重氮—偶合分光光度法测定猩红酸中J酸

对猩红酸中J酸重氮化，J酸重氮盐在碱性水溶液中和H酸偶合发色，J酸重氮盐也可以在乙腈－乙醇－盐酸水混合溶剂中和萘乙二胺偶合发色，分光光度法测定猩红酸中J酸。对重氮化反应和偶合反应的条件，分光光度测定条件进行讨论。     

分光光度法测定含硫气体中微量氯化物

在碱性介质中将Ｓ２－氧化成ＳＯ４２－，再用分光光度法测定微量氯化物     

倍增显色TPB增敏间接分光光度法测定微量锰

将倍增显色反应和表面活性剂ＴＰＢ增敏作用结合起来，建立了间接水相分光光度法测定微量锰的新方法，该法具有较高的灵敏度，摩尔吸光系数达１．６５×１０５Ｌ·ｍｏｌ－１·ｃｍ－１，是目前水相分光光度法测锰最灵敏的方法之一，用于水样中微量锰的测定，结果满意。     

分光光度法测定含硫气体中微量氯化物

在碱性介质中将Ｓ＾２－氧化成ＳＯ４＾２－，再用分光光度法测定微量氯化物。     

红外分光光度法测定PVDC树脂中的ESO和ATBC

用二硫化碳萃取PVDC树脂中的增塑剂ESO和ATBC，红外分光光度法测定，以解联立方程的方法同时求得ESO和ATBC的量。测定的相对误差：ESO为－3．5～5．5％，ATBC为－3．0～5．7％。     

分光光度计测量硝体

本文论述了用Ｎ－１－萘乙二胺盐酸盐作显色剂，直接显色而测定硝体含量的新方法。通过新旧分析方法的比较，确定了分光光度法测定硝体含量其操作简便易行，结果准确合理。     

食品中痕量黄曲霉毒素B1的分析

联用高效液相色谱－荧光分光光度法，测定食品中黄曲霉毒素Ｂ１的含量。     

测定聚酯切片中锑含量方法的改进

利用Ｓｂ（Ⅱ）与Ⅰ－，在酸性介质中形成ＳｂⅠ４－黄色络合物的方法，进行分光光度测定聚酯中的锑含量．     

聚乙二醇6000对Tween-80含量测定的影响

目的了解聚乙二醇６０００对测定Ｔｗｅｅｎ－８０含量的影响。方法将被检样品加９５％乙醇沉淀蛋 白后，上清加二氯甲烷，再加铵钻硫氰酸盐溶液，用紫外分光光度计测Ａ６２０吸收峰。结果 ＰＥＧ－６ ０００含量＞ ５００ｕｇ／ ｍｌ时，干扰 Ｔｗｅｅｎ－８０含量测定。结论一定浓度的 ＰＥＧ－６ ０００对测定 Ｔｗｅｅｎ－８０含量有干扰。     

新型原子吸收分光光度法测定工业废水中的铜

研究了用液化石油气－空气焰代替乙炔－空气焰原子吸收分光光度法测定工业废水中的铜。其测定范围为０．２６４７～５．２９４０ｍｇ·Ｌ－１，灵敏度为１．８×１０－５ｍｇ·Ｌ－１。此法分析费用低，简便、快速，可用于实则工作中。     

Effect of introducing proline residues on the stability of Aspergillus awamori

In Aspergillus awamori glucoamylase, Ala27, Ala393, Ala435, Ser436 and Ser460 were replaced with proline residues, in order to stabilize the enzyme by forming more rigid peptide backbones. Specific activities were unaffected except for a decrease in Ser460-->Pro glucoamylase. Thermostability was increased in Ser436-->Pro glucoamylase, unchanged in Ala435-->Pro glucoamylase and decreased in Ala27-->Pro, Ala393-->Pro glucoamylases. As measured by circular dichroism, mutant glucoamylases Ala435-->Pro and Ser436-->Pro resisted unfolding caused by guanidine hydrochloride at pH 4.5 and 25 degrees C better than wild-type glucoamylase, whereas mutant glucoamylases Ala27-->Pro, Ala393-->Pro and Ser460-->Pro were more susceptible to unfolding than wild-type glucoamylase, reaching a level of 50% unfolded enzyme at guanidine hydrochloride concentrations 0.50-0.75 M lower than that of the wild- type enzyme. Mutations Ala435-->Pro and Ser436-->Pro are located in a non-regular structure, which is assumed to be stabilized by these mutations. The Ala27-->Pro residue is partially buried, which may result in unfavorable steric contact and/or regional strains; mutation Ala393-->Pro results in loss of a hydrogen bond, since the N of the proline residue does not have an extra hydrogen to act as donor; and mutation Ser480-->Pro eliminates an O-glycosylation site, which could explain how these mutations destabilized glucoamylase.      

