若干杂环模型化合物的热氧化稳定性

<正> 自五十年代以来,耐热的杂环高分子取得了很多进展。曾报道聚酰亚胺、聚苯并咪唑、聚苯并噻唑、聚苯并噁唑、聚喹噁林及聚苯并噁嗪酮等都是性能较好的耐热高分子,而有些在工业上已得到应用。我们在进行芳杂环二腈聚合的工作中,曾将上述杂环结构引入二腈,以期获得性能优良的耐热高分子,所得结果已陆续报道。     

过渡金属催化的有机硼酸与不饱和键的加成反应

概述了过渡金属催化的有机硼酸与不饱和键的加成反应,包括铑催化、镍催化、钯催化三部分内容.     

INFLUENCE OF COMPOSITIONAL HETEROGENEITY ON MORPHOLOGY AND PROPERTIES OF SEGMENTED COPOLYMERS

Polyethylene terephthalate(PET)/polycaprolactone(PCL) segmented copolymers with different hard segment contents and a blend of two of them were studied by using DSC, WAXS, TEM and IR techniques and dynamic mechanical, stress-strain and isothermal crystallization measurements. Emphasis was laid on the studies of influence of compositional heterogeneity on the morphology and properties of these segmented copolymers. It was found that the solution cast specimens of the more heterogeneous sample exhibit better segregation of segments, high crystallinity and melting temperature. They have higher thermal stability of mechanical properties at small deformations. However, they are less stable against large deformations and may become softer than the more homogeneous ones.     

Spectroscopy Investigation on Conformational Transition of Tea Glycoconjugate from Green Tea

The conformational transition of a new glycoconjugate, tea glycoconjugate (TGC), was investigated by spectroscopy techniques including circular dichroism (CD) and ultraviolet (UV) spectroscopy. The solution behaviors of TGC in the mediums of different temperature, pH value, and ions were compared. Results showed that the native conformation of TGC was partially ordered. The CD value and UV absorbance of TGC altered with the change of pH value, temperature, the addition of ions, and also accompanied order-disorder transition. Especially the conditions with temperature higher than the glass transition temperature (Tg=62℃), higher pH value or lower pH value will have the most impact on the conformation of TGC, which will destroy the hydrogen bonds between the TGC molecules. The results indicated that the outside factors play important roles on the stability of the conformation of TGC.     

离子色谱法测定水果及其树叶的含氯量

本文提出用离子色谱法测定水果及其树叶中氯含量的方法,在IC-PAK阴离子柱上,用4 mmol/L邻苯二甲酸(pH4.5)作流动相进行洗脱,电导检测器检测。方法简便、快速,灵敏、准确。氯的最小检出量为0.14μg,相对标准偏差为2.4%,回收率为99.4%。