辣木叶总黄酮提取方法的优化研究

采用正交实验的方法,以辣木叶总黄酮含量为考察指标,探讨了乙醇浓度、乙醇用量、提取温度、提取时间、提取次数对辣木叶中总黄酮提取效果的影响,并在单因素试验的基础上对提取方法进行了优化。结果表明,辣木叶总黄酮提取的最佳实验条件为：用70%的乙醇作为提取溶剂,提取温度80℃,乙醇用量20倍,提取时间1.5h,提取次数3次,在此条件下,辣木叶总黄酮含量为6.593%.     

广枣中黄酮类化合物提取工艺研究

用正交试验方法对广枣中黄酮类化合物的提取工艺进行了探讨.选取乙醇浓度、乙醇倍量、提取时间、提取次数四个考察因素,进行L16正交试验.确定了最佳提取工艺条件为:用12倍量、60%乙醇回流提取4次、每次1.5h.乙醇浓度对总黄酮含量的影响特别显著.在此条件下总黄酮的平均得率为3.653%.     

穿心莲内酯提取工艺研究

采用正交实验法探讨穿心连内酯的提取工艺,以提取的内酯量为参考指标,考察了料液比、乙醇浓度、提取温度和提取时间等影响因素。确定影响穿心莲内酯提取率的因素大小顺序为：乙醇浓度〉提取温度〉料液比〉提取时间,其最佳工艺条件为：60℃下,用1500mL75%的乙醇对100g穿心莲进行浸提2h,得622mg穿心莲内酯。     

紫萁黄酮类化合物的提取条件研究

在60℃条件下,分别采用水、不同浓度的醇和丙酮提取紫萁中黄酮类化合物,通过比较提取液中黄酮的含量,得出最佳提取方法是丙酮法。对丙酮法设计正交实验,得出最佳条件。考虑乙醇法和丙酮法黄酮得率差异不大,且乙醇成本低、易操作,比丙酮安全,故对乙醇提取法亦做正交实验。结果表明：丙酮法的最佳条件：丙酮浓度为50%、固液比1：120、水浴温度70℃;乙醇法的最佳条件：水浴温度90℃、乙醇浓度为50%、固液比1：120。     

香叶黄酮提取工艺研究

本实验主要研究香叶黄酮的提取工艺。在单因素试验的基础上进行正交试验,结果表明：乙醇浸提法提取香叶总黄酮的最佳工艺条件为：香叶黄酮的最佳提取工艺为：25倍70%乙醇,温度60℃条件下提取1h。按照此条件做验证试验,香叶黄酮得率为49.8mg/g。     

乙醇超声提取毛冬青（Llex pubescens）茎中总黄酮的工艺研究

目的：筛选乙醇提取毛冬青茎中总黄酮的最佳条件．方法：采用正交试验研究乙醇浓度、料液比、提取时间、提取次数对毛冬青茎中总黄酮提取的影响,用紫外分光光度法测定总黄酮含量．结果：乙醇作为提取溶剂的最佳工艺是乙醇浓度30％,料液比1：20,提取3h,提取3次,此条件下吸光值为0．529．结论：乙醇浓度影响最大,其次是提取次数,提取时间、料液比对毛冬青茎中总黄酮提取影响较小     

柚皮总黄酮超声波辅助提取工艺的研究

采用超声波提取柚皮总黄酮,以乙醇为提取剂,探讨了影响柚皮总黄酮提取率的因素——超声时间、乙醇浓度、提取温度及液料比,通过正交试验确立了最佳提取工艺。结果表明:在60℃条件下,液料比(V(溶剂)∶m(柚皮))为20 mL/g,用70%(体积分数)的乙醇超声提取1 h时,柚皮总黄酮提取效果最好,此条件下总黄酮的质量分数为0.66%。     

蕨根总黄酮提取工艺研究

本研究采用乙醇提取法从蕨根中提取总黄酮,在单因素试验的基础上用正交试验进行工艺参数的优化,其优化的工艺条件为:提取温度90℃,提取时间3h,乙醇浓度60%,固液比1∶20.在此工艺条件下,总黄酮得率为3.021%.     

不同方法提取荸荠皮中总黄酮含量的比较

研究了