Search (6 results, page 1 of 1)

  • × author_ss:"Bornmann, L."
  • × author_ss:"Leydesdorff, L."
  1. Bauer, J.; Leydesdorff, L.; Bornmann, L.: Highly cited papers in Library and Information Science (LIS) : authors, institutions, and network structures (2016) 0.02 
    0.021194125 = product of:
  0.04238825 = sum of:
    0.04238825 = product of:
      0.169553 = sum of:
        0.169553 = weight(_text_:authors in 3231) [ClassicSimilarity], result of:
          0.169553 = score(doc=3231,freq=16.0), product of:
            0.23803101 = queryWeight, product of:
              4.558814 = idf(docFreq=1258, maxDocs=44218)
              0.052213363 = queryNorm
            0.7123147 = fieldWeight in 3231, product of:
              4.0 = tf(freq=16.0), with freq of:
                16.0 = termFreq=16.0
              4.558814 = idf(docFreq=1258, maxDocs=44218)
              0.0390625 = fieldNorm(doc=3231)
      0.25 = coord(1/4)
  0.5 = coord(1/2)
    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.
  2. Leydesdorff, L.; Bornmann, L.; Mutz, R.; Opthof, T.: Turning the tables on citation analysis one more time : principles for comparing sets of documents (2011) 0.02 
    0.01559464 = product of:
  0.03118928 = sum of:
    0.03118928 = product of:
      0.06237856 = sum of:
        0.06237856 = weight(_text_:k in 4485) [ClassicSimilarity], result of:
          0.06237856 = score(doc=4485,freq=4.0), product of:
            0.18639012 = queryWeight, product of:
              3.569778 = idf(docFreq=3384, maxDocs=44218)
              0.052213363 = queryNorm
            0.33466667 = fieldWeight in 4485, product of:
              2.0 = tf(freq=4.0), with freq of:
                4.0 = termFreq=4.0
              3.569778 = idf(docFreq=3384, maxDocs=44218)
              0.046875 = fieldNorm(doc=4485)
      0.5 = coord(1/2)
  0.5 = coord(1/2)
    Abstract
    We submit newly developed citation impact indicators based not on arithmetic averages of citations but on percentile ranks. Citation distributions are-as a rule-highly skewed and should not be arithmetically averaged. With percentile ranks, the citation score of each paper is rated in terms of its percentile in the citation distribution. The percentile ranks approach allows for the formulation of a more abstract indicator scheme that can be used to organize and/or schematize different impact indicators according to three degrees of freedom: the selection of the reference sets, the evaluation criteria, and the choice of whether or not to define the publication sets as independent. Bibliometric data of seven principal investigators (PIs) of the Academic Medical Center of the University of Amsterdam are used as an exemplary dataset. We demonstrate that the proposed family indicators [R(6), R(100), R(6, k), R(100, k)] are an improvement on averages-based indicators because one can account for the shape of the distributions of citations over papers.
