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91.
92.
Wen-ting Xu Hai-ling Tu Da-li Liu Ran Teng Qing-hua Xiao Qing Chang 《Journal of nanoparticle research》2011,13(12):7095-7098
An innovative fabrication technique for the nanometer-sized SiGe/Si heterostructure was developed in this study. Ge was induced
in Si substrate by two-step ion implantation. The spherical SiGe nanoclusters are self-assembled in the Si substrate by subsequent
rapid thermal annealing at 1,100 °C. The diameter of the spherical SiGe nanoclusters is 5–7 nm. Visible photoluminescence
from this nanometer-sized SiGe/Si heterostructure at room temperature was investigated. We found three peak energies of visible
luminescence spectra at 1.97, 2.13, and 2.16 eV, respectively. The luminescence intensity depends on the number of the nanoclusters
and will be decreased because of the micro-defects around the heterostructure, which is discussed in detail. 相似文献
93.
In this paper, the qualitative properties of general nonautonomous Lotka-Volterra n-species competitive systems with impulsive effects are studied. Some new criteria on the permanence, extinction and global
attractivity of partial species are established by used the methods of inequalities estimate and Liapunov functions. As applications,
nonautonomous two species Lotka-Volterra systems with impulses are discussed. 相似文献
94.
Jonathan A. Kelner James R. Lee Gregory N. Price Shang-Hua Teng 《Geometric And Functional Analysis》2011,21(5):1117-1143
We present a method for proving upper bounds on the eigenvalues of the graph Laplacian. A main step involves choosing an appropriate
“Riemannian” metric to uniformize the geometry of the graph. In many interesting cases, the existence of such a metric is
shown by examining the combinatorics of special types of flows. This involves proving new inequalities on the crossing number
of graphs. 相似文献
95.
96.
97.
There are always some local damages in spatial steel structures induced by strong earthquakes, such as welding cracks of steel nodes, anchor loose of supports etc. If these local damages of spatial steel structures occur, there will be serious dangers to the structural safety. In order to detect the position of local damage under earthquake quickly and accurately, the method of support damage diagnosis of spatial steel structures under earthquakes is studied by using wavelet packet decomposition, data fusion and cluster analysis. Furthermore, a scale model of spatial steel structure was tested on a seismic simulation shaking table to detect the position of damaged support. Results show that the damaged support position can be detected accurately by using the method proposed in this paper, which has practical applications to the damage detection of spatial steel structures. 相似文献
98.
The paper investigated the dynamical behaviors of a two-species discrete ratio-dependent predator-prey system. The local stability
of the equilibria is obtained by using the linearization method. Further, a new sufficient condition on the global asymptotic
stability of the positive equilibrium is established by using an iteration scheme and the comparison principle of difference
equations. 相似文献
99.
Qi Teng Wenxiu Mao Dong Chen Zhen Wang Chen‐Ho Tung Zhenghu Xu 《Angewandte Chemie (International ed. in English)》2020,59(6):2220-2224
A rhodium(I)‐BINAP‐catalyzed highly enantioselective [2+2+2] cycloaddition of enynes with alkynes has been developed. Diverse fused tricyclic hydronaphthofuran scaffolds with three consecutive stereogenic centers were constructed in one step from easily available materials with excellent chemo‐, regio‐, diastereo‐, and enantioselectivity. Notable features of these reactions include 100 % atom economy, very broad scope, and mild reaction conditions. 相似文献
100.
对小学科学课程标准与五年制专科小学教育专业“科学·化学”教学大纲中对化学知识内容的要求,以及小学《科学》和高等专科学校《科学·化学》教材中涉及的化学知识内容进行了对比。同时就五年制专科层次小学教育专业化学课程存在的问题进行了讨论,并提出了选择合适的课程教学内容、加强化学实验和化学教材建设、建立理论课程和实验教学新体系模块等建议。 相似文献