Description, acquisition, retrieval, and

Description, Acquisition, Retrieval, and Correlation File. This is the only other pubhc substmcture search system, apart from CAS Online, that provides full access to the CAS Chemical Registry File. The DARC file, commercially available on-line from Telesystems-Questel, offered the first pubhc on-line implementation of substmctural searching of the CAS Chemical Registry System. The advantages and disadvantages of the CAS Online and DARC systems have been discussed (49). 

Databases include the Beilstein File, the Gmeliu File, the Registry File, the Description. Acquisition. Retrieval, and Correlation File, and Ihc Structure and Nomenclature Search System. 

The method calls for a combination of the DARC system (Description, Acquisition, Retrieval and Computer-aided design) and the PELCO procedure (Perturbation of an Environment Limited Concentric and Ordered). 

The method is based on a combination of the DARC system (Description, Acquisition, Retrieval and Computer-aided design) and the PELCO (Perturbation of an Environment Limited Concentric and Ordered) procedure. Moreover, it accounts for the simultaneous representation of all the data set compounds and the population of the compounds structurally contained in them the data set compounds, which are those compounds for which a molecular property has been experimentally evaluated, generate an ordered multidimensional space that constitutes a —> hyperstructure. 

Description, Acquisition, Retrieval and Computer-aided design DARC/PELCO analysis... 

The atom connection table has been used for many years, mainly for storage and retrieval of chemical structures and substructures. CAS became the first major user of connection tables when the Chemical Registry System was established. It was then followed by Telesystemes-DARC (Description, Acquisition, Retrieval, and Correlation) devised at the University of Paris. In comparison with the CAS format, that used in DARC was definitely more compact and easier to process on minicomputers. 

The Chemical Abstracts Registry File became substructure searchable online in the early 1980s, first by means of the DARC (Description, Acquisition, Retrieval and Correlation) system (75) as implemented by Telesystemes and, soon afterwards, in the CAS ONLINE Service (76). 

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