超细铜粉的水合肼还原法制备及其稳定性研究

以水合肼为还原剂分别制备了不同粒径的超细铜粉，研究了铜粉的制备工艺和不同粒径的铜粉在空气中的稳定性：２００ｎｍ以下的铜粉在空气中不能稳定存在；３００￣４００ｎｍ的铜粉在空气中其表面会逐渐被氧化成氧化亚铜；５００ｎｍ以上的铜粉在空气中是稳定的。还采用葡萄糖预还原法改善了以水合肼直接还原得到的铜粉的均匀性。     

铜超微粉末的表面改性及其抗氧化性能

采用液相化学还原法制备了粒径约为５０ｎｍ的铜粉。研究了高分子吸附对铜粉在空气中的稳定性影响及粉末在水溶液中的稳定性。分别采用表面包银和磷化处理的方法，提高了铜粉的抗化性能，使５０ｎｍ铜超微粉末能稳定地存在于空气中，磷化处理后铜粉末的氧化温度高于２２０℃。     

以甲醛为还原剂制备超细铜粉的研究

研究了采用葡萄糖预还原法，以甲醛为还原剂制备超细铜粉的工艺，并且制得了20～400nm范围的超细铜粉。通过实验，研究了制各工艺条件：温度、pH值、表面活性剂、抗氧化剂对超细铜粉的粒度、均匀性、防蚀性等的影响，获得了较佳工艺条件。     

铜酞菁废水资源化处理工艺研究

以资源化处理铜酞菁废水为目的,采用沉淀-吹脱-SBR法处理铜酞菁废水,对于沉淀的铜采用葡萄糖-水合肼还原法制备超细铜粉。分析了投加量、水温、pH对处理效果的影响。结果表明:超细铜粉为0.3～0.9μm的类球形,出水能够达到国家一级排放标准。     

超细氧化铋的制备与结构特性

采用弱碱液相沉淀－灼烧法制备了超细氧化铋粉末，该法具有流程简单、引入杂质少、灼烧温度低、产品纯度高（９９．９％以上）、粒度细（平均粒径０．０２μｍ）、性能优越等特点，很值得研究和开发．     

超细铜粉粒径和形貌的研究

采用电解法、机械球磨法和化学法制备了超细铜粉 ,利用扫描电镜对其粒径和形貌特征进行了分析 ,讨论了各种制备方法对铜粉粒径、形貌特征产生的影响     

改进的溶胶-凝胶法制备超细铜粉

对溶胶－凝胶法进行了改进，由溶胶直接制备出超细铜粉，找到了制备超细铜的Ｇ分散剂及最佳制备条件，并获得了平均粒径为１０ｎｍ的铜粉。     

化学沉淀法制备超细仲钨酸铵粉末的研究

为了开发高性能超细硬质合金,需要制备获得高品质超细仲钨酸铵前驱体。通过调整合适工艺条件,采用化学沉淀法,一步反应制得了超细级仲钨酸铵粉末。利用X射线衍射仪和扫描电镜对仲钨酸铵的结构、成分、形貌、粒度、分散性等进行表征,结果表明,采用本文方法制备的仲钨酸铵粉末平均粒径为3.8μm、粒径分布范围窄、晶粒发育完整、晶型理想、分散性良好。利用化学沉淀法制备仲钨酸铵,由于时间较短、温度较低,能够大大降低仲钨酸铵粉末粒度和粒径分布范围。     

尺寸和球磨对细晶钨粉烧结体致密度的影响

采用溶胶喷雾干燥-煅烧-氢热还原法制备了粒径为0.14μm的超细纯钨粉末。研究不同球磨(干磨,湿磨)方式对钨粉形貌以及粉末成形性的影响,探讨纯钨样品性能随样品不同尺寸(2.5mm厚小样品和2cm厚大样品)的变化。此外还详细研究了纯钨烧结体组织形貌、晶粒尺寸等性能随球磨方式及样品尺寸的变化规律。结果表明,使用干磨法和湿磨法球磨处理都可以有效提高粉末的成形性。使用干磨法球磨制备的粉末的烧结体致密度高于湿磨法所制备的,且在大尺寸样品中其致密度分布也较湿磨法所制备粉末的烧结体更加均匀。湿磨粉颗粒粒径分布较广,颗粒容易长大。干磨粉由于活化效果较弱,烧结体颗粒更加细小。     

液相还原法制备纳米铜粉

以CuCl2和KBH4为原料采用液相还原法制备了铜粉，经XRD检测确定了反应生成物确为纳米铜粉，且经TEM检测粒径为20—40nm．该方法具有工艺简单，效率高，成本低等优点．并讨论了配位剂、反应温度等对反应结果的影响．     

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。