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951.
952.
O. V. Zagorskaya V. V. Smirnov T. N. Rostovshchikova V. L. Kofman 《Journal of Structural Chemistry》1992,33(2):310-313
Moscow State University. Translated from Zhurnal Strukturnoi Khimii, Vol. 33, No. 2, pp. 170–174, March–April, 1992. 相似文献
953.
A radiochemical solvent extraction method has been developed for the simultaneous determination of submicrogram amounts of Cd and Hg using115mCd and203Hg tracers respectively and thionalide as a single complexing reagent. Hg was determined by 0.05% thionalide in ethyl methyl ketone (EMK) at pH 8.5, masking Cd with 0.1M KCN. From the aqueous phase Cd was demasked using formal-dehyde-acetic acid, pH adjusted to 9.5 and extracted into 0.05% thionalide in chloroform. The method is simple, fast and yields accurate results. 相似文献
954.
Pure adaptive search in global optimization 总被引:10,自引:0,他引:10
Pure adaptive seach iteratively constructs a sequence of interior points uniformly distributed within the corresponding sequence of nested improving regions of the feasible space. That is, at any iteration, the next point in the sequence is uniformly distributed over the region of feasible space containing all points that are strictly superior in value to the previous points in the sequence. The complexity of this algorithm is measured by the expected number of iterations required to achieve a given accuracy of solution. We show that for global mathematical programs satisfying the Lipschitz condition, its complexity increases at mostlinearly in the dimension of the problem.This work was supported in part by NATO grant 0119/89. 相似文献
955.
956.
MacLatchy C.S. Smith H.C.L. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1991,19(6):1254-1258
The electron current to a Langmuir probe in a moving high-pressure plasma has been measured and analyzed. The plasma is an atmospheric-pressure propane flame, and the probe's speed relative to the plasma was varied from 10 ms-1 to 30 ms-1. The current is linearly dependent on the speed and appears to be comprised of two components-one driven by diffusion and the other by convection. A model is devised which can be used to measure the electron density. By comparing the density computed from this model to that measured from the ion current, it has been possible to measure the electron mobility in the flame gases. The value obtained by the authors is in good agreement with theoretical calculations found in the literature 相似文献
957.
Yu. M. Kargin E. I. Gritsenko V. V. Yanilkin V. V. Plemenkov L. K. Dubovik N. I. Maksimyuk B. M. Garifullin Sh. K. Letypov A. V. Il'yasov 《Russian Chemical Bulletin》1992,41(9):1572-1579
The electrochemical reduction of 1,1-dihalo-2-R-2-methylcyclopropanes was studied by polarography and preparative electrolysis. A mixture of stereoisomeric monoboro- and monochlorocyclopropanes was obtained with preparative yield of 60–70% in preparative electroreduction in methanol against a background of 0.1 M LiClO4. In the case of bromine derivatives of cyclopropanes (except when R = CN) an effect was found on the part of the current density on the ratio of cis and trans isomers, which was interpreted as a change, in dependence on current density, of the contributions of the reactions of reduction of the starting compounds (SN2 mechanism) and ionic pairs (SN1 mechanism). The effect of the solvent (CHCl3, DMF, DMSO, MeOH) and background salt (LiClO4, Et4NBr) on the ratio of stereoisomers is in agreement with this interpretation.A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan Science Center, Russian Academy of Sciences, Kazan. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 9, pp. 2023–2032, September, 1992. 相似文献
958.
959.
Spin-flip (paramagnetic) scattering and neutron depolarization studies were performed on Ce2Fe17 in its paramagnetic phase on the Dhruva neutron polarization analysis spectrometer. The absence of normalQ dependence of the scattered spin flip intensity shows that Ce2Fe17 is not a normal paramagnetic and there exist superparamagnetic clusters of sufficiently large dimensions (~100Å). The observed neutron depolarization gives an indication of the dynamics of these Ce2Fe17 superparamagnetic clusters. 相似文献
960.
The influence of spatio-temporal external multiplicative fluctuations on a single kink in a bistable distributed system is studied. For this purpose we derive a stochastic dynamic equation for the position of the shifted kink. An analytical estimate for spatio-temporally uncorrelated fluctuations is represented and discussed. We draw the conclusion that multiplicative noise induces a propagation of the most probable kink into the region of larger noise. This effect is demonstrated in numerical simulations. 相似文献