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Exact match search

The simplest type of structure search is the identity, or exact match, search. Testing a pair of explicit structures for identity is a problem that has been solved, and for which efficient algorithms now exist [4]. Even between explicit structures, identity comparison can become complicated when issues such as tautomerism, oligomerization, and idiomatic differences in representation (Fig. 5) are considered. [Pg.271]

Before finally storing the structure in the database, the registration program may search the database for some level of match to the input structure or reaction, and skip the registration if it is a duplicate. This is sometimes termed "deduplication" through "exact match" searching. There is usually some redundancy in chemical databases, and to save search time and disk space, most companies do not store duplicate structures or reactions, but rather store pointers to them. [Pg.378]

Exact Match Searching. Here, the chemist has a particular structure (or reaction) that he wishes to find in the database. The structure/reaction is drawn using a drawing program and then passed to a search program. The program submits the query to the... [Pg.379]

Deduplication. When registering into a chemical structure database, the process of finding whether the given structure already exists in the database. This usually involves performing an exact match search with the given structure as the search query. Note that the definition of exact match may vary with the database, and it may even be configurable. For example, some databases may consider tautomers to be acceptable as exact matches, whereas others may require a more strict definition. [Pg.403]

Exact Match Search. One type of structure searching in which a query molecule is searched for in a database of structures. To exactly match the query, the target structure must be topologically identical and not be a substructure or superstructure of the query. [Pg.403]

Flexmatch Search. Term used in MDL structure searching to allow "relaxed" exact match searching of structures. One can specify, for instance, that everything must match except bond orders, or stereochemistry, or valence at atom centers, etc. By turning on or off various flags, one can for a given structure query, retrieve isomers of various types, salts of a the structure, or instances of the structure that may contain different values of certain types of attached data. [Pg.404]

The major capabilities of chemical information retrieval today are formula searches, substructure searches, exact match searches, and sequence match, homology, and subsequence searches. (Name, textual, and data searches are ignored in this note, as essentially belonging to the realm of text and data retrieval.)... [Pg.10]

Exact match searching can also take into account the "phase shift possibility of SRUs. The choice of the crossing bonds for any SRU is arbitrary. While the bonds are usually chosen to correspond to those formed in the polymerisation reaction, such a choice is not required. The searching algorithm used has been developed in a way that does not require the same choice of crossing bonds in the query and database structure. [Pg.225]

With these features, all of the structures depicted in Figure 2 will find each other in an exact match search. [Pg.226]

By definition, any molecule compared to itself has a similarity value of 100. In this sense, a similarity search can be viewed as a fuzzy exact match search. [Pg.400]

Once the query has been entered, the search for the compound can be executed with an exact match or a substructure search. All resulting matches, up to 10 000,... [Pg.244]

When no explicitly correct force constant is found, HyperChem proceeds to stage two and finally to stage three. In stage two, you can use wildcards to relax the explicitness of the match between the atom types of the torsion in question and the available MM-t parameters. In the torsional case, as many as three searches of the mmp.par file are performed. If the exact match between A-X-Y-B and entries in mmp.par fails, then a search in mmp.par looks for an entry labeled, -X-Y- where is the designation for wildcard, don t-care, any-atom-type, unknown, etc. This search looks... [Pg.205]

In our example, EC book and Empath find an exact match to HMG-CoA reductase. The Empath link shows the metabolic step that the enzyme catalyzes (Figure 10.5 [50]). The reaction is between S-3-hydroxy-3-methylglutaryl-CoA and Mevalonate. The step summary on the right side of the chart image shows activation and regulation of the enzyme, its biological scope, direction, reversibility and stoichiometry. A pathway search... [Pg.259]

If one s purpose is to determine only the presence or absence in a data base of a specific structure, this can be accomplished with the search option IDENT , as is shown in Figure 11. This program hash-encodes the query structure connection table and searches through a file of hash-encoded connection table for an exact match. The search, which is very fast by substructure search standards, has been designed specifically for those users who, to comply with the Toxic Substances Control Act [26l have to determine the presence or absence of specific compounds in Environmental Protection Agency files. [Pg.271]

NCI-3D database - Search the NCI-3D database of over 126,000 compounds from ChemWeb.com via a substructure, similarity, or exact match query on the chemical structure. [Pg.226]

The other widely used program to search a database is called BLAST [57, 58]. BLAST follows a similar scheme in that it relies on a core similarity, although with less emphasis on the occurrence of exact matches. This program also aims at identifying core similarities for later extension. The core... [Pg.59]


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See also in sourсe #XX -- [ Pg.378 , Pg.379 , Pg.380 , Pg.403 ]

See also in sourсe #XX -- [ Pg.378 , Pg.379 , Pg.380 , Pg.403 ]




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