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991.
半导体纳米材料非线性光学性质的研究进展 总被引:1,自引:0,他引:1
半导体纳米材料由于具有重要的理论研究意义和潜在的巨大应用前景而成为当今理论和材料研究的特点,该文综述了半导体纳米材料非线性光学性质的研究进展。 相似文献
992.
In systematic research on a series of new nonlinear organic materials, we found that Bis (4-nitrophenoxy) methane (BNPM) showed a large intensity of second harmonic light, which was 4.4 times as large as that of urea crystal by powder technique and easily crystallized from a solution. The crystal structure of BNPM, obtained by the X-ray diffraction method, was orthorhombic, space group P21212 (point group 222), with unit-sell dimension a = 10.205 Å; b = 12.854 Å; c = 4.8822 Å. In addition, we found that the absorption edge of BNPM was 430 nm with a 0.9-mm-thick crystal, and we observed the second harmonic light with BNPM single crystal at the wavelength of 1064 nm and in the range from 906 nm to 990 nm. 相似文献
993.
We present the study of spin and charge transport in nanostructures in the presence of spin-orbit (SO) interaction. Single
band tight binding Hamiltonians for Elliot-Yafet and Rashba SO interaction are derived. Using these tight binding Hamiltonians
and spin resolved Landauer-Büttiker formula, spin and charge transport is studied. Specifically numerical results are presented
for a new method to perform magnetic scanning tunneling microscopy with non-magnetic tip but in the presence of Elliot-Yafet
SO interaction. The spin relaxation phenomena in two-dimensional electron gas in the presence of Rashba SO interaction are
studied and contrary to naive expectation, it is shown that disorder helps to reduce spin relaxation. 相似文献
994.
995.
996.
Nano-scale nickel hydroxide was prepared by precipitate transformation method in the paper. Effect of rinse pH on the agglomeration degree and electrochemical performance of nano-scale Ni (OH)2 was investigated. The measurement results of XRD and TEM indicate that the prepared nano-scale Ni (OH)2 is β (II)-phase, the grain size is in the rang of 10 ~ 50nm, and rinse pH exerts a great influence on the agglomeration degree of nano-scale Ni(OH) 2.The agglomeration of material becomes very obvious when rinse pH = 11, and the density of nano-scale Ni(OH)2 is enhanced obviously. Cyclic voltammetry(CV) and simulate cells experiment show that nano-scale Ni(OH)2 with suitable agglomeration degree have better electrochemical CV performance than those with ideal disperse Ni (OH)2and micron Ni(OH)2, and its proton diffusion coefficient is also the highest. It can elevate the discharge potential platform and prolongs discharge time, so the utilization ratio of Ni (OH)2 is raised.`` 相似文献
997.
Four new compounds were identified in a mixture of tetracyclic methyl ketones obtained by alkaline cleavage of acids of Siberian fir needles. Two of them correspond to natural acids of the 17,13-fridolanostane series of yet unknown structure.For Part 19, see Ref. 1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2997–2999, December, 1996. 相似文献
998.
用高温应变计和热偶计等诊断技术,研究连续波氧碘化学激光(CW/COIL)与铝合金板作用产生的激光热应力。当照射靶面激光强度约1 000 W/cm2时,激光热应力随靶厚的增加而快速减小。当激光辐照靶材厚度h=1.00 mm、激光强度I=640~980 W/cm2时,激光热应力随辐照靶面激光强度的增加而增大。两者的激光热应力-时间曲线随靶厚的减薄或随辐照靶面激光强度的增加而变得越来越复杂。当靶厚h≤2.50 mm,辐照靶面激光强度I≥800 W/cm2时,激光热应力强度超过激光辐照区材料断裂强度,萌生许多孔洞裂纹,引起材料断裂破坏。 相似文献
999.
We consider a mathematical model which describes the frictional contact between a viscoelastic body and a reactive foundation. The process is assumed to be dynamic and the contact is modeled with a general normal damped response condition and a local friction law. We present a variational formulation of the problem and prove the existence and uniqueness of the weak solution, using results on evolution equations with monotone operators and a fixed point argument. We then introduce and study a fully discrete numerical approximation scheme of the variational problem, in terms of the velocity variable. The numerical scheme has a unique solution. We derive error estimates under additional regularity assumptions on the data and the solution. 相似文献
1000.
Li Wenfang South China University of Technology Guangzhou R. R. ChinaDu Shanyi Harbin Institute of Technology Harbin 《Acta Mechanica Solida Sinica》1995,8(1):75-83
The modified equivalent inclusion theory by the authors and the internalvariable theory are employed to investigate the evolution of the microcracks in whiskertoughening ceramics and the influence of the microcracks on the mechanical propertiesof the material. The effect of residual thermostrain, whisker content and aspect ratio isconsidered. The modulus, initial nonlinear load, strength and nonlinear constitutiverelation are calculated and some important conclusions are given. 相似文献