A new synthesis of alkynyl tellurides promoted by CsOH and 4(A°) MS

The mixture of cesium hydroxide and terminal alkynes in dry DMF in the presence of 4(A°), molecular sieves was stirred for 3.0 h at room temperature under N2, then aryltellurenyl bromide in THF was added, and the reaction mixture was stirred for 2.0 h. Alkynyl tellurides were obtained in about 90% yields by flash chromatography.     

Kinetic Study of the Degradation of PAC-1 and Identification of a Degradation Product in Alkaline Condition

A selective and validated stability-indicating LC method was developed for the kinetic study of the degradation of PAC-1, which was carried out in aqueous solutions at 37, 60, 80 and 100 °C with pH 1.5–9.0. Separation was performed on a Kromasil C₁₈ column with acetonitrile–water–fomic acid (30:70:0.1, v/v/v) as mobile phase with a flow rate of 1.0 mL min⁻¹ at 281 nm. The degradation rate obtained indicated a first-order reaction law and the activation energy (E _a) was calculated. The results showed that temperature and pH values were significant factors affecting the degradation of PAC-1. An unknown degradation product in alkaline condition was isolated using a reverse-phase semi-preparative LC system. The structure of the degradation product is identified as 2-hydroxy-3-(2-propenyl)-[[2-hydroxy-3-(2-propenyl)phenyl]methylene]hydrazone utilizing the ¹H NMR, ¹³C NMR, IR and Q-TOF-MS techniques.

     

Double Modification of Electrode Surface for the Selective Detection of Epinephrine and Its Application to Flow Injection Amperometric Analysis

A glassy carbon electrode having two polymer layers has been applied to selectively detect epinephrine. The inner layer formed by electropolymerization of macrocyclic nickel complex functioned as an electrocatalyst for epinephrine oxidation and the outer layer composed of hydrolyzed polyurethane γ‐benzyl L ‐glutamate as a screening layer. Differential pulse voltammetry showed almost 100% recovery of epinephrine even in 100‐fold excess of interferents. When applied to a dual glassy carbon electrode as an amperometric detector in flow injection analysis, a linear response over 0.1 μM and 10 μM was obtained. Recovery tested for 5‐fold diluted human urine samples was 97.5%.     

光学相干层析系统的耦合效率分析

在高斯光束传输理论的基础上，利用矩阵光学原理和高斯光束耦合理论，得出光学相干层析系统中参考反射镜的空间位置对系统耦合效率影响的表达式，并用计算机模拟系统的耦合效率与参考反射镜和棒透镜间的距离及参考反射镜偏转角度的关系曲线。实验结果和理论分析相符合。     

Numerical study on flanging and spring-back of stamped thick metal plate

A quasi-three-dimensional shell element model, which can be effectively used to simulate the flanging and spring-back deformation, is introduced into the independently developed CAE software, KMAS. In this model, a double surface contact algorithm, which allows the gap between punch and die to change, and a spring-back treatment scheme based on finite element meshing are described. And then the flanging and spring-back deformations of the retractor's kickstand of a railcar made of stamped thick metal plate are numerically simulated. The simulation results of flanging deformation are compared with those of international commercial software, PAM-STAMP, and experimental ones. Finally, a predicting scheme of spring-back quantily for this problem is given. Project supported by the National Natural Science Foundation of China (No. 19832020) and the Ministry of Education of China.     

一类多偏差变元的n种群Lotka-Volterra模型的周期正解

本文研究了一类多偏差变元Lotka-Volterra种群模型的间期正解问题,利用重合度拓展定理和一些分析技巧,得到了周期正解存在性的新结果.与已有文献相比,本文所讨论的模型更具一般性,它包含了以前人们所研究的竞争-种群模型、捕食-种群模型等,而且估计先验界的方法也是全新的.     

Generalized Strang–Fix condition for scattered data quasi-interpolation

Quasi-interpolation is very useful in the study of the approximation theory and its applications, since the method can yield solutions directly and does not require solving any linear system of equations. However, quasi-interpolation is usually discussed only for gridded data in the literature. In this paper we shall introduce a generalized Strang–Fix condition, which is related to nonstationary quasi-interpolation. Based on the discussion of the generalized Strang–Fix condition we shall generalize our quasi-interpolation scheme for multivariate scattered data, too. AMS subject classification 41A63, 41A25, 65D10Zong Min Wu: Supported by NSFC No. 19971017 and NOYG No. 10125102.     

纵向数据半参数回归模型估计的r阶平均相合性

本文考虑纵向数据下半参数回归模型:yij=xij′β g(tij) eij,i=1,…,m,j=1,…,ni.基于最小二乘法和一般的非参数权函数方法给出了模型中参数β,回归函数g(·)和误差方差σ2的估计,并在适当条件下证明了估计量的r(r≥2)阶平均相合性.