碳酸氢钠活化过氧化氢对烯烃的环氧化

研究了碳酸氢钠活化H<,2>O<,2>(BAP)体系对苯乙烯和不饱和脂肪酸甲酯的环氧化.分别考察了碳酸氢钠、表面活性剂、加料方式、反应时间、H<,2>O<,2>用量和反应温度对BAP体系H<,2>O<,2>分解和烯烃环氧化的影响.在n(苯乙烯):n(H<,2>O<,2>):n(NaHCO<,3>)=1:10:0.25,...     

Synthesis, Crystal Structure, and Herbicidal Activities of 2-Cyanoacrylates Containing 1,3,4-Thiadiazole Moieties

Three series of novel 2‐cyanoacrylates 7a – 7f , 9a – 9f , 10a – 10f containing 1,3,4‐thiadiazole ring moieties were synthesized as herbicidal inhibitors of photosystem II (PS II) electron transportation. Their structures were clearly verified by ¹H NMR, ¹³C NMR, elemental analysis (or HRMS analysis) and single‐crystal X‐ray diffraction analysis. Bioassay showed that a suitable group at the 3‐position of acrylates was essential for high herbicidal activity. In particular, compound 7e showed the best herbicidal activities and gave 100% inhibitory activity against rape and amaranth pigweed at a dose of 1.5 kg/ha. Introduction of substituent with higher polarity such as sulfinyl or sulfonyl to the 5‐position of 1,3,4‐thiadiazole decreased herbicidal activities.     

Knowledge-based scoring functions in drug design: 3. A two-dimensional knowledge-based hydrogen-bonding potential for the prediction of protein-ligand interactions

Hydrogen bonding is a key contributor to the molecular recognition between ligands and their host molecules in biological systems. Here we develop a novel orientation-dependent hydrogen bonding potential based on the geometric characteristics of hydrogen bonds observed in 44,585 protein-ligand complexes. We find a close correspondence between the empirical knowledge and the energy landscape inferred from the distribution of HBs. A scoring function based on the resultant hydrogen-bonding potentials discriminates native protein-ligand structures from incorrectly docked decoys with remarkable predictive power.     

Discrete-time orthogonal spline collocation methods for the nonlinear Schrödinger equation with wave operator

In this paper, discrete-time orthogonal spline collocation schemes are proposed for the nonlinear Schrödinger equation with wave operator. These schemes are constructed by using orthogonal spline collocation approaches combined with finite difference methods. The conservative property, the convergence, and the stability of these methods are theoretically analyzed and also verified by extensive numerical experiments. In addition, some interesting phenomena which require further theoretical analysis are discussed numerically.     

基于电子交易市场的最优采购策略

随着电子交易市场的发展,企业在传统的远期合约采购基础上,开始从现货市场采购产品.在假定制造商通过远期合约和现货市场采购产品的情况下,研究了影响市场需求和现货市场价格的公共因子与特殊因子对制造商决策的影响.首先建立了最优采购策略的数学模型,其次对所建立的数学模型进行了求解,最后结合数值例子进行了灵敏度分析.研究表明:在相...     

First principles investigation on the key factors of broad absorption spectra and electronic properties for oligothiophene and its derivatives for solar cells

On the basis of optimized structures of two kinds thiophene oligomers, we investigated the configuration and conformation dependent optical and electronic properties of α or β substituted oligothiophene (PT) and oligo(thienylenevinylene) (PTV) isomers, respectively, at the TD‐DFT/6‐31+G(d,p)//PBE0/6‐31G(d) level. The corresponding properties of polymers were predicted by extrapolation method. The broad absorption regions for polythiophene and/or poly(thienylenevinylene) can be ascribed to the coexistence of various conformational and/or configurational isomers with similar energies and each corresponding excited state possessing different absorption spectrum and overlapping each other. Furthermore, the reorganization energies for electron (λ_e) and hole (λ_h) of α or β substituted PTV and PT indicate them to be potential ambipolar charge transport materials under the proper operating conditions. Therefore, these results are important because they can provide a rational way for the design of multifunctional materials with broad absorption and ambipolar charge transport properties for solar cells devices. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

Paley‐Wiener‐Type theorems for the Clifford‐Fourier transform

In the framework of Clifford analysis, we consider the Paley‐Wiener type theorems for a generalized Clifford‐Fourier transform. This Clifford‐Fourier transform is given by a similar operator exponential as the classical Fourier transform but containing generators of Lie superalgebra.     

Blow-up for 3-D compressible isentropic Navier-Stokes-Poisson equations

Czechoslovak Mathematical Journal - We study compressible isentropic Navier-Stokes-Poisson equations in ?3. With some appropriate assumptions on the density, velocity and potential, we show...     

Infrared and near infrared emission spectra of SbH and SbD

The X³Σ⁻ ground state vibration-rotation spectrum of SbH and the near infrared spectra of the b¹Σ⁺-X³Σ⁻ transitions of SbH and SbD have been measured at high resolution by Fourier transform spectroscopy. The SbH and SbD radicals were generated in a tube furnace with a D.C. discharge of a flowing mixture of argon, hydrogen (or deuterium), and antimony vapor. In the infrared region, the 1-0 and 2-1 bands of the three components (0⁺, 1_e, and 1_f) as well as the 0⁺ component of the 3-2 band were observed for ¹²¹SbH and ¹²³SbH. In the near infrared region, the 0-0, 1-1, and 2-2 bands of the b¹Σ⁺-X³Σ⁻ system of both SbH and SbD as well as the 3-3 band of SbD were observed. Except for a few lines, the antimony isotopic shift was not resolved for these electronic spectra. The present data set was combined with the available ground state data on SbD and a¹Δ data for SbH and SbD from previous work, and a least-squares fit was performed for each of the four isotopologues: ¹²¹SbH, ¹²³SbH, ¹²¹SbD, and ¹²³SbD. Improved spectroscopic constants were obtained for the observed vibrational levels of the X³Σ⁻, a¹Δ, and b¹Σ⁺ states of these four isotopologues. In addition, all the above data were also fitted simultaneously to a multi-isotopologue Dunham model, which yielded Dunham constants and Born-Oppenheimer breakdown parameters for these three electronic states. Interestingly, we found that Born-Oppenheimer breakdown corrections were also required for some of the spin-spin and spin-rotation parameters of the X³Σ⁻ state.     

目标极点提取的改进算法

针对强电磁脉冲孔耦合瞬态响应的极点参数提取问题,将传统的矩阵束算法进行改进。通过对含有噪声的瞬态响应数据进行互相关处理,能有效提高低信噪比时极点的提取精度。再将数据经离散化后构造Hankle矩阵,结合奇异值分解,求解其广义特征值,即可提取信号的极点参数信息。最后通过仿真分析以及对波形的重构,验证改进算法具有抗噪能力强、拟合度高的特点。