citation studies of publications in...

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


30 / 95

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%


31 / 95

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).


China 6147 88%

Other Country 830 12%

Total: 6977 100%

Table-5.5.2 Number of Reprint Authors in Total Number of Articles


32 / 95

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.


33 / 95

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


34 / 95

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.


35 / 95

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


36 / 95

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.


37 / 95

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.


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


38 / 95

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.


39 / 95

6.5 Citations by Institutions


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%


40 / 95

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.

Citing-China-refine/Citing-institutions.xls#Institute!A17





41 / 95

6.6 Citations by Subject Areas


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


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%


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


44 / 95

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).


45 / 95

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


Chart-7.1.1 Growth of Original Articles through the Years by Country


46 / 95

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).


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


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%


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


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


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


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

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ER

S

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AC

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NS

ON

MA

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ICA

B

PH

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ICA

L R

EV

IEW

B

SO

LID

ST

AT

E

CO

MM

UN

ICA

TIO

NS


Chart-7.1.2.3 Common Core Original Source Journals and Number of Articles


51 / 95

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).


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


All Focus

Chart-7.1.3.1 Number of Subject Areas by Country


52 / 95

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.


53 / 95

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


2259 2177 2916 4664 6767 2669 10224 31676

PHYSICS, MULTIDISCIPLINARY

1218 765 1284 1641 2961 1726 3987 13582


309 548 426 855 2803 433 3172 8546


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


103 128 170 147 581 91 541 1761

PHYSICS, MATHEMATICAL

223 105 116 161 213 147 572 1537


155 60 200 225 428 132 314 1514


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


54 / 95

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

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L &

MA

TE

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SC

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CE

,

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CE

S

PH

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, A

PP

LIE

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,

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ND

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SE

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PH

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ICS

,

MU

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IDIS

CIP

LIN

AR

Y

PH

YS

ICS

,

PA

RT

ICL

ES

&

TH

ER

MO

DY

NA

MIC

S


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).


55 / 95

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)


56 / 95

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).


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


57 / 95

0

10000

20000

30000

40000

50000

60000

70000

80000

90000


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%


Self-

citations

Non-self-

citations

Chart-7.2.1.1.2 Self and Non-self Citations Rate by Country


58 / 95

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).


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


Average Citations Converted Average Non-self-citations

Chart-7.2.1.2 Average Citations by Country


59 / 95

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


60 / 95

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.


61 / 95

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).


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


Chart-7.2.1.4 h-index


62 / 95

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)


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


Chart-7.2.2.1 Number of Citing Countries


63 / 95

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).


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%


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).

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A


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).


Record Count

445 462 483 601 669 418 826

Table-7.2.3.1 Number of Citations Source Journals

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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


281 483 266 631 820 235 877 3593


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


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

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APPL P

HYS

LETT

IEEE

T A

PPL S

UPE

RCOND

J APPL P

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AG M

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OND M

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PHYS

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PHYS

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PHYS

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PHYS

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SUPE

RCOND S

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TEC

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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).


Record Count

75 82 69 94 96 60 114

Table-7.2.4.1 Number of Citations Subject Areas by Country

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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


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


500 528 709 1011 1264 389 1881 6282


198 409 301 726 1045 298 1234 4211


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


124 154 267 281 439 132 563 1960

PHYSICS, NUCLEAR 140 27 121 281 188 96 516 1369


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

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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).


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

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25

30

35

40


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).

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N A

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UNIV

CALIF

Chart-7.3.1.3.1 Top Institution by Country – Number of Articles


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0%

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15%

20%

25%

30%

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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

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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%


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

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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.


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


81 / 95

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.

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Chart-7.4.1.1.1 Number of Collaborative Countries by Country

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Chart-7.4.1.1.2 Number of Collaborative Articles by Country


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0%

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30%

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60%

70%

80%

90%


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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Chart-7.4.1.2.1 Important Collaborators and Number of Collaborative Articles

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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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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


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%


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.


93 / 95

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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