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21.
Chunyi Liu Zuoxiang Wang Hailian Xiao Yan Lan Xiaomin Li Songpei Wang Jie Tang Zhengping Chen 《Journal of chemical crystallography》2009,39(12):881-884
Abstract
The title compound, 3-methyl-4-phenyl-5-(2-pyridyl)-1,2,4-triazole was synthesized by reaction of diphenylphosphazoanilide with N-acetyl-N′-(2-pyridoyl)hydrazine. Crystals suitable for X-ray analysis were obtained from a mixed solution of water and ethanol in a one-to-one volume ratio. The crystal is orthorhombic, space group P212121 with crystallographic parameters: a = 19.414(4) Å, b = 17.172(3) Å, c = 7.4850(15) Å, β = 90.00°, μ = 0.079 mm−1, V = 2495.3(8) Å3, Z = 8, Dc = 1.258 g/cm3, F(000) = 992, T = 295(2) K. The X-ray results showed that in the crystal structure of the title compound, the 1,2,4-triazole, pyridine and benzene rings are not coplanar. 相似文献22.
MH/Ni电池用稀土系储氢合金的失效及回收研究 总被引:5,自引:0,他引:5
探讨了深度过放电对MH/Ni电池负极储氢合金的影响。发现在过放电后,负极储氢合金的XRD结构图中,除了储氢合金的主相外,还出现了十分明显的Al(OH3),La(OH)3的衍射峰。结合各种情况下储氢合金失效的,原因利用化学处理及再熔炼的方法对失效MH/Ni电池的负极粉进行了回收实验,并对比了回收合金与原合金的结构及电化学性能。XRD测试结果表明回收合金与原合金的结构相同,均为CaCu5型。恒电流充放电实验发现,回收合金与原合金粉相比,放电容量接近,放电电位高。不寿命测试结果表明,回收合金较原合金容量衰减更缓慢。 相似文献
23.
Jian Fangfang Wang Zuoxiang Bai Zhiping You Xiaozeng Chen Wei 《Transition Metal Chemistry》1999,24(5):589-594
Two modifications of the and forms of bis(imidazole)copper(II) dibenzoate, [Cu(im)2(OBz)2], have been obtained by recrystallization from EtOH. X-ray analysis reveals that the two modifications have the same structure with different geometric parameters. The form crystallizes in the C2/c space group and the form, in the P2(1)/n space group. The crystal structures of both consist of centrosymmetric monomeric molecules of [Cu(im)2(OBz)2] with a distorted octahedral geometry for the CuN2O2O2
chromophore. The e.s.r. spectra of the and forms exhibit a shf structure that consists of 9 lines, and these signals are also different from those of monomeric tetra(imidazole)copper(II) diacetate. Electronic and i.r. spectra are in agreement with the structural data. 相似文献
24.
25.
Limit distributions of maxima of dependent Gaussian sequence are different according to the convergence rate of their correlations. For three different conditions on convergence rate of the correlations, in this paper, we establish the Piterbarg theorem for maxima of stationary Gaussian sequences. 相似文献
26.
Let X
1, X
2, ...X
n
be independent and identically distributed random variables with common distribution function F. Necessary and sufficient conditions for F to belong to the domains of attraction of Φ
α
and Ψ
α
are derived in terms of conditional moments.
相似文献
27.
28.
The authors prove an almost sure central limit theorem for partial sums based on an irreducible and positive recurrent Markov chain using logarithmic means,which realizes the extension of the almost sure central limit theorem for partial sums from an i.i.d.sequence of random variables to a Markov chain. 相似文献
29.
In this work, a novel type of deep eutectic solvents (DES: CTAB–DES) based on cetyl trimethyl ammonium bromide (CTAB) was successfully synthesized by mixing CTAB with p-toluenesulfonic acid monohydrate and applied as catalysts for the esterification reaction of ethanol and lauric acid. The kinetics of the reaction of ethanol and lauric acid catalyzed by CTAB–DES was investigated in the temperature range of 328.15–348.15 K. The influence of different parameters including agitation speed, temperature, catalyst loading, and the lauric acid to ethanol molar ratio on the conversion of lauric acid was discussed. The kinetic experimental data obtained were correlated by the pseudo-homogeneous model, and the results show that it can predict the reaction process well. Moreover, CTAB–DES can be reused six times without any significant decrease in catalytic activity. 相似文献
30.
Let X, X1, X2, … be i.i.d. random variables with nondegenerate common distribution function F, satisfying EX = 0, EX2 = 1. Let Xi and Mn = max{Xi, 1 ≤ i ≤ n }. Suppose there exists constants an > 0, bn ∈ R and a nondegenrate distribution G (y) such that Then, we have almost surely, where f (x, y) denotes the bounded Lipschitz 1 function and Φ(x) is the standard normal distribution function (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献