1985 article. Therefore, in Table 7.1.1
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the number of 1986 articles has technically included some 1985 dated
articles of 1986 labeled journal volumes, and the number of 2007 articles
has included some 2008 dated articles of 2007 labeled journal volumes,
although these are the rare cases.
Publication Year
China England France Germany Japan Russia USA
1986 27 13 52 138 253
1987 94 44 101 621 549
1988 131 106 194 3 568 835
1989 165 86 197 68 580 977
1990 183 110 196 266 601 15 848
1991 238 254 419 563 1345 55 2019
1992 192 255 353 507 836 94 1538
1993 196 276 431 569 936 580 1561
1994 279 364 582 691 1137 730 1762
1995 265 376 390 572 911 589 1549
1996 277 353 484 763 1289 663 1481
1997 476 410 524 716 1288 713 1440
1998 281 299 379 569 1006 532 1255
1999 263 351 415 666 1287 509 1420
2000 438 383 508 661 1373 534 1463
2001 364 286 376 673 1540 505 1410
2002 389 305 412 705 1525 446 1349
2003 524 339 356 752 1790 437 1450
2004 473 279 391 683 1384 409 1310
2005 562 278 365 664 1447 371 1364
2006 550 244 405 631 1355 351 1303
2007 610 264 371 641 1362 360 1204
Total 6977 5675 7901 11363 24319 7893 28340
Table-7.1.1 Number of Original Articles by Year and Country
It is seen that there is a general trend of growth in the number of
articles by all countries through the years, with the rapid growth of most
countries occurred during 1986-1997. From 1998, most countries except
Japan and China do not have an obvious sign of growth; and some of the
countries even show a sign of slight decline. China displays a continuous
growth through all years, and actually more rapid growth from 1999, which
could be a sign that China has been catching up in superconductivity
research in terms of the number of original articles (Chart-7.1.1).
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It is also seen that, in terms of the number of original articles, USA
and Japan are super countries; China, England, France, Germany, and
Russia seem to be at about the similar level, while China has been
catching up and overtaken England, France and Russia since 2001, and
on the other hand, Germany appears to have published more than the
rest of the other four countries. (Chart-7.1.1)
0
500
1000
1500
2000
2500
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
China England France Germany Japan Russia USA
Chart-7.1.1 Growth of Original Articles through the Years by Country
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7.1.2 Publication Source Journals
The numbers of source journals which have published the original
articles in superconductivity research of the seven countries under study
are presented in Table-7.1.2.1. The “core” source journals are those each
has published at least 1% original articles of one of the countries.
It is seen that USA publishes in the broadest range of 897 source
journals, followed by Japan and Germany with the number of 672 and 582
respectively. Articles by China, England, France and Russia are all
published within the range of 400-500 number of source journals which
are close and less than USA, Japan and Germany. However, there are
only slight differences in the numbers of core original source journals
where each country has published at least 1% articles, (Chart-7.1.2.1).
China England France Germany Japan Russia USA
All 422 442 477 582 672 407 897
Core 18 17 18 18 17 21 15
Table-7.1.2.1 Number of Original Source Journals by Country
0
100
200
300
400
500
600
700
800
900
1000
China England France Germany Japan Russia USA
All Core
Chart-7.1.2.1 Number of Original Source Journals by Country
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A combined list of core original source journals of different countries is
presented in Talbe-7.1.2.2. It is seen that some of the source journals are
very popular for all countries, such as: Physica C, Physical Review B,
IEEE Transactions on Applied Superconductivity, Physical Review Letters,
Physica B, Superconductor Science and Technology, while every country
publishes heavily with these source journals, they are either European or
American journals. On the other hand, China, Japan and Russia have
published a substantial amount of articles uniquely in the journals of their
own countries. China published over 12% articles uniquely in the journals
of China, i.e. Acta Physica Sinica (2.34%), Chinese Physics (2.59%),
Chinese Physics Letters (3.64%), Chinese Science Bulletin (1.58%), and
Communications in Theoretical Physics (2.01%), etc.; Japan published
over 13% articles uniquely in the journals of Japan, i.e. Japanese
Journals of Applied Physics (7.75%), and Journal of the Physical Society
of Japan (5.52%), etc.; Russia published more than 16% articles uniquely
in the journals of Russia, i.e. FIZIKA TVERDOGO TELA (1.57%),
Inorganic Materials (1.82%), JETP letters (5.89%), Journal of
Experimental and Theoretical Physics (2.98%), Technical Physics Letters
(1.31%), and Physics of the Solid State (3.14%), etc.
Therefore, it could be concluded that, within the countries under study,
there are some common core source journals where all countries have
published heavily. Besides, China, Japan and Russia have some of their
favorite source journals of their own countries.
Source Title China England France Germany Japan Russia USA
ACTA PHYSICA SINICA 2.34%
APPLIED PHYSICS LETTERS 1.45% 1.76% 2.35% 1.69% 4.54%
CHINESE PHYSICS 2.59%
CHINESE PHYSICS LETTERS 3.64%
CHINESE SCIENCE BULLETIN 1.58%
COMMUNICATIONS IN THEORETICAL PHYSICS
2.01%
CRYOGENICS 1.26% 1.37% 1.99%
CZECHOSLOVAK JOURNAL OF PHYSICS
1.33%
EUROPEAN PHYSICAL JOURNAL B
1.38% 1.00%
EUROPHYSICS LETTERS 2.21% 1.65%
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FIZIKA TVERDOGO TELA 1.57%
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY
2.64% 5.69% 3.24% 5.34% 7.35% 3.60% 6.79%
IEEE TRANSACTIONS ON MAGNETICS
1.04% 1.89% 2.13%
INORGANIC MATERIALS 1.82%
INTERNATIONAL JOURNAL OF MODERN PHYSICS B
1.85% 1.06%
JAPANESE JOURNAL OF APPLIED PHYSICS
7.75%
JETP LETTERS 5.89%
JOURNAL DE PHYSIQUE IV 1.46%
JOURNAL OF ALLOYS AND COMPOUNDS
1.44% 1.10%
JOURNAL OF APPLIED PHYSICS 1.71% 1.15% 1.09% 1.53% 1.27% 2.82%
JOURNAL OF EXPERIMENTAL AND THEORETICAL PHYSICS
2.98%
JOURNAL OF LOW TEMPERATURE PHYSICS
1.34% 1.34% 2.34% 1.13% 1.22%
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
1.24% 1.06% 1.28%
JOURNAL OF MATERIALS CHEMISTRY
1.20%
JOURNAL OF MATERIALS RESEARCH
1.08%
JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS
1.37% 1.24%
JOURNAL OF PHYSICS-CONDENSED MATTER
2.52% 3.14% 1.33% 1.28% 1.13%
JOURNAL OF SOLID STATE CHEMISTRY
1.48%
JOURNAL OF SUPERCONDUCTIVITY
1.72% 1.27% 1.38% 1.57% 1.44%
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN
5.52%
NATURE 1.06%
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A
1.11% 1.45% 1.42% 1.29%
PHYSICA B 3.88% 4.19% 4.38% 4.44% 2.28% 1.90%
PHYSICA C 19.20% 12.72% 15.43% 13.28% 19.74% 12.36% 10.44%
PHYSICAL REVIEW B 10.16% 12.55% 13.54% 16.73% 8.45% 11.35% 19.46%
PHYSICAL REVIEW LETTERS 1.43% 5.06% 5.83% 5.72% 3.09% 3.38% 8.53%
PHYSICS LETTERS A 2.48% 1.38%
PHYSICS OF THE SOLID STATE 3.14%
SOLID STATE COMMUNICATIONS
3.91% 1.13% 2.57% 1.85% 1.38% 1.51% 1.58%
SUPERCONDUCTOR SCIENCE & TECHNOLOGY
5.19% 6.84% 2.33% 3.03% 2.94% 2.43% 1.72%
SYNTHETIC METALS 1.07% 1.77% 1.82% 1.05%
TECHNICAL PHYSICS LETTERS 1.31%
ZEITSCHRIFT FUR PHYSIK B-CONDENSED MATTER
1.57%
ZHURNAL EKSPERIMENTALNOI I TEORETICHESKOI FIZIKI
1.41%
% of Total Articles by Country 67.67% 62.33% 62.92% 67.05% 73.10% 64.13% 66.01%
Table 7.1.2.2 Combined List of Core Original Source Journals
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The common core source journals are hereby defined as that each of
these journals has published at least 1% original articles of one of the
countries; besides, the altogether number of articles by all seven
countries it has published is more than 1,000. It is seen that there are 12
such defined common core original source journals (Table-7.1.2.3).
