Search (6 results, page 1 of 1)

  • × author_ss:"Leydesdorff, L."
  • × theme_ss:"Citation indexing"
  • × year_i:[2000 TO 2010}
  1. Leydesdorff, L.: Dynamic and evolutionary updates of classificatory schemes in scientific journal structures (2002) 0.00
    3.255793E-4 = product of:
      0.0048836893 = sum of:
        0.0048836893 = product of:
          0.009767379 = sum of:
            0.009767379 = weight(_text_:information in 1249) [ClassicSimilarity], result of:
              0.009767379 = score(doc=1249,freq=4.0), product of:
                0.050870337 = queryWeight, product of:
                  1.7554779 = idf(docFreq=20772, maxDocs=44218)
                  0.028978055 = queryNorm
                0.1920054 = fieldWeight in 1249, product of:
                  2.0 = tf(freq=4.0), with freq of:
                    4.0 = termFreq=4.0
                  1.7554779 = idf(docFreq=20772, maxDocs=44218)
                  0.0546875 = fieldNorm(doc=1249)
          0.5 = coord(1/2)
      0.06666667 = coord(1/15)
    
    Abstract
    Can the inclusion of new journals in the Science Citation Index be used for the indication of structural change in the database, and how can this change be compared with reorganizations of reiations among previously included journals? Change in the number of journals (n) is distinguished from change in the number of journal categories (m). Although the number of journals can be considered as a given at each moment in time, the number of journal categories is based an a reconstruction that is time-stamped ex post. The reflexive reconstruction is in need of an update when new information becomes available in a next year. Implications of this shift towards an evolutionary perspective are specified.
    Source
    Journal of the American Society for Information Science and technology. 53(2002) no.12, S.987-994
  2. Leydesdorff, L.: Caveats for the use of citation indicators in research and journal evaluations (2008) 0.00
    2.79068E-4 = product of:
      0.0041860198 = sum of:
        0.0041860198 = product of:
          0.0083720395 = sum of:
            0.0083720395 = weight(_text_:information in 1361) [ClassicSimilarity], result of:
              0.0083720395 = score(doc=1361,freq=4.0), product of:
                0.050870337 = queryWeight, product of:
                  1.7554779 = idf(docFreq=20772, maxDocs=44218)
                  0.028978055 = queryNorm
                0.16457605 = fieldWeight in 1361, product of:
                  2.0 = tf(freq=4.0), with freq of:
                    4.0 = termFreq=4.0
                  1.7554779 = idf(docFreq=20772, maxDocs=44218)
                  0.046875 = fieldNorm(doc=1361)
          0.5 = coord(1/2)
      0.06666667 = coord(1/15)
    
    Abstract
    Aging of publications, percentage of self-citations, and impact vary from journal to journal within fields of science. The assumption that citation and publication practices are homogenous within specialties and fields of science is invalid. Furthermore, the delineation of fields and among specialties is fuzzy. Institutional units of analysis and persons may move between fields or span different specialties. The match between the citation index and institutional profiles varies among institutional units and nations. The respective matches may heavily affect the representation of the units. Non-Institute of Scientific Information (ISI) journals are increasingly cornered into transdisciplinary Mode-2 functions with the exception of specialist journals publishing in languages other than English. An externally cited impact factor can be calculated for these journals. The citation impact of non-ISI journals will be demonstrated using Science and Public Policy as the example.
    Source
    Journal of the American Society for Information Science and Technology. 59(2008) no.2, S.278-287
  3. Leydesdorff, L.: Visualization of the citation impact environments of scientific journals : an online mapping exercise (2007) 0.00
    2.3255666E-4 = product of:
      0.0034883497 = sum of:
        0.0034883497 = product of:
          0.0069766995 = sum of:
            0.0069766995 = weight(_text_:information in 82) [ClassicSimilarity], result of:
              0.0069766995 = score(doc=82,freq=4.0), product of:
                0.050870337 = queryWeight, product of:
                  1.7554779 = idf(docFreq=20772, maxDocs=44218)
                  0.028978055 = queryNorm
                0.13714671 = fieldWeight in 82, product of:
                  2.0 = tf(freq=4.0), with freq of:
                    4.0 = termFreq=4.0
                  1.7554779 = idf(docFreq=20772, maxDocs=44218)
                  0.0390625 = fieldNorm(doc=82)
          0.5 = coord(1/2)
      0.06666667 = coord(1/15)
    
