胰酶水解干酪素的动力学行为

研究了胰酶水解干酪素制备蛋白胨过程中胰酶在不同温度下的失活行为,以及底物浓度对反应速率和平衡的影响,ｐＨ对反应浓度和平衡的影响。胰酶在４０℃下４ｈ基本不丧失水解大分子的活力;在５０℃,ｍｉｎ、５５℃,１００ｍｉｎ、６０℃,９０ｍｉｎ完全丧失对大分子的水解活性。胰酶短时间在高温下丧失的活性,当其返回到４０℃时可部分恢复。底物和产物对反应有抑制作用。底物初始浓度高,最终平衡转化率低。当ｐＨ８时的反应速     

超临界CO2的溶剂特性对脂肪酶催化反应的影响

分别用溶解度参数和介电常数表征超临界流体的溶剂特性，并计算了不同压力下二氧化碳的溶解度参数和介电常数。测定了不同压力下脂肪酶催化月桂酸和正丁醇酯化反应的最大反应速率和米氏常数，研究了溶解度参数δ和介电常数ε对最大反应速率Ｖｍ的影响，并比较好地进行了关联：ｌｎ［Ｖｍａｘ／（ｍｍｏｌｈ－１ｇ－１）］＝４．４６５－０．１５３（δ／ＭＰａ０．５），ｌｎ［Ｖｍａｘ／（ｍｍｏｌｈ－１ｇ－１）］＝４．１８７－８．３１８（ε－１）／（ε＋１）．从而通过溶剂特性将压力这一操作条件直接与反应动力学相联系。     

酶法合成组胺的研究

为探究生物催化法合成组胺,通过对IPTG浓度、诱导时间和酶学性质的研究,确定组氨酸脱羧酶诱导表达条件以及最适反应条件.结果表明:不同IPTG诱导浓度对酶活影响不大;酶活随着诱导时间的增加而升高;酶反应最适温度为30℃,pH为6.0;随着产物浓度增加,酶活降低,具有产物抑制现象;5%底物时转化率达到60%,3%底物时转化率达到97.7%.可见,该组氨酸脱羧酶有工业应用开发潜力.     

温度、压力、底物浓度和光照强度对过氧化氢酶动力学性质的影响

本试验以极谱氧电极法测定苹果叶片中过氧化氢酶促反应曲线的斜率表示酶的活性,研究了温度、压力、底物浓度和光照强度等物理因子对过氧化氢酶活性的影响。结果表明,酶活性在10～50℃范围内随温度升高酶活性增强,底物浓度对酶的影响符合米氏方程;压力对酶活性的影响,随负压的加大,酶活性有提高的趋势;光强对酶活性的影响,表现为二次曲线型。     

根霉脂肪酶催化水解（R,S）—环氧丙醇丁酸酯的反应特性

对根霉脂肪酶的粗酶拆分（Ｒ,Ｓ）－环氧丙醇丁酸酯的水解反应进行了初步研究,结果表明：３０℃下ＰＨ５．３时反应初速度最大;ＰＨ５．５－６．０地酶的立体选择季最高,对映体比率（Ｅ值）为５７。４２℃下ＰＨ５．５时反应初速度最大;酶的立体选择性随温度升高而下降,酶促水解反应中未到产物和底物抑制现象,根霉发酵液中脂肪酶的反应特性与硫酸铵沉淀法所得粗酶相吻合。     

固定化酶催化合成半乳糖寡糖

以壳聚糖固定化米曲霉β－半乳糖苷酶，连续催化合成半乳糖寡糖（ＧＯＳ），在填充床固定化酶反应器中，研究底物浓度、ｐＨ，反应温度和停留时间对ＧＯＳ连续合成的影响，最佳反应条件为：底物浓度４００ｇ／Ｌ，反应温度５０℃，ｐＨ５．８，停留时间３５ｍｉｎ，产物的最高得率为６２％。     

