聚乙烯醇作保护剂的反滴定共沉淀法制备纳米晶LaFeO_3

以聚乙烯醇或十二烷基苯磺酸钠作保护剂,采用反滴定共沉淀法制备纳米晶LaFeO_3的前体.     

浅谈流体在流管出口下游形成“缩脉”的物理实质

一般流体,在流出管口后均有形成“缩脉”的现象.该文就流体在流出管口后,形成“缩脉”的物理实质进行了定性的分析,将其归结为在流管出口附近,流体受管口发出的扰动波的影响,而形成“缩脉”.     

A degradation-sensitive anionic trypsinogen (PRSS2) variant protects against chronic pancreatitis

Chronic pancreatitis is a common inflammatory disease of the pancreas. Mutations in the genes encoding cationic trypsinogen (PRSS1) and the pancreatic secretory trypsin inhibitor (SPINK1) are associated with chronic pancreatitis. Because increased proteolytic activity owing to mutated PRSS1 enhances the risk for chronic pancreatitis, mutations in the gene encoding anionic trypsinogen (PRSS2) may also predispose to disease. Here we analyzed PRSS2 in individuals with chronic pancreatitis and controls and found, to our surprise, that a variant of codon 191 (G191R) is overrepresented in control subjects: G191R was present in 220/6,459 (3.4%) controls but in only 32/2,466 (1.3%) affected individuals (odds ratio 0.37; P = 1.1 x 10(-8)). Upon activation by enterokinase or trypsin, purified recombinant G191R protein showed a complete loss of trypsin activity owing to the introduction of a new tryptic cleavage site that renders the enzyme hypersensitive to autocatalytic proteolysis. In conclusion, the G191R variant of PRSS2 mitigates intrapancreatic trypsin activity and thereby protects against chronic pancreatitis.     

Internet网络考试系统

将计算机与网络技术应用于教学考试领域是一个值得探讨的问题,本文详细描述了该考试试系统的指导思想、系统模块、设计原则及运行环境.     

两圆内外公切线方程的求法

讨论了圆的切线及两圆内外公切线的一般求法及步骤。     

BALB／c突变无毛小鼠离体鼠皮透皮吸收的研究

本文用甲硝唑作为模型药物,Ａｚｏｎｅ为透皮吸收促进剂,对ＢＡＬＢ／ｃ突变无毛小鼠的离体皮肤的透皮吸收情况进行了初步研究,并与国内在透皮吸收研究常用的昆明小鼠的离体鼠皮进行了初步比较,为无毛小鼠在皮肤病学研究中的应用提供一些依据,实验结果表明,ＢＡＬＢ／ｃ突变无毛小鼠离体鼠对甲硝唑的透皮吸收明显低于昆明小鼠,而离散程度优于昆明小鼠。