It is also seen that, USA, Japan and Germany publish more articles in
general in these common core original source journals, and sometimes
have their different favorite journals; the publication patterns of China,
England, France and Russia are quite similar, and the number of articles
by these four countries in each of these journals are close (Chart-7.1.2.3).
Source Title China England France Germany Japan Russia USA Total
PHYSICA C 1339 722 1219 1509 4802 976 2958 13525
PHYSICAL REVIEW B 709 712 1070 1901 2055 896 5515 12858
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY
184 323 256 607 1787 284 1923 5364
PHYSICAL REVIEW LETTERS
100 287 461 650 752 267 2418 4935
PHYSICA B 30 220 331 498 1080 180 538 2877
SUPERCONDUCTOR SCIENCE & TECHNOLOGY
362 388 184 344 715 192 487 2672
APPLIED PHYSICS LETTERS
101 100 53 267 410 58 1288 2277
JAPANESE JOURNAL OF APPLIED PHYSICS
30 13 11 11 1885 4 101 2055
SOLID STATE COMMUNICATIONS
273 64 203 210 335 119 447 1651
JOURNAL OF APPLIED PHYSICS
119 65 86 174 308 54 799 1605
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN
6 8 16 17 1343 8 47 1445
IEEE TRANSACTIONS ON MAGNETICS
44 50 82 89 460 32 604 1361
Table-7.1.2.3 Common Core Original Source Journals and Number of Articles
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0
1000
2000
3000
4000
5000
6000
AP
PL
IED
PH
YS
ICS
LE
TT
ER
S
IEE
E T
RA
NS
AC
TIO
NS
ON
MA
GN
ET
ICS
JO
UR
NA
L O
F A
PP
LIE
D
PH
YS
ICS
PH
YS
ICA
B
PH
YS
ICA
L R
EV
IEW
B
SO
LID
ST
AT
E
CO
MM
UN
ICA
TIO
NS
China England France Germany Japan Russia USA
Chart-7.1.2.3 Common Core Original Source Journals and Number of Articles
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7.1.3 Publication Subject Areas
The numbers of subject areas where the seven countries under study
have published their original articles in superconductivity research are
presented in Table-7.1.3.1. The “focus” subject areas are those each
subject area has included at least 1% articles of one of the countries
It is seen that the original articles by USA and Japan are published in
the broadest range of more than 100 subject areas; while articles by
China are published in only less than 70 subject areas. However, there
are only slight differences in the number of focus subject areas of different
countries (Chart-7.1.3.1).
China England France Germany Japan Russia USA
All 69 82 78 88 105 59 124
Focus 19 20 21 17 16 19 18
Table-7.1.3.1 Number of Subject Areas by Country
0
20
40
60
80
100
120
140
China England France Germany Japan Russia USA
All Focus
Chart-7.1.3.1 Number of Subject Areas by Country
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The focus subject areas as well as the percentage rate of the country
total of the articles published in these subject areas are listed in
Table-7.1.3.2.
Subject Area China England France Germany Japan Rusia USA
ASTRONOMY & ASTROPHYSICS
1.39% 1.03% 1.28%
CHEMISTRY, INORGANIC & NUCLEAR
1.59% 3.00% 1.21% 2.23%
CHEMISTRY, MULTIDISCIPLINARY
1.48% 2.26% 2.15% 1.29% 2.39% 1.15% 1.91%
CHEMISTRY, PHYSICAL 2.59% 5.53% 6.68% 3.43% 2.56% 3.56% 2.87%
CRYSTALLOGRAPHY 1.06% 1.05% 1.61% 1.28%
ENGINEERING, ELECTRICAL & ELECTRONIC
4.43% 9.66% 5.39% 7.52% 11.53% 5.49% 11.19%
INSTRUMENTS & INSTRUMENTATION
2.61% 2.30% 3.06% 1.67% 2.94% 2.83%
MATERIALS SCIENCE, MULTIDISCIPLINARY
8.06% 9.18% 11.52% 7.30% 7.99% 6.82% 7.69%
MATHEMATICS 1.02%
MATHEMATICS, APPLIED 1.32%
METALLURGY & METALLURGICAL ENGINEERING
2.22% 1.06% 2.53% 1.98% 1.76% 1.67% 1.11%
MULTIDISCIPLINARY SCIENCES 2.16% 1.78% 1.44% 1.22% 2.18%
NUCLEAR SCIENCE & TECHNOLOGY
1.62% 1.50% 1.97% 3.37% 2.22% 2.14% 2.37%
OPTICS 1.26% 1.08%
PHYSICS, APPLIED 41.42% 37.76% 33.31% 35.86% 49.88% 32.36% 37.87%
PHYSICS, ATOMIC, MOLECULAR & CHEMICAL
1.61% 1.74% 1.54% 1.94% 1.33% 1.73%
PHYSICS, CONDENSED MATTER
32.38% 38.36% 36.91% 41.05% 27.83% 33.81% 36.08%
PHYSICS, FLUIDS & PLASMAS 1.52% 1.30%
PHYSICS, MATHEMATICAL 3.20% 1.85% 1.47% 1.42% 1.86% 2.02%
PHYSICS, MULTIDISCIPLINARY 17.46% 13.48% 16.25% 14.44% 12.18% 21.87% 14.07%
PHYSICS, NUCLEAR 1.71% 1.30% 2.32% 1.04% 1.01% 1.57%
PHYSICS, PARTICLES & FIELDS 1.66% 3.14% 1.84% 3.63% 1.35% 2.93% 3.30%
POLYMER SCIENCE 1.11% 1.84% 1.89% 1.14%
SPECTROSCOPY 1.34% 1.24% 1.92% 1.96% 1.74%
THERMODYNAMICS 1.30% 1.41% 1.03% 2.07% 1.12%
Table-7.1.3.2 Combined List of Focus Original Subject Areas
It is seen that different countries have overlaps and differences in the
focus subject areas where they have heavily published their articles. This
obviously indicates the overlaps and differences in research focus of
different countries.
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The common focus original subject areas of all countries as well as
the number of articles by each country are listed in Table-7.1.3.3. The
common focus original subject areas are defined as that each of these
subject areas has included at least 1% articles by one of the countries,
besides, the altogether number of articles by all seven countries it has
covered is more than 1,000.
