Phrase-indexing

Bibliographic data, keyword phrases, index entries, general subject headings, and CAS Registry Number(s) for documents covered by Chemical Abstracts Service... 

CAS ONLINE American Chemical Society, Columbus, Ohio CAS ONLINE The Chemical Search System From Chemical Abstracts Service 1967-present CHEMICAL ABSTRACTS SERVICE Equivalent of the printed Chemical Abstraets(CA). Bibliographic data, keyword phrases, index entries, general subject headings, and CAS Registry Number(s) for chemistry-related publications in 50 languages from 150 countries. Includes worldwide patent documents. Easy crossover to the CAS CHEMICAL REGISTRY... 

Indexing differentiates between single word- and phrase-indexing. If a field is single word indexed, every single word of this field is searchable. STN calls it single terms. A word is defined as a sequence of alphanumeric characters which are separated from each other by blanks and special characters. Hyphenated words have to be searched as two words ... 

If a field is phrase-indexed entries are searchable only as a whole, so-called hound phrases by STN. This includes searching for all characters. In databases the author or inventor field is often phrase-indexed. This makes searching for names more complicated and several variations have to be requested ... 

In the field CN, proximity operators are not allowed for searching, but truncation is possible. The search term must be entered exactly as it is entered in the database record, inch brackets, hyphens and blanks. The field is phrase-indexed. There is one document for every substance. The simplest search is the search with a trade name ... 

The system does not distinguish between small and capital letters. Search terms that are misunderstandable should be entered with spaces as in the case of Co and CO. The MF field is phrase-indexed and proximity operators are not allowed for searching. 

The field Author (AU) may contain up to ten names of authors for every publication, or inventors names for patents. The field is phrase-indexed, proximity operators cannot be used. The surname comes first and given Christian names and/or initials always follow. 

Title terms contain phrase-indexed words, such as X-RAY, which have to be searched with a hyphen. 

Since mid-1992 the system allows 30 letters for the inventor s name and three initials for Christian names. The field is phrase-indexed and thus not searchable with proximity operators. 

The search for chemical compounds is processed as in the Registry File (Sect. 7.1.2). As the field Chemical Name (CN) is phrase-indexed, the entry of the search string must correspond exactly to the occurrence in the file. Preceding the query with the EXPAND command, as demonstrated in Fig. 143, will allow the precise entry to be found. 

The field Geographic Term (GT) contains the geographic data found in the Abstract (AB) and the Supplementary Terms (ST). As it is phrase-indexed, the entry of the search string must correspond exactly to the occurence in the file. The use of the EXPAND command is again advised. The file does not only mention country names, but also geographic areas like East Africa or economic areas like the OECD. There is a summary of all Geographic Terms employed in the appendix of the database manual The CIN File Database Description. 

Provides access to textual and numeric data in its databases for information retrieval and reporting needs. Features word proximity and phrase searching thesaurus and index. 

A few comments on the layout of the book. Definitions or common phrases are marked in italic, these can be found in the index. Underline is used for emphasizing important points. Operators, vectors and matrices are denoted in bold, scalars in normal text. Although I have tried to keep the notation as consistent as possible, different branches in computational chemistry often use different symbols for the same quantity. In order to comply with common usage, I have elected sometimes to switch notation between chapters. The second derivative of the energy, for example, is called the force constant k in force field theory, the corresponding matrix is denoted F when discussing vibrations, and called the Hessian H for optimization purposes. 

The trend described by the Late - Early rule can be phrased in terms of the expected inclusion relations of those electron density threshold intervals where the density domains of individual nuclei exist as separate entities. A given set of the nuclei of type A is ordered according to the increasing effective electronegativity of the neighbor nuclei BOO involved in the first merger of each of the density domains of nuclei of type A. This ordering is represented by the index k ... 

The web is the most popular Internet application. It allows easy links to information and files which may be located on computers anywhere in the world. The WWW allows access to millions of home pages or websites , the initial point of reference with companies, institutes and individuals. Besides their own text and images, these contain hypertext links , highlighted words or phrases that you chck on to take you to another page on the same website or to a completely different site with related subject material. Certain sites specialize in such links, acting like indexes to other websites these are particularly useful. 

Entries under a formula heading consist of the formula, in bold-faced type the name as it has been used in the subject index, in lightface roman type—that part of the entry in this type is the exact equivalent of the formula given occasionally a modifying phrase or word in italics which represents that part of the compound indexed not represented in the formula, as "Na salt or di-HCl and the column-fraction reference to the abstract proper. 

A chemical name should not be a phrase. In the early days of chemistry prior to the general acceptance of atomic and subsequent theories, many substances were characterized by clumsy and inconvenient expressions derived from various associations. Examples of these would include "oil of vitriol, "butter of antimony, "cream of tartar, "flowers of zinc, "liver of sulfur, "milk of lime, "sugar of lead, "spirits of nitre, etc. Very possibly de Morveau anticipated the probability that the substances designated by such names would occasionally, by careless classification, become indexed under "oil "butter, "cream, "flowers, "liver, "milk, and "sugar, and thus be withdrawn from the chemist to the kitchen. Despite his warning, however, chemical names were frequently rendered as phrases for the next one hundred years and such forms as "acetate of sodium, "peroxide of hydrogen, and "permanganate of potash have only recently disappeared from texts and books of reference. 

In this paper indexing is defined as a system which provides leads to needed information by the three steps—selection of appropriate terminology (most of which is usually found in the material being indexed) modification of the selected terms by suitable words and phrases and alphabetical arrangement of the selected terms and their modifications. 

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