Support : Dialog Search Aids : File 399: /DE, /DF and GS= Fields

The Descriptor (/DE, /DF) and General Subject Index Heading (GS=) Fields in CA SEARCH® (File 399)

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The Descriptor field in CA SEARCH is constructed by Dialog from the CA General Subject Index entries and CA Chemical Substance Index entries created by CAS for each volume of Chemical Abstracts.

Descriptors based on General Subject Index Heading entries. Descriptors are presented in statement format and consist of the CA General Subject Index Heading, which, if it is very broad, may be made more specific by the heading subdivision. With or without subdivision, a General Subject Index Heading may be further subdivided by the free text Index Modification. DIALOG displays Descriptor statements in the following general format:

General Subject Index Heading, subdivision...
 Index Modification

Ellipses signify the end of each General Subject Index Heading entry. Index Modifications are always indented under the General Subject Index Heading(s) to which they apply. Several General Subject Index Headings may share the same Index Modification. The following examples illustrate the various forms of CA General Subject Index Headings:

This format for Descriptor statements is used to minimize redundancy in displayed records. To permit the full range of proximity searching, the Index Modification is internally linked to each of the General Subject Index Headings it modifies. Use the (S) operator to retrieve search terms from the same Descriptor statement, e.g.,

?S CARBONYLS(S)CATALYST?/DE
           18829  CARBONYLS/DE
          463359  CATALYST?/DE
     S1    1644  CARBONYLS(S)CATALYST?/DE
?T 1/DE


1/DE/6
DIALOG(R)File 399:(c) 2000 American Chemical Society.
 All rts. reserv.

  DESCRIPTORS:
Oxidation catalysts...
    aerobic oxidn. of .alpha.-hydroxy carbonyls 
    catalyzed by trichlorooxovanadium
Ketones,reactions...
    .alpha.-hydroxy; aerobic oxidn. of .alpha.-hydroxy 
    carbonyls catalyzedby trichlorooxovanadium
Ketones,preparation...
    diketones; aerobic oxidn. of .alpha.-hydroxy 
    carbonyls catalyzed by trichlorooxovanadium
  CAS REGISTRY NUMBERS:
119-52-8  119-53-9  134-81-6P  951-88-2P  
    1226-42-2P  1801-77-0  3008-41-1P 3457-46-3
    P  4254-20-0  4358-87-6  4443-63-4P 4443-65-6  
    4727-18-8 6790-29-0  7727-18-6  10373-78-1P    
    10373-81-6 15206-55-0P  19025-38-8 23427-69-2P      
    32153-87-0P 41172-04-7P 55409-09-1  73634-76-1 
    245651-31-4  245651-32-5P aerobic oxidn. of 
    .alpha-.hydroxycarbonyls catalyzed by 
    trichlorooxovanadium

?S KINETICS(1N)HYDROGENATION(S)PALLADIUM/DE
          427666  KINETICS/DE
           82083  HYDROGENATION/DE
           59964  PALLADIUM/DE
      S1     568  KINETICS(1N)HYDROGENATION(S)
                        PALLADIUM/DE
?T/DE


 1/DE/1
DIALOG(R)File 399:(c) 2000 American Chemical Society.
 All rts. reserv.

  DESCRIPTORS:
Hydrogenation catalysts... Hydrogenation kinetics
    ... Hydrogenation...effect of hydrogen concn. 
    on propyne hydrogenation over carbon-supported 
    palladium  
    -catalyst under continuous-flow conditions
  CAS REGISTRY NUMBERS:
74-99-7  effect of hydrogen concn. on propyne  
    hydrogenationover carbon-supported palladium 
    catalyst under continuous-flow conditions
7440-05-3  7440-44-0  uses, effect of hydrogen concn. 
    on propyne hydrogenation over carbon-supported 
    palladium catalyst under continuous-flow conditions

Qualifiers and categories. Some General Subject Index Headings represent classes of chemical substances, e.g., CARBONYLS, HYDROCARBONS, AMINO ACIDS, etc. Because these General Subject Index Headings convey substance information, the subdivisions that are used with highly posted Chemical Substance Index entries may also be used with highly posted classes of chemical substances, e.g., HYDROCARBONS,POLYMERS or AMINO ACIDS,ANALYSIS.

CAS uses the following designated "standard qualifiers" and "standard categories" with highly posted General Subject Index Headings that represent classes of chemical substances:

The "standard qualifiers" used as subdivisions are topic oriented --

¹Before the 13th Collective Index Period (volume 116), these qualifiers are the single qualifier, "uses and miscellaneous".

The "standard categories" used as subdivisions refer to chemical derivative types:

Additional information about standard qualifiers is available in New and Revised Indexing Terms - 1992, and in the CA Index Guide available from Chemical Abstracts Service.

Index Modification. The free text Index Modification may include standard CAS abbreviations, as illustrated in the above examples of Descriptor statements. Although abbreviations end in a period in displayed records, they are searched without punctuation.