Subject Area China England France Germany Japan Russia USA Total
PHYSICS, APPLIED 2890 2143 2632 4075 12130 2554 10731 37155
PHYSICS, CONDENSED MATTER
2259 2177 2916 4664 6767 2669 10224 31676
PHYSICS, MULTIDISCIPLINARY
1218 765 1284 1641 2961 1726 3987 13582
ENGINEERING, ELECTRICAL & ELECTRONIC
309 548 426 855 2803 433 3172 8546
MATERIALS SCIENCE, MULTIDISCIPLINARY
562 521 910 830 1943 538 2180 7484
CHEMISTRY, PHYSICAL
181 314 528 390 622 281 814 3130
PHYSICS, PARTICLES & FIELDS
116 178 145 413 329 231 936 2348
INSTRUMENTS & INSTRUMENTATION
68 148 182 348 406 232 801 2185
NUCLEAR SCIENCE & TECHNOLOGY
113 85 156 383 539 169 672 2117
CHEMISTRY, MULTIDISCIPLINARY
103 128 170 147 581 91 541 1761
PHYSICS, MATHEMATICAL
223 105 116 161 213 147 572 1537
METALLURGY & METALLURGICAL ENGINEERING
155 60 200 225 428 132 314 1514
PHYSICS, ATOMIC, MOLECULAR & CHEMICAL
112 99 122 220 324 74 490 1441
MULTIDISCIPLINARY SCIENCES
151 101 114 84 157 96 618 1321
PHYSICS, NUCLEAR 119 46 103 264 254 80 444 1310
SPECTROSCOPY 35 76 98 218 231 155 493 1306
THERMODYNAMICS 91 80 81 112 504 70 316 1254
Table-7.1.3.3 Common Focus Original Subject Areas and Number of Articles
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0
2000
4000
6000
8000
10000
12000
14000
CH
EM
IST
RY
,
MU
LT
IDIS
CIP
LIN
AR
Y
EN
GIN
EE
RIN
G,
EL
EC
TR
ICA
L &
MA
TE
RIA
LS
SC
IEN
CE
,
MU
LT
IDIS
CIP
LIN
AR
Y
SC
IEN
CE
S
PH
YS
ICS
, A
PP
LIE
D
PH
YS
ICS
,
CO
ND
EN
SE
D
PH
YS
ICS
,
MU
LT
IDIS
CIP
LIN
AR
Y
PH
YS
ICS
,
PA
RT
ICL
ES
&
TH
ER
MO
DY
NA
MIC
S
China England France Germany Japan Russia USA
Chart-7.1.3.3 Common Focus Original Subject Areas and Number of Articles
It is seen that there are 17 such common focus original subject areas
for all countries. The top 3 subject areas of general interest are: applied
physics, condensed matter physics, and multidisciplinary physics where
all countries have published most heavily and the total number of articles
is more than 100,000 in each of these top 3 subject areas. It is also seen
that USA and Japan adopt very similar patterns in the number of original
articles published in these 17 common focus subject areas, and apart
from the top 3 subject areas of general interest, both USA and Japan have
published many more original articles in the subject areas of electrical and
electronic engineering as well as materials science. Besides, the numbers
of articles by USA and Japan in each of these subject areas are close and
many more than any other countries. On the other hand, China, England,
France, and Russia also adopt very similar patterns which are slightly
different from those of USA and Japan, besides, the numbers of original
articles by these four countries in each of the common focus subject
areas are very close. This indicates that China, England, France, and
Russia have not only similar research focus but also similar results of
output from their research focus, and the same is with USA and Japan
(Chart-7.1.3.3).
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7.2 Citations Analyses of Different Countries
Since the comparative studies of original articles are based on data of
1986-2007, it would be ideal to compare the citations statistics for the
same period. However, Web of Sciences could only provide citations
reports for less than 10,000 original publications, in which case, the
citations reports are not available for USA, Japan, and Germany all with
more than 10,000 original articles during 1986-2007.
Therefore, the year range for citations comparative studies is limited
to 2001-2007. It is to optimize the effectiveness of the citations data that
the limit of year range is set to 7 years, because the previous study has
revealed that most original articles of superconductivity research are
published in top 3 subject areas, and further investigation has indicated
that the average “Aggregate Cited Half-Life”2 is 6.7 years for articles of
these subject areas. In order to be consistent, the subject areas of original
articles are restricted within these three subject areas. Besides, this
restriction of subject areas also helps to make it fair when compare the
extent of impact of original articles upon different subject areas because
all countries are thus set to the same starting point, regardless of how
many subject areas in which they have published their original articles.
2“The cited half-life is the median age of the articles that were cited in the JCR year.
The aggregate cited half-life is an indication of the turnover rate of the body of work on a subject.” (Thomason Scientific, 2008c)
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7.2.1 Citations Count, Averages, Growth, and h-index
The number of both total and non-self citations, as well as the
percentage rate of non-self in total citations of the seven countries under
study are given in Table-7.2.1.1.
It is seen that there are huge gaps in the total number of citations
among USA, Japan, Germany and the rest of countries, while USA and
Japan are super countries both with over 50K citations, followed by
Germany with a distance of more than 20K, and then by the group of all
other countries of China, England, France and Russia with a distance of
more than 10K. However, in terms of the number of non-self-citations,
these gaps are reduced dramatically, while USA remains the highest and
the group of countries of China, England, and Russia remains the lowest,
the numbers of Japan and Germany are getting very close. This is
because the rate of non-self-citations of Japan is very much lower than
that of Germany. In terms of the rate of non-self citations, England ranks
the highest, Japan and USA rank the lowest, China, France, Germany
and Russia are close and have the moderate rates. Nevertheless, China
unfortunately has the lowest number of both total and non-self citations
(Chart-7.2.1.1.1 and Chart-7.2.1.1.2).
China England France Germany Japan Russia USA
Total Citations 10170 12262 17963 31071 56651 13458 78798
Non-self-citations 5380 7912 10216 15521 16360 7248 26642
Non-self % Total 52.90% 64.52% 56.87% 49.95% 28.88% 53.86% 33.81%
Table-7.2.1.1 Total and Non-self Citations by Country
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0
10000
20000
30000
40000
50000
60000
70000
80000
90000
China England France Germany Japan Russia USA
Total Citations Non-self-citations
Chart-7.2.1.1.1 Total and Non-self Citations by Country
0%
20%
40%
60%
80%
100%
120%
China England France Germany Japan Russia USA
Self-
citations
Non-self-
citations
Chart-7.2.1.1.2 Self and Non-self Citations Rate by Country
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Since the numbers of original articles by different countries are very
different, it should be a good idea to have a look at the average citations
as well. Table-7.2.1.2 lists the average citations of different countries. The
average non-self-citations are converted using the percentage rate known
above. It is seen that USA has the highest average citation in general,
however only a moderate average non-self-citations. England, France,
Germany, Japan and Russia have moderate to high average citations in
general. However, England and France have the highest average
non-self-citations, and Japan has the lowest average non-self-citation of
all. China has the lowest average citations in general, but a relative higher
average non-self-citation compared to Japan (Chart-7.2.1.2).
China England France Germany Japan Russia USA
Average Citations 3.68 7.47 8.09 7.92 6.29 5.69 9.92
Converted Average Non-self-citations
1.95 4.82 4.6 3.96 1.82 3.06 3.35
Table-7.2.1.2 Average Citations by Country
0
2
4
6
8
10
12
China England France Germany Japan Russia USA
Average Citations Converted Average Non-self-citations
Chart-7.2.1.2 Average Citations by Country
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It is also of interest to have a look at the trend of citations growth or
decline of different countries through the years. The total numbers of
citations and converted non-self-citations of different countries by years
are listed in Table-7.2.1.3.1 and Table-7.2.1.3.2.
PubYear China England France Germany Japan Russia Usa
2001 45 154 128 238 264 115 520
2002 239 581 611 982 1130 490 1807
2003 451 833 979 1590 1747 701 2821
2004 591 1001 1310 1987 2109 1036 3422
2005 831 1167 1674 2511 2571 1194 4203
2006 1005 1423 1908 2839 2924 1297 4716
2007 1352 1756 2270 3442 3505 1520 5755
2008 866 997 1336 1932 2110 895 3398
Table-7.2.1.3.1 Citations by Year and Country
PubYear China England France Germany Japan Russia USA
2001 24 99 73 119 76 62 176
2002 126 375 347 491 326 264 611
2003 239 537 557 794 505 378 954
2004 313 646 745 993 609 558 1157
2005 440 753 952 1254 743 643 1421
2006 532 918 1085 1418 844 699 1594
2007 715 1133 1291 1719 1012 819 1946
2008 458 643 760 965 609 482 1149
Table-7.2.1.3.2 Non-self-citations by Year and Country
0
1000
2000
3000
4000
5000
6000
7000
2001 2002 2003 2004 2005 2006 2007 2008
China
England
France
Germany
Japan
Russia
Usa
Chart-7.2.1.3.1 Citations Growth through the Years by Country
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0
500
1000
1500
2000
2500
2001 2002 2003 2004 2005 2006 2007 2008
China
England
France
Germany
Japan
Russia
USA
Chart-7.2.1.3.2 Non-self-citations Growth through the Years by Country
It is seen that citations of all countries grow continuously through the
years. The downfall of 2008 is because this study is carried out in the
middle of the year 2008 and the citations data for original articles
published ending in 2007 is not complete yet. However, the paces of
growth are quite different for different countries. It is remarkable that,
China has been catching up with faster growing pace since 2004
(Chart-7.2.1.3.1 and Chart-7.2.1.3.2). This might be because all other
countries have had a general decline in the number of original articles
during 2001-2007, but the number of original articles by China had been
continuously growing through the years (Chart-7.1.1).
