Pd/Al_2O_3 催化合成2,3,5-三甲基氢醌的连续工艺

利用Ｐｄ／Ａｌ２Ｏ３催化剂,采用固定床的连续工艺将２,３,５－三甲基苯醌催化加氢得到高纯度的２,３,５－三甲基氢醌．考察了溶剂对加氢反应的影响,并通过实验确定了加氢工艺条件：２,３,５－三甲基苯醌的空速为０．２７ｇ（ｇｈ）－１,氢分压为０．１ＭＰａ,加氢反应温度为５０℃．同时将Ｐｄ／Ａｌ２Ｏ３与Ｐｔ／Ａｌ２Ｏ３的催化性能进行了比较,发现Ｐｄ／Ａｌ２Ｏ３催化剂在使用过程中选择性上升．     

铁化合物对煤加氢液化的催化作用

用微型高压釜，以四氢萘和十氢萘为溶剂，在氢初压６．０ Ｍ Ｐａ，反应温度３９０～ ４５０℃，反应时问０－６０ｍｉｎ下，添加铁化合物为催化剂进行煤炭加氢液化，考察各 种影响因素，并用穆斯堡尔谱测试液化残渣，探索其催化机理。结果表明，液化时 ＦｅＳ２完全转变为磁黄铁矿Ｆｅ１－ｘＳ；Ｆｅ２Ｏ３－Ｓ或Ｆｅ３Ｏ４－Ｓ直接或经过中间物ＦｅＳ２间接转变为磁黄铁矿。Ｆｅ１－ｘＳ生成量增多，液化转化率增大。进一步有力地证 实，Ｆｅ１－ｘＳ是以铁化合物为催化剂进行煤炭液化时的活性物种。     

用离子交换树脂－Pd催化丙酮和氢气一步法合成甲基异丁基酮的研究

以较为简便的方法制备了几种离子交换树脂－Ｐｄ催化剂，并将此类双功能催化剂用于丙酮和氢气一步法合成甲基异丁基酮（ＭＩＢＫ）．实验发现，催化剂的吸氢越大，反应选择性越好；而其交换容量过高则降低了选择性，升高温度有利于提高反应活性和选择性，但有一适宜值增大丙酮空速（ＬＨＳＶ）降低了反应活性和选择性，压力对反应影响不大．在各种树脂－Ｐｄ催化剂中Ｐｄ－干氢树脂（Ｐｄ－ＤＨ）的性能最好．在较佳的反应条件：温度１３０℃，压力２ＭＰａ，ＬＨＳＶ５ｈ－１，氢酮比０．４下，用ｐｄ—ＤＨ催化合成ＭＩＢＫ，丙酮转化率为４８％，ＭＩＢＫ选择性可达９８％．     

在CeO＿2／SiO＿2催化剂上丁烯－1异构化动力学的内扩散影响

用外循环流动玻璃无梯度反应器研究了ＣｅＯ＿２／ＳｉＯ＿２催化剂上丁烯－１异构化动力学的内扩散影响。当用３０～４０目催化剂时丁烯－１异构化在动力学区域。当催化剂厚度增大到４ｍｍ时反应在内扩散区域进行。催化剂有效因子在０．０５８～０．１２之间，说明内扩散影响严重。丁烯－１异构成ｃ－２－丁烯的催化剂有效因子比丁烯－１异构成ｔ－２－丁烯的要小。用Ｒｕｎｇｅ－Ｋｕｔｔａ方法计算了丁烯－１在催化剂孔内的分压分布。     

氢传感法测定熔融铝中氢含量的研究

采用固相合成法直接合成ＣａＺｒ０．９Ｉｎ０．１Ｏ３－ａ用交流阻抗谱技术，在８６９～１３００Ｋ温度范围内，空气气氛下测得其电导率为１０＾－４～１０＾－２ｓ．ｃｍ＾－１制得ＣａＺｒ０．９Ｉｎ０．１Ｏ３－ａ固体电解质管，以含Ｈ２的标准气为参比电极，组装成氢浓差电池。Ｆｅ含Ｈ２标准气│ＣａＺｒ０．９Ｉｎ０．１Ｏ３－ａ│（Ｈ）ＡｌＦｅ并构成氢传感探头，研究其对熔融铝中氢含量的传感特性，实验证明，该传感器响应     

