In recent years we have witnessed an explosion in the production and availability of scholarly research results.  This growth is reflected in the gradual expansion of journal coverage in the Web of Science.

 
    Journal coverage in Web of Science consists of three major indexes, namely the (Science Citation Index Expanded, the Social Sciences Citation Index, and the Arts & Humanities Citation Index.  In addition, the Conference Proceedings Citation Index (formerly ISIProceedings) became an edition of Web of Science in October) 2008.

    In 2000 journal coverage in Web of Science totaled 8,684 titles.  In 2005, Web of Science covered 9,467 journals, an increase of 9%.  As of April 1, 2010 11,519 journals are covered in Web of Science, and increase of 22%.  At the level of the specific journal citation indexes the growth even more pronounced:

SCI to SCIE – 1965…2010    浠嶴CI 鏍稿績鐗堝埌SCI鎵╁睍鐗?nbsp; 1965 - 2010骞?/u>
    Lengthening the historical perspective to include the early days of the Science Citation Index (available now in print and CDROM formats only) we see the full scope of the expansion of scientific research:

    The Science Citation Index, first produced in 1965, has gradually been supplanted as the key citation index of the scientific journal literature by the Science Citation Index Expanded, the science component of the Web of Science.  In recent years especially, as the Science Citation Index Expanded has extended its reach to include the top tier Regional Journals, the gap between these two indexes has widened.  The SCIE has gradually expanded, while journal coverage in the SCI has remained relatively static:

    Selection of journals for the Science Citation Index, however, is still a carefully executed process.   The Science Citation Index (SCI) in print and CDROM is a subset of the Science Citation Index Expanded (SCIE).   All Thomson Reuters indexed science journals are covered in the SCIE.  However, because of the limitations of the physical media in which it is published, coverage in the SCI has been strictly limited to include only the highest ranked journals in each category and, as much as possible, the highest ranked journals from each country or region.  Rank is determined by Journal Impact Factor in the specific category.

    Whereas the Science Citation Index Expanded has become the world standard for search, discovery,  and for bibliometric analyses, the Science Citation Index, because of its exceptionally rigorous selection standards, is now regarded as a collection of the highest impact, most influential international and regional journals.  The selection by Thomson Reuters of a journal for coverage in the SCI, therefore, is a much sought after goal for the world’s journal publishers.  Likewise for authors, being accepted for publication in SCI-covered journals is often perceived as a high achievement (in some parts of the world?).  The reason for this perception is the objective standard for quality that the SCI represents in scholarly publishing. 

SSCI: Print and Online   绀句細绉戝寮曟枃绱㈠紩  鍗板埛鐗堜笌缃戠粶鐗?/strong>
    Journal coverage in the Social Science Citation Index, in recent years, has also differed according to the publishing medium. 

    The limited use and circulation of the print SSCI necessitates the limited expansion of its coverage whereas the SSCI in Web of Science has seen enormous growth in recent years.   This growth reflects the growing corpus of social science research worldwide and the Thomson Reuters commitment to represent the best of this scholarship in the Web of Science.
 

AHCI:  Print and Online 鑹烘湳鍜屼汉鏂囩瀛﹀紩鏂囩储寮?
    The Arts & Humanities Citation Index coverage in print is duplicated in the Web of Science.  Coverage in AHCI has grown significantly in recent years.

    Recent growth in both SSCI and AHCI is greatly influenced by new coverage of Regional Journals.  
 

Conference Proceedings Citation Index  浼氳褰曞紩鏂囩储寮?/strong>
    From 1999 to 2010 the CPCI covers over 100,000 conferences in every subject area of the sciences, social sciences and arts & humanities.  Each year the file expands by at least another 10,000 conferences.  Metadata on these conferences includes full conference information, and all cited references. 

SUMMARY:
The Web of Science, including four major citation indexes that cover 11,519 top tier international and regional journals and over 100,000 conference proceedings reflects the ongoing expansion of scholarly research and is the world’s most reliable source of information for both search and discovery purposes as well as bibliometric analysis.