Finally, h-index is a line indicator, which means, the number of items
above this line, which is h, have at least h citations. Within a country,
h-index could be used to define the highly cited articles, i.e. articles with
number of citations above h are defined as highly cited articles. Obviously,
with different h, an article which is defined as highly cited in one country
may not be considered as highly cited at all in another country, because
the numbers of publications and citations of different countries are never
balanced. Nevertheless, with different h-index, the level of standard for
highly cited articles as well as the general impact of such defined highly
cited articles of different countries could be clearly indicated.
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Table-7.2.1.4 has presented h-indexes for different countries. It is
seen that USA has the highest h-index, which indicates that it has the
highest level of standard for highly cited articles and its highly cited
articles are cited much more than other countries. On the other hand,
China has the lowest h-index, which indicates that it has the lowest level
of standard for highly cited articles and its highly cited articles are cited
much less than other countries (Chart-7.2.1.4).
China England France Germany Japan Russia USA
h-index 32 43 51 57 75 41 88
Table-7.2.1.4 h-index
0
10
20
30
40
50
60
70
80
90
100
China England France Germany Japan Russia USA
Chart-7.2.1.4 h-index
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7.2.2 Citations Distribution in Different Countries
The numbers of citing countries which have cited the original articles
of the seven countries under study are presented in Table-7.2.2.1.
It is seen that USA and Germany have the highest number of
countries citing their original articles, and China has the lowest. However,
there is no big gap among the average countries. (Chart-7.2.2.1)
China England France Germany Japan Russia USA
Record Count 85 87 91 99 94 88 101
Table-7.2.2.1 Number of Citing Countries
75
80
85
90
95
100
105
China England France Germany Japan Russia USA
Chart-7.2.2.1 Number of Citing Countries
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It is also of interest to have a look at how many of the citations have
come from the same country where the original articles are produced.
Table-7.2.2.2 lists the percentage rate of self-country citations of different
countries.
It is seen that China, Japan and USA have more than 1/4 of their
citations coming from their own countries; England, France, Germany and
Russia have 10-20% of their citations from their own countries, among
which the lowest rate of self-country citations is of England, only slightly
above 10% (Chart-7.2.2.2).
China England France Germany Japan Russia USA
Self-country Citations
28.33% 10.11% 13.43% 18.43% 26.31% 12.86% 26.22%
Table-7.2.2.2 Self-country Citations
0%
5%
10%
15%
20%
25%
30%
China England France Germany Japan Russia USA
Chart-7.2.2.2 Self-country Citations
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Table-7.2.2.3 has listed in rows the most important citing countries,
and in columns the seven countries under the comparative studies, as
well as the number of citations of each of the seven countries. The most
important citing countries are defined as that each of these countries has
contributed at least 1% of the number of citations that one of the seven
countries has received from all countries in total; besides, the altogether
citations it has contributed to the seven countries under study are more
than 1,000 (excluding self-country citations).
Country China England France Germany Japan Russia USA Total
USA 1214 2211 2824 4120 4255 1850 16474
JAPAN 895 1492 1921 2944 1140 5214 13606
GERMANY 524 1134 1671 2156 1169 3796 10450
CHINA 603 670 1202 1618 484 2605 7182
FRANCE 250 682 1320 1240 661 2124 6277
ITALY 256 524 826 1114 876 552 1695 5843
RUSSIA 245 419 702 1102 896 1607 4971
ENGLAND 236 664 912 854 406 1569 4641
SWITZERLAND 179 462 670 826 740 466 1207 4550
SOUTH KOREA 254 268 269 584 764 216 1014 3369
CANADA 194 346 392 541 602 221 955 3251
INDIA 224 236 247 387 434 176 842 2546
SPAIN 120 214 373 480 325 215 765 2492
NETHERLANDS 72 214 307 439 359 309 687 2387
POLAND 119 214 281 464 359 216 688 2341
UKRAINE 65 155 214 328 240 214 452 1668
BRAZIL 82 140 172 312 278 126 506 1616
AUSTRALIA 134 181 148 206 292 97 460 1518
SWEDEN 63 122 159 285 212 175 418 1434
ISRAEL 84 111 143 255 204 146 410 1353
BELGIUM 76 133 155 193 186 165 356 1264
AUSTRIA 55 93 156 241 186 107 325 1163
Table-7.2.2.3 Most Important Citing Countries and their Number of Citations
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It is seen that there are 22 such above defined most important citing
countries, and in general, the countries which have cited highly on other
countries are those which have published high number of original articles.
Besides, the countries which have high rate of self-country citations have
also cited highly on other countries. This is of no surprise because
research activities and publications always have mutual impacts on each
other (Table-7.2.2.3).
It is also seen that USA receives most citations from each of these
important citing countries; Japan and Germany compete for the 2nd
highest number of citations, followed by England, France and Russia;
China receives the lowest number of citations in general but is close to
Russia, France and England in the number of citations from most of the
citing countries outside the seven countries under the comparative
studies (Chart-7.2.2.3).
0
1000
2000
3000
4000
5000
6000
AU
ST
RA
LIA
AU
ST
RIA
BE
LG
IUM
BR
AZ
IL
CA
NA
DA
CH
INA
EN
GL
AN
D
FR
AN
CE
GE
RM
AN
Y
IND
IA
ISR
AE
L
ITA
LY
JA
PA
N
NE
TH
ER
LA
ND
S
PO
LA
ND
RU
SS
IA
SO
UT
H K
OR
EA
SP
AIN
SW
ED
EN
SW
ITZ
ER
LA
ND
UK
RA
INE
US
A
China England France Germany Japan Russia USA
Chart-7.2.2.3 Most Important Citing Countries and their Number of Citations
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7.2.3 Citations Source Journals
The numbers of citations source journals which have cited the original
articles of the seven countries under study are given in Table-7.2.3.1.
It is seen that the original articles of USA are cited by many more
source journals than the rest of the countries; Japan and Germany are
cited by less source journals than USA but more than China, England,
France and Russia. The numbers of source journals which have cited
China, England, France and Russia are very close (Chart-7.2.3.1).
China England France Germany Japan Russia USA
Record Count
445 462 483 601 669 418 826
Table-7.2.3.1 Number of Citations Source Journals
0
100
200
300
400
500
600
700
800
900
China England France Germany Japan Russia USA
Chart-7.2.3.1 Number of Citations Source Journals
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Table-7.2.3.2 lists the common core citations source journals and their
citations upon different countries. The common core citations source
journals are defined as that each of these journals has contributed at least
1% of the number of citations that one of the countries has received from
all citations source journals in total; besides, the altogether citations it has
contributed to the seven countries under study are more than 1,000.
It is seen that there are 12 such above defined common core citations
source journals. USA receives most citations from each of these journals;
Japan and Germany compete for the 2nd highest number of citations from
each of these journals; and the number of citations that China, England,
France and Russia receive from each of these journals are very close
except that China receives much less citations from Physical Review B
and Physical Review Letters which are two of the most important source
journals in terms of both original articles and citations, and with very high
journal impact factors (Chart-7.2.3.2).