金属含量对非贵金属催化剂异构化性能的影响

在压力连续微反－色谱装置上,以正己烷为反应物,研究了用非贵金属Ｎｉ和Ｍｏ改性的ＺＳＭ－５催化剂的异构化催化性能。逐步负勒Ｎｉ和Ｍｏ后,ＨＺＳＭ－５催化剂的催化性能逐渐提高。在空速为２ｈ＾－１,氢烃摩尔比为８．１,压力为１．５ＭＰａ,反应温度为２３０℃的条件下,当Ｎｉ含量为１．０％、Ｍｏ含量为２．０％时,催化剂的异构化活性、选择性和转化率分别高达１８．６％、３９．９％和４６．６％。     

Friedel－Crafts反应合成无规支化聚苯乙烯及其支化结构表征

将阴离子聚合所得窄分布聚苯乙烯（ｄ＜１．１）在无水ＺｎＣｌ＿２催化下以氯甲醚对其进行氯甲基化（Ｃ１％＜１．５），再用自制无水ＡｌＣｌ＿３作催化剂，使氯甲基化聚苯乙烯（ＣＭＰＳ）发生大分子链间的Ｆｒｉｅｄｅｌ－Ｃｒａｆｔｓ反应，一步合成主链与支链等长的无规支化聚苯乙烯（ＡＢＰＳ）．研究了支化反应条件及支化结构，实验表明，反应条件：Ｔ＝４０～４５Ｃ、Ｃ＿（ＣＭｐＳ）＝０．１～０，１５ｇ·Ｍｌ￣（－１）、Ｃ＿（ｃａｔ）＝０．０５～０．１ｇ·ｍｌ￣（－１）、ｔ＞ｌ２ｈ达到良好的支化效果，支化臂数为１～２０．     

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．     

N－酰基－（R）－四氢噻唑－2－硫酮－4－羧酸乙酯的合成

在三乙胺存在下，使ＲＣＯＣｌ与（Ｒ）－四氢噻唑－２－硫酮－４－羧酸乙酯反应，得到相应的标题化合物ａ～ｆ，它们的［α］Ｄ分别为十１．４３，＋７．８，＋１．３１，－１１０．８，－４３．０，－４９．７９．实验可见，Ｒ为芳基的标题化合物的旋光度的绝对值较Ｒ为脂肪基的标题化合物的旋光度低．     

六苄基六氮杂异伍兹烷氢解脱苄反应动力学的研究

目的研究以Ｐｄ（ＯＨ）２作催化剂,溴苯为添加剂,以六苄基六氮杂异伍兹烷（ＨＢＩＷ）在乙酸酐及Ｎ,Ｎ－二甲基甲酰胺（ＤＭＦ）混合溶液中氢解脱苄合成四乙酰基二苄基六氮杂异伍兹烷（ＴＡＤＢＩＷ）反应的动力学．方法固定催化剂用量,通过空白实验修正催化剂对反应吸Ｈ２量的影响,以吸Ｈ２量来表征反应程度．采用积分反应速率方程,对不同温度下该反应的实验数据进行了动力学计算,求得该反应表观活化能为４８ｋＪ·ｍｏｌ－１,指前因子为２．４３×１０６ｍｉｎ－１．３０℃时的表观反应速率常数为１．３３×１０－２ｍｉｎ－１．结果与结论实验表明,从反应开始至产物生成转化率（按物质的量计算）约８０％,这一阶段遵循一级反应动力学     

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.     

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     

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.     

Wuhan University Journal of Natural Sciences TOTAL CONTENTS

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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。