Synthesis of large building blocks for dendritic polyethers

Summary Building blocks containing multi-aryl ethers linkage in larger size for rapid building larger dendrimers were prepared with 3,5-di(4-hydroxyphenoxy)benzyl alcohol (1) as branch monomer and 1,3,5-tri(4-hydroxyphenoxy)benzene (2) as core molecule. Two generation of dendritic polyethers (12 and 15) were obtained by Fréchet convergent approach with 3,5-diphenoxybenzyl bromide (3) as starting molecule. They were characterized firstly by ¹H-NMR, ¹³C-NMR, and MS.     

流体在环形狭缝中流动时园柱体的微振动

本文讨论了在两个园柱体的环形狭缝中不可压缩流体的流动．在一定的假设下，运用流体力学方程和流体对柱体的作用方程，导出了附加质量和转动惯量、振动频率和衰减系数．并对文（１）中的某些结果进行了必要的修正．     

水泥砌块·欧洲文明

谈及水泥砌块生产与应用的成熟和普及,业内人士首推欧洲和美国;谈及水泥砌块生产机械性能的先进性,也首推欧洲和美国.欧洲砌块应用的成熟和普及,是与欧洲的建筑发展史、地理环境与资源供应、人文风情有着极其密切的关系的,是与欧洲文明的发展一脉相承的,表现了强烈的地域色彩.     

高能超声处理Al-1Si合金凝固组织分析

采用高能超声处理Al-1Si合金熔体,借助金相显微镜和电子探针进行组织分析,并测定合金的熔化潜热,分析了熔体中超声空化效应和声流效应影响凝固过程的机理。结果表明,试样晶粒平均尺寸由超声处理前的94μm减小到超声处理后的34μm;合金试样的熔化吸热量由263.90J/g降低为159.81J/g,在熔体中施加高能超声显著改善了合金成分的均匀性并细化了晶粒。     

时间分幅全息技术及其应用

本文介绍了一种对研究发动机燃烧过程有着重要应用价值的实验技术－时间分幅全息技术，本文就该技术中常常出现的重影问题做了重点研究，通过分析重影出现的根源，找到了一种消除重影的新方法，文章还举例说明了该技术在液体破碎机理问题保研究中的应用。     

Acid-base equilibrium—A thermodynamic study of formation and stability of the Bi-2223 phase

A general acid-base equilibrium theory was proposed to explain the formation and stability of the Bi-2223 phase based on the Lewis acid-base theory, and principle of metallurgical physical chemistry. The acid-base nature of oxide was defined according to the electrostatic force between cation and oxygen anion. A series of experimental facts were systematically explained based on the theory: substitution of Bi for Ca in. the Pb-free 2223 phase, and the effect of substitution of the high-valent cation for Bi³⁺; oxygen-pressure atmosphere, and the heat-schocking technique on the formation and stability of the 2223 phase.     

颗粒增强TiAl基复合材料及其Si的韧化作用研究EI

运用ＸＤ工艺制备了颗粒增强ＴｉＡｌ基复合材料。增强颗粒均匀分布于ＴｉＡｌ基体中并细化ＴｉＡｌ合金。通过在ＴｉＢ_２／ＴｉＡｌ、ＴｉＣ／ＴｉＡｌ复合材料中加入适量的Ｓｉ，颗粒增强ＴｉＡｌ基复合材料的室温延性得到了改善。     

在高速气流粉碎作用下PVC的力化学降解及形态变化的研究

通过ＧＰＴ、ＦＴ－ＩＲ、ＳＥＭ和力学性能测试，研究了在高速气流作用下聚氯乙烯（ＰＶＣ）的力化学降解反应、颗粒形态和微晶结构变化及其对ＰＶＣ物理、力学性能的影响。实验结果表明，经过高速气流处理ＰＶＣ，分子量将有所降低，晶体结构发生变化，颗粒尺寸和表观密度降低，比表面积增大，加工性能和力学性能得到明显改善。