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991.
Microwave-assisted synthesis and electrochemical capacitance of polyaniline/multi-wall carbon nanotubes composite 总被引:1,自引:0,他引:1
Hongyu Mi Xiaogang Zhang Shuying An Xiangguo Ye Sudong Yang 《Electrochemistry communications》2007,9(12):2859-2862
Polyaniline/multi-wall carbon nanotubes composite (PANI/MWNTs) was rapidly synthesized by microwave-assisted polymerization. Transmission electron microscope (TEM) image revealed that this composite was a core–shell structure with PANI layers (50–70 nm). Electrochemical behavior of the composite was evaluated by cyclic voltammetry (CV) and galvanostatic charge–discharge tests with a two-electrode system. An enhanced specific capacitance of 322 F/g with a specific energy density of 22 W h/kg was about 12 times that of MWNTs. This composite also exhibited a good rate capability, retaining up to 87% of initial capacity at a current density of 5 mA/cm2. 相似文献
992.
A. Ye. Svezhentsev 《Radiophysics and Quantum Electronics》2007,50(2):123-134
We consider the problem of excitation of a periodic cylindrical microstrip antenna array which consists of N elements placed
periodically in the azimuthal plane on the surface of a dielectric substrate. Each element is an array of M patches having
the rectangular-cylindrical shape. Each patch is fed by a rod which is approximately modeled by a charged filament of finite
length. An integral equation for the surface current on the patches is formulated and solved by the method of moments in the
spatial domain. Far-field patterns of the antenna are calculated for different values of N and M at the resonant frequencies.
It is shown that a two-frequency N-lobe antenna having two different far-field patterns at two different resonant frequencies
can be developed.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 50, No. 2, pp. 134–146, February 2007. 相似文献
993.
以实际人体解剖学数据为基础,利用流体力学软件构建了口腔模型。由于口腔形状不规则,流场中会有湍流产生,所以本文选用的是k-ω方程。在此基础上,假设吸入空气流量为一个常量,改变吸入气体、气溶胶粒子的物理参数,以调整St数的变化,模拟不同情况下气溶胶粒子运动情况。由模拟结果可知:气溶胶粒子在口腔中的沉淀率受粒子半径、密度、及流速的影响,并随这些量的增加而增加;沉淀率可以视作St数的函数,并随St数的增加而增加;气溶胶粒子在口腔中的沉淀分布受模型几何形状和湍流的影响,在喉部附近沉淀较为明显;粒子在口腔中将沿怎样的轨迹运动则取决于粒子在入口处的初始位置。 相似文献
994.
本文研究了n奎乙醇的合成方法.由于采用较高效率的相转移催化剂和乙醇一水作重结晶溶剂,得到高纯度,高产率的喳乙醇. 相似文献
995.
Summary A method based on a linear model enabling the efficient determination of the ionization constants (K
a) of saccharides by capillary zone electrophoresis with amperometric detection has been demonstrated. TheK
a values obtained from the plots of the reciprocal effective mobility against the inverse concentration of sodium hydroxide
were in agreement with literature values. 相似文献
996.
The method for the structural anisotropy determination, which is based on a comparison of the degree of polarization of absorption and resonance Raman bands, is tested with three dyes having different molecular dimensions in one nematic liquid crystal. The experimentally observed correlation between the variation of the structural anisotropy factor and the order parameters deviates from the predictions of the Segre model. This method could also be applied to determine the local field anisotropy for liquid crystals, but we must take into account the observed dependence of the structural anisotropy on the dimensions of the probe molecules. 相似文献
997.
强场下煤的13C NMR谱 总被引:4,自引:1,他引:3
由强场静态13C煤谱可以获得与低场魔角旋转高分辨谱相同的fa,从而避免了样品的快速旋转的要求,同时得到了高灵敏度。 相似文献
998.
Daiqi Ye Mingli Fu Liuqing Tian Hong Liang Tiezhi Rong Shengzhong Cheng Xianshen Pang 《Research on Chemical Intermediates》2003,29(3):271-284
A series of vanadyl pyrophosphate (VPO) modified by several additives has been investigated with the aim to reveal the promotion mechanism of the additives for selective conversion of n-butane to maleic anhydride (MA). Catalyst performance and various physicochemical characterization including XPS, XRD, FT-IR, DTA and BET indicated that the properties of additives, such as electronegativity and ion radius, contributed much to the effect of the additives on the structure and surface characteristics of VPO catalysts, and then influenced the catalytic behavior. The remarkable effects of additives on the surface vanadium and oxygen species were discussed. It was shown that maximum MA selectivity could be found with a moderate V5+ /V4+ ratio, and the catalytic activity and selectivity were improved, respectively, with the increase of surface active oxygen species, as well as as their amount and stability. 相似文献
999.
设P(G,λ)是图G关于变量λ的色多项式,P(G,λ)=P(H,λ),称G和H色等价,由连接两个顶点的S条内部不交的路组成的图叫S-桥图。本讨论了5-桥图F(2,a,a,b,c)(c≥b≥a 1,a≥2)的色性,完整刻画了这类图的色等价图。 相似文献
1000.