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排序方式: 共有2754条查询结果,搜索用时 14 毫秒
1.
Komarov Pavel D. Nifant’ev Ilya E. Roitershtein Dmitrii M. Minyaev Mikhail E. 《Journal of chemical crystallography》2021,51(3):352-362
Journal of Chemical Crystallography - The crystal structure of decakis(μ-chloro)-tetrakis(1,2,4-triphenylcyclopentadienyl)-hexakis(tetrahydrofuran)-di-potassium-tetra-neodymium(III)... 相似文献
2.
Physics of Atomic Nuclei - In this paper, two options for damping higher order modes (HOMs) using rectangular waveguides and corrugated cylindrical waveguides are considered. The tuning of the two... 相似文献
3.
Zegrya G. G. Shashkov E. V. Karpova A. A. Vorobiev N. S. Freiman V. M. Zegrya A. G. Solomonov Yu. S. 《JETP Letters》2021,114(4):227-231
JETP Letters - In the explosive reaction of composites based on porous silicon with perchlorate oxidizers, a new effect has been discovered: the intensity accompanying the explosive reaction... 相似文献
4.
The effect of surface tension on laminar natural convection in a vertical cylindrical cavity filled with a weak evaporating liquid has been analyzed numerically. The cylindrical enclosure is insulated at the bottom, heated by a constant heat flux from the side, and cooled by a non-uniform evaporative heat flux from the top free surface having temperature-dependent surface tension. Governing equations with corresponding boundary conditions formulated in dimensionless stream function, vorticity, and temperature have been solved by finite difference method of the second-order accuracy. The influence of Rayleigh number, Marangoni number, and aspect ratio on the liquid flow and heat transfer has been studied. Obtained results have revealed that the heat transfer rate at free surface decreases with Marangoni number and increases with Rayleigh number, while the average temperature inside the cavity has an opposite behavior; namely, it growths with Marangoni number and reduces with Rayleigh number. 相似文献
5.
Mikhail Chebotar 《Israel Journal of Mathematics》2018,227(1):233-238
Let δ be a derivation of a locally nilpotent ring R. Then the differential polynomial ring R[X; δ] cannot be mapped onto a ring with a non-zero idempotent. This answers a recent question by Greenfeld, Smoktunowicz and Ziembowski. 相似文献
6.
Dmitry I. Bugaenko Alexey A. Volkov Dr. Mikhail V. Livantsov Prof. Dr. Marina A. Yurovskaya Dr. Alexander V. Karchava 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(54):12502-12506
The visible-light-induced arylation of tertiary phosphines with aryl(mesityl)iodonium triflates to produce the quaternary phosphonium salts occurs under mild, metal, and catalyst-free conditions. Photo-excited EDA complexes between diaryliodonium salts and phosphines supposedly enable this transformation, which is difficult to achieve through the traditional ground-state reactions. Demonstrating high functional group tolerance, broad scope, and complete selectivity of the aryl group transfer, the method is particularly compatible with sterically congested phosphines, which are challenging under metal-based catalytic methods. 相似文献
7.
Arbatsky N. P. Kenyon J. J. Shashkov A. S. Shneider M. M. Popova A. V. Kalinchuk N. A. Hall R. M. Knirel Yu. A. 《Russian Chemical Bulletin》2019,68(1):163-167
Russian Chemical Bulletin - The K5 capsular polysaccharide (CPS) was isolated from the bacterium Acinetobacter baumannii (A. baumannii) SDF and studied by 1D and 2D 1H and 13C NMR spectroscopy... 相似文献
8.
Konstantin L. Ivanov Anna A. Kravtsova Elena A. Kirillova Mikhail Ya. Melnikov Ekaterina M. Budynina 《Tetrahedron letters》2019,60(30):1952-1955
A convenient synthetic strategy for the diastereoselective assembly of spiro[azepane-4,3′-oxindoles] was developed via a Staudinger/Michael/aza-Wittig/reduction/N-deprotection reaction sequence starting from PMB-protected oxindole-substituted ethylazides. The key step of the method is a domino self-catalytic Michael/aza-Wittig reaction wherein the phosphazene moiety acts first as the catalyst and then as the reactant, resulting in the formation of a seven-membered N-heterocycle. 相似文献
9.
Alexander Safrygin Dmitry Darin Alexei Lukin Anna Bakholdina Alexander Sapegin Mikhail Krasavin 《Tetrahedron letters》2019,60(11):777-779
The versatile conversion of propargylic amides to the respective 2-substituted 5-methyloxazoles was efficiently catalyzed by Zn(OTf)2 (5?mol%) under microwave irradiation in toluene. The method was applicable to a wide range of aliphatic, aromatic and heteroaromatic propargylic amides and thus represents a useful method which is complementary to the existing metal-catalyzed protocols, considering the ready availability of Zn(OTf)2. 相似文献
10.
Yuliya S. Rozhkova Irina V. Plekhanova Alexey A. Gorbunov Olga G. Stryapunina Evgeny N. Chulakov Victor P. Krasnov Marina A. Ezhikova Mikhail I. Kodess Pavel A. Slepukhin Yurii V. Shklyaev 《Tetrahedron letters》2019,60(11):768-772
A new approach for the synthesis of functionalized racemic 3,4-dihydroferroceno[c]pyridines via the Ritter reaction of 2-methyl-1-ferrocenylpropan-1-ol with nitriles in the presence of methansulfonic acid was developed. The scope and limitations of the reaction were evaluated. Selected racemic 3,4-dihydroferroceno[c]pyridines were successfully separated by preparative HPLC on a Chiralcel OD-H column. The absolute configuration of the enantiomers was determined by X-ray crystal structure analysis. 相似文献