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71.
72.
Summary An approach is described which makes use of X-ray structural data from enzyme-ligand complexes in order to obtain information for application in receptor modelling. The atomic surroundings of five different ligand functional groups were determined for all complex structures recorded in the Brookhaven Protein Data Bank. These atomic surroundings were then superimposed with respect to the atoms of the functional groups of the ligands in order to obtain clouds of neighbouring atoms. General principles were sought to describe the orientiation or favoured position of groups or atoms around those functional groups when bound to a macromolecule. Some simple conclusions and leads for further modelling were thus derived. 相似文献
73.
The segmentation of customers on multiple bases is a pervasive problem in marketing research. For example, segmentation service providers partition customers using a variety of demographic and psychographic characteristics, as well as an array of consumption attributes such as brand loyalty, switching behavior, and product/service satisfaction. Unfortunately, the partitions obtained from multiple bases are often not in good agreement with one another, making effective segmentation a difficult managerial task. Therefore, the construction of segments using multiple independent bases often results in a need to establish a partition that represents an amalgamation or consensus of the individual partitions. In this paper, we compare three methods for finding a consensus partition. The first two methods are deterministic, do not use a statistical model in the development of the consensus partition, and are representative of methods used in commercial settings, whereas the third method is based on finite mixture modeling. In a large-scale simulation experiment the finite mixture model yielded better average recovery of holdout (validation) partitions than its non-model-based competitors. This result calls for important changes in the current practice of segmentation service providers that group customers for a variety of managerial goals related to the design and marketing of products and services. 相似文献
74.
W. S. Andrews E. J. Waller P. Brousseau G. Roy X. Cao K. A. M. Creber L. S. Erhardt 《Journal of Radioanalytical and Nuclear Chemistry》2009,282(3):919-922
During the past decade, interest has increased in qualifying and quantifying the threat posed to the public by the illegal
use of radionuclides. In order to take investigations beyond the laboratory bench into more realistic scenarios, environmental
and safety considerations dictate that these studies be performed on stable and benign surrogates. This paper discusses some
of these studies, specifically the use of cerium dioxide for actinide ceramics and calcium and natural strontium ceramics
for those based on 90Sr. 相似文献
75.
L. Andrews und J. W. Richards 《Fresenius' Journal of Analytical Chemistry》1899,38(12):796-797
Ohne Zusammenfassung 相似文献
76.
77.
L. W. Andrews H. Morawitz E. Rupp H. Bauer W. F. Schirmer Karin Thaulow H. Lescoeur E. Biilman F. Lehmann J. Knox P. W. Robertson H. Wastenson G. S. Jamieson F. Utz L. Garnier F. Reinthaler J. A. Muller A. Kolb A. Feldhofen G. Adanti B. Oddo L. Vignon H. R. Procter und R. A. Seymour-Jones 《Fresenius' Journal of Analytical Chemistry》1923,62(10):401-407
Ohne Zusammenfassung 相似文献
78.
79.
Antony V. Wilson Timothy Nguyen Felix Brosi Xuefeng Wang Lester Andrews Sebastian Riedel Adam J. Bridgeman Nigel A. Young 《ChemInform》2016,47(14):no-no
Binary palladium fluorides from PdF to PdF6 are investigated by matrix‐isolation methods using thermal evaporation and laser ablation to generate Pd atoms for reaction with F2‐doped Ar and Ne matrices as well as neat F2 matrices. 相似文献
80.
Eric S. Simon Panagiotis G. Papoulias Philip C. Andrews 《Journal of the American Society for Mass Spectrometry》2010,21(9):1624-1632
The fragmentation characteristics of peptides derivatized at the side-chain ε-amino group of lysyl residues via reductive
amination with benzaldehyde have been examined using collision-induced dissociation (CID) tandem mass spectrometry. The resulting
MS/MS spectra exhibit peaks representing product ions formed from two independent fragmentation pathways. One pathway results
in backbone fragmentation and commonly observed sequence ion peaks. The other pathway corresponds to the unsymmetrical, heterolytic
cleavage of the Cζ-Nε bond that links the benzyl derivative to the side-chain lysyl residue. This results in the elimination of the derivative
as a benzylic or tropylium carbocation and a (n − l)+-charged peptide product (where n is the precursor ion charge state). The frequency of occurrence of the elimination pathway
increases with increasing charge of the precursor ion. For the benzylmodified tryptic peptides analyzed in this study, peaks
representing products from both of these pathways are observed in the MS/MS spectra of doubly-charged precursor ions, but
the carbocation elimination pathway occurs almost exclusively for triply-charged precursor ions. The experimental evidence
presented herein, combined with molecular orbital calculations, suggests that the elimination pathway is a charge-directed
reaction contingent upon protonation of the secondary ε-amino group of the benzyl-derivatized lysyl side chain. If the secondary
ε-amine is protonated, the elimination of the carbocation is observed. If the precursor is not protonated at the secondary
ε-amine, backbone fragmentation persists. The application of appropriately substituted benzyl analogs may allow for selective
control over the relative abundance of product ions generated from the two pathways. 相似文献