Structure query operators

Readers who are familiar with the MDL database should not be surprised to see MDL s structure query operators such as sss, molsim, and flexmatch. The CompoundMapper s StatementSource objects use ChemDBQueryBuilder to append these structure search operators to the structure search SQL statements. Take the substructure search as an example. In CompoundMapper, we have an inner class FindBySubstructure whose getSql() method is as follows ... 

The trained counterpvopagation network is then able to predict the spectrum for a new structure when operating as a look-up table (see Figure 10.2-9) the encoded query or th.c input structure is input into the trained network and the winning neuron is determined by considering just the upper part of the network. The neuron points to the corresponding neuron in the lower part of the network, which then provides the simulated IR spectrum. 

By clicking the appropriate buttons on the form, the user can combine molecular structure queries of sample, CSP and solvent, using operators AND, OR, NOT with data queries in one search. A query for the search of chiral separations of alpha-aromatic acids on any polysaccharide phases coated on silica gel providing an alpha value superior to 1.2 is shown in Eig. 4-4. 

Data storage and querying are the most fundamental requirements of all informatics systems. Thanks to the Oracle Extensibility Framework (a.k.a. Oracle Data Cartridge Technology), chemical structure data can be stored and queried using direct SQL and special query operators, such as substructure search, flexmatch search, similarity search, and formula search. Also, some indexing techniques make these otherwise slow searches fast. Detailed discussions about these databases and cartridges are beyond the scope of this book. Please refer to the vendor s website and product documentation for more information. 

The problem facing the enterprise as whole is that the proliferation of distributed systems may result in different database management systems. The use of so-called relational models and the structure query language (SQL) for data access and retrieval will simplify the interface problems. If the proper software is used, these distributed databases will appear as if they were a single information source. A user will be able to get the information he or she needs without having to know where the data are stored. Furthermore, such software will run under different types of network protocol, media, and operating systems. 

REACCS is organized into six operational modes MAIN and BUILD, which are used to draw molecular structures, build reactions, and construct graphic queries and SEARCH, VIEWLIST, PLOT, and FORMS, which are used to create custom forms to display data associated with reactions and molecules. Each of the modes provides a characteristic menu and a set of options, which normally perform tasks that relate to the general function of that mode. 

In addition to investigations by mere structure overlapping methods and retrieval of three-dimensional substructures, there have been studies focused on developing an automated operation for recognizing common substructures, which takes into account the three-dimensional geometry of the molecules [49-54]. These approaches are greatly different from conventional one in that the designation of a query structure is not required. 

Field. In database terminology a column of data in a table. Fields are commonly selected in searches of the database, such as "SELECT MOLSTRUCTURE, MOLWEIGHT FROM MOLTABLE WHERE SSS(MOLSTRUCTURE, query.moT)=l AND MOLWEIGHT<500.0 . Here, MOLSTRUCTURE and MOLWEIGHT are fields in the MOLTABLE table. SSS is a function that operates on the MOLSTRUCTURE field to find molecules that contain the structure contained in the file query.mol, as a substructure. 

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