Objective: This paper examines the temporal change of citations between disciplines in science. Data: 4,463 journals that were continuously recorded in the 2001-2009 Journal Citation Reports Science Edition were classified into 22 fields, and the citations between those fields were counted. Methods: Citations between the fields were normalized by the number of papers in both the citing and cited fields. The slope of the linear regression obtained from year of 2001 - 2009 was used as the change ratio of the normalized citation number. The citing-cited field pairs were extracted that show significant change in the normalized citations and also have fixed number of citations. Results / Discussion: As for the change in normalized citations between fields, 14 pairs showed the increasing tendency and 42 pairs showed the decreasing trend. Most of the field pairs showing the decreasing trend were belonged to life sciences, such as Multidisciplinary, Molecular Biology & Genetics. In those fields of life sciences, however, citations to articles published in journals other than 4,463 targeted journals increased temporally, thus cited journals were spreading. It was confirmed that the influence of the difference of scale (the number of papers) of field could be eliminated as a result of normalization.
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