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Leydesdorff, L.; Bihui, J.: Mapping the Chinese Science Citation Database in terms of aggregated journal-journal citation relations (2005)
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- Date
- 8. 1.2006 18:53:23
-
Zhou, P.; Leydesdorff, L.: ¬A comparison between the China Scientific and Technical Papers and Citations Database and the Science Citation Index in terms of journal hierarchies and interjournal citation relations (2007)
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- Date
- 3. 3.2007 18:23:57
-
Leydesdorff, L.: How are new citation-based journal indicators adding to the bibliometric toolbox? (2009)
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- Date
- 19. 7.2009 12:23:20
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Leydesdorff, L.; Persson, O.: Mapping the geography of science : distribution patterns and networks of relations among cities and institutes (2010)
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- Date
- 23. 7.2010 13:10:08
-
Leydesdorff, L.; Rafols, I.: ¬A global map of science based on the ISI subject categories (2009)
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- Date
- 23. 2.2009 19:54:19
-
Leydesdorff, L.; Moya-Anegón, F.de; Guerrero-Bote, V.P.: Journal maps on the basis of Scopus data : a comparison with the Journal Citation Reports of the ISI (2010)
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- Date
- 31. 5.2010 15:02:23
-
Bauer, J.; Leydesdorff, L.; Bornmann, L.: Highly cited papers in Library and Information Science (LIS) : authors, institutions, and network structures (2016)
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- Abstract
- As a follow-up to the highly cited authors list published by Thomson Reuters in June 2014, we analyzed the top 1% most frequently cited papers published between 2002 and 2012 included in the Web of Science (WoS) subject category "Information Science & Library Science." In all, 798 authors contributed to 305 top 1% publications; these authors were employed at 275 institutions. The authors at Harvard University contributed the largest number of papers, when the addresses are whole-number counted. However, Leiden University leads the ranking if fractional counting is used. Twenty-three of the 798 authors were also listed as most highly cited authors by Thomson Reuters in June 2014 (http://highlycited.com/). Twelve of these 23 authors were involved in publishing 4 or more of the 305 papers under study. Analysis of coauthorship relations among the 798 highly cited scientists shows that coauthorships are based on common interests in a specific topic. Three topics were important between 2002 and 2012: (a) collection and exploitation of information in clinical practices; (b) use of the Internet in public communication and commerce; and (c) scientometrics.
-
Leydesdorff, L.; Salah, A.A.A.: Maps on the basis of the Arts & Humanities Citation Index : the journals Leonardo and Art Journal versus "digital humanities" as a topic (2010)
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- Abstract
- The possibilities of using the Arts & Humanities Citation Index (A&HCI) for journal mapping have not been sufficiently recognized because of the absence of a Journal Citations Report (JCR) for this database. A quasi-JCR for the A&HCI ([2008]) was constructed from the data contained in the Web of Science and is used for the evaluation of two journals as examples: Leonardo and Art Journal. The maps on the basis of the aggregated journal-journal citations within this domain can be compared with maps including references to journals in the Science Citation Index and Social Science Citation Index. Art journals are cited by (social) science journals more than by other art journals, but these journals draw upon one another in terms of their own references. This cultural impact in terms of being cited is not found when documents with a topic such as digital humanities are analyzed. This community of practice functions more as an intellectual organizer than a journal.
-
Leydesdorff, L.; Zhou, P.; Bornmann, L.: How can journal impact factors be normalized across fields of science? : An assessment in terms of percentile ranks and fractional counts (2013)
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- Abstract
- Using the CD-ROM version of the Science Citation Index 2010 (N = 3,705 journals), we study the (combined) effects of (a) fractional counting on the impact factor (IF) and (b) transformation of the skewed citation distributions into a distribution of 100 percentiles and six percentile rank classes (top-1%, top-5%, etc.). Do these approaches lead to field-normalized impact measures for journals? In addition to the 2-year IF (IF2), we consider the 5-year IF (IF5), the respective numerators of these IFs, and the number of Total Cites, counted both as integers and fractionally. These various indicators are tested against the hypothesis that the classification of journals into 11 broad fields by PatentBoard/NSF (National Science Foundation) provides statistically significant between-field effects. Using fractional counting the between-field variance is reduced by 91.7% in the case of IF5, and by 79.2% in the case of IF2. However, the differences in citation counts are not significantly affected by fractional counting. These results accord with previous studies, but the longer citation window of a fractionally counted IF5 can lead to significant improvement in the normalization across fields.
