萃取催化显色动力学光度法测定痕量铅的研究

在pH=3.0的邻苯二甲酸氢钾-盐酸缓冲溶液中,用吡啶作活化剂,铅(Ⅱ)能催化溴酸钾氧化邻氨基酚显色.研究了动力学条件,通过氯仿萃取终止反应,建立了室温下测定痕量铅的萃取催化动力学光度法.吸光度与铅(Ⅱ)的浓度在0～50μg/mL范围内成线性关系,检出限为2.3×10-2ng/mL.使用铜铁试剂-氯仿萃取和硝酸反萃取消除Ni(Ⅱ)、Co(Ⅱ)和Sn(Ⅱ)的干扰.用于地下水、人发和松花蛋中铅的测定,加标回收率为98.2%～102.3%,RSD值为1.3%～3.2%.     

分离富集动力学光度法测定痕量钯(Ⅱ)

研究了在稀硫酸介质中 ,痕量钯 (Ⅱ )催化溴酸钾氧化对溴偶氮氯膦腿色的指示反应及其动力学条件 ,据此建立测定痕量钯 (Ⅱ )的新方法 ,该方法的检出限为 1.33× 10 -10g/mL ,测定范围为 0～ 0 .4 μg/ 10mL。采用聚酰胺在盐酸或王水介质中分离富集样品中的钯 ,使方法的选择性大大提高。用于样品的测定获得满意结果     

碘化物-甲基紫体系共振瑞利散射法测定痕量铅

在稀磷酸介质中,铅(Ⅱ)与过量的I-形成[PbI4]2-配阴离子并进一步与甲基紫形成离子缔合配合物时,会 明显增强共振瑞利散射(RRS)强度,最大RRS波长位于327nm.研究了该体系的共振瑞利散射光谱特性、主要影 响因素和反应的最佳条件,在2.0×10-3～3.0×10-2μg/mL范围内,共振瑞利散射强度与铅的浓度成线性关系, 实验结果表明该方法有很高的灵敏度,铅(Ⅱ)的检出限为0.6ng/mL,可用于对自来水中痕量铅的直接测定.     

微分电位溶出法同时测定食品中铅、锡

利用微分电位溶出分析法,以0.09 mol/L草酸、7.5×10-5mol/L中性红为底液,同时测定了4种样品中的铅、锡含量,二元素峰电位分别为-0.52 V和-0.62 V(vs SCE),铅、锡的线性范围分别为2.0~100.0 ng/mL、5.0~250.0 ng/mL.当富集时间为60 s时,铅、锡的检出限分别为2 ng/mL和5 ng/mL.将此法应用于测定食品中痕量铅和锡,结果满意.     

流动注射偶合反应化学发光法测定白酒中铅的研究

讨论了流动注射偶合反应化学发光法测定白酒中的铅的最佳条件。检出限达1×10-8g/mL,检测线性范围在5×10-8～1×10-5g/mL。对白酒样品进行测定,加标回收率在99.0和101.0之间,RSD≤2.2%。与国标相比本法使用的仪器简单,尤其适合于较低铅含量的样品测定,可方便地应用于各种酒样中铅的检测。     

催化动力学光度法测定痕量钯

研究了催化动力学光度法测定痕量钯(Ⅱ).在H3PO4介质溶液中及加热的条件下,钯(Ⅱ)对高碘酸钾氧化甲基红褪色的反应具有显著的催化作用,由此建立了催化动力学光度法测定钯(Ⅱ)的新方法.该催化反应为准一级反应,△A与钯(Ⅱ)浓度呈线性的范围为0.000-0.600μg/mL,检出限为2.48×10-9g/mL,反应的表观活化能为84.12 kJ/mol,反应表观速率常数为1.25×10-4s-1.该方法可用于某些含钯催化剂样品的测定,结果满意.     

催化褪色光度法测定痕量汞

基于在PVA存在下,痕量汞(Ⅱ)催化过氧化氢氧化镍-依来铬红B络合物的褪色反应,建立了催化褪色光度法测定痕量汞的新方法.汞(Ⅱ)浓度在0.01—0.06μg/L范围内符合比尔定律,检出限为1.2×10~(-12)g/mL。此法用于人发和废水等样品中痕量汞(Ⅱ)的测定,获得满意的结果。     

流动注射化学发光分析法测定锌和镉

锌和镉含量测定的化学发光分析法已有报道,本文所建立的方法基干Zn(Ⅱ)、Gd(Ⅱ)对Luminol—H_2O_2—Cr(Ⅲ)体系化学发光的抑制作用,用于食品、药物及环境水样中Zn和Cd的分析测定,结果较为满意。检测限分别降低为:Zn(Ⅱ),0.42×10~(-9)g/mL;Cd(Ⅱ),0.30×10~(-9)g/mL,线性范围加宽,均在10~(-8)～10~(-5)g/mL之间,测定Zn,Cd的相对标准偏差均不大于3.5％。     

铅的MIP-AAS测定

通过测铅来研究用常压氩微波诱导等离子体(MIP)作为原子吸收光谱法(AAS)的原子化器的可行性。样品用钽丝电热蒸发并经浓硫酸去溶后引入MIP。文中考查了各实验参数对测铅的影响。用本法测铅的特征浓度为O.1μg/mL。对实际样品的测定,取得了令人满意的结果。     

碱性氢化物发生原子吸收法测定钢铁中的微量铅

采用碱性氢化物体系发生原子吸收方法测定了钢铁中的微量铅.选择铁氰化钾-酒石酸钠为氢化物发生的氧化剂和配位剂,还原剂硼氢化钾的质量浓度为1 g/L,测定液中氢氧化钠的质量浓度为3.6g/L,用12.5 g/L的草酸酸化,方法特征浓度为0.073 ng/mL,检出限为0.20ng/mL.此体系允许2.5mL测定液中含铁、钴、镍的量为30,3,3mg,可以满足直接测定钢铁中的微量铅的需要.通过对含铅0.002%(质量分数)的样品测定实验,得到了满意的结果.     

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。