Polymer structures retrieval

Lambert N. How to Search the IFI Comprehensive Database Online. Tips and Techniques. Database 1986 10(6) 46-59. A description of the indexing systems used for the IFICDB for retrieval of chemical structures, polymer structures, general thesaurus terms, and standardized bibliographic elements. Although use of the IFICDB files is restricted to subscribers, the general term vocabulary and a less detailed chemical indexing system are available to nonsubscribers for limited use in a sister file, the IFIUDB. 

Retrieval of Polymer Structures, it is axiomatic that to conduct an efficient search, searchers need to know the rules of the database or file being searched. Although this article is not intended to be a teaching manual on how to search polymer files or databases, some basic differences between searching the CAS Registry File and searching an MDL database by means of the ISIS program merit discussion. 

For moderate spinning speeds in the range of a few kHz, the anisotropic chemical shift is not spun out , but leads to sideband patterns, from which the anisotropies can be retrieved [IS. lb]- However, in complex polymer structures... 

Such complex structure-based representations pose no problems for more recent systems such as MDL s ISIS 2.1 program with features designed expressly for polymer structure storage and retrieval. 

Although the majority of CIR systems support this extended specification syntax only for query formulation, more recently developed systems provide the capability to store chemical entities with these specifications intact. Some implementations are useful for representing and retrieving polymer structures other versions were designed to store patent related Maikush structures. 

In addition, the surface should be free of contaminating particles and occlusions that would interfere with the information retrieval process. A typical ablative-mode optical disk has the structure shown in Figme 16.14. The substrate is an optically transparent material such as polycarbonate, PMMA, polyfethylene terephthalate), or polyfvinyl chloride) topped by a subbing layer to provide an optically smooth surface for the recording layer. A metal reflector (typically aluminum) is then incorporated next to a transparent dielectric medium such as poly(a-methyl styrene) and, finally, the absorbing layer where the information pits are created is added. The latter can be a metal-polymer composite (silver particles in a gel) or a dye molecule dispersed in a polymer matrix such as squaryllium dyes, which act as infrared absorbers for GaAs lasers, typically... 

Provides access to chemical and chemically related patents. Subject indexing for each chemical patent from a controlled vocabulary designed to facilitate retrieval of chemical structures and polymers. Indexing is prepared from a review of the full text of patent documents 20 or more Uniterm codes are then added to each record. CLAIMS/UNITERM 1950-1970, File 223, parallels coverage of File 23, CLAIMS/CHEM 1950-1970 CLAIMS/UNITERM 1971-1977, File 224, parallels File 24, CLAIMS/U.S. PATENTS 1971-1977 and CLAIMS/ UNITERM 1978 to present. File 225, parallels File 25, CLAIMS/U.S. PATENT ABSTRACTS. 

Provided (1) both structure-based and source-based types of representation are stored, (2) all practical representational possibilities for both types are stored, and (3) the storage/retrieval system is capable of retrieving all stored representations when only one is specified, a key advantage of using separate expressions for representations of a polymer is that searchers can find a polymer by searching any possible representation. Currently, condition (1) is sometimes met, whereas conditions (2) and (3) are frequently not, which results in scattered data and frequent failure to retrieve critical information. 

Jin, W. 2001. An investigation on the microcellular structure of polystyrene/LCP blends prepared by using supercritical carbon dioxide. Polymer 42 (19) (September) 8265-8275. doi 10.1016/80032-3861(01)00343-3. http //hnkinghub.elsevier.com/retrieve/ pii/S0032386101003433. 

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