Synthesis and properties of alkylated imidazoles

Alkylation of 4(5)-nitroimidazole-5(4)-sulfonamide with benzyl bromide occurred on both ring nitrogens. The structures of the products could be assigned by comparison of the chemical shifts of the sulfonamide hydrogens in the nmr spectra with those of the isomeric methyl derivatives, which were prepared by differing routes. Uv and nmr spectral data are reported for a number of bromo-, nitro-, mercapto-, sulfamyl- and amino- substituted imidazoles as well as for both of the isomeric methylated derivatives of the series.     

一类抛物型方程的粘性解

讨论一类退化、奇异抛物型方程的初边值问题. 通过构造上下解 ,利用粘性解的比较原理和 Perron方法 ,证明了这类问题粘性解的存在性和唯一性.     

图像序列运动检测算法的研究及其应用

探讨了监控图像序列中进行运动检测的若干基本算法 ,结合统计方法和边缘检测筛选出运动边缘点 ,对运动边缘点逐个进行了块匹配最优搜索 ,估算出其运动矢量 .此方法在数字视频监控系统中用于运动物体检测和报警 ,不但提供了智能型监控 ,而且也有效的压缩了存储数据 ,改善了系统性能 ,有较好的实用价值 .     

Preparation and nonisothermal crystallization behavior of polyamide 6/montmorillonite nanocomposites

Polyamide 6 (PA6)/montmorillonite (MMT) nanocomposites were prepared via melt intercalation. The structure, mechanical properties, and nonisothermal crystallization kinetics of PA6/MMT nanocomposites were investigated by X‐ray diffraction (XRD), tensile and impact tests, and differential scanning calorimetry (DSC). Before melt compounding, MMT was treated with an organic surfactant agent. XRD traces showed that PA6 crystallizes exclusively in γ‐crystalline structure within the nanocomposites. Tensile measurements showed that the MMT additions are beneficial in improving the strength and the stiffness of PA6, at the expense of tensile ductility. Impact tests revealed that the impact strength of PA6/MMT nanocomposites tended to decrease with increasing MMT content. The nonisothermal crystallization DSC data were analyzed by Avrami, Ozawa, modified Avrami‐Ozawa, and Nedkov methods. The validity of these empirical equations on the nonisothermal crystallization process of PA6/MMT nanocomposites is discussed. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2878–2891, 2004     

用样条函数表示非球面方程式的光线追迹

提出用样条函数来表示非球面方程式,它优于一般的非球面方程式表示法,便于计算。