逆向工程技术的应用

本文介绍了逆向工程技术，阐述了逆向工程技术的应用过程，运用PRO／E软件生成了三维曲面模型，具有一定的使用价值。     

Molecular determinants of xylose isomerase thermal stability and activity: analysis of thermozymes by site-directed mutagenesis

Xylose isomerases (XIs) from Thermoanaerobacterium thermosulfurigenes(TTXI) and Thermotoga neapolitana (TNXI) are 70.4% identicalin their amino acid sequences and have a nearly superimposablecrystal structure. Nonetheless, TNXI is much more thermostablethan TTXI. Except for a few additional prolines and fewer Asnand Gln residues in TNXI, no other obvious differences in theenzyme structures can explain the differences in their stabilities.TNXI has two additional prolines in the Phe59 loop (Pro58 andPro62). Mutations Gln58Pro, Ala62Pro and Gln58Pro/Ala62Pro inTTXI and their reverse counterpart mutations in TNXI were constructedby site-directed mutagenesis. Surprisingly, only the Gln58Promutation stabilized TTXI. The Ala62Pro and Gln58Pro/Ala62Promutations both dramatically destabilized TTXI. Analysis of thethree-dimensional (3D) structures of TTXI and its Ala62Pro mutantderivative showed a close van der Waal's contact between Pro62-C     

Expanding and engineering the genetic code in a single expression experiment

Expanding and engineering the code simultaneously: This concept was experimentally realized in a single in vivo expression experiment whereby residue-specific, sense codon reassignments Met→Nle/Pro→(4S-F)Pro (code engineering) were combined with position-specific STOP→Bpa read-through by an amber suppressor tRNA (code expansion).     

The structural roles of conserved Pro196, Pro197 and His199 in the mechanism of thymidylate synthase

We generated replacement sets for three highly conserved residues,Pro196, Pro197 and His199, that flank the catalytic nucleophile,Cys198. Pro196 and Pro197 have restricted mobility that couldbe important for the structural transitions known to be essentialfor activity. To test this hypothesis we obtained and characterized13 amino acid substitutions for Pro196, 14 for Pro197 and 14for His199. All of the Pro196 and Pro197 variants, except P197R,and four of the His199 variants complemented TS-deficient Escherichiacoli cells, indicating they had at least 1% of wild-type activity.For all His199 mutations, k_cat/K_m for substrate and cofactordecreased more than 40-fold, suggesting that the conserved hydrogenbond network co-ordinated by His199 is important for catalysis.Pro196 can be substituted with small hydrophilic residues withlittle loss in k_cat, but 15- to 23-fold increases in K_m^dUMP.Small hydrophobic substitutions for Pro197 were most active,and the most conservative mutant, P197A, had only a 5-fold lowerk_cat/K_m^dUMP than wild-type TS. Several Pro196 and Pro197 variantswere temperature sensitive. The small effects of Pro196 or Pro197mutations on enzyme kinetics suggest that the conformationalrestrictions encoded by the Pro–Pro sequence are largelymaintained when either member of the pair is mutated. Received February 24, 2003; revised June 19, 2003; accepted June 20, 2003.     

基于Pro／ENGINEER软件的倒装注射模具设计

本文以柜机下面板倒装注射模具设计为例,详细地介绍了Pro/ENGINEER软件中的零件模块、模具模块、装配模块等在倒装注射模具设计过程中的使用方法和程序,希望对初次接触倒装模的设计人员有一定的帮助和借鉴作用。     

不溶性硫黄Crystex Cure Pro在全钢子午线轮胎中的应用

不溶性硫黄Crystex Cure Pro(简称Cure Pro)具有高分散性、高热稳定性、高含量等特点。在全钢子午线轮胎中使用Cure Pro替代不溶性硫黄HDOT20可减少胶料的喷霜,提高胶料与钢丝的粘合性能。同时因Cure Pro的有效硫含量较高,其在配方中的用量可减小,性价比较高。     

基于ProE的工业电器外壳注塑模设计

介绍利用Pro／E Wildfire3．11及其专家模架系统（EMX4．1）和Moldflow对工业用电器外壳注塑模进行了设计,并且对模具结构做出了具体分析,阐述了利用Pro／E进行注塑模设计的高效性、先进性、该模具结构新颖采用压入式滑块侧抽和树脂开闭器进行阶段开模,相对传统结构简化了成型复杂塑件的模具结构、在保证精度的前提下,提高了设计、生产效率．最大程度上节约了成本     

Synthesis of well‐defined comb‐like amphiphilic copolymers with protonizable units in the pendent chains: 1. Preparation of narrow polydispersity copolymers of methyl methacrylate and 2‐hydroxyethyl methacrylate by atom‐transfer radical polymerization

Well‐defined methyl methacrylate (MMA) and 2‐(trimethylsiloxy)ethyl methacrylate (Pro‐HEMA) copolymers were prepared by atom‐transfer radical polymerization(ATRP), using CuCl/2,2′‐bipyridine as catalytic system and p‐toluenesulfonyl chloride as initiator. ATRP process of MMA and Pro‐HEMA was monitored by ¹H NMR, and the kinetic curves of the MMA/Pro‐HEMA copolymerization were plotted in terms of the ¹H NMR data. At low content of Pro‐HEMA in the feed composition, the copolymerization can be well controlled with the molecular weight, polydispersity and the monomer distribution in the copolymer chain. With the increase of Pro‐HEMA content in the feed mixture, the composition of the final copolymer deviates from the composition of the feed mixture gradually, and gradient copolymers of MMA/Pro‐HEMA can be obtained. Through the hydrolysis process, well‐defined copolymers of MMA/HEMA were obtained from poly(MMA/Pro‐HEMA). Copyright © 2003 Society of Chemical Industry     

基于Pro／ENGINEER软件的积水盘注射模具设计

本文以壁挂空调器积水盘注射模具设计为例，详细地介绍了Pro／ENGINEER软件中的零件模块、模具模块、装配模块等在复杂注射模具设计过程中的使用方法和程序，充分展现了定模侧两复杂斜导柱滑块组件的结构设计要点，希望能对复杂注射模具设计有一定的指导意义。