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Source Title China England France Germany Japan Russia USA Total
PHYSICAL REVIEW B 1100 2046 2755 3845 3552 1890 5681 20869
PHYSICAL REVIEW LETTERS
315 670 1035 1277 1210 688 2300 7495
PHYSICA C 387 639 554 1020 1303 496 1765 6164
SUPERCONDUCTOR SCIENCE & TECHNOLOGY
281 483 266 631 820 235 877 3593
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY
135 309 228 524 793 189 903 3081
JOURNAL OF PHYSICS-CONDENSED MATTER
139 255 282 407 409 188 717 2397
APPLIED PHYSICS LETTERS
139 202 162 379 350 171 791 2194
PHYSICAL REVIEW A 95 96 329 285 211 246 759 2021
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN
99 151 284 342 384 128 594 1982
PHYSICA B 70 147 261 352 488 114 549 1981
JOURNAL OF APPLIED PHYSICS
123 153 155 293 285 88 568 1665
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
40 86 165 210 238 60 337 1136
Table-7.2.3.2 Common Core Citations Source Journals and Number of Citations
0
1000
2000
3000
4000
5000
6000
APPL P
HYS
LETT
IEEE
T A
PPL S
UPE
RCOND
J APPL P
HYS
J M
AG M
AG M
ATE
R
J PHYS-C
OND M
AT
J PHYS S
OC J
APAN
PHYS
ICA B
PHYS
ICA C
PHYS
REV A
PHYS
REV B
PHYS
REV L
ETT
SUPE
RCOND S
CI &
TEC
H
China England France Germany Japan Russia USA
Chart-7.2.3.2 Common Core Citations Source Journals and Number of Citations
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7.2.4 Citations Subject Areas
The numbers of citations subject areas which have included the
citations of the seven countries under study are given in Table-7.2.4.1.
It is seen that the original articles within only 3 subject areas have
been cited in a wide range of subject areas by all countries. USA articles
are cited most widely, followed closely by Japan and Germany in terms of
the range of subject areas; articles of England and China are cited less
widely compared to USA, Japan and Germany, but more widely than
France and Russia (Chart-7.2.4.1).
China England France Germany Japan Russia USA
Record Count
75 82 69 94 96 60 114
Table-7.2.4.1 Number of Citations Subject Areas by Country
0
20
40
60
80
100
120
China England France Germany Japan Russia USA
Chart-7.2.4.1 Number of Citations Subject Areas by Country
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Table-7.2.4.2 has listed the common focus citations subject areas and
the number of citations of different countries in different subject areas.
The common focus citations subject areas are defined as that each of
these subject areas has included at least 1% of the total number of
citations that one of the countries has received in all subject areas;
besides, the altogether citations it has included for the seven countries
under study are more than 1,000.
It is seen that there are 16 such above defined common focus
citations subject areas, and the top 3 subject areas where the original
articles have been published most heavily have included the most
citations (Chart-7.2.4.2). This is of no surprise because research activities
and publications usually have their most impact in their own or nearby
subject areas.
It is also seen that USA receives most citations in all of the common
focus subject areas; Japan and Germany compete for the 2nd highest
number of citations in each of these subject areas; and the numbers of
citations that China, England, France, Russia have received are very
close in most of the subject areas, while China receives the lowest
number of citations in almost all subject areas. Noticeably, there are
distinct gaps of citations numbers in the top 3 subject areas which have
included the most citations, and within each of these three subject areas,
China receives much less citations than all other countries
(Chart-7.2.4.2).
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Subject Area China England France Germany Japan Russia USA Total
PHYSICS, CONDENSED MATTER
2119 3740 4692 6867 7012 3169 10575 38174
PHYSICS, APPLIED 1526 2386 2139 4081 4920 1755 7132 23939
PHYSICS, MULTIDISCIPLINARY
1113 1483 2274 3123 2898 1611 5388 17890
MATERIALS SCIENCE, MULTIDISCIPLINARY
500 528 709 1011 1264 389 1881 6282
ENGINEERING, ELECTRICAL & ELECTRONIC
198 409 301 726 1045 298 1234 4211
PHYSICS, ATOMIC, MOLECULAR & CHEMICAL
177 172 511 489 386 342 1134 3211
CHEMISTRY, PHYSICAL 238 254 347 498 617 199 865 3018
OPTICS 137 148 428 417 333 366 1113 2942
PHYSICS, MATHEMATICAL
139 194 261 419 356 186 843 2398
PHYSICS, PARTICLES & FIELDS
158 104 148 516 318 117 929 2290
CHEMISTRY, MULTIDISCIPLINARY
124 154 267 281 439 132 563 1960
PHYSICS, NUCLEAR 140 27 121 281 188 96 516 1369
METALLURGY & METALLURGICAL ENGINEERING
111 104 113 190 289 81 343 1231
NANOSCIENCE & NANOTECHNOLOGY
85 95 132 179 163 105 376 1135
MULTIDISCIPLINARY SCIENCES
73 107 124 194 209 56 377 1140
ASTRONOMY & ASTROPHYSICS
67 56 90 295 173 52 494 1227
Table-7.2.4.2 Common Focus Citations Subject Areas and Number of Citations
0
2000
4000
6000
8000
10000
12000
ASTR
ONOM
Y & A
STROPH
YSIC
S
CHEM
ISTR
Y, M
ULTID
ISCIP
LINARY
CHEM
ISTR
Y, P
HYS
ICAL
ENGIN
EER
ING, E
LECTR
ICAL &
ELEC
TRONIC
MATE
RIA
LS S
CIE
NCE, M
ULTID
ISCIP
LINARY
META
LLURGY &
META
LLURGIC
AL E
NGIN
EER
ING
MULTID
ISCIP
LINARY S
CIE
NCES
NANOSC
IENCE &
NANOTEC
HNOLO
GY
OPTIC
S
PHYS
ICS, A
PPLIED
PHYS
ICS, A
TOM
IC, M
OLE
CULA
R &
CHEM
ICAL
PHYS
ICS, C
ONDEN
SED M
ATTER
PHYS
ICS, M
ATH
EMATIC
AL
PHYS
ICS, M
ULTID
ISCIP
LINARY
PHYS
ICS, N
UCLEA
R
PHYS
ICS, P
ARTIC
LES & F
IELD
S
China England France Germany Japan Russia USA
Chart-7.2.4.2 Common Focus Citations Subject Areas and Number of Citations
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7.3 Key and Top Institutions
7.3.1 Definitions and Numbers
It is also of interest to have a look at the key institutions of the seven
countries under study. It would be ideal to define the key institutions by
the number of both original articles and citations. However, since the
institutions which have published more original articles are usually cited
more, it is decided to take a more simple and practical way as to define
key institutions by only the number of original articles. Thus, the key
institutions of any one of the seven countries are defined hereby as that
each of these institutions has published at least 100 original articles and
no less than 1% of the total number of articles of the country it belongs to
during 1986-2007. The “100 articles” criteria is set for a common standard
so that key institutions of different countries are comparable; and the “1%”
criteria is set because different countries are not at the same productive
level in terms of the number of articles, and helps to give reasonable
account of country differences. Based on the above criteria, a list of key
institutions is obtained for each of the seven countries, and the list of key
institutions of China is presented in Table-7.3.1.1.
Institution Name Record Count % of 6977
CHINESE ACAD SCI 2047 29.34%
NANJING UNIV 888 12.73%
UNIV SCI & TECHNOL CHINA 739 10.59%
BEIJING UNIV 585 8.38%
TSING HUA UNIV 327 4.69%
ZHEJIANG UNIV 261 3.74%
UNIV HONG KONG 240 3.44%
NW INST NONFERROUS MET RES 228 3.27%
CCAST (China Center of Advanced Science and Technology)
154 2.21%
FUDAN UNIV 152 2.18%
SHANGHAI JIAO TONG UNIV 110 1.58%
BEIJING NORMAL UNIV 109 1.56%
GEN RES INST NONFERROUS MET 102 1.46%
Table-7.3.1.1 Key Institutions of China
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ISI Web of Sciences analyzing tools present the institutions by
abbreviations only, and have included collaborative institutions of other
countries under the lists of analyzed results of the primary countries.
