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...00 journals (Leydesdorff, 2006). Most researchers have therefore focused on chunks of the database or used seed journals for the collection of a sample (Doreian & Farraro, 1985; Tijssen et al., 1986; =-=Leydesdorff, 1986-=-). Boyack et al. (2005) used the VxInsight algorithm (Davidson et al., 1998) in order to map the whole journal structure as a representation of the structure of science. 3 However, the journal set rem...

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...on that journals can be grouped either using the ISI subject categories (e.g., Leeuwen & Tijssen, 2000; Morillo et al., 2003) or on the basis of clustering citation matrices (Doreian & Farraro, 1985; =-=Leydesdorff, 1986-=-; Tijssen et al., 1987). 5sBefore one can delineate groups of journals in “interdisciplinary” fields, one would need an indicator of “interdisciplinarity” at the level of individual journals. To what ...

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...zel & Schubert, 2003). Alternatively, researchers have focused on local contexts of journal sets and the optimization of the delineation of specialties in a bottomup approach (Doreian & Fararo, 1985; =-=Leydesdorff, 1986-=-, 1987; Tijssen et al., 1987). For example, Leydesdorff & Cozzens (1993) developed an optimization procedure that stabilizes approximations of eigenvectors of the network as representations of special...

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...an be distinguished from its cognitive mapping (Frenken et al., 2009; Jones et al., 2008; Small & Garfield, 1985). The sciences can be mapped cognitively, for example, in terms of journal maps (e.g., =-=Leydesdorff, 1986-=-; Tijssen et al., 1987), co-citations (Small & Griffith, 1974; Small, 1999), or co-words (Callon et al., 1983). Using techniques such as multi-dimensional scaling (e.g., Kruskal & Wish, 1978; Borgatti...

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...linary structure of science (Narin, Carpenter, & Berlt, 1972). Journal–journal citations have also been used in scientometric mapping by many authors (Carpenter & Narin, 1973; Doreian & Fararo, 1985; =-=Leydesdorff, 1986-=-; Tijssen, de Leeuw, & van Raan, 1987). More recently, Leydesdorff and Cozzens have also used these journal mappings to indicate change in science (Leydesdorff & Cozzens, 1993). The generalized biblio...

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...basis of the information contained in a similarity matrix (or a visualization thereof). Using MDS, one previously had to pencil groupings and relations into the resulting visualizations of positions (=-=Leydesdorff, 1986-=-; Leydesdorff & Cozzens, 1993). Network visualization programs, however, have the advantage above traditional MDS that the links, partitions, and clusters can be visualized by the software. Ahlgren et...

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...ross fields of science Since the 1980s scientometricians have tried to use the grand matrix of aggregated journal– journal citations for the delineation of fields of science (Doreian and Fararo 1985; =-=Leydesdorff 1986-=-; Tijssen et al. 1987). This matrix can be constructed from the data in the Journal Citation Reports (JCR) which have been available (in print) since the mid-1970s. However, the emphasis remained init...

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...c journals using JCR citation information.A variety of techniques for analyzing J-J citation relationships have been reported in the literature to cluster scientific journals (Doreian & Fararo, 1985; =-=Leydesdorff, 1986-=-; Tijssen, De Leeuw, & Van Raan, 1987). For example, by applying the notion of structure equivalence to analyze a small set of journals, Doreian and Fararo have delineated a set of blocks, which conta...