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121.
辉光放电原子发射光谱法快速分析生铸铁 总被引:3,自引:0,他引:3
通过对辉光光源参数-放电电流、放电电压、预溅射时间和分析时间对生铸铁标样放电强度和稳定性影响的研究,优化光源参数,建立了辉光放电原子发射光谱法同时测定生铸铁中碳、硅、锰、磷、硫等12个元素的快速分析方法。分析生铸铁试样时发现了不同灰口铸铁在碳分析结果方面存在偏差,对碳的偏差进行了讨论并通过制样条件和光源参数的调整可以有效地减小偏差。通过对不同生铸铁样品进行准确度和精密度试验,结果表明:分析结果与标准值或化学法结果一致。分析一件试样的时间仅需2~5 min。 相似文献
122.
Mohammad Ali Ghasemzadeh Boshra Mirhosseini‐Eshkevari Mohammad Hossein Abdollahi‐Basir 《应用有机金属化学》2019,33(1)
A novel and simple approach for the efficient and rapid synthesis of pyrano[2,3‐c]‐pyrazoleshas been accomplished via the four‐component condensation reaction of malononitrile, hydrazine hydrate, ethyl acetoacetate, and substituted aldehydes using MIL‐53(Fe) metal–organic framework (MOF) as a catalyst in ethanol at room temperature. Recycling studies have shown that the MIL‐53(Fe) can be readily recovered and reused six times without significant loss of its activity. The present protocol offers the advantages including short reaction times, simple workup, high yields, elimination of toxic solvents, no chromatographic purification and recoverability of the catalyst. Also, the catalyst was fully characterized by SEM, EDX, FT‐IR, XRD, TGA and TEM analysis. 相似文献
123.
We present novel inorganic–organic hybrid catalyst to accomplish domino multi‐component reaction (MCR) for synthesis of 3‐amino‐2′‐oxospiro[benzo[c]pyrano[3,2‐a]phenazine‐1,3′‐indoline]‐2‐carbonitrile/carboxylate derivatives. This methodology offers remarkable development by easy production of H3PMo12O40/Hyd‐SBA‐15 in regard to solving the problem of using harsh catalysts, also it demonstrates to be impressive and environmentally friendly in term of low reaction times and high yields. 相似文献
124.
This paper applies discrete wavelet transform (DWT) with various protein substitution models to find functional similarity of proteins with low identity. A new metric, 'S' function, based on the DWT is proposed to measure the pair-wise similarity. We also develop a segmentation technique, combined with DWT, to handle long protein sequences. The results are compared with those using the pair-wise alignment and PSI-BLAST. 相似文献
125.
Uchida K Saito M Murakami A Kobayashi T Nakamura S Irie M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(2):534-542
A photochromic polymer film containing three different diarylethene derivatives, that is, 1,2-bis(3,5-dimethyl-2-thienyl)perfluorocyclopentene (1), 1,2-bis(2,5-dimethyl-3-thienyl)perfluorocyclopentene (2), and 1,2-bis(2-methyl-5-phenyl-3-thienyl)perfluorocyclopentene (3) was prepared. Upon UV irradiation, the three derivatives changed to their closed-ring isomers having different colors, yellow, red, and blue. They showed different spectra not only in UV/Vis region but also in the IR spectral region. Upon irradiation with visible light of appropriate wavelengths, each closed-ring isomer was selectively bleached, and three bits eight states recording was performed. The eight states could be read out nondestructively by using IR light of appropriate wavenumbers. 相似文献
126.
127.
Exploring the discrete complexes with multi-step coloration is still a challenge in the field of electron transfer photochromic materials. Herein, we synthesized a series of dinuclear Ln-diphosphonate compounds[Ln=Dy(1); Gd(2); Tb(3); Y(4)] with a remarkably and reversibly photoactive coloration phenomenon. These compounds showed two-step coloration behavior, which were the first discrete architectures in the reported electron transfer photochromic complexes. This two-step coloration phenomenon was originated from the large distortion of H3-TPT acceptors, which in turn reduced the π-conjugation of electron acceptors and slowed the decay process of electron transfer. The photogenerated stable doublet radicals originated from electron transfer from diphosphonate donor to polypyridine acceptor in these complexes were detected by UV-Vis and electron spin resonance(ESR) spectra. Furthermore, the photogenerated radicals were estimated by direct current magnetic susceptibilities and variable temperature ESR spectra, suggesting the doublet radicals in the dinuclear structure for all the compounds. This work revealed a series of discrete phosphonate-based systems with a multi-step coloration process, providing a new pathway for designing multicolor photochromic materials with potential photoswitching or other applications. 相似文献
128.
129.
Julien Racine Denis Hagebaum‐Reignier Yannick Carissan Stéphane Humbel 《Journal of computational chemistry》2016,37(8):771-779
A method is proposed to obtain coefficients and weights of valence bond (VB) determinants from multi configurational wave functions. This reading of the wave functions can apply to ground states as well as excited states. The method is based on projection operators. Both energetic and overlap‐based criteria are used to assess the quality of the resulting VB wave function. The approach gives a simple access to a VB rewriting for low‐lying states, and it is applied to the allyl cation, to the allyl radical and to the ethene (notably to the V‐state). For these states, large overlap between VB and multi reference wave functions are easily obtained. The approach proves to be useful to propose an interpretation of the nature of the V‐state of ethene. © 2015 Wiley Periodicals, Inc. 相似文献
130.
Hermiticity of Hamiltonian Matrix using the Fourier Basis Sets in Bond-Bond-Angle and Radau Coordinates 下载免费PDF全文
In quantum calculations a transformed Hamiltonian is often used to avoid singularities in a certain basis set or to reduce computation time. We demonstrate for the Fourier basis set that the Hamiltonian can not be arbitrarily transformed. Otherwise, the Hamiltonian matrix becomes non-hermitian, which may lead to numerical problems. Methods for correctly constructing the Hamiltonian operators are discussed. Specific examples involving the Fourier basis functions for a triatomic molecular Hamiltonian (J=0) in bond-bond angle and Radau coordinates are presented. For illustration, absorption spectra are calculated for the OClO molecule using the time-dependent wavepacket method. Numerical results indicate that the non-hermiticity of the Hamiltonian matrix may also result from integration errors. The conclusion drawn here is generally useful for quantum calculation using basis expansion method using quadrature scheme. 相似文献