Therefore, further examinations have been taken to identify the
institutions inclusive of the primary countries. Besides, international
research facilities (e.g. CERN) have been excluded from the list of any of
the countries. On the other hand, consortium institutions such as Chinese
Academy of Sciences, University of Paris, etc. are used instead of that
individual institutes of Chinese Academy of Sciences, or University of
Paris 6, 7, 11, etc. are used. This is because ISI Web of Sciences
analyzing tools sometimes could not differentiate among the different
individual institutions such as the different individual institutes of Chinese
Academy of Sciences and presents only the consortium institutions such
as Chinese Academy of Sciences instead in such cases.
The numbers of key institutions of different countries based on the
above criteria are given in Table-7.3.1.2. It is seen that the numbers of key
institutions in Germany, Japan and USA are about double or even triple of
the number of key institutions in China, England, France and Russia. This
indicates that there are many more institutions which are active and
playing important roles in superconductivity research in the countries of
Germany, Japan and USA (Chart-7.3.1.2).
China England France Germany Japan Russia USA
Number of Key
Institutions 13 16 16 33 34 10 30
Table-7.3.1.2 Number of Key Institutions by Country
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0
5
10
15
20
25
30
35
40
China England France Germany Japan Russia USA
Chart-7.3.1.2 Number of Key Institutions by Country
Within the key institutions of each country, the institution which
publishes the highest number of original articles might be technically
defined as the top institution of that country. Table-7.3.1.3 has presented a
list of such top institutions of the seven countries under study, as well as
the number of articles and the percentage rate of country totals that they
have contributed.
Country Institution Name Record Count % of
Country Total
China CHINESE ACAD SCI 2047 29.34%
England UNIV CAMBRIDGE 1376 24.25%
France CNRS 1669 21.12%
Germany MAX PLANCK INST 1963 17.28%
Japan UNIV TOKYO 3643 14.98%
Russia RUSSIAN ACAD SCI 3292 41.71%
USA UNIV CALIF 3876 13.68%
Table-7.3.1.3 Top Institution by Country
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It is seen that University of California in USA, University of Tokyo in
Japan, and Russian Academy of Sciences in Russia all have published
more than 3,000 articles, the numbers of articles by Chinese Academy of
Sciences in China is over 1,000 less than these three institutions, but
better than all other institutions of other countries (Chart-7.3.1.3.1). It is
also seen that except University of Cambridge in England and University
of Tokyo in Japan, all other top institutions in other countries are of
consortium institutions.
It is also seen that Russian Academy of Sciences has contributed
over 40% articles of Russia, and Chinese Academy of Sciences has
contributed nearly 30% articles of China. The high percentage rates have
indicated the relative importance of Russian Academy of Sciences in
Russia and Chinese Academy of Sciences in China in superconductivity
research. On the other hand, the low percentage rates of Max Plank
Institute in Germany, University of Tokyo in Japan and University of
California in USA, are in consistency with that there are many more
institutions which are active in superconductivity research in these
countries (Chart-7.3.1.3.2).
0
500
1000
1500
2000
2500
3000
3500
4000
4500
CHIN
ESE A
CAD S
CI
UNIV
CAM
BRID
GE
CNRS
MAX P
LANCK IN
ST
UNIV
TOKYO
RUSSIA
N A
CAD S
CI
UNIV
CALIF
Chart-7.3.1.3.1 Top Institution by Country – Number of Articles
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0%
5%
10%
15%
20%
25%
30%
35%
40%
45%
CHINESE
ACAD SCI
UNIV
CAMBRIDGE
CNRS MAX
PLANCK
INST
UNIV TOKYO RUSSIAN
ACAD SCI
UNIV CALIF
Chart-7.3.1.3.2 Top Institution by Country – % of Country Total Articles
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7.3.2 Citations of Top Institutions
It is decided to select the above defined top institutions only in stead
of all key institutions for citations comparative study of the seven countries
because this helps to make the citations analyses more simple and the
results more identical.
In previous sections, there had been more exhausted citations
analyses of the seven countries under study. It is intended hereby only to
have a look at some general numbers of citations of the top institutions of
these countries. Table-7.3.2.1 has presented the average citations,
average non-self citations and the percentage rate of non-self in total
citations of the top institutions of the seven countries.
Chinese
Acad. Sci. Univ.
Cambridge CNRS
Max Plank Inst.
Univ. Tokyo
Russian Acad. Sci.
Univ. California
Average Citations
4.93 16.06 13.69 15.7 18.96 7.2 24.32
Average Non-self Citations
3.33 10.2 9.5 8.69 9.38 4.18 13.33
% 67.55% 63.51% 69.39% 55.35% 49.47% 58.06% 54.81%
Table-7.3.2.1 Average Citations of Top Institutions of Different Countries
0
5
10
15
20
25
30
Chinese
Acad. Sci.
Univ.
Cambridge
CNRS Max Plank
Inst.
Univ. Tokyo Russian
Acad. Sci.
Univ.
California
Average Citations Average Non-self Citations
Chart-7.3.2.1.1 Average Citations of Top Institutions of Different Countries
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0%
10%
20%
30%
40%
50%
60%
70%
80%
Country Overall 52.90% 64.52% 56.87% 49.95% 28.88% 53.86% 33.81%
Top Institution 67.55% 63.51% 69.39% 55.35% 49.47% 58.06% 54.81%
China England France Germany Japan Russia USA
Chart-7.3.2.1.2 % of Non-self in Total Citations
It is seen that University of California receives the highest averages of
both overall and non-self citations; Chinese Academy of Sciences
receives the least but is very close to Russian Academy of Sciences in
both numbers (Chart-7.3.2.1.1). By the way, compare the non-self
citations rates in Table 7.3.2.1 and Table-7.2.1.1, it is remarkable to see
that except that the rate of University of Cambridge is only 1% different
from the rate of England, the rate of all other top institutions are
significantly higher than that of their belonging countries. Besides,
Chinese Academy of Sciences ranks the 2nd highest as of 67.55% for the
non-self citations rate among all of the top institutions of the seven
countries under study (Chart-7.3.2.1.2).
Table-7.3.2.2 has presented the h-index of the top institutions of the
seven countries under study. It is seen that the h-index of University of
California and University of Tokyo are much higher than the rest of
institutions; University of Cambridge, CNRS, Max Plank Institute, and
Russian Academy of Sciences all have much lower h-index than the
above two institutions; and Chinese Academy of Sciences has the lowest
h-index (Chart-7.3.2.2).
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Chinese
Acad. Sci. Univ.
Cambridge CNRS
Max Plank Inst.
Univ. Tokyo
Russian Acad. Sci.
Univ. California
h-index 34 64 66 76 109 61 130
Table-7.3.2.2 h-index of Top Institutions of Different Countries
0
20
40
60
80
100
120
140
Chinese
Acad. Sci.
Univ.
Cambridge
CNRS Max Plank
Inst.
Univ. Tokyo Russian
Acad. Sci.
Univ.
California
Chart-7.3.2.2 h-index of Top Institutions of Different Countries
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7.4 International Collaborations
7.4.1 Original Publications
It is of interest to have a look at the international collaborations of the
seven countries under study. Table-7.4.1.1 has listed by country the
number of collaborative countries, the number of collaborative articles and
its percentage rate of collaborative articles in country total.
China England France Germany Japan Russia USA
Number of Collaborative Countries
53 78 78 75 76 68 86
Number of Collaborative Articles
2041 4603 6771 9214 7163 5779 13440
Collaborative Articles of % of Country Total
29.25% 81.11% 85.70% 81.09% 29.45% 73.22% 47.42%
Table-7.4.1.1. International Collaborations
It is seen that all countries have collaborated extensively with other
countries. There are only slight differences in the number of collaborative
countries of different countries. (Chart-7.4.1.1.1) However, the gaps of the
number of collaborative articles of different countries are remarkable
(Chart-7.4.1.1.2). Compare Chart-7.4.1.1.1, Chart-7.4.1.1.2 and
Chart-7.4.1.1.3, it is seen that USA has collaborated with the highest
number of other countries and produced the highest number of
collaborative articles, but the percentage rate of collaborative articles of
USA is only moderate. England, France, Germany and Japan have very
close number of international collaborators, but their total numbers of
collaborative articles are very different, however, the percentage rate of
collaborative articles of England, France, Germany are very close and as
high as over 80%, which are by 10% more than Russia on average and
30-50% more than USA, Japan and China. Therefore, it might be
concluded that the majority of the original articles by England, France,
Germany and Russia have been benefited from international
collaborations. On the other hand, China seems to have much less
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international collaborations than its counterpart countries: it has the least
number of collaborative countries, the least number of collaborative
articles and the lowest percentage rate of collaborative articles.