  3. Leydesdorff, L.; Bornmann, L.; Wagner, C.S.: ¬The relative influences of government funding and international collaboration on citation impact (2019) 0.01 
    0.0106112845 = product of:
  0.021222569 = sum of:
    0.021222569 = product of:
      0.042445138 = sum of:
        0.042445138 = weight(_text_:22 in 4681) [ClassicSimilarity], result of:
          0.042445138 = score(doc=4681,freq=2.0), product of:
            0.1828423 = queryWeight, product of:
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.052213363 = queryNorm
            0.23214069 = fieldWeight in 4681, product of:
              1.4142135 = tf(freq=2.0), with freq of:
                2.0 = termFreq=2.0
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.046875 = fieldNorm(doc=4681)
      0.5 = coord(1/2)
  0.5 = coord(1/2)
    Date
    8. 1.2019 18:22:45
  4. Bornmann, L.; Leydesdorff, L.: Which cities produce more excellent papers than can be expected? : a new mapping approach, using Google Maps, based on statistical significance testing (2011) 0.01 
    0.0089919055 = product of:
  0.017983811 = sum of:
    0.017983811 = product of:
      0.071935244 = sum of:
        0.071935244 = weight(_text_:authors in 4767) [ClassicSimilarity], result of:
          0.071935244 = score(doc=4767,freq=2.0), product of:
            0.23803101 = queryWeight, product of:
              4.558814 = idf(docFreq=1258, maxDocs=44218)
              0.052213363 = queryNorm
            0.30220953 = fieldWeight in 4767, product of:
              1.4142135 = tf(freq=2.0), with freq of:
                2.0 = termFreq=2.0
              4.558814 = idf(docFreq=1258, maxDocs=44218)
              0.046875 = fieldNorm(doc=4767)
      0.25 = coord(1/4)
  0.5 = coord(1/2)
    Abstract
    The methods presented in this paper allow for a statistical analysis revealing centers of excellence around the world using programs that are freely available. Based on Web of Science data (a fee-based database), field-specific excellence can be identified in cities where highly cited papers were published more frequently than can be expected. Compared to the mapping approaches published hitherto, our approach is more analytically oriented by allowing the assessment of an observed number of excellent papers for a city against the expected number. Top performers in output are cities in which authors are located who publish a statistically significant higher number of highly cited papers than can be expected for these cities. As sample data for physics, chemistry, and psychology show, these cities do not necessarily have a high output of highly cited papers.
  5. Leydesdorff, L.; Bornmann, L.: How fractional counting of citations affects the impact factor : normalization in terms of differences in citation potentials among fields of science (2011) 0.01 
    0.008842737 = product of:
  0.017685475 = sum of:
    0.017685475 = product of:
      0.03537095 = sum of:
        0.03537095 = weight(_text_:22 in 4186) [ClassicSimilarity], result of:
          0.03537095 = score(doc=4186,freq=2.0), product of:
            0.1828423 = queryWeight, product of:
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.052213363 = queryNorm
            0.19345059 = fieldWeight in 4186, product of:
              1.4142135 = tf(freq=2.0), with freq of:
                2.0 = termFreq=2.0
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.0390625 = fieldNorm(doc=4186)
      0.5 = coord(1/2)
  0.5 = coord(1/2)
    Date
    22. 1.2011 12:51:07
  6. Bornmann, L.; Wagner, C.; Leydesdorff, L.: BRICS countries and scientific excellence : a bibliometric analysis of most frequently cited papers (2015) 0.01 
    0.0074932543 = product of:
  0.0149865085 = sum of:
    0.0149865085 = product of:
      0.059946034 = sum of:
        0.059946034 = weight(_text_:authors in 2047) [ClassicSimilarity], result of:
          0.059946034 = score(doc=2047,freq=2.0), product of:
            0.23803101 = queryWeight, product of:
              4.558814 = idf(docFreq=1258, maxDocs=44218)
              0.052213363 = queryNorm
            0.25184128 = fieldWeight in 2047, product of:
              1.4142135 = tf(freq=2.0), with freq of:
                2.0 = termFreq=2.0
              4.558814 = idf(docFreq=1258, maxDocs=44218)
              0.0390625 = fieldNorm(doc=2047)
      0.25 = coord(1/4)
  0.5 = coord(1/2)
    Abstract
    The BRICS countries (Brazil, Russia, India, China, and South Africa) are notable for their increasing participation in science and technology. The governments of these countries have been boosting their investments in research and development to become part of the group of nations doing research at a world-class level. This study investigates the development of the BRICS countries in the domain of top-cited papers (top 10% and 1% most frequently cited papers) between 1990 and 2010. To assess the extent to which these countries have become important players at the top level, we compare the BRICS countries with the top-performing countries worldwide. As the analyses of the (annual) growth rates show, with the exception of Russia, the BRICS countries have increased their output in terms of most frequently cited papers at a higher rate than the top-cited countries worldwide. By way of additional analysis, we generate coauthorship networks among authors of highly cited papers for 4 time points to view changes in BRICS participation (1995, 2000, 2005, and 2010). Here, the results show that all BRICS countries succeeded in becoming part of this network, whereby the Chinese collaboration activities focus on the US.

Authors