H3PW12O40/H2O2/H2O体系催化氧化苯甲醇合成苯甲醛

合成一系列杂多酸(盐)并采用红外光谱对其进行表征,研究它们对苯甲醇氧化合成苯甲醛反应的催化性能.并以H3PW1 2O40为催化剂,分别考察溶剂类型、反应时间、反应温度、催化剂用量和H2O2用量对该反应的影响,并且初步探讨该反应的反应机理.实验结果表明:5种杂多酸(盐)均具有Keggin型结构,以水为溶剂时,5种杂多酸(盐)均具有催化活性,其中H3PW12O40催化活性最高.在催化剂用量0.04mmol、w(H2O2)=30%的H2O2用量0.015mol、反应时间3.5h、反应温度90℃、溶剂水用量10mL的优化反应条件下,苯甲醇的转化率为95.59%,苯甲醛的收率可达91.62%.由此可知,H3PW12O40/H2O2/H2O体系是环境友好的高效催化体系,具有工业化应用前景.     

一种新型噻唑盐的微波辅助合成及对安息香缩合的催化作用

以4-甲基-5-羟乙基噻唑和对氰基氯化苄为原料微波合成一种新型噻唑盐,3-(对氰基苄基)-4-甲基-5-(2-羟乙基)噻唑氯化物,再用此噻唑盐替代VB1作为安息香缩合反应的催化剂,检验其催化性能,发现催化苯甲醛得苯偶姻收率为74.5％、催化糠醛得糠偶姻收率为76.1％,此噻唑盐不仅具有天然VB1的无毒性,且可回收利用;考察了物质的量投料比、反应时间、反应温度及微波反应器功率对此噻唑盐收率的影响;并用HPLC测定产物的纯度,通过熔点、元素分析、IR及LC-MS对噻唑盐性质和及苯偶姻结构进行了表征.     

腐植酸负载钯催化剂对Heck反应的催化性能

研究了腐植酸负载钯催化剂对碘苯、溴苯及其芳基卤衍生物与丙烯酸的Heck芳基化反应的催化性能.在氮气保护下,讨论了时间、温度、催化剂用量、碱和溶剂对反应产率的影响.结果表明:以溴苯与丙烯酸的反应为例,催化剂在130℃反应12 h,三丁胺作为碱,催化剂用量为0.44 mol%的钯含量,四丁基溴化铵作为溶剂的条件下具有较好的催化性能;对碘苯及溴苯的衍生物与丙烯酸的反应也有很高的催化活性.     

固体酸TiO2/SO42-催化合成紫罗兰酮

本文以固体强酸TiO2/SO42-作催化剂,苯/三氯甲烷(2:1)作溶剂,研究了假性紫罗兰酮环化合成紫罗兰酮的反应.探索了反应温度、反应时间、催化剂用量和溶剂用量等因素对反应结果的影响.最佳合成条件:5.6mL假性紫罗兰酮,催化剂用量为2.1g,溶剂用量为8mL,环化反应温度为20℃,反应时间为2.0h,在此条件下所得紫罗兰酮的产率约为77%~78%左右,高于文献值70.4%.     

松香胺希夫碱-铜催化松香的氧化反应研究

研究了以松香胺希夫碱 铜配合物为催化剂催化H2O2氧化松香的情况.探索了H2O2浓度、溶剂、催化剂的用量、温度等因素对反应的影响 实验结果表明,在无水乙醇作溶剂,松香胺希夫碱 铜催化剂用量为2%情况下,温度对反应的影响最大 其次为H2O2的用量,而时间对反应的影响最小.通过正交实验得出最佳实验条件为:在松香与无水乙醇的质量比为1∶5,松香胺希夫碱 铜催化剂用量为2%情况下,反应温度80℃,35%H2O2的用量7ml,反应时间1h较理想.     

苯偶酰的高效简便合成

以Fe3 /Cu2 为氧化剂,绿色氧化苯偶姻合成了苯偶酰,研究了铜盐、铵盐和硝酸盐的类型及其用量对反应的影响,讨论了可能的反应的机理.结果表明:以10 mmol苯偶姻为原料,2 mL 2%的Cu(OAc)2溶液为氧化剂,10mmol硝酸铵为助剂,14mL冰醋酸为溶剂,添加1 g FeCl3·6H2O,回流温度下反应时间可从90 min减少至60 min,苯偶酰的收率高达98.4%,其结构经红外光谱、元素分析等进行了表征.     

1,2-双(N-癸基咪唑鎓)乙烷溴盐的合成研究

以N-癸基咪唑和1,2-二溴乙烷为原料,经季铵化反应合成1,2-双(N-癸基咪唑鎓)乙烷溴盐。通过正交试验,确定1,2-双(N-癸基咪唑鎓)乙烷溴盐较佳合成工艺条件为:反应温度(45±2)℃,原料摩尔比为2.4∶1(N-癸基咪唑∶1,2-二溴乙烷),反应时间10h。利用IR和1H-NMR对产物进行结构表征。     

SiO_2负载磷钨酸铯盐催化剂上香兰素与1,2-丙二醇的缩合反应

制备一系列硅胶(SiO2)负载的磷钨酸铯盐催化剂,将其用于香兰素与1,2-丙二醇的缩合反应,合成香兰素丙二醇缩醛,考察催化剂中Cs+取代数、磷钨酸铯盐负载量、催化剂用量、1,2-丙二醇与香兰素摩尔比及反应时间对缩合反应的影响.结果表明:磷钨酸铯盐的Cs+取代数为2.5、负载量为40%时催化剂活性最高;在反应温度368 K、n(1,2-丙二醇)/n(香兰素)=2.4、催化剂用量占反应体系质量分数1.5%、带水剂苯的用量30 mL、回流反应3 h的条件下,香兰素的转化率达到86.6%,香兰素丙二醇缩醛的选择性为100%.     

以双雌甾为模板的双核铜蛋白模型化合物的合成及催化苯偶姻的氧化

以２，４－双（Ｎ－咪唑甲基）－１７β－雌二醇与１，３－二溴丙烷通过醚化偶联，继与［Ｃｕ（ＣＨ３ＣＮ）４］ＣｌＯ４反应，合成了含双雌二醇、四咪唑基的新型双核铜蛋白模型化合物．研究了该模型物与相关模拟体系催化氧化苯偶姻的反应，发现双雌甾模型物与底物间的疏水相互作用有利于苯偶姻的氧化反应     

1,3-双(2,4,6-三甲基苯基)氯化咪唑的制备及其催化的安息香缩合反应——推荐一个有机化学设计实验

介绍了一个有机化学设计实验.该实验以乙二醛、 2,4,6-三甲基苯胺、氯甲基乙基醚为原料,通过两步反应高效制得氮杂环卡宾前体盐1,3-双(2,4,6-三甲基苯基)氯化咪唑.然后利用合成的咪唑盐在碱性条件下原位形成的氮杂环卡宾对醛极性反转的特性,催化苯甲醛的安息香缩合反应,合成2-羟基-1,2-二苯基乙酮.使用IR,~1H NMR,~(13) C NMR等多种方法对催化剂及产物结构进行了表征.     

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.     

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。     

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