克鲁维酵母y－85菊粉酶水解菊粉的研究及其中试

克鲁维酵母（Ｋｌｕｖｅｒｏｍｙｃｅｓｓｐ．）Ｙ－８５在菊粉提取液培养基中生长产菊粉酶，其细胞和胞外的菊粉酶活力分别约占菊粉酶总活力的７６％和２４％．试验中以酶发酵液作酶液．该酶的Ｓ／Ｉ值为１５．２．酶液在５０，５５和６０℃下保温１ｈ，活力分别残留１００％，９６％和６５％；在８℃下放置７ｄ，１４ｄ，酶活力分别残留９８％和９６％．在ｐＨ３．６～７．０内，酶活性十分稳定．５ｍｍｏｌＬ－半胱氨酸和Ｆｅ＋２分别可使酶活力提高１０．４％和４１．２％．ｙ－８５菊粉酶水解菊粉的适宜条件是：底物为总糖浓度１０％～１５％菊粉提取液，ｐＨ５．０，温度为５５℃，酶用量为底物每克糖加酶８００ｕ（以蔗糖为底物测酶活力）或２６．３ｕ（以菊糖为底物测酶活力）、搅拌酶解６ｈ．在上述条件上，底物降解率最高可达９８．５％．酶解液中，果糖占总还原糖量的８５％．用１１００Ｌ罐进行酶解中试，５批试验，底物降解率平均达９４．２％．     

溶剂,酰化剂和底物浓度对手性氯醇酶促酯化的影响

利用脂肪酶在非水相体系中催化的对映选择性酯化反应,对外消旋手性药物中间体（±）－１－氯－３－（１－萘氧）－２－丙醇（简称萘氧氯丙醇）进行了拆分,考察了溶剂、酰化剂和底物浓度对酶活性和选择性的影响。结果表明,当溶剂为异辛烷,酰化剂为醋酸酐、底物浓度为氯醇１００ｍｍｏｌ／Ｌ、酸酐５０ｍｍｏｌ／Ｌ时,酶显示出最佳的催化活性和选择性,产物酶的光学纯度可达９０％。     

漆酶催化二氰基氢醌类化合物反应的微量热研究

用微量热法测定丁３０℃，ｐＨ为４．０时漆酶与底物２，３－二氰基－５，６－二氯－１，４－苯二酚，２，３－二氰基－５，６－二溴－１，４－苯二酚，２，３－二氰基－５，６－二碘－１，４－苯二酚催化反应的米氏常数ＫＭ，速率常数Ｋ，结合能△Ｇ０和活化自由能△Ｇ＾≠Ｔ，同时计算了漆酶与２，３－二氰基－５，６－二氯－１，４－苯二酚在３０℃，ｐＨ＝４．０时的反应活性，对实验结果进行了讨论。     

莲子蛋白酶解的扩散-反应动力学

为了探索莲子蛋白质的酶水解动力学特性,于温度为55℃和pH为5.0的条件下,用木瓜蛋白酶酶解莲子蛋白研究酶解莲子蛋白的拟态条件下的米氏常数Km,构建考虑底物抑制和无抑制等影响因素下的扩散-反应动力学模型.研究结果表明:酶和底物在反应体系中的扩散影响酶解反应;当底物初始质量浓度高于13.63 g/L时,反应底物对酶解产生抑制作用;建立的数学模型能够合理地描述和解释莲子蛋白降解的动力学过程,为确定酶解反应的各种参数提供依据.     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Wuhan University Journal of Natural Sciences TOTAL CONTENTS

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Advances in broadband wireless communications under high-mobility scenarios

Future mobile communication systems aim at providing very high data transmission rates, even in high-mobility scenarios such as high-speed wheel-track trains, maglev trains, highway vehicles, airplanes, guided missiles or spacecraft. A particularly important commercial application is the strong and increasing worldwide demand for high- speed broadband wireless communications （up to 574.8 km/ h test speeds or 380 km/h commercial speeds） in railways, providing data, voice and video services for applications such as onboard entertainment services to passengers, train control, train dispatch, train sensor status handling and sur- veillance. In such high-mobility scenarios, there are a number of communication challenges, including fast hand- over, location updating, high-speed channel modeling, estimation and equalization, anti-Doppler spreading tech- niques, fast power control, and dedicated network architec- ture. Because signal transmission in very high-speed scenarios will inevitably experience serious deterioration, it is imperative to develop key broadband mobile communi- cation techniques for such high-speed vehicles.     