    Abstract
    Aggregated journal-journal citation networks based on the Journal Citation Reports 2004 of the Science Citation Index (5,968 journals) and the Social Science Citation Index (1,712 journals) are made accessible from the perspective of any of these journals. A vector-space model Is used for normalization, and the results are brought online at http://www.leydesdorff.net/jcr04 as input files for the visualization program Pajek. The user is thus able to analyze the citation environment in terms of links and graphs. Furthermore, the local impact of a journal is defined as its share of the total citations in the specific journal's citation environments; the vertical size of the nodes is varied proportionally to this citation impact. The horizontal size of each node can be used to provide the same information after correction for within-journal (self-)citations. In the "citing" environment, the equivalents of this measure can be considered as a citation activity index which maps how the relevant journal environment is perceived by the collective of authors of a given journal. As a policy application, the mechanism of Interdisciplinary developments among the sciences is elaborated for the case of nanotechnology journals.
    Source
    Journal of the American Society for Information Science and Technology. 58(2007) no.1, S.25-38
  4. Leydesdorff, L.; Bihui, J.: Mapping the Chinese Science Citation Database in terms of aggregated journal-journal citation relations (2005) 0.00
    1.9733087E-4 = product of:
      0.002959963 = sum of:
        0.002959963 = product of:
          0.005919926 = sum of:
            0.005919926 = weight(_text_:information in 4813) [ClassicSimilarity], result of:
              0.005919926 = score(doc=4813,freq=2.0), product of:
                0.050870337 = queryWeight, product of:
                  1.7554779 = idf(docFreq=20772, maxDocs=44218)
                  0.028978055 = queryNorm
                0.116372846 = fieldWeight in 4813, product of:
                  1.4142135 = tf(freq=2.0), with freq of:
                    2.0 = termFreq=2.0
                  1.7554779 = idf(docFreq=20772, maxDocs=44218)
                  0.046875 = fieldNorm(doc=4813)
          0.5 = coord(1/2)
      0.06666667 = coord(1/15)
    
    Source
    Journal of the American Society for Information Science and Technology. 56(2005) no.14, S.1469-1479
  5. Leydesdorff, L.: Can scientific journals be classified in terms of aggregated journal-journal citation relations using the Journal Citation Reports? (2006) 0.00
    1.9733087E-4 = product of:
      0.002959963 = sum of:
        0.002959963 = product of:
          0.005919926 = sum of:
            0.005919926 = weight(_text_:information in 5046) [ClassicSimilarity], result of:
              0.005919926 = score(doc=5046,freq=2.0), product of:
                0.050870337 = queryWeight, product of:
                  1.7554779 = idf(docFreq=20772, maxDocs=44218)
                  0.028978055 = queryNorm
                0.116372846 = fieldWeight in 5046, product of:
                  1.4142135 = tf(freq=2.0), with freq of:
                    2.0 = termFreq=2.0
                  1.7554779 = idf(docFreq=20772, maxDocs=44218)
                  0.046875 = fieldNorm(doc=5046)
          0.5 = coord(1/2)
      0.06666667 = coord(1/15)
    
    Source
    Journal of the American Society for Information Science and Technology. 57(2006) no.5, S.601-613
  6. Leydesdorff, L.: On the normalization and visualization of author co-citation data : Salton's Cosine versus the Jaccard index (2008) 0.00
    1.9733087E-4 = product of:
      0.002959963 = sum of:
        0.002959963 = product of:
          0.005919926 = sum of:
            0.005919926 = weight(_text_:information in 1341) [ClassicSimilarity], result of:
              0.005919926 = score(doc=1341,freq=2.0), product of:
                0.050870337 = queryWeight, product of:
                  1.7554779 = idf(docFreq=20772, maxDocs=44218)
                  0.028978055 = queryNorm
                0.116372846 = fieldWeight in 1341, product of:
                  1.4142135 = tf(freq=2.0), with freq of:
                    2.0 = termFreq=2.0
                  1.7554779 = idf(docFreq=20772, maxDocs=44218)
                  0.046875 = fieldNorm(doc=1341)
          0.5 = coord(1/2)
      0.06666667 = coord(1/15)
    
    Source
    Journal of the American Society for Information Science and Technology. 59(2008) no.1, S.77-85