0
10
20
30
40
50
60
70
80
90
100
China England France Germany Japan Russia USA
Chart-7.4.1.1.1 Number of Collaborative Countries by Country
0
2000
4000
6000
8000
10000
12000
14000
16000
China England France Germany Japan Russia USA
Chart-7.4.1.1.2 Number of Collaborative Articles by Country
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0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
China England France Germany Japan Russia USA
Chart-7.4.1.1.3 Collaborative Articles of % of Country Total
Table-7.4.1.2.1 and Table-7.4.1.2.2 have presented detailed maps of
how different countries are collaborating with each other. The countries in
1st rows are the seven countries under study, and the countries in 1st
column are the most important collaborative countries of the seven
countries under study. The most important collaborative countries are
defined as that each of these countries has contributed at least 1% of the
total number of articles for at least one of the seven countries under study,
and the altogether collaborative articles it has contributed to all seven
countries are more than 1,000.
It is seen that all countries under study have collaborated with each
other closely, especially European countries; and USA is the most
important collaborator for almost every country except Russia of which
Germany is the most important collaborator. China collaborates most with
USA and Japan, but is not active in collaboration with European countries
(Table-7.4.1.2.1 and Table-7.4.1.2.2).
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It is also seen that USA has produced most collaborative articles with
each of the important collaborative countries, and China the least
(Chart-7.4.1.2.1). Besides, China and Japan are most similar in the
patterns of international collaborations in terms of that the percentage rate
of collaborative articles with most collaborative countries are very close
(Chart-7.4.1.2.2).
Collaborative Country
China England France Germany Japan Russia USA Total
USA 555 768 1035 1677 1881 818 6734
GERMANY 200 455 814 699 1144 1677 4989
JAPAN 390 426 524 699 390 1881 4310
FRANCE 86 435 814 524 497 1035 3391
RUSSIA 40 229 497 1144 390 818 3118
SWITZERLAND 20 245 513 517 334 316 669 2614
ENGLAND 83 435 455 426 229 768 2396
ITALY 82 202 392 354 223 221 519 1993
CANADA 58 119 126 182 211 63 737 1496
NETHERLANDS 33 167 207 300 176 228 381 1492
CHINA 83 86 200 390 40 555 1354
Table-7.4.1.2.1 Important Collaborators and Number of Collaborative Articles
Collaborative Country
% of China
% of England
% of France
% of Germany
% of Japan
% of Russia
% of USA
CANADA 0.83% 2.10% 1.59% 1.60% 0.87% 0.80% 2.60%
CHINA 1.46% 1.09% 1.76% 1.60% 0.51% 1.96%
ENGLAND 1.19% 5.51% 4.00% 1.75% 2.90% 2.71%
FRANCE 1.23% 7.67% 7.16% 2.15% 6.30% 3.65%
GERMANY 2.87% 8.02% 10.30% 2.87% 14.49% 5.92%
ITALY 1.18% 3.56% 4.96% 3.12% 0.92% 2.80% 1.83%
JAPAN 5.59% 7.51% 6.63% 6.15% 4.94% 6.64%
NETHERLANDS 0.47% 2.94% 2.62% 2.64% 0.72% 2.89% 1.34%
RUSSIA 0.57% 4.04% 6.29% 10.07% 1.60% 2.89%
SWITZERLAND 0.29% 4.32% 6.49% 4.55% 1.37% 4.00% 2.36%
USA 7.95% 13.53% 13.10% 14.76% 7.73% 10.36%
Total % 22.17% 55.15% 58.58% 55.81% 21.58% 49.99% 31.90%
Table-7.4.1.2.2 Collaborative articles of % of country total articles
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0
200
400
600
800
1000
1200
1400
1600
1800
2000
CANADA
CHIN
A
ENGLA
ND
FRANCE
GERM
ANY
ITALY
JAPAN
NETH
ERLA
NDS
RUSSIA
SW
ITZER
LAND
USA
China England France Germany Japan Russia USA
Chart-7.4.1.2.1 Important Collaborators and Number of Collaborative Articles
0%
2%
4%
6%
8%
10%
12%
14%
16%
CANADA
CHIN
A
ENGLA
ND
FRANCE
GERM
ANY
ITALY
JAPAN
NETH
ERLA
NDS
RUSSIA
SW
ITZER
LAND
USA
China England France Germany Japan Russia USA
Chart-7.4.1.2.2 Collaborative articles of % of country total articles
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7.4.2 Citations boosted?
In order to find out whether or not citations have been boosted by
international collaborations, it would be ideal to compare the citations
numbers of articles from independent works and those from collaborative
works. However, the complete comparison is rather difficult if not
impossible with current available ISI Web of Sciences analyzing tools or
any other software. Therefore, it is decided to look at the highly cited
articles which are defined by h-index of different countries and the
citations of these highly cited articles.
Table-7.4.2.1 lists the h-indexes of different countries based on the
original articles during 1986-2007, which represent the total number of
highly cited articles of different countries; the number of collaborative
highly cited articles; and the percentage rate of collaborative highly cited
articles. Table-7.4.2.2 lists the number of citations of the highly cited
articles, the number of citations of the collaborative highly cited articles;
and the percentage rate of citations of the collaborative highly cited
articles. The collaborative highly cited articles are the highly cited articles
which come out of the international collaborations.
It is seen that for most countries except USA, more than 50% of their
highly cited articles are of international collaborations; and for Russia, the
percentage rate of collaborative highly cited articles is as high as nearly
95% (Table-7.4.2.1). On the other hand, citations of the collaborative
highly cited articles have contributed substantially to the total number of
citations of the highly cited articles, with the percentage as of 46%-70%
except USA (Table-7.4.2.2). The closeness of the percentage rate of
collaborative highly cited articles and that of the citations of these articles
for all countries (Chart-7.4.2) indicates that the collaborative highly cited
articles contribute significantly to the total number of citations of the highly
cited articles, i.e. in other words, international collaborations have
significantly boosted the number of citations.
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China England France Germany Japan Russia USA
Highly cited articles 50 97 121 116 152 93 260
Collaborative-highly cited articles 34 67 84 68 78 88 67
% 68.00% 69.07% 69.42% 58.62% 51.32% 94.62% 25.77%
Table-7.4.2.1 Highly Cited Articles and Collaborative Highly Cited Articles
China England France Germany Japan Russia USA
TC-highly cited articles 4366 17484 26859 22881 51109 15669 128990
TC-Collaborative-highly cited articles 3063 11852 18232 13243 24013 14741 29996
% 70.16% 67.79% 67.88% 57.88% 46.98% 94.08% 23.25%
Table-7.4.2.2 Citations of Highly Cited Articles and Collaborative Highly Cited Articles
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
China England France Germany Japan Russia USA
Collaborative-h % Citations %
Chart-7.4.2 % of Collaborative Highly Cited Articles and their Citations
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Chapter 8 Conclusions
During 1986-2007 there are 6,977 original articles by China in
superconductivity research, with over 95% in English. Compare to other
leading countries of the world in superconductivity research, the total
number of original articles by China is more than England, but less than
France, Russia, Germany, and far less than Japan and USA. However, it
has been catching up with rapid growth since 1999, and by the end of
2003 the number of original articles by China of the year has already
overtaken England, France, Russia, and by the end of 2007 the number is
very close to Germany. This indicates that China has rising up in
superconductivity research in terms of the number of original articles.
