Searching Comparison

With the availability of computerized data acquisition and storage it is possible to build database libraries of standard reference spectra. When a spectrum of an unknown compound is obtained, its identity can often be determined by searching through a library of reference spectra. This process is known as spectral searching. Comparisons are made by an algorithm that calculates the cumulative difference between the absorbances of the sample and reference spectra. For example, one simple algorithm uses the following equation... 

Chen, X., Reynolds, . H. (2002) Performance of similarity measures in 2D fragment-based similarity searching comparison of... 

FATCAT http //fatcat.ljcrf.edu Similarity search/comparison... 

The advantage of using topological indices is that they occupy very little memory and the search process is extremely simple, a comparison between numbers. The main disadvantage is that most of them are not unique, or as is usually said they are d enerate, i.e., for distinct structures they produce the same values. 

Figure 10.3-16. The principle of similarity searches. The query (target, precursor) as well as the catalog compound are transformed by the criterion maximum oxidation state". Since the transformation for both compounds results in the samie transformed structure, the catalog compound is presented to the user as a suitable starting material. The comparison of the structure is performed by a hashcode algorithm.

A comparison of fine different conformational searching algorithms. (Data from [Saunders et at 1990].)... 

Search the literature for the experimental results for the H—O bond lengths and the H—O—H bond angle, and include a discussion of the comparison in your report. 

WR Pearson. Comparison of methods for searching protein sequence databases. Protein Sci 4 1145-1160, 1995. 

K Fidelis, PS Stern, D Bacon, I Moult. Comparison of systematic search and database methods for constructing segments of protein structure. Protein Eng 7 953-960, 1994. 

When automated searches are implemented, the LEED I-V calculation and the R factor comparison are called by the master search program either as subroutines or as separate programs through the operating system. The LEED I-V calculations are... 

ISIS provides means for manipulation, comparison, search and retrieval of records. 

As a comparison, the results from a back-propagation training routine with a gradient search for PTE is... 

In order to understand the possibilities of these two databases, a comparison can be made of a central database like Polymat and Campus. The Polymat central database provides the following (1) all the products of the various firms represented are included (2) the search is independent of the manufacturers and can be performed for all the products of all the manufacturers (3) available are not only the values contained in the list of basic values but other data specified in such standards as DIN, ASTM, and BS (although a search can nevertheless be confined to products whose data conform to the list of basic values) (4) the information is presented only once and is then maintained centrally and (5) a selection can be made between a greater number of materials and manufacturers. 

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