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The Comparative Molecular Field Analysis (CoMFA) was developed to investigate a three-dimensional quantitative structure activity relationship (3D-QSAR) model of ligands for the sigma 1 receptor. The starting geometry of sigma-1 receptor ligands was obtained from the Tripos force field minimizations and conformations were decided from DISCOtech using the SYBYL 6.8. program. The structures of 48 molecules were fully optimized at the ab initio HF/3-21G* and semiempirical AM1 calculations using GAUSSIAN 98. The electrostatic charges were calculated using several methods such as semiempirical AM1, density functional B3LYP/3-21G*, and ab initio HF/3-21G*, MP2/3-21G* calculations within GAUSSIAN 98. Using the optimized geometries, the CoMFA results derived from the HF/3-21G method were better than those from AM1. The best CoMFA was obtained from HF/3-21G* optimized geometry and charges (R2 = 0.977). Using the optimized geometries, the CoMFA results derived from the HF/3-21G methods were better than those from AM1 calculations. The training set of 43 molecules gave higher R2 (0.989-0.977) from HF/3-21G* optimized geometries than R2 (0.966-0.911) values from AM1 optimized geometries. The test set of five molecules also suggested that HF/3-21G* optimized geometries produced good CoMFA models to predict bioactivity of sigma 1 receptor ligands but AM1 optimized geometries failed to predict reasonable bioactivity of sigma 1 receptor ligands using different calculations for atomic charges. 相似文献
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3,3-Dichlorotricyclo[5.1.0.01,4]oct-5-en-2-one () was prepared by addition of dichloroketene to 1,3-cyclohexadiene followed by allylic bromination and dehydrobromination. 相似文献
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Two chiral cyclohexanones were linked to polystyrene resin. The polymer-bound auxiliaries were subjected to a sequence of four reactions, the last of which cleaves the desired alpha-chiral carbonyl compound off the resin, concurrently regenerating the resin-bound auxiliary in its original form. The resin can then be reused. 相似文献
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D. Habs O. Kester T. Sieber H. Bongers S. Emhofer P. Reiter P.G. Thirolf G. Bollen J. Aystö O. Forstner H. Ravn T. Nilsson M. Oinonen H. Simon J. Cederkall F. Ames P. Schmidt G. Huber L. Liljeby O. Skeppstedt K.G. Rensfelt F. Wenander B. Jonson G. Nyman R. von Hahn H. Podlech R. Repnow C. Gund D. Schwalm A. Schempp K.-U. Kühnel C. Welsch U. Ratzinger G. Walter A. Huck K. Kruglov M. Huyse P. Van den Bergh P. Van Duppen L. Weissman A.C. Shotter A.N. Ostrowski T. Davinson P.J. Woods J. Cub A. Richter G. Schrieder 《Hyperfine Interactions》2000,129(1-4):43-66
The Radioactive Beam Experiment REX-ISOLDE [1–3] is a pilot experiment at ISOLDE (CERN) testing the new concept of post acceleration
of radioactive ion beams by using charge breeding of the ions in a high charge state ion source and the efficient acceleration
of the highly charged ions in a short LINAC using modern ion accelerator structures. In order to prepare the ions for the
experiments singly charged radioactive ions from the on-line mass separator ISOLDE will be cooled and bunched in a Penning
trap, charge bred in an electron beam ion source (EBIS) and finally accelerated in the LINAC. The LINAC consists of a radiofrequency
quadrupole (RFQ) accelerator, which accelerates the ions up to 0.3 MeV/u, an interdigital H-type (IH) structure with a final
energy between 1.1 and 1.2 MeV/u and three seven gap resonators, which allow the variation of the final energy. With an energy
of the radioactive beams between 0.8 MeV/u and 2.2 MeV/u a wide range of experiments in the field of nuclear spectroscopy,
astrophysics and solid state physics will be addressed by REX-ISOLDE.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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Ionics - Polyaniline thin films have been prepared by the simple and inexpensive successive ionic layer adsorption and reaction (SILAR) method at room temperature in the presence of three different... 相似文献