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41.
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Helmut Duddeck Blagoy Blagoev Nikolina D. Berova Vassil Vassilev 《Magnetic resonance in chemistry : MRC》1983,21(2):122-124
Three diastereomeric bornane derivatives have been assigned configurational structures by 13C NMR measurements in the presence of Yb(dpm)3. 相似文献
43.
Summary. Malonaldehyde rotamer geometries were optimized using ab initio calculations at the HF level with STO-3G** and 6-21G** basis sets. The most stable rotamer is the ω-shaped one with cyclic structure and intramolecular hydrogen bond. The most
unstable rotamer is that obtained by rotation of the ω-rotamer around the CO single bond by 180° due to the loss of the additional
stabilization contributed by the intramolecular H-bond. The energy barriers separating the different rotamers vary between
13 and 233 kJċmol−1. The structure of the transition states is non-planar with rotation angles varying between 72 and 98°.
Received January 18, 1999. Accepted (revised) August 4, 1999 相似文献
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Vassil Vassilev Subhash C. Narula 《The Journal of the Operational Research Society》1993,44(12):1201-1209
In this paper, we propose a reference direction approach and an interactive algorithm to solve the general multiple objective integer linear programming problem. At each iteration, only one mixed integer linear programming problem is solved to find an (weak) efficient solution. Each intermediate solution is integer. The decision maker has to provide only the reference point at each iteration. No special software is required to implement the proposed algorithm. The algorithm is illustrated with an example. 相似文献
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Hideo Matsumura Vassil Neytchev Nelly Terezova Iana Tsoneva 《Colloids and surfaces. B, Biointerfaces》2004,33(3-4):243-249
Phospholipid liposomes that contain Ca ions in inside compartment were subjected to external alternating electric fields of square wave form at several frequencies: 10, 100 Hz, 1, 10, 100 kHz. The leakage of Ca ions from inside to bulk solution caused by the electric fields was detected by the fluorescence change due to Ca-Quin 2 (fluorescent dye) complex formation in the bulk aqueous solution. The temperature increments of the sample solution in the chamber were also measured. The amplitude of the electric field and time interval between application of the electric field were varied. The frequency dependency of both the leakage of Ca ion and the temperature increments was observed. It was observed that the efficiency of the leakage had a minimum at 1 kHz. The origin of the frequency dependency of the leakage is discussed, and it is concluded that the energy consumption on a microscopic scale in the liposome membrane zone can be the reason for membrane permeation in this experimental system. 相似文献
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Vassil St. Georgiev Grace A. Saeva C. Richard Kinsolving 《Journal of heterocyclic chemistry》1986,23(4):1023-1025
The synthesis of a series of new substituted 4-azatricyclo[4.3.1.13.8]undecane and 4-azatricyclo[4.3.1.13.8]-undecan-5-one derivatives is described. Compounds 4f and 4g displayed antiviral activity. 相似文献