排序方式: 共有45条查询结果,搜索用时 15 毫秒
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R. R. Sharipova O. A. Lodochnikova I. Yu. Strobykina R. Z. Musin V. M. Babaev V. I. Morozov S. N. Pod“yachev R. V. Chestnova V. E. Kataev 《Russian Chemical Bulletin》2013,62(1):175-182
New nitrogen-containing derivatives of the diterpenoid isosteviol (16-oxo-ent-beyeran-19-oic acid) containing oxo, hydroxyimine, and thiosemicarbazone groups were synthesized. Isosteviol 15-oxo-16-thiosemicarbazone forms a 1: 1 complex with CuII and inhibits the growth of Mycobacterium tuberculosis (H37RV, in vitro) at the minimum inhibitory concentration of 20 μg mL?1. 相似文献
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Yu. V. Korneeva A. A. Novakova A. M. Ob”edkov A. A. Zaitsev G. A. Domrachev 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2007,1(4):369-372
The structure and phase composition of a carbon nanomaterial obtained by the thermal decomposition of toluene-ferrocene mixtures are studied by Mössbauer spectroscopy, high-resolution electron microscopy, and x-ray diffraction. Variations in the structural state of the catalyst and in the quantitative yield of the nanomaterial are analyzed as functions of the synthesis time. 相似文献
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Attenuation of Stoneley waves and higher Lamb modes propagating along an irregular surface of a fluid-filled borehole is investigated. This problem generalizes the problem on the attenuation of Rayleigh waves by an irregular surface of an empty borehole [10]. The technique used to evaluate the attenuation coefficient is based on the perturbation method (surface irregularity heights are considered to be small in comparison with the wavelength) and the mean field method. As a result, an expression is obtained for the partial coefficients of the eigenmode attenuation due to the scattering of eigenmodes by the irregularities of the borehole walls into the same or other eigenmodes, as well as into the bulk longitudinal and transverse waves. The frequency-dependent behavior of the partial attenuation coefficients of both Stoneley waves and higher modes is analyzed against the ratio between the irregularity correlation length and the borehole radius for different correlation functions of irregularities. 相似文献
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Thotsaporn ‘Aek’ Thanatipanonda 《Journal of Difference Equations and Applications》2013,19(9):1344-1349
Using the methodology of (rigorous) experimental mathematics, we give a simple and motivated solution to Zudilin's question concerning a q-analogue of a problem posed by Asmus Schmidt about a certain binomial coefficients sum. Our method is based on two simple identities that can be automatically proved using the Zeilberger and q-Zeilberger algorithms. We further illustrate our method by proving two further binomial coefficient sums. 相似文献
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A. V. Kadomtseva A. M. Ob”edkov M. N. Semenov B. S. Kaverin S. A. Gusev 《Russian Journal of Applied Chemistry》2016,89(11):1797-1805
Pyrolytic tungsten coatings were deposited onto the surface of sol microspheres with tungsten hexacarbonyl used as precursor. A method was developed for reduction of germanium tetrachloride in the presence of a catalyst based on sol microspheres coated with pyrolytic tungsten. The method makes it possible to reduce the process temperature and diminish the number of stages in production of germanium. The kinetic characteristics of the catalytic reduction of germanium tetrachloride with hydrogen were determined. 相似文献
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Caroline K. Williams Gavin A. McCarver Ashwin Chaturvedi Dr. Soumalya Sinha Marcus Ang Prof. Konstantinos D. Vogiatzis Prof. Jianbing “Jimmy” Jiang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(52):e202201323
Electrocatalytic hydrogen gas production is considered a potential pathway towards carbon-neutral energy sources. However, the development of this technology is hindered by the lack of efficient, cost-effective, and environmentally benign catalysts. In this study, a main-group-element-based electrocatalyst, SbSalen , is reported to catalyze the hydrogen evolution reaction (HER) in an aqueous medium. The heterogenized molecular system achieved a Faradaic efficiency of 100 % at −1.4 V vs. NHE with a maximum current density of −30.7 mA/cm2. X-ray photoelectron spectroscopy of the catalyst-bound working electrode before and after electrolysis confirmed the molecular stability during catalysis. The turnover frequency was calculated as 43.4 s−1 using redox-peak integration. The kinetic and mechanistic aspects of the electrocatalytic reaction were further examined by computational methods. This study provides mechanistic insights into main-group-element electrocatalysts for heterogeneous small-molecule conversion. 相似文献
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A series of amphiphilic macroporous mixed-mode acrylamide-based continuous beds bearing positively charged quaternary ammonium groups is synthesized for capillary electrochromatography (CEC) under variation of the concentration of the cationic monomer in the polymerization mixture. Positively charged mixed-mode monolithic stationary phases are synthesized in pre-treated fused silica capillaries of 100 µm I.D via single step free radical copolymerization of cyclodextrin-solubilized N-tert-butylacrylamide, a hydrophilic crosslinker (piperazine diacrylamide), a hydrophilic neutral monomer (methacrylamide), and a positively charged monomer ([2-(methacryloyloxy)ethyl]trimethyl ammonium methyl sulfate) in aqueous solution containing the lyotropic salt ammonium sulfate as a pore-forming agent. The synthesized monolithic stationary phases contain hydrophobic, hydrophilic, and charged functionalities. They can be employed for the CEC separations of different classes of neutral and charged solutes (with varied polarity) in the reversed-phase mode, in the normal-phase mode, in the ion-exchange mode, in a mixed-mode, or in the hydrophilic interaction liquid chromatography (HILIC) mode. The influence of the concentration of the cationic monomer in the polymerization mixture on retention factor, electroosmotic mobility, and methylene selectivity (αmeth) is studied under isocratic conditions for alkylphenones in the reversed-phase mode by capillary electrochromatography (CEC). Scanning electron microscopy (SEM) micrographs demonstrate that the morphology of the synthesized monoliths (i.e., the domain size) is strongly influenced by the variation of the concentration of the cationic monomer in the polymerization mixture. 相似文献