Perspherical Approaches for Electrons in Atoms and Charged Excitons in Quantum Wells

Instead of following Fock’s expansion,we solve the Schrodinger equation for some quantum mechanical manybody systems such as electrons in atoms and charged excitons in quantum wells in a similar way in hyperspherical coordinates by expanding the wave functions into orthonormal complete basis sets of the hyperspherical hannonics(HHs)of hyperangles and generalized Laguerre polynomials(GLPs)of the hyperradius.This leads the equation to     

Scale-based spatial data model for GIS

Being the primary media of geographical information and the elementary objects manipulated, almost all of maps adopt the layer-based model to represent geographic information in the existent GIS. However, it is difficult to extend the map represented in layer-based model. Furthermore, in Web-Based GIS, It is slow to transmit the spatial data for map viewing. In this paper, for solving the questions above, we have proposed a new method for representing the spatial data. That is scale-based model. In this model we represent maps in three levels: scale-view, block, and spatial object, and organize the maps in a set of map layers, named Scale-View, which associates some given scales.Lastly, a prototype Web-Based GIS using the proposed spatial data representation is described briefly.     

英文诗歌中的喻类修辞

为了有助于提高英文爱好者的个人情操、文化素养和学习兴趣,以及专业人员对英语学习和研究进行多途径的探索,本文通过一些精选诗歌的引证和分析,着重论述了喻类修辞法在英文诗歌中的运用其及效果。     

Man Is Unable to Change the Miserable Life——Analysis of the Arrangement of Four Characters in The Glass Menagerie

Tennessee Williams is considered as one of the most important American playwrights since World War II.The Glass Menagerie is his first successful drama,which describes a tragic situation of family and means to say that Man is unable to change the miserable life,no matter whatever means he try,This essay focuses on the analysis of the arrangement of the four main characters:Laura.Amanda,Jim and Tom to reveal the theme.Laura is fragile.Amanda is brave.Jim is vital.Tom is sensible.And all of them develop and try the different means to struggle against life,but fail tragically.With the evidence,the paper comes to conclusion naturally that Man is unable to change the miserable life,and he dooms to fail.     

Characterization of root-nodulating bacteria on Retama raetam in arid Tunisian soils

The aim of this study is to investigate the diversity of Retama raetam root-nodule bacteria isolated from arid regions of Tunisia. Twelve isolates, chosen as representative for different 16S rRNA gene patterns, were characterized by 16S rRNA gene sequencing and phenotypic analysis. Isolates were assigned to Sinorhizobium, Rhizobium and Agrobacterium. Symbiotic properties of Sinorhizobium and Rhizobium isolates showed a large diversity in their capacity to infect their host plant and fix atmospheric nitrogen. Strain RK 22 identified as Rhizobium was the most effective isolate.     

An Affordable Accurate Evaluation of the Binding Conformations Predicted by Molecular Docking Studies in Bio-System

正Recently,docking has been widely used to predict the binding-modes of protein-inhibitors,when the crystal complexes structure was absent.Most docking algorithms are able to generate a large number of probable conformations,it,however,is difficult to effectively evaluate these docking poses and identify the most reasonable bindingmode.In the present study,on the basis of the crystallographic data of human 3-hydroxy-3-methylglutaryl coenzyme     

WIMAX与WI-FI技术分析及联合组网

介绍了WiMAX与Wi-Fi两种无线宽带接入技术,并对两者之间的关系及相互之间的影响做了对比及分析,并对WiMAX的关键技术进行了详细说明,最后对两者的联合组网方式做了简单的探讨。