The DIALOG system uses the related term feature to incorporate cross references in the Basic Index to frequently used abbreviations. To verify the presence of an abbreviation for a term, use the EXPAND command with the term enclosed in parentheses, e.g., EXPAND (AQUEOUS). If an abbreviation is shown, use both the term and its abbreviation in the search strategy to ensure comprehensive results.

Use the (S) operator to link any word or phrase from the Index Modification with a word or phrase from a General Subject Index Heading for precise retrieval, e.g.,

?S CARBONYLS(S)CATALYST?(S)POLYMN
           20686  CARBONYLS
          478793  CATALYST?
          185847  POLYMN  (POLYMERIZATION)
      S2      70  CARBONYLS(S)CATALYST?(S)POLYMN
?T/DE/5

2/DE/5
DIALOG(R)File 399:(c) 2000 American Chemical Society.
All rts. reserv.

  DESCRIPTORS:
Transition metal carbonyls...
    catalyst, for polymn. of silane tetramines
Polymerization catalysts...
    lithium aluminum hydride and transition metal  
    carbonyls, for silane tetramines to silazanes
Ceramic materials and wares... Synthetic fibers,silicon 
    nitride... manuf. of, by pyrolysis of silazanes
Silazanes...
    manuf. of, from silane tetramines
  CAS REGISTRY NUMBERS:
16853-85-3  catalyst, for polymn. of silane tetramines
10026-04-7  condensation of, with methylamine
12033-89-5P  preparation, manuf. of, by pyrolysis of 
silazanes
31978-09-3P  61919-86-6P  prepn. of
34089-90-2P  prepn. of, by thermal polymn., and 
pyrolysis to ceramics

Related terms based on the CA Index Guide. Most of the General Subject Index Headings listed in the CA Index Guide include cross-references to related, broader, or narrower General Subject Index Headings. These cross-references are incorporated online though the DIALOG related terms feature. CAS reviews and revises General Subject Index Headings for each collective index period. Therefore, over the time span of the database, some related terms may have been added, while others may have been deleted. If a term is EXPANDed in File 399, the related terms from the current Collective Index Period are displayed, plus the current CA Section codes, if that term is also a Section Heading. If, however, a term is EXPANDed in any one of the individual Collective Index Period files (Files 308 - 314), the related terms and CA Section codes appropriate for that Collective Index Period are displayed. For example,

In File 399:

?E (CATALYSTS)


Ref   Items Type  RT  Index-term
R1   443902       40 *CATALYSTS
R2      876   R    9  ADDITION REACTION CATALYSTS
R3       36   R    3  ALKENYLATION CATALYSTS
R4     1152   R    7  ALKYLATION CATALYSTS
R5      148   R    1  AMIDATION CATALYSTS
R6      411   R    2  AMINATION CATALYSTS
R7    57837   R    9  CATALYSIS
R8     1663   R    1  CATALYST SUPPORTS
R9       55   R    1  COAL GASIFICATION CATALYSTS
R10     217   R    1  COAL LIQUEFACTION CATALYSTS
R11     625   R    5  CONDENSATION REACTION CATALYSTS
R12     856   R    3  COUPLING REACTION CATALYSTS

         Enter P or PAGE for more

Note there are 29 additional terms not shown in the EXPAND display above.

In File 308:

?E (CATALYSTS)


Ref   Items Type  RT  Index-term
R1    34925        2 *CATALYSTS (SEE ?IGNOTE)
R2    15407   R    4  CATALYSIS
R3      959   R    2  PROMOTERS

Scope notes based on the CA Index Guide. Some General Subject Index Headings are used to index a document only under special conditions that are described in detail in assumption notes or index heading notes in the CA Index Guide. Because these explanations are too detailed to incorporate online, Dialog has added short online scope notes to indicate that an explanatory note for the term exists in the CA Index Guide and that the role of the term in the search strategy should be carefully considered. The four scope notes used online and their meanings are summarized below. To view the entire explanation of the notes online, enter the appropriate term, e.g., ?BROAD.

Indexing and Searching of Descriptor Statements based on General Subject Index Heading entries. For maximum flexibility in searching, each General Subject Index Heading with subdivision is indexed as a whole phrase in the Basic Index. The General Subject Index Heading without its subdivision is also indexed as a whole phrase in the Basic Index and in the GS= index. Individual meaningful words in the heading, subdivision, and the Index Modification are indexed in the Basic Index.

Use a General Subject Index Heading with subheading to get precise search results, when precision in more important than comprehensiveness. For example, SELECT 'CATALYSTS AND CATALYSIS,PHASE-TRANSFER' retrieves some highly relevant documents, but omits records that are indexed to the General Subject Index Heading CATALYSTS AND CATALYSIS, but have the "phase-transfer" concept in another part of the record.

For a broader search, use a General Subject Index Heading without a subdivision and retrieve all records with that General Subject Index Heading regardless of the subdivision. For example SELECT 'CATALYSTS AND CATALYSIS' or SELECT GS='CATALYSTS AND CATALYSIS' retrieves records on catalysis, including those on phase-transfer catalysis.

