Screen dictionary

Figure 2 Examples of linear sequence fragments and ring descriptor developed for the CAS ONLINE screen dictionary. An example structure is given at the top. The sequences start from the acyclic carbon on the left and go along the bottom of the ring to the acyclic oxygen on the right. Bonds marked r are explicitly ring. Note that only the bond sequence has completely specific bond types.

Screens can be yielt from the Screen Dictionary, which contains approx. 6000 codes. To illustrate the criteria for their structure, please refer to the 12 classes of screens below defining certain types of structure fragments. 

CAS ONLINE Screen Dictionary for Substructure Search. 2nd Edition. 1981. 

The dictionary is the interface between the informal and the formal. It has an entry for the name of each named feature together with both its formal and its informal definitions. Whether or not the dictionary is presented as an actual table (either in printed matter or on screen—a good tool should be able to extract it and present it if you so require), the dictionary is the notional holder of all the features defined within the package. 

LI ou know that atoms make up the matter around you, from stars to steel to J chocolate ice cream. You might think that there must be many different kinds of atoms to account for the huge diversity of matter, but the number of different kinds of atoms is surprisingly small. The great variety of substances results from the many ways a few kinds of atoms can be combined. Just as the three colors red, green, and blue can be combined to form any color on a television screen, or the 26 letters of the alphabet make up all the words in a dictionary, only a few kinds of atoms combine in different ways to produce all substances. To date, we know of slightly more than 100 distinct atoms. Of these, about 90 are found in nature. The remaining atoms have been created in the laboratory. 

Entry screens fimction as expected (e.g., range checks, look-up tables, auto-encoding using the appropriate dictionary, derived data calculations). 

A database that collects the 3-D structures of protein domains involved in interactions (patches). See Preissner, R., Goode, A., and Frommel, C., Dictionary of interfaces in proteins (DIP). Data bank of complementary molecules, J. Mol. Biol. 280, 535-550, 1998 Frommel, C., Gille, C., Goede, A. et al.. Accelerating screening of 3-D protein data with a graph theoretical approach. Bioinformatics 19, 2442-2447, 2003. 

Details on system screen designs, report layouts, data dictionary with data flow diagram, system configurations, system security, file design, system limitations and memory requirements are laid out by system developers and are usually formally inspected with members of the development team. Major outputs of this phase are the internal design documents and prototypes. The design documents are based on the ERS and can be used as a source for the technical support documentation. 

The fragments that have been chosen to act as screens are listed in a fragment coding dictionary. When a query or a new molecule is to be processed, the corresponding connection table is analyzed to identify those screens from the coding dictionary that are present in the structure. A database structure or query substructure is then represented by a fixed-length bit string... 

One of the principal features of this book is that it serves as a reference to some important general terms related to natural products such as alkaloids, caroti-noids, glycoproteins, and snake venoms. Moreover, historical coverage and overview texts, even headings like screening , can be found, indicating that this book is much more than a mere dictionary of natural products. 

The search engine architecture will substitute inverted file searching for sequential screen searching. This will permit the structure screen set size to be increased because new screens simply become new terms in the inverted dictionary. It will also permit other numeric or textual information associated with a structure to be added to the inverted screen file and processed as part of the inverted screen searching process. 

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