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31.
Zhen Wang Zuliang Zhang Qian Yao Prof. Dr. Xiaohua Liu Yunfei Cai Dr. Lili Lin Prof. Dr. Xiaoming Feng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(26):8591-8596
The highly Z‐selective asymmetric conjugate addition of 3‐substituted oxindoles to alkynyl carbonyl compounds has been developed by using scandium complexes of chiral N,N′‐dioxides under mild conditions. The thermodynamically unstable Z‐olefin derivatives were obtained in excellent yields and high enantiomeric and geometric control. The catalyst was also found to be effective in the asymmetric acetylenic substitution reaction of 3‐substituted oxindoles, giving excellent enantioselectivities. 相似文献
32.
Emerald ash borer (EAB), Agrilus planipennis Fairmaire, is an invasive insect that has killed millions of ash trees in Canada and the USA. (3Z)-Dodecen-12-olide is a known female-produced pheromone of this insect, and a concise, three-step synthesis of a 2:1 blend of (3Z)-dodecen-12-olide and (3E)-dodecen-12-olide starting from commercially available (2-carboxyethyl)triphenylphosphonium bromide and 10-bromo-1-decene is described. The key steps in this synthesis are a lithium-salt-free Wittig reaction and an intramolecular SN2 esterification. Both of these macrocyclic lactones are behaviorally active toward EAB, and the 2:1 blend whose synthesis is described here has the potential to be a detection agent, mating disruptor, or mass trapping agent, which could be used in the control of EAB. 相似文献
33.
FtsZ蛋白和细菌的繁殖过程有关,是药物设计理想的靶点。本文采用Sybyl分子模拟软件,利用比较分子场方法(CoMFA)及比较分子相似性指数的方法(CoMSIA)对已报道的33个噁唑-苯甲酰胺类FtsZ受体抑制剂进行了分析,建立了三维定量构效关系(3D-Qsar)模型。CoMFA模型的交互验证系数q2为0.619,线性回归系数r2为0.988;CoMSIA模型的q2为0.633,r2为0.936。模型具有较好的预测能力,为今后噁唑-苯甲酰胺类化合物的设计和改造提供了理论依据。 相似文献
34.
Dr. Jiu Chen Prof. Dr. Qing Tang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(38):9925-9933
The recent successful growth of MoSi2N4 and WSi2N4 monolayers led to the discovery of a new class of the two-dimensional (2D) MA2Z4 materials with no known 3D layered allotropes, which renders great possibilities to integrate diverse properties by proper design of sandwiched “MZ2” building blocks and “A−Z” passivation layers. In this work, the dynamic stability, electronic properties, and surface reactivity of the new MA2Z4 family, in which M is Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, A refers to Si or Ge, and Z is N, P or As, is theoretically probed. Among the proposed 54 possible combinations, about 42 compositions are dynamically stable, which vary from non-magnetic, anti-ferromagnetic, to ferromagnetic semiconductors, metals and half-metals. In particular, the VB (V, Nb, Ta) MA2Z4 possesses robust intrinsic ferromagnetism that is essential for spintronics applications. In regard to surface activity, most MA2Z4, particularly N- or P-terminated IVB and VB MA2Z4, have high catalytic potential for hydrogen evolution, and the ▵GH of non-magnetic MA2Z4 is highly correlated to the highest occupied p electronic states of the surface Z atoms. The photocatalytic activity is also evaluated. MoSi2N4 and WSi2N4 within 4 % tensile strain are capable of photocatalytic overall water splitting. The findings indicate the new 2D MA2Z4 family has fascinating properties and possesses strong potential for applications but not limited to electronics, spintronics and catalysts, which will stimulate the interests of experimental synthesis. 相似文献
35.
We introduce the notion of strong supercommutativity of self-adjoint operators on a
-graded Hilbert space and give some basic properties. We clarify that strong supercommutativity is a unification of strong commutativity and strong anticommutativity. We also establish the theory of super quantization. Applications to supersymmetric quantum field theory and a fermion-boson interaction system are discussed. 相似文献
36.
Shih‐I Lu 《Journal of computational chemistry》2009,30(14):2176-2180
In this article, we examined the Gibbs energy of activation for the Z/E thermal isomerization reaction of (1Z)‐acetaldehyde hydrazone and (1Z)‐acetaldehyde N,N‐dimethylhydrazone, at 298.15 K in the solvent of cyclohexane. We carried out computations employing both the Gaussian‐4 (G4) theory and the coupled cluster method using both single and double substitutions and triple excitations noniteratively, CCSD(T). The CCSD(T) energy is extrapolated to the complete basis set (CBS). We compared the calculated results to the available experimental observation. It appeared that both G4 and CCSD(T)/CBS computations overestimated the experimental value by as much as about 6 and 12 kcal/mol in the present two cases. We discussed possible sources of error and proposed the experimental kinetic data could be questionable. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2009 相似文献
37.
Lie group method is investigated for solving the problem of heat transfer in an unsteady, three-dimensional, laminar, boundary-layer flow of a viscous, incompressible and electrically conducting fluid over inclined permeable surface embedded in porous medium in the presence of a uniform magnetic field and heat generation/absorption effects. A uniform magnetic field is applied in the y-direction and a generalized flow model is presented to include the effects of the macroscopic viscous term and the microscopic permeability of porous medium. The infinitesimal generators accepted by the equations are calculated and the extension of the Lie algebra for the problem is also presented. The restrictions imposed by the boundary conditions on the generators are calculated. The investigation of the three-independent-variable partial differential equations is converted into a two-independent-variable system by using one subgroup of the general group. The resulting equations are solved numerically with the perturbation solution for various times. Velocity, temperature and pressure profiles, surface shear stresses, and wall-heat transfer rate are discussed for various values of Prandtl number, Hartmann number, Darcy number, heat generation/absorption coefficient, and surface mass-transfer coefficient. 相似文献
38.
基于MPEG-4硬件解码的视频终端设计 总被引:1,自引:0,他引:1
以JADE Z228多媒体Soc芯片为核心,设计了一款适用于多媒体教学的MPEG-4视频终端.介绍了以Z228单处理器芯片实现MPEG-4解码输出的软、硬件设计过程以及与周边外设的接口方法,实现了VGA640×480分辨率、每秒30帧的MPEG-4视频解码输出的目标,使视频终端具有很高的性价比. 相似文献
39.
Two new sesquiterpenes, madolins Y ( 1 ) and Z ( 2 ) were isolated from the dried roots and stems of Aristolochia mollissima, and their structures were determined by spectroscopic methods. 相似文献
40.
V. Bonnaillie-Noël F. Nier Y. Patel 《Annales de l'Institut Henri Poincaré (C) Analyse Non Linéaire》2008
We describe the asymptotics of the steady states of the out-of-equilibrium Schrödinger–Poisson system, in the regime of quantum wells in a semiclassical island. After establishing uniform estimates on the nonlinearity, we show that the nonlinear steady states lie asymptotically in a finite-dimensional subspace of functions and that the involved spectral quantities are reduced to a finite number of so-called asymptotic resonant energies. The asymptotic finite dimensional nonlinear system is written in a general setting with only a partial information on its coefficients. After this first part, a complete derivation of the asymptotic nonlinear system will be done for some specific cases in a forthcoming article [V. Bonnaillie–Noël, F. Nier, M. Patel, Far from equilibrium steady states of 1D-Schrödinger–Poisson systems with quantum wells II, Prépublications IRMAR, 2007]. 相似文献