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Chemical Literature (Chem 184/284) |
Lecture 9: Indexes and Abstracts
Indexes & Abstracts: Definitions
- Index -- A tool which provides access to some body of information by a "pointer" derived from the original.
- Examples of pointers: author names, subject terms, chemical formulas, cited references.
- Abstract -- A brief summary of the content of a document.
Considerations in Selecting an Index for Searching
- What subject areas does the index cover?
- Broad scope is useful for comprehensive searches, and "interdisciplinary" topics. Example: Science Citation Index covers the whole of science, engineering and medicine.
- Narrow scope may be quicker and easier to use, cover less irrelevant material and/or have specialized indexes useful to your search. Example: Catalysts and Catalysed Reactions
- What kinds of documents are covered?
- Most indexes are aimed primarily at journal articles. Examples: Expanded Academic ASAP, Web of Science.
- Others specialize in conference papers, technical reports or patents. Examples: NTIS for technical reports; Conference Papers Index for reports and conference papers; ProQuest Dissertations & Theses for dissertations.
- Some cover multiple document types. Example: Chemical Abstracts.
- How much of the world literature does it attempt to cover? Some are limited geographically.
- Example: Though both cover medical literature worldwide, MEDLINE/PubMed favors US literature; Excerpta Medica (EMBASE) favors European literature.
- Dissertation Abstracts only covers North American and European dissertations.
- Everything or just "the best"?
- Chemical Abstracts attempts to cover all of the chemical literature.
- Science Citation Index/Web of Scinece goes by the rule "20% of the journals publish 80% of the literature" and only indexes the top journals in each field, as measured primarily by citation count.
- What years does the source cover?
- Few sources do retrospective coverage, i.e. indexing the literature before the index began publication. But some do: Science Citation Index has been extended online back to 1900 (though UCSB only has access back to 1945.) Chemical Abstracts Service has now started retroactively indexing pre-1907 literature in its online database.
- Many electronic sources don't go back as far as the corresponding printed tools. That, too, has changed in many cases. In addition to the Web of Science version of Science Citation Index and the electronic versions of Chemical Abstracts (see above), the Compendex, INSPEC and BIOSIS databases, among others, now extend all the way back to the beginning of the printed indexes.
- Sometimes you only need recent years. For example, in biotechnology or particle physics, information dates quickly. Not so in synthesic chemistry, taxonomy, geology, or mathematics, however.
- How often does the index come out? Online is usually faster than print, which may be faster than CD-ROM. Since almost all indexes are available online these days, using print editions for current material is usually a bad choice.
- How much time lag between publication of the original document and its appearance in the index does the index have?
- Web of Science is very fast...since it doesn't do detailed indexing.
- May vary depending on type of document and source of document. Chemical Abstracts does rapid indexing for a set of key chemistry journals, slower processing for others. Similarly, patents from several key patent issuing authorities get rapid indexing. Technical reports and dissertations are delayed further since CAS uses secondary sources for that information.
- Sometimes an index listing can appear before the issue arrives in the library.
- To get an idea of the indexing lag, compare the publication date of the most recently issued publication of the type you are interested in to the date of the index.
- Subject indexing
- Some use keywords from document titles and/or abstracts. Example: Biological Abstracts in print and some older years of Science Citation Index use title keywords only. The Web of Science version of Science Citation Index uses title and abstract keywords. Chemical Abstracts weekly issues in print use text keywords.
- Some use standard subject headings or classification codes, like the Chemical Abstracts volume indexes or Index Medicus. Such indexes may have a thesaurus - an alphabetical listing of headings with cross-references to broader, narrower and related terms.
- Many electronic files use a combination of keyword searching and assigned subject headings or classification codes.
- Keyword indexing responds more quickly to new concepts, may be easier for quick, limited searching.
- For some documents, indexers enhance the author's title and/or abstracts with additional keywords. Used often in patents.
- Subject headings and classification codes bring related concepts together regardless of jargon; are better for browsing and comprehensive searching.
- The combination of the two provides maximum power and flexibility; in electronic forms, it lets you use keyword searching as a first step to discover the assigned headings or codes which apply.
- Author Access
- Nearly all indexes have an author index but...
- Some don't index all authors of a paper.
- Some use initials for first names (example: Science Citation Index), some use full names where available (example: Chemical Abstracts).
- Some try to bring different forms of an author's name together; most don't.
- Access points -- Specialized indexing
- Corporate source
- Useful for locating the research of a given company.
- Can be combined with author searching to distinguish authors with similar names.
- Geographic indexing -- common for biological, environmental, geological indexes.
- Genus/species indexing
- Chemical substance indexing
- A specialized form of subject indexing.
- Some index individual compounds; example: Chemical Abstracts
- Some index classes of compounds.
- Some index compounds and component elements.
- Indexing may be by name (sometimes multiple forms), chemical formula or structural feature.
- More sophisticated forms, such as structure, reaction, substructure or similiarity indexing usually are available in electronic tools only.
- Patent indexing
- Indexes by patent country and number, as well as inventor and patent assignee. Subject indexing may take advantage of classification codes in national or international use.
- Concordances relate "families" of patents from different countries.
- Citation Indexing
- Connects cited papers to citing papers.
- Can be effectively used for subject searching, based on the premise that an author only cites papers which are directly relevant to the current paper.
- Some electronic forms use co-citation techniques (e.g. Related Record searching.)
- Combining access points
- By their nature, print indexes rarely allow combination of different access points, such as author and keyword.
- Electronic indexes can allow combinations of multiple access points (and usually have more access points to begin with...)
For electronic indexes, the same considerations of interface features apply as in online catalogs. (See Lecture 3.):
- Search features -- Basic vs. advanced searching; truncation, Boolearn searching, proximity searching.
- Display features -- Short vs. long record displays; record sorting options; record marking; printing/downloading/e-mailing records; linking between records and/or to full-text sources.
- Personalization features -- Settable preferences; Stored searches and/or answer sets; Alerting services.
- Help features -- On-screen examples; In-context help; Indexed and/or searchable help screens.
We will look at the interface features of some of the major electronic databases in Lecture 8.
See Important Indexes and Abstracts in Sciences and Engineering for more details on some specific electronic indexes and abstracts and their print counterparts.
This page created by Chuck Huber (huber@library.ucsb.edu).
Updated: 01/05/08 03:15:43