-
Leydesdorff, L.: Theories of citation? (1999)
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- Source
- Scientometrics. 43(1998) no.1, S.5-25
-
Leydesdorff, L.: Why words and co-word cannot map the development of the science (1997)
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- Source
- Journal of the American Society for Information Science. 48(1997) no.5, S.418-427
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Leydesdorff, L.: Can scientific journals be classified in terms of aggregated journal-journal citation relations using the Journal Citation Reports? (2006)
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- Source
- Journal of the American Society for Information Science and Technology. 57(2006) no.5, S.601-613
-
Egghe, L.; Leydesdorff, L.: ¬The relation between Pearson's correlation coefficient r and Salton's cosine measure (2009)
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- Source
- Journal of the American Society for Information Science and Technology. 60(2009) no.5, S.1027-1036
-
Leydesdorff, L.; Rafols, I.: Local emergence and global diffusion of research technologies : an exploration of patterns of network formation (2011)
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- Source
- Journal of the American Society for Information Science and Technology. 62(2011) no.5, S.846-860
-
Leydesdorff, L.; Opthof, T.: Citation analysis with medical subject Headings (MeSH) using the Web of Knowledge : a new routine (2013)
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- Source
- Journal of the American Society for Information Science and Technology. 64(2013) no.5, S.1076-1080
-
Rotolo, D.; Leydesdorff, L.: Matching Medline/PubMed data with Web of Science: A routine in R language (2015)
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- Abstract
- We present a novel routine, namely medlineR, based on the R language, that allows the user to match data from Medline/PubMed with records indexed in the ISI Web of Science (WoS) database. The matching allows exploiting the rich and controlled vocabulary of medical subject headings (MeSH) of Medline/PubMed with additional fields of WoS. The integration provides data (e.g., citation data, list of cited reference, list of the addresses of authors' host organizations, WoS subject categories) to perform a variety of scientometric analyses. This brief communication describes medlineR, the method on which it relies, and the steps the user should follow to perform the matching across the two databases. To demonstrate the differences from Leydesdorff and Opthof (Journal of the American Society for Information Science and Technology, 64(5), 1076-1080), we conclude this artcle by testing the routine on the MeSH category "Burgada syndrome."
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Zhou, Q.; Leydesdorff, L.: ¬The normalization of occurrence and co-occurrence matrices in bibliometrics using Cosine similarities and Ochiai coefficients (2016)
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- Abstract
- We prove that Ochiai similarity of the co-occurrence matrix is equal to cosine similarity in the underlying occurrence matrix. Neither the cosine nor the Pearson correlation should be used for the normalization of co-occurrence matrices because the similarity is then normalized twice, and therefore overestimated; the Ochiai coefficient can be used instead. Results are shown using a small matrix (5 cases, 4 variables) for didactic reasons, and also Ahlgren et?al.'s (2003) co-occurrence matrix of 24 authors in library and information sciences. The overestimation is shown numerically and will be illustrated using multidimensional scaling and cluster dendograms. If the occurrence matrix is not available (such as in internet research or author cocitation analysis) using Ochiai for the normalization is preferable to using the cosine.
-
Comins, J.A.; Leydesdorff, L.: Identification of long-term concept-symbols among citations : do common intellectual histories structure citation behavior? (2017)
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- Source
- Journal of the Association for Information Science and Technology. 68(2017) no.5, S.1224-1233
-
Leydesdorff, L.; Moya-Anegón, F. de; Guerrero-Bote, V.P.: Journal maps, interactive overlays, and the measurement of interdisciplinarity on the basis of Scopus data (1996-2012) (2015)
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- Source
- Journal of the Association for Information Science and Technology. 66(2015) no.5, S.1001-1016
-
Leydesdorff, L.; Bornmann, L.; Mingers, J.: Statistical significance and effect sizes of differences among research universities at the level of nations and worldwide based on the Leiden rankings (2019)
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- Source
- Journal of the Association for Information Science and Technology. 70(2019) no.5, S.509-525
