Search techniques chemical databases

Bures, M. G., Searching Techniques for Databases of Three-Dimensional Chemical Structures, 21, 467. 

Searching Techniques for Databases of Three-Dimensional Chemical Structures... 

M. G. Bures, Y. C. Martin, and P. Willett, Tbp. Stereochem., 21, 467 (1994). Searching Techniques for Databases of Three-Dimensional Chemical Structures. 

The reaction database compiled on Biochemical Pathways can be accessed on the web and can be investigated with the retrieval system C ROL (Compound Access and Retrieval On Line) [211 that provides a variety of powerful search techniques. The Biochemical Pathways database is split into a database of chemical structures and a database of chemical reactions that can be searched independently but which have been provided with efficient crosslinks between these two databases. 

The previous sections have summarized the basic techniques available for searching chemical databases for specific types of query. Another important database application is compound selection, the ability to select a subset of a database for submission to a biological testing program. The selection procedure can be applied to in-house databases, to externally available compound collections, or to virtual libraries, that is, sets of compounds that could potentially be synthesized. 

Chemithon film sulfonating-sulfating systems, 23 544-547 Chemithon reactor, 23 544 Chemoinformatics, 6 1-25 chemical databases, 6 19-20 chemical information retrieval, 6 6—19 chemical information storage, 6 2-6 chemical library design, 6 17-18 clustering techniques, 6 16-17 conformational flexibility, 6 10-11 conformational searches, 6 10-11 data analysis and preparation, 6 20-21 data searching, 6 6-19 diversity searches, 6 14-18... 

The new subset-selection methods draw heavily upon the techniques that are used for searching and clustering databases of two-dimensional (2D) and three-dimensional (3D) chemical structures [1-4], These techniques were... 

There has been a rapid proliferation of commercial search interfaces, such as DataStar and STN International. STN may deserve special mention since it is a science information service operated by Chemical Abstracts Service (CAS) in North America, Fachinformationszentrum-Karlsruhe (FIZ-K) in Europe, and Japan Association for International Chemical Information (JAICI) in Japan. It is available as online subscriber access to 220 databases (STN Express) and as web access (STN on the Web for experienced searchers and STN Easy for infrequent searchers). See www.cas.org/stn. html and/or www.stn-international.de/. Since Internet search techniques depend on the interface available, no detailed explanations are given here. There are several published guides to database searches for chemical and physical properties, but the situation is evolving rapidly and it is recommended that you consult a reference librarian for information about the current situation concerning search interfaces at the library you use. 

In the simplest sense, searching chemical information consists of (IXinding structures or reactions that meet the chemist s search criteria and/or (2) finding data that meets the search criteria. Data searching (numbers and text) is a well-established informatics activity, supported by spreadsheets, word processors, and relational database systems. Chemical structures and reactions are a unique form of data. Searching for full or partial matches to structures, models, and reactions requires highly specialized databases and search techniques. 

In a broad sense, the term computational chemistry includes several fields such as quantum chemistry, statistical molecular mechanics, molecular modeling, approaches based on graph invariants, molecular graphics and visualization, evaluation of experimental data in X-ray crystallography, NMR spectroscopy, and, in general, spectroscopic techniques moreover, in this broad sense, analysis, exploration, and modeling performed by chemometrics on experimental data, searching for structure-response correlations, information retrieval from chemical databases, and expert chemical systems are also included in computational chemistry, as constitutive parts of —> chemoinformatics. 

Technique 29, Section 29.11). You may need to search a computerized database to get the necessary information, or you may be able to find it in the Aldrich Catalog Handbook of Fine Chemicals, issued by the Aldrich Chemical Company. Current issues of this catalogue include listings of substances by CAS number. In your report, you should also report the relative percentage of the substance in the tablet extract. Finally, your instructor may also ask you to include the "quality" parameter from the "hit list." If possible, determine which components have antihistamine activity and which ones are present for another purpose. The Merck Index may provide this information. 

Those who choose to search a private database such as one created with MDL s ISIS must learn a different set of search techniques. ISIS /Draw, the ISIS chemical drawing package, is a presentation package for polymer structures. ISIS/Draw allows scientists to draw polymer structures with ease and speed, and then to search and share them. Researchers also have the enhanced capability of accessing 2D and 3D databases, with a wide range of search options and a link to global data. ISIS/Draw includes full annotation capabilities, which enable researchers to label collections of atoms or bonds with related function or process information (6). 

There are at least three reasons why one might wish to apply cluster analysis to a large chemical database. Hie simplest approach is to cluster the output resulting from a substructure search that retrieves too many molecules, to enable the searcher to gain a rapid overview the extent of the structural heterogeneity in the retrieval list. Second, one may wish to duster an entire database so that individual dusters can be retrieved and examined by more computationally expensive procedures this can be particularly appropriate for structure—activity techniques that require homogeneous subsets of molecules from the main database. Finally, there has been substantial interest in the use of... 

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