罗丹明6G分光光度法测定镉的研究

本文研究了在聚乙烯醇—124存在下,C_d~(2+)—I~-—罗丹明6G高灵敏度显色体系。用加权单纯形最优化法进行了最佳实验条件的选择。缔合物的λ_(max)=560nm。表观摩尔吸光系数ε_(560)=9.5×10~4l·mol~(-1)·cm~(-1)。测定了络合物的组成,研究了20多种共存离子对测定的影响。方法用于纯铝、纯锌中镉的测定。     

新试剂6-(2-羟基-4-二乙基氨苯偶氮)-2,3-二氢-1.4-酞嗪二酮的电化学发光研究

应用自制的ＥＣＬ－１型电致化学发光仪，对新试剂６－（２－羟基－４－二乙基氨苯偶氮）－２．３－二氢－１，４－酞嗪二酮（ＨＤＥＡ）在Ｎａ２ＣＯ３－ＮａＨＣＯ３缓冲介质中的电化学发光行为作了研究．结果发现，当介质ｐＨ值为 １０．５４时，在一定的实验条件下，施加 １．７Ｖ （ＶＳ．ＳＣＥ）三角波脉冲电压，体系的发光强度与ＨＤＥＡ浓度在５．０ × １０－９～１．０×１０－６ｍｏｌ／Ｌ范围内呈线性关系，反应的检测限达１．０×１０－９ｍｏｌ／Ｌ．     

Hepatic hydroxylation of melatonin in the rat is induced by phenobarbital and 7,12-dimethylbenzy[a]anthracene — implications for cancer etiology

The protective function of the pineal hormone melatonin in the etiology of cancer and carcinogenic activation is increasingly well-established. Low melatonin levels seem to parallel cancer growth. The question arises as to which factors cause the depression of melatonin levels and what the direct effects are. Melatonin is known to be metabolized in the liver by hydroxylation and subsequent conjugation yielding 6-sulfatoxymelatonin as a main product. Nevertheless, the microsomal monoxygenases catalyzing the first step have been poorly investigated. To further characterize these enzymes, typical inducers of three different sub-classes, namely phenobarbital, 7,12-dimethylbenz[a]anthracene, and 17-estradiol, were administered to female Fischer rats. Circadian urinary excretion patterns of melatonin and 6-sulfatoxymelatonin were determined over a 24-hour period on the third (second) day of induction. Liver homogenates were used to monitor the in vitro conversion of melatonin or 6-hydroxymelatonin to 6-sulfatoxymelatonin. Results of both approaches showed the microsomal monoxygenases catalyzing the 6-hydroxylation of melatonin to be strongly inducible by phenobarbital and to a lesser degree by the polyaromatic hydrocarbon 7,12-dimethylbenz[a]anthracene. The dramatic depletion of circulating melatonin as a result of these induction patterns and its possible implications for oncogenesis are discussed.     

Genetic and molecular approaches to synthesis and action of the yeast killer toxin

Summary The K1 killer toxin ofSaccharomyces cerevisiae is a secreted, virally-coded protein lethal to sensitive yeasts. Killer yeasts are immune to the toxin they produce. This killer system has been extensively examined from genetic and molecular perspectives. Here we review the biology of killer yeasts, and examine the synthesis and action of the protein toxin and the immunity component. We summarise the structure of the toxin precursor gene and its protein products, outline the proteolytic processing of the toxin subunits from the precursor, and their passage through the yeast secretory pathway. We then discuss the mode of action of the toxin, its lectin-like interaction with a cell wall glucan, and its probable role in forming channels in the yeast plasma membrane. In addition we describe models of how a toxin precursor species functions as the immunity component, probably by interfering with channel formation. We conclude with a review of the functional domains of the toxin structural gene as determined by site-directed mutagenesis. This work has identified regions associated with glucan binding, toxin activity, and immunity.     

浅谈300MW机组采用临时6kV电源进行系统调试

本文针对300MW燃煤火力发电厂中由于外线路无法投用,升压站无法正常倒送厂用电时利用原有机组的6kV电源进行临时性厂用受电,为新建发电机组的安装、单体调试、系统调试等方面如期进行争取时间。列举了应用中出现的有代表性的问题并提出解决对策,提供有益的借鉴,从而保证电厂施工的里程碑进度如期实现。     

量子辛型群O（Spq（6））的一种实现

通过Uq（sp（6））的最高权模的自然表示理论,给出了量子辛型群O（Spq（6））的所有定义关系式。     

非化学计量Li_6F_5团簇的几何结构和电离能

基于非化学计量Li6F5团簇的电离能的实验测量值,从第一性原理出发间接地确定了这个团簇的几何结构.首先选取若干可能的初始结构,然后在密度泛函理论框架内,使用B3LYP泛函和6-311+G(d)基组优化所有初始结构,从而获得能量较低的同分异构体.对该团簇本文找到8个同分异构体,其中最低能量结构是一个对称性为Cs的三维构型.其计算的绝热电离能3.9 eV与实验值4.1±0.1 eV符合很好,表明本文找到的最低能量结构是可靠的.     

PAN-6S分光光度法测定钢铁中的铅

利用PAN-6S与Pb2+的显色反应测定钢铁中铅的含量.在pH=7.0~10.0范围内PAN-6S与Pb2+形成物质的量比为1∶1的红色配合物,其最大吸收峰在543 nm处,摩尔吸光系数为1.12×104,加入掩蔽剂后可直接测定钢铁中铅的含量.     

建设“文化强国”给公共图书馆带来新的契机和挑战

基于党的十七届六中全会的有关精神,探讨了建设"文化强国"给公共图书馆带来的新的契机和挑战,指出图书馆应以高度文化自觉推动图书馆事业的发展与繁荣,阐述了通过建设文化强国应使公共图书馆惠及更多百姓的问题,从机制体制建设、服务内容创新、图书馆新文化等方面提出了图书馆推动社会主义文化大发展的思路。     

浅谈下一代互联网的新技术标准——IPv6

21世纪进入了网络时代，网络的发展已经进入我们生活的方方面面，成为我们日常学习和工作的必备工具。然而现有的IPv4地址的匮乏，严重的阻碍和制约了网络的应用和未来的发展。IPv6作为下一代互联网的标准和基础，有着广阔的发展前景。从IPv6的产生、结构以及其发展前景3个方面进行了简要阐述。