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排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
Pakhurova T. F. Paulin'sh Ya. Ya. Gudrinietse É. Yu. Dashkevich S. V. Ablovatskaya M. V. 《Chemistry of Heterocyclic Compounds》1982,18(11):1217-1217
Chemistry of Heterocyclic Compounds - 相似文献
992.
F. A. Potra 《Journal of Optimization Theory and Applications》1989,63(3):415-431
We give sufficient conditions for a sequence to have theQ-order and/or theR-order of convergence greater than one. If an additional condition is satisfied, then the sequence has an exactQ-order of convergence. We show that our results are sharp and we compare them with older results.This work was supported in part by the National Science Foundation under Grant No. DMS-85-03365. The author wishes to thank J. E. Dennis and R. A. Tapia for helpful comments, and the referee for pointing out a number of typographical and mathematical errors in the original version of this paper. 相似文献
993.
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995.
W. Rattanasakulthong C. Sirisathitkul 《Applied Physics A: Materials Science & Processing》2006,83(1):77-81
Thermal and magnetotransport properties of mechanically alloyed Co30Cu70 powders of three different milling times are studied. Both milling and annealing bring about oxidation of the samples. The powders show exothermic behaviors corresponding to the lattice-recovery process. Different milling times and annealing temperatures give rise to different exothermic peaks because of oxidation and the cluster distribution. At room temperature, the compressed powders show, on average, up to 11% giant magnetoresistance (GMR) under 10 kOe with sharp switching. The results may be understood in terms of spin-dependent scattering across Co/oxide/Cu interfaces. Annealing reduces the resistance but does not promote the GMR. By annealing at 400 °C, the GMR is entirely suppressed as the magnetic content is largely replaced by oxides. PACS 72.15.Eb; 75.47.De; 75.47.Np 相似文献
996.
M. Piana M. Arrabito S. Bodoardo A. D'Epifanio D. Satolli F. Croce B. Scrosati 《Ionics》2002,8(1-2):17-26
Solid State Reaction was employed to prepare phospho-olivines LiMPO4 (where M=Fe, Co) as pure phase and LiNiPO4 in presence of foreign phases, as cathodic materials for lithiumions batteries. The relationship between structural, morphological
and electrochemical properties were investigated in the case of LiFePO4. Structural investigation has been carried out by means of X-ray powder diffraction (XRPD) and Rietveld refinement. The influence
on the morphology of annealing temperature, different flowing gas mixture and addition of ascorbic acid during the synthesis,
has been analysed via scanning electron microscopy. The electrochemical cycling performances on LiFePO4 showed to be positively affected by the modifications of the experimental conditions. Cyclic voltammetry showed a good reversibility
during insertion-extraction mechanism, in particular in presence of additives. LiCoPO4 and LiNiPO4 are interesting as high voltage cathode materials for Li-ion batteries and have been taken into account, but their electrochemical
operating conditions are still to be optimised. In the case of LiNiPO4 it is very difficult to obtain, by solid state synthesis, suitable purity powders, having a grain size small enough to exploit
it usefully as cathodic material for Li-ion cells.
Paper presented at the 8th EuroConference on Ionics, Carvoeiro, Algarve, Portugal, Sept. 16 – 22, 2000. 相似文献
997.
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999.
This paper presents the simulation of surface acoustic wave (SAW)-induced absorption coefficient and refractive index change in InGaAs-GaAs multiple quantum well (MQW) structures operating near 980 nm. The exciton problem is solved in two dimensional momentum space to include the non-axial effect due to strain induced valance band mixing and nonparabolicity. The optical absorption coefficient and refractive index changes near the band gap in the MQWs are calculated as a function of SAW power. 相似文献
1000.
F. Farid 《Linear and Multilinear Algebra》2002,50(3):223-239
An upper bound for the number of components of the numerical range of matrix polynomials is established. We also establish a necessary condition and a sufficient condition for the connectedness of the numerical range of a quadratic selfadjoint matrix polynomial. The boundary of the numerical range of linear matrix polynomials is also considered. 相似文献