With regard of the number of source journals where original articles
are published, China, England, France and Russia are all at the range of
400 - 500, less than Germany, Japan and USA. However, the number of
core original source journals for different countries are only slightly
different, and there are 12 common core original source journals for all
countries. With these journals, the publication patters of China, England,
France and Russia are very similar in terms of the number of articles
published in each of these journals. On the other hand, China tends to
publish more in the source journals of China, and on average, about 2/3 of
original articles by China are published in journals with average impact
factors. This indicates that China has published in a wide range of source
journals; besides, it has published adequately in the important source
journals recognized by all countries and journals, or the source journals
with average academic influence. .
With regard of the number of subject areas covered by the original
articles, different countries range from 50 to over 120, with USA and
Japan at the top and China and Russia at the bottom. However, the
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number of focus subject areas for different countries are only slightly
different, and there are 17 common focus subject areas for all countries.
Within these subject areas, China, England, France, and Russia adopt
very similar patterns in terms of the number of articles included in each of
these subject areas. This indicates that China has less wide range of
subject areas of research interest, but has similar research focus and
output as England, Franc and Russia in superconductivity research.
By the time of this study, there have been 29,838 total citations to the
6,977 original articles in superconductivity research by China, among
which the total number of non-self citations is 15,735. Within this study,
citations analyses of China are based on these non-self citations.
In general, citations of the original articles in superconductivity
research by China are from over 4,400 institutions, more than 100
countries, over 1,000 source journals, and 140 subject areas. This
indicates that the general impact of China in superconductivity research
has reached a broad range of institutions, countries, source journals and
subject areas. Besides, there has been continuous growth in the number
of citations of China, with its continuously increasing number of original
articles through the years. This indicates that the general impact of China
in superconductivity research has been rising continuously.
With regard of the citing institutions, there are 48 important institutions,
and Chinese Academy of Sciences, University of Tokyo, and Tohoku
University are on the top of the list. This indicates that China has its most
distinct impact in superconductivity research upon these institutions, with
the most distinct domestic impact upon one of the most important
institutions of China, and most distinct overseas impact upon two of the
most important universities of Japan.
With regard of the citations source journals, there are 12 core citations
source journals which have contributed nearly 50% of the total number of
citations. Besides, 11 of the 12 core citations source journals overlap the
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core original source journals, and these 11 journals could be defined as
key source journals in terms of the importance of both original articles and
citations. China has its most distinct impact in superconductivity research
within these key source journals.
With regard of the citations subject areas, there are 20 focus citations
subject areas with the top 3 subject areas as condensed matter physics,
applied physics, and multidisciplinary physics, which are the same as
those of original articles. Besides, there are substantial overlaps between
the focus citations subject areas and the focus original subject areas. This
indicates that China has its most distinct impact in superconductivity
research within the same or near-by subject areas where most of its
original articles are published.
With regard of citing countries, the majority of citations come from the
collaborative countries of China, such as USA, Japan, Germany, etc. This
indicates that China has its most distinct impact in superconductivity
research within its collaborative countries.
The comparative studies on citations of different countries are based
on 2001-2007 original articles in top 3 subject areas of general interest of
all countries.
With regard of the total number of citations, there are huge gaps
among different countries; but in terms of the number of non-self-citations,
these gaps are reduced dramatically. China has the lowest numbers of
both total and non-self citations among all seven countries under study. It
is believed that the lowest numbers of citations of China are partly due to
the comparatively lower number of original articles of China. However,
China has been catching up with a faster growing pace in the number of
citations in recent years, which indicates that it has been rising up in terms
of general impact in superconductivity research.
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In terms of average citations, China has the lowest overall average
citations, but has a relatively higher average non-self-citations compared
to Japan. Compare to USA and Japan, the rate of non-self citations of
China is much higher. This indicates that the impact of the original articles
by China in superconductivity research tend to be more beyond the
authors‟ research groups.
In terms of h-index, China ranks the lowest, far less than USA and
Japan, and also less than all other leading countries. This indicates that
China has far less number of high impact articles, and its high impact
articles are defined by much lower standard with far less academic
influence in superconductivity research, compared to all other leading
countries.
With regard of the number of citing countries of the citations of
different countries, USA and Germany rank the highest, and China the
lowest. China, Japan and USA all have more than 1/4 of the citations from
their own countries in which case the rates of self-country citations are the
highest. This indicates that the impact of China in superconductivity
research is within less wide range of countries, and more constrained in
its own country, compared to all other leading countries. Besides, there
are 22 most important citing countries, from which all countries have been
cited heavily. USA receives most citations from each of these important
citing countries; while China receives the lowest number of citations in
general, it is close to Russia, France and England in the number of
citations from most of the citing countries outside the seven countries
under study. This indicates that China has the lowest impact in
superconductivity research upon the most important citing countries in
general; however, the impact of China upon the important citing countries
outside the seven countries under study is close to that of Russia, France
and England.
With regard of citations source journals, USA are cited by much more
source journals than the rest of the countries. The numbers of source
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journals which have cited China, England, France and Russia are very
close. This indicates that the extent and range of impact of China in
superconductivity research are far less wide than USA, but very close to
that of England, France and Russia in terms of the general influence in
the number of source journals. Besides, there are 12 common core
citations source journals from which all countries have been heavily cited.
USA receives the most citations from each of these journals; and the
number of citations that China, England, France and Russia have
received from each of these journals are very close except that China are
cited much less from Physical Review B and Physical Review Letters
which are two of the most important source journals. This indicates that
the impact of China in superconductivity research is similar to that of
England, France and Russia in terms of the influence within the important
source journals, but this impact is far less than these countries within two
of the most important source journals.
With regard of citations subject areas, all countries have been cited
widely. China is cited far less widely than USA, Japan and Germany, less
widely than England, but more widely than France and Russia in terms of
the number of subject areas. This indicates that China has its impact in
superconductivity research within less wide range of subject areas than
USA, Japan, Germany and England, but better than France and Russia.
Besides, there are 16 common focus citations subject areas where all
countries have been cited heavily, and the top 3 subject areas have
included the highest number of citations. Within these 16 subject areas,
China receives the lowest number of citations in almost all subject areas,
however, the numbers of citations of China is very close to England,
France, and Russia in most subject areas. Besides, there are distinct
gaps of citations numbers in the top 3 subject areas, and within each of
these subject areas, China receives much less citations than all other
leading countries. This indicates that the impact of China in
superconductivity research is close to that of England, France, and
Russia in most of the important subject areas, but this impact is far less in
the top 3 subject areas compared to all other leading countries.
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Comparative studies of key and top institutions as well as the
international collaborations of different countries are based on the
1986-2007 original articles and citations of these articles.
China has 13 key institutions in terms of the number of original articles
in superconductivity research, among which Chinese Academy of
Sciences is the top institution. Compare to other top institutions of other
leading countries, the number of original articles by Chinese Academy of
Sciences is moderate. With regard of citations, Chinese Academy of
Sciences receives the lowest number of average citations, with both of its
overall and non-self average citations are very close to Russian Academy
of Sciences, but far less than other top institutions of other leading
countries. This indicates that the general impact of the top institution of
China in superconductivity research is at about the similar level as that of
the top institution of Russia, but far less than other top institutions of other
leading countries. On the other hand, Chinese Academy of Sciences has
the lowest h-index which is much lower than other top institutions of other
leading countries. This indicates that the top institution of China in
superconductivity research has far less number of high impact articles
and its high impact articles are defined by much lower standard with far
less academic influence, compared to other top institutions of other
leading countries.
In respect of the international collaborations, China has the least
number of collaborative countries, the least number of collaborative
articles and the lowest percentage rate of collaborative articles. This
indicates that China is far less active in international collaborations
compared to other leading countries. Citations analyses based on the
h-index of different countries reveal that international collaborations have
significantly increased the number of citations of the original articles in
superconductivity research of all leading countries. This might imply that
China needs to have more international collaborations in order to increase
its general impact in superconductivity research.
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In conclusion, China is one of the leading countries of the world in
superconductivity research in terms of both the number of original articles
and citations. The general impact of China in superconductivity research
is far less than the super countries of USA and Japan, and less than
Germany; however, China has been catching up or over taken England,
France and Russia in many cases with increasing impact in
superconductivity research in recent years.
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