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91.
本文得到了正定Hermitian阵的Hadamard积的Schur补的一些不等式,进而,给出了他们的一些应用,这些改进了近期的一些结束.  相似文献   
92.
基于零点的函数K图和dj图的转换   总被引:9,自引:7,他引:2       下载免费PDF全文
介绍了函数的最大项展开式和CRM展开式及其图形表示,提出函数K图和dj图的零点的概念,并以此为基础讨论了基于零点的函数K图和dj图之间的转换方法。  相似文献   
93.
原子吸收法在有机分析中的应用(Ⅵ)香烟中氢氰酸的分析谢志海,郎惠云,高云(西北大学化学系,西安,710069)关键词:氢氰酸,测定,原子吸收光谱香烟中的尼古丁,烟焦油等含氮有机物燃烧后将产生氢氰酸,吸入人体后极为有害。国外在这方面的研究始于七十年代,...  相似文献   
94.
The adsorption of alginate (Alg) onto the surface of in water dispersed Fe3O4 nanoparticles and zeta potential of alginate-coated Fe3O4 nanoparticles have been investigated to optimize the colloidal stability of Alg-coated Fe3O4 nanoparticles. The adsorption amount of Alg increased with the decrease of adsorption pH. The zeta potential of Fe3O4 nanoparticles shifted to a lower value after adsorption of Alg. The lower adsorption pH was the lower zeta potential of Fe3O4 nanoparticles became. The Alg-coated Fe3O4 nanoparticles were found to be stabilized by steric and electrostatic repulsions. Those prepared at pH 6 were not stable around pH 5, and those prepared at pH 4 became unstable at pH below 3.5. Alg of Mw 45 kDa was a little bit more adsorbed onto nanoparticles surface than that of Mw 24 kDa. An average Fe3O4 core size of 9.3 ± 1.7 nm was found by transmission electronic microscopy. An average hydrodynamic diameter of 30-150 nm was measured by photon correlation spectroscopy. However, an average core size of 10 nm and an average hydrodynamic diameter of 38 nm were estimated from the magnetization curve of the concentrated magnetic fluids (MFs). The maximum available saturation magnetization of MFs was about 3.5 kA/m.  相似文献   
95.
In this paper, the pulsed injection method is extended to measure the chip temperature of various packaged laser modules, such as the DFB laser modules, the FP laser modules, and the EML laser modules. An optimal injection condition is obtained by investigating the dependence of the lasing wavelength on the width and period of the injection pulse in a relatively wide temperature range. The small-signal frequency responses and large-signal performances of packaged laser modules at different chip temperature are measured. The adiabatic small-signal modulation characteristics of packaged LD are first extracted. In the large-signal measurement, the effects of chip temperature, bias current and driving signal on the performances of the laser modules are discussed. It has been found that the large-signal performances of the EML modules depend on the different red-shift speeds of the DFB and EAM sections as chip temperature varying, and the optimal characteristics may be achieved at higher temperature.  相似文献   
96.
This article will combine the finite element method, the interpolated coefftcient finite element method, the eigenfunction expansion method, and the search-extension method to obtain the multiple solutions for semilinear elliptic equations. This strategy not only grently reduces the expensive computation, but also is successfully implemented to obtain multiple solutions for a class of semilinear elliptic boundary value problems with non-odd nonlinearity on some convex or nonconvex domains. Numerical solutions illustrated by their graphics for visualization will show the efficiency of the approach.  相似文献   
97.
合肥同步辐射软X射线显微术研究   总被引:1,自引:0,他引:1  
谢行恕  徐向东 《物理》1996,25(2):104-111
合肥国家同步辐射实验室首期建设的光束线之一用于软X射线显微成像研究。实验站现已装置初型的扫描透射X射线显微镜,并正在进行亲一代的扫描显微建设,同时还使同步辐射光进行接触软X射线呈微成像研究,并对选取的一些生物样品进行了成像试验。本文介绍了合肥同步辐射光源上软X射线显微术实验线站的建设及完成的一些实验结果。  相似文献   
98.
报道了分别用溶胶-凝胶法合成的Y2SiO5∶Eu纳米晶和用高温固相法合成常规尺度的Y2SiO5∶Eu材料的光致发光光谱和猝灭浓度的实验研究.结果表明:纳米Y2-xEuxSiO5比常规尺度的Y2-xEuxSiO5有更高的猝灭浓度和更高的发光亮度.理论分析认为这是由于在纳米材料中能量共振传递被阻断和猝灭中心在各个纳米晶内分布的涨落造成的.这个结果为高亮度的Y2SiO5∶Eu纳米材料的实际开发应用展示了广阔前景.  相似文献   
99.
A three-body system of identical particles is considered in order to demonstrate that the quantum-mechanical symmetry plays a decisive role in determining microscopic structures. Received March 14, 1994; revised July 29, 1994; accepted for publication October 19, 1994  相似文献   
100.
An evolutionary method for optimization of plate buckling resistance   总被引:9,自引:0,他引:9  
Optimization of plate buckling resistance is very complicated, because the in-plane stress resultants in the prebuckled state of a plate are functions of thickness distribution. This paper discusses the problem of finding the optimum thickness distribution of isotropic plate structures, with a given volume and layout, that would maximise the buckling load. A simple numerical method using the finite-element analysis is presented to obtain the optimum thickness distribution. Optimum designs of compression-loaded rectangular plates with different boundary conditions and plate aspect ratios are obtained by using the proposed method. Optimum designs from earlier studies and the methods of buckling analysis used to attain these results are discussed and compared with the designs from the proposed method. This paper also examines the reliability of the optimality criterion generally used for plate buckling optimization, which is based on the uniform strain energy density.  相似文献   
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