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排序方式: 共有967条查询结果,搜索用时 671 毫秒
1.
Kacimi Rachid Bourass Mohamed Toupance Thierry Wazzan Nuha Chemek Mourad El Alamy Aziz Bejjit Lahcen Alimi Kamel Bouachrine Mohammed 《Research on Chemical Intermediates》2020,46(6):3247-3262
Research on Chemical Intermediates - A theoretical study on four organic dyes based on bis(4-hexyloxy)triphenylamine as donor and electron acceptor cyanoacrylic acid with a... 相似文献
2.
The structural properties of polycrystalline silicon films, prepared by plasma enhanced chemical vapor deposition system, with different flow rates of SiH4/SiF4 mixtures at 300 °C were investigated. This study indicates that the low hydrogen coverage on the growing surface, under optimum fluorine radicals, will be leaded to an improvement of crystallized area as compared with case of high hydrogen coverage surface. Moreover, the studies of the role of SiH4 and SiF4 radicals show that the SiH4 radicals are important in the nucleation and growth of grains. However, SiF4 radicals are effective in the structural change of grain boundaries regions and by this way, in the present system, establish the growth of grains under the dominant 〈1 1 0〉 direction. The stress investigation indicates that addition of high flow rate of SiF4 in amorphous film, results in the nearly stress free films. Finally, we found that the changes in g-value reflect the changes in the intrinsic compressive and tensile stress in the both polycrystalline and amorphous silicon films. 相似文献
3.
Mohamed Hilmy Elnagdi Ramadan Maawad Abdel-Motaleb Mona Mustafa Mohamed Foad Zayed Eman Moustafa Kamel 《Journal of heterocyclic chemistry》1987,24(6):1677-1681
The behaviour of several 2-amino-3-cyano-4H-pyran derivatives toward a variety of nucleophilic reagents is reported. 相似文献
4.
Summary The possible correlation between the self-attenuation correction in gamma-spectrometric assay of uranyl nitrate samples and
spectral line intensity ratios was investigated experimentally and simulated numerically using MCNP code. The characteristic
gamma- and X-lines of uranium were measured using a low energy Ge gamma-spectrometer. The simulation results agreed with the
experimental data and showed obvious correlation between the self-attenuation correction and the intensity ratios [(185.7
keV)/(143.8 keV), (98.44 keV)/(185.7 keV) and (185.7 keV)/(63.23 keV)]. This correlation greatly simplifies the determination
of the self-attenuation correction and reduces the troublesome traditional procedures used to determine this coefficient. 相似文献
5.
Standard solutions (at 10(-5) M levels) of Cu(I)- and Fe(II)-cyanide complexes were stabilized for at least 5 h using 0.5 mM cyanide solution (around pH 9) as a medium. Complexes of Cu(I)- and Fe(III)-cyanide also could be stabilized without any dissociation by adding 1 mM cyanide to an acetonitrile-water (18:82, v/v) mobile phase (pH 7.0) containing 10 mM tetra-n-propylammonium salt (TPA). Under the optimal conditions, the six complexes of Cu(I)-, Ag(I)-, Ni(II)-, Fe(II)-, Fe(III)- and Au(I)-cyanides were resolved from their mixtures within about 45 min, with well-shaped chromatographic peaks. 相似文献
6.
Mousa Z. Al-Noaimi Raid J. Abdel-Jalil Mustafa M. El-Abadelah Salim F. Haddad Younis N. H. Baqi Wolfgang Voelter 《Monatshefte für Chemie / Chemical Monthly》2006,37(12):745-750
In the presence of RuCl3, N-phenylamidrazone underwent oxidative cyclization into 1,4-dihydro-1-phenyl-1,2,4-benzotriazine, the structure of which is
established by spectral and X-ray diffraction data. 相似文献
7.
In this paper, we apply Adomian decomposition method (shortly, ADM) to develop a fast and accurate algorithm of a special second-order ordinary initial value problems. The ADM does not require discretization and consequently of massive computations. This paper is particularly concerned with the ADM and the results obtained are compared with previously known results using the Quintic C2-spline integration methods. The numerical results demonstrate that the ADM is relatively accurate and easily implemented. 相似文献
8.
Samir Kamel 《先进技术聚合物》2004,15(10):612-616
Rice straw was employed for the preparation of lignocellulosic‐poly(vinyl chloride) (PVC) composites. The effect of pretreatment of rice straw, concentration of PVC, pressure as well as pressing temperature on the mechanical properties and water absorption was studied. Also, the effect of lignin as coupling agent on the mechanical properties and water absorption of composite was studied. Composites of rice straw comprising both PVC and a coupling agent offer superior properties compared to those made from only rice straw and PVC. The extent of improvement in the mechanical properties and dimensional stability of composites depended not only on the pretreatment of rice straw, concentration of PVC and lignin but also on pressure and pressing temperature. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
9.
Tanaka K Ding MY Helaleh MI Taoda H Takahashi H Hu W Hasebe K Haddad PR Fritz JS Sarzanini C 《Journal of chromatography. A》2002,956(1-2):209-214
In this preliminary study, a new approach to ion-exclusion chromatography is proposed to overcome the relatively poor conductivity detection response which occurs in ion-exclusion chromatography when acids are added to the eluent in order to improve peak shape. This approach, termed vacancy ion-exclusion chromatography, requires the sample to be used as eluent and a sample of water to be injected onto a weakly acidic cation-exchange column (TSKgel OApak-A). Vacancy peaks for each of the analytes appear at the retention times of these analytes. Highly sensitive conductivity detection is possible and sharp, well-shaped peaks are produced, leading to efficient separations. Retention times were found to be affected by the concentration of the analytes in the eluent, and also by the presence of an organic modifier such as methanol in the eluent. Detection limits for oxalic, formic, acetic, propionic, butyric and valeric acids were 0.1, 0.2, 0.3, 0.3, 0.4 and 0.5 microM, respectively, and linear ranges for some acids extended over two orders of magnitude. Precision values for retention times were 0.21% and for peak areas were <1.90%. The vacancy ion-exclusion chromatography method was found to give detection responses four to 10 times higher than conventional ion-exclusion chromatography using sulfuric acid eluent and two to five times higher than conventional ion-exclusion chromatography using benzoic acid eluent. 相似文献
10.
Summary Nickel dithiocarbamate complexes derived from some sympathomimetic drugs are examined on silica Radial-Pak columns using binary solvents containing a small percentage of an organic polar modifier. Both the type and concentration of this modifier was found to influence the separation of the ternary from the parent binary complexes. When the two ligands in a ternary complex are racemic to each other, separation of the ternary complex is only possible when certain structural requirements of the molecule are fulfilled. Ternary complexes which contain structurally similar, but nonracemic ligands, are shown to be readily separated from binary complexes. When two such complexes differ only in that one of the ligands in one is enantiomeric to a ligand in the second complex, then it can be shown that the ternary complex with the (+) enantiomer ligand elutes faster from the silica column than the one with the (–) enantiomer ligand. An example of the use of ternary complexes for the identification of optical and structurally related impurities in pharmaceutical products is also given. 相似文献