From the beginning of the 14^th CIP (beginning with Volume 126), the CATALYSTS AND CATALYSIS General Subject Index Heading has been split into two General Subject Index Headings, i.e., GS=CATALYSIS and GS=CATALYSTS. In addition, the heading GS=PHASE TRANSFER CATALYSTS is now in use and GS=PHASE TRANSFER POLYMERIZATION CATALYSTS has also been used sparingly. Thus, depending on the aim of the search to be performed, the entire time span of the file can best be covered using a Basic Index search with proximity operators, e.g.,

?S CATALYSTS(S)PHASE(W)TRANSFER/DE
          443483  CATALYSTS
          320565  PHASE/DE
          271267  TRANSFER/DE
      S2    4535  CATALYSTS(S)PHASE(W)TRANSFER/DE
?T2/DE/50

2/DE/50
DIALOG(R)File 399:(c) 2000 American Chemical Society. 
All rts. reserv.

  DESCRIPTORS:
Addition reaction catalysts...
    phase transfer; synthesis of p-methoxyphenylglycolic
     acid by phase transfer catalysis with 
     triethylbenzylammonium chloride
  CAS REGISTRY NUMBERS:
67-66-3  123-11-5  reactions, synthesis of 
    p-methoxyphenylglycolic acid by phase transfer 
    catalysis
56-37-1  10502-44-0P  synthesis of 
    p-methoxyphenylglycolic acid by phase transfer
    catalysis

Note also that with a Basic Index search, the entire phrase may occur in the Index Modification portion of the Descriptor statement.

Descriptors based on Chemical Substance Index entries. Descriptors based on Chemical Substance Index entries represent the chemical substance by its CAS Registry Number and include the free text Index Modification. The Index Modification portion of the Descriptor statement is searchable with the /DE suffix. The general format of substance Descriptors is similar to general subject Descriptors. Each CAS Registry Number is followed by an Index Modification. Several CAS Registry Numbers may share the same Index Modification. Use (S) proximity to link a word or phrase from the Index Modification with a CAS Registry Number, e.g.,

?S RN=79-21-0(S)SPECTROPHOTOMETRY
           2576  RN=79-21-0
           47225  SPECTROPHOTOMETRY
      S6       2  RN=79-21-0(S)SPECTROPHOTOMETRY
?T/DE

 6/DE/1
DIALOG(R)File 399:(c) 2000 American Chemical Society. 
All rts. reserv.

  DESCRIPTORS:
Acids,peroxy,analysis... Carboxylic acids,peroxy,
    analysis... detn. and adjustment of, in solns., 
    by spectrophotometry
Bactericides, Disinfectants, and Antiseptics,
   industrial... per acid detn. and adjustment 
   in solns. of, by spectrophotometry
Spectrochemical analysis,spectrophotometric...
    per acid detn. in solns. by
  CAS REGISTRY NUMBERS:
79-21-0  detn. and adjustment of, in solns., by 
spectrophotometry
7553-56-2  7722-84-1  uses and 
     miscellaneous, in detn. and adjustment of per acids
     in solns. by spectrophotometry.

Frequently indexed substances. Approximately 850 frequently indexed CAS Registry Numbers also include a standard qualifier between the CAS Registry Number and the Index Modification. The standard qualifiers are the ones listed above for General Subject Index Headings. Use (S) proximity to link the qualifier and CAS Registry Number, e.g.,

?S RN=50-00-0(S)BIOLOGICAL(W)STUDIES
           46186  RN=50-00-0  (SEE ?IGNOTE)
         2516736  BIOLOGICAL
         2488335  STUDIES
      S7    7951  RN=50-00-0(S)BIOLOGICAL(W)STUDIES
?T/DE

7/DE/2
DIALOG(R)File 399:(c) 2000 American Chemical Society. 
All rts. reserv.

  DESCRIPTORS:
Antibacterial agents... Spirulina...
    redn. of bacterial load in lab. scale open Spirulina
     culture by different disinfectants
  CAS REGISTRY NUMBERS:
50-00-0  64-17-5  64-19-7  biological studies, 
    redn. of bacterial load in lab. scale open Spirulina 
    culture by different disinfectants

Searching Descriptors. As illustrated above, the General Subject Heading part of the Descriptor can be searched as a complete phrase or by individual words of the phrase using proximity operators. The Index Modification portion of the Descriptor can be searched by individual words using proximity operators. Searching by words with proximity operators is recommended to ensure that retrieval can be from anywhere within the entire Descriptor statement.

Segmentation. Algorithmic segmentation of chemical substance terms in the Descriptor field provides additional search terms. For details, please see the separate document on Chemical Substance Names in CA SEARCH.

Un-segmented Descriptors. Use the /DF suffix to search a term as a complete, unsegmented Descriptor. For example SELECT BENZENE/DF retrieves records in which the Descriptors refer to the substance benzene rather than a substituted benzene. Use the /DF suffix also with a term that contains segments, but could also be a recombined term from a longer chemical name. For example SELECT CHLOROBENZENE/DF retrieves records in which the Descriptors refer to the substance chlorobenzene, but generally excludes those records that contain Descriptors that refer to dichlorobenzene, trichlorobenzene, etc.