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991.
992.
腺嘌呤及其β-环糊精包结物的光谱研究 总被引:4,自引:0,他引:4
通过紫外光谱的摩尔比法确定了腺嘌呤与β-环糊精(β-CD)包结物的包结比为1:1,通过紫外光谱和荧光光谱研究了腺嘌呤在酸性,中性,及碱性条件下的光谱变化及与β-CD包结物的光谱变化,分别求得了它们与β-CD包结的平衡常数。 相似文献
993.
由于原子簇化合物在催化,生物活性,功能材料等方面所呈现的重要性,使其成为无机和物理化学最重要的研究领域之一。文章中和谱学方法对一些具有混配体的过渡金属簇合物的结构及其两者之间的关系进行. 相似文献
994.
H. Blancher R. Occelli J. M. Moynault 《International Journal of Infrared and Millimeter Waves》1991,12(11):1309-1314
Utilization of metallic grids stacks for F.I.R filters needs a good knowledge of optical properties of each grid. We study here an experimental method in order to determine the wave's change of phase by reflection on a wire grid. We use a Perot-Fabry interferometer constituted by these grids. 相似文献
995.
V. G. Artjuschenko K. I. Kalaidjian M. M. Mirakian 《International Journal of Infrared and Millimeter Waves》1991,12(10):1175-1185
The results of the efficiency of low-mode excitation of a parallel-plate hollow metallic waveguides (HMW) as a function of beam and waveguide parameters are represented. Coupling of two waveguides is also discussed. 相似文献
996.
X光底片在位相对标定 总被引:3,自引:0,他引:3
本文描述了X光底片在位相对标定技术。其原理是使X射线谱经阶梯形吸收滤片透射后,对X光底片曝光,测量底片的曝光量。文中给出了标定方法和数据处理方法,而且也给出了在X光激光实验中得到的Kodak AA5底片的特性曲线。 相似文献
997.
998.
A four-noded rectangular element with seven degrees of freedom at each node is developed for buckling analysis of laminated plate structures having any number of layers with a constant thickness of individual layers. The displacement model is so chosen that it can explain adequately the parabolic distribution of transverse shear stresses and the non-linearity of in-plane displacements across the thickness. A geometrical stiffness matrix is developed using in-plane stresses. A wide range of plates from thick to thin are examined under uniaxial loading conditions. The results are compared with the existing analytical and numerical solutions. The present formulations confirm its applicability for buckling analysis of a wide range of plates. 相似文献
999.
Vaporizing solid samples of metals and semiconductors with a YAG Laser is a method well suited for producing molecules and
clusters of those materials. The clusters are examined by either laser-induced fluorescence (LIF) or mass spectroscopic methods.
The technique is valuable for both gas phase and matrix studies. The method is described and some applications, studying either
the structure of small metal molecules or their reactions, are reviewed, with emphasis on our recent results from the LIF
studies of LiBe, Al2 and the reaction of Al with oxygen, yielding A12O. For larger clusters, Ion Cyclotron Resonance is an extremely valuable method, as we demonstrate by its application to the
reactions of small charged silicon clusters with strong oxidising agents. 相似文献
1000.
M. Sperling Xuefeng Yin B. Welz 《Spectrochimica Acta Part B: Atomic Spectroscopy》1991,46(14):1789-1801
Arsenic(III) can be quantitatively extracted using sodium diethyldithiocarbamate (NaDDTC) as the complexing agent and C18 reversed phase packing as the column material for solid phase extraction. Arsenic(V) must be reduced to its trivalent oxidation state prior to extraction. A mixture of sodium sulphite, hydrochloric acid, sodium thiosulphate and potassium iodide was found to be optimum for on-line reduction. When the sorbent extraction is carried out without and with the addition of the reduction mixture, arsenic(III) and total arsenic can be determined sequentially by graphite furnace atomic absorption spectrometry with detection limits (3 σ) of 0.32 ng for As(III) and 0.43 ng for total arsenic. A 7.6-fold enhancement in peak area compared to direct injection of 40 μl samples was obtained after 60 s preconcentration. Results obtained for sea water standard reference materials, using aqueous standards for calibration, agree well with certified values. A precision of 5.5% RSD was obtained for total arsenic in a sea water sample (1.65
As). Results obtained for synthetic mixtures of trivalent and pentavalent arsenic agreed well with expected values. 相似文献