Cross references, Chemical Abstracts

A computer search of volumes 70-95 of Chemical Abstracts using the keyword Pyrazine resulted in more than 2600 references, and, after removal of fused pyrazine systems and cross-referencing the remaining references, this number increased to approximately 7000 in total. When the benzopyrazines quinoxaline and phenazine were added the number of references was in excess of 10 000, all of which might be considered to be relevant to a chapter devoted to pyrazines and their benzo analogues. 

The material presented here is a compilation obtained by critically screening approximately 20,000 references from the literature (mainly from the Petroleum Abstracts Data Base and Patent Data Bases). Only materials that are accessible to the public have been included. The literature was screened from a chemist s point of view. Unfortunately several papers and patents did not disclose the chemical nature of the additives that are proposed for certain applications. In most cases it was not possible to learn the components by looking up cross-references and other sources. Papers of this kind are useless and have been omitted from the reference list. Research and procedures that are obviously not working, as well as wonder additives that are supposedly good for everything you can imagine, have also been left out. 

A single unstable compound of known composition is placed in the main first volume and is located on the basis of its empirical molecular formula expressed in the Hill system used by Chemical Abstracts (C and H if present, then all other element symbols alphabetically). The use of this indexing basis permits a compound to be located if its structure can be drawn, irrespective of whether a valid name is known for it. A representation of the structure of each compound is given on the third bold title line while the name of the compound appears as the first bold title line. References to the information source are given, followed by a statement of the observed hazard, with any relevant explanation. Cross-reference to similar compounds, often in a group entry, completes the entry. See Trifluoroacetyl nitrite p. 244. 

A check of recent Chemical Abstracts indexes reveals, however, that many of the subject entries for bicyclic terpene hydrocarbons are listed under the common terpene names, and frequently the corresponding bicyclo names are not used either as synonym names or cross references. 

Chemical Abstracts, Subject Index, 40 (1947), cross reference to "Norcamphene. See... 

In Chemical Abstracts, abstracts on the vitamin itself are indexed under the letter used to designate that vitamin, but derivatives are indexed under the chemical name of the vitamin. For example, vitamin Bi is listed as such under vitamin, but the ethyl derivative is listed under aneurine, ethyl. More about indexing and the difficulties involved appears in Crane s paper. A beautiful Job of cross indexing is found in Chemical Abstracts. The searcher should follow up all of these cross references, and on some subjects should add a few of his own topics, particularly where a broad field is being covered. For example, in extensive literature search on the agglomeration of fine particles the following subjects were covered in Chemical Abstracts ... 

An adequate supply of cross references strongly increases the usefulness of an index, or at least facili in its use. Chemical Abstracts maintains a growing master file of approximately 50,000 cross references which are used as needed, which help in the indexing work, and which are applied both in regular form and in inverted form at editing time to guarantee consistency of the indexes. 

In this bibliography we have assembled the references dealing specific with H bonds. We have not tried to include every casual mention of this 1 Chemical Abstracts, plus cross checking of review article reference lists, wer pte main sources, and reasonable completeness is claimed through the year 1956. During 1957 and 1958 some additional entries were inserted but without comprehensive search. 

The users of an abstract journal have a right to expect good nomenclature in the make-up of abstracts and indexes. It is the policy of Chemical Abstracts to accept and use the nomenclature as recommended by the Nomenclature, Spelling, and Pronunciation Committee of the American Chemical Society and as approved by the International Union of Pure and Applied Chemistry. A special effort is made to use good, consistent, systematic nomenclature in the subject indexing of Chemical AbstraHs with an adequate supply of cross references. These subject indexes are sometimes used as a source of nomenclature information in addition to their use as a key. 

Cross references, abundantly used in the subject indexes to Chemical Abstracts serve not only to guide the index user from place to place as a help in making his search a thorough one, but also to overcome some of the limitations of words as an exact and definitive medium of expression. The cross references in the indexes to Chemical Abstracts are put there for use, for more use than they sometimes get by inexperienced index users. 

The purpose of this section is to provide a brief review of the methods and techniques commonly used in the elemental analysis of humic substances with special emphasis placed on areas that may cause difficulties in their analysis. There are few specific references to methods of elemental analysis of humic substances. A computerized search of Chemical Abstracts since 1966 revealed no references to techniques of elemental analysis when elemental analysis was cross-referenced with humic or fulvic acid materials. In general, the methods of analysis have been developed to be applicable to a wide range of organic materials. However, it should be pointed out that most methods have been validated on the basis of the analysis of stable, nonhy-groscopic, nonvolatile, pure compounds and not heterogeneous mixtures. 

Cross-references are inserted in the index for many common names and for some systematic names. Trademark names appear in the index. Names that are incorrect, misleading, or ambiguous are avoided. Formulas are given very frequendy in the text to help in identifying compounds. The spelling and form used, even for industrial names, follow American chemical usage, but not always the usage of Chemical Abstracts (eg, coniine is used instead of (S)-2-propylpiperidine, aniline instead of benzenamine, and acrylic acid instead of 2-propenoic acid). 

In view of these changes in practice, it has seemed advisable to make entries or cross references under all names used in the Vol. I index and under specific names for compounds entered under group headings. Thus, two or more entries may be made for one compound in these and a few other Cases. As in Chemical Abstracts indexes, for example, two entries are made for compounds having two cations. 

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