1,2,4-三嗪类化合物的研究(ⅪⅤ)——3-甲氧基-5-甲基-6-乙酰-1,2,4-三嗪的合成及其与芳香醛的反应

5或6-取代芳乙烯基-1,2,4-三嗪类化合物具有广谱抑菌活性,本文将3-甲氧基-5-甲基-6-乙酰-1,2,4-三嗪(Ⅱ)在HCI/AcOH体系中与芳香醛进行缩合反应,分别得到3-甲氧基-5-甲基-4′-羟基-肉桂酰基-1,2,4-三嗉(Ⅲ)和3-甲氧基-6-乙酰-5-[2-取代芳基-乙烯基]-1,2,4-三嗪(Ⅳ)。     

Self‐assembling directed synthesis of a novel terephthalamide‐bridged ladderlike polysiloxane

A novel, soluble terephthalamide‐bridged ladderlike polysiloxane ( L ) was synthesized successfully for the first time by stepwise coupling polymerization. The process involved the hydrogen‐bonding self‐assembly of amido groups, which resulted in the formation of a more highly ordered polymeric structure. A novel monomer, bis(3‐methyldimethoxysilylpropyl) terephthalamide ( M ), was prepared by a hydrosilylation reaction in the presence of dicyclopentadienyl platinum dichloride as a catalyst. The structures of the monomer ( M ) and the polymer ( L ) were characterized by Fourier transform infrared, ¹H NMR, ¹³C NMR, ²⁹Si NMR, mass spectrometry, X‐ray diffraction, differential scanning calorimetry, and vapor pressure osmometry. All the characterization data indicated that the synthesized polymer ( L ) possessed an ordered ladderlike structure. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3161–3170, 2002     

BaLaB9O16中Ce3+敏化Dy3+发光的机理

在紫外光激发下,研究了BaLaB₉O₁₆中Dy³⁺、Ce³⁺的发光光谱、激发光谱、发光强度及荧光寿命随着组成变化的规律性.结果表明;De³⁺对Dy³⁺的发光有相当强的敏化作用,Ce³⁺→Dy³⁺的能量传递效率可高达93%,能量传递的机理为电偶极-偶极相互作用的共振传递.根据349nm激发下Dy³⁺发光强度与浓度的关系,证明了Dy³⁺发光的自身浓度猝灭机理也为电偶极-偶极相互作用.     

熔盐辅助法制备g-C3N4纳米结构及其光催化制氢性能

以尿素作为原料, 采用熔盐辅助热聚合法在KCl-NaCl-BaCl₂体系中制备了带隙可调的g-C₃N₄纳米结构. 采用X射线衍射仪、 扫描电子显微镜、 X射线光电子能谱仪、 紫外-可见漫反射光谱仪及荧光光谱仪对产物的结构、 形貌、 成分及光学性能进行了表征. 对g-C₃N₄纳米结构可见光条件下的光催化制氢性能进行了测试, 研究了不同的尿素/熔盐比对其光催化性能的影响. 结果表明, 熔盐辅助热聚合法制备的g-C₃N₄ 纳米结构吸收光谱出现明显宽化, 吸收边由普通热聚合法制备g-C₃N₄的约450 nm红移至约500 nm左右. 同时光生载流子复合几率明显降低, 从而有效提升其光催化制氢性能. 最优化的g-C₃N₄(60)样品析氢速率达到12301.1 μmol?g^?1?h^?1, 为普通热聚合法制备g-C₃N₄析氢速率的4倍.     

Indirect inverse substructuring identification method for coupling dynamic stiffness of vibrational structures

Coupling dynamic stiffness is a key parameter in vibrational analysis of complex coupled structures, for both estimation of structural vibrational characteristics and design of vibration control. An indirect method of inverse substructuring analysis to identify the stiffness is studied further by using frequency response functions that are tested on the models of coupled structures. The theoretical effectiveness of this method is here verified by two ‘mass-rubber' experimental models constructed as two-level substructures with mono-coupling and tri-coupling connections, and the identification error is also analyzed. The coincidence of numerical and experimental results show that the indirect method has better feasibility and effectiveness than the existing direct method of inverse substructuring analysis, and with more applicable conditions and higher acceptable precision in determining the stiffness. It provides more solid theoretical basis for the stiffness identification by inverse substructuring analysis.     

基于反求的医疗辅助弹性护具应变能的计算

提出了基于反求工程的医疗辅助弹性护具的设计方法,推导出弹性护具应变能的计算公 式. 设计中应用网格简化技术减少扫描数据以及参数化技术将三维转化为二维进行计算,减 少了网格点应变能的计算量,提高了设计效率. 应用应变能密度函数建立起弹性护具几何尺 寸与应变能之间的关系,为医生或患者科学地选择医疗护具提供了依据.     

地质和岩土工程光纤传感监测技术综述

光纤传感器与常规传感器相比具有很大的优越性,已经成为地质和岩土工程监测领域中的研究热点。本文介绍了光纤传感监测系统的种类、基本测量原理和目前国内外的研究发展状况,并对各种传感技术的性能和特点进行了比较,指出了光纤传感监测技术应用于地质和岩土工程监测尚需研究的相关课题。     

双手性选择单元手性固定相的研究进展

手性固定相（chiral stationary phase,CSP）作为手性色谱分离的核心技术,在手性化合物的识别和分离中得到广泛应用。以双手性选择单元结合作为CSP是近些年的研究热点,研究表明,两种手性选择单元相结合的CSP可增加手性识别位点,显著提高分离效果。本文介绍了近几年双手性选择单元手性固定相在手性分离中的研究进展,并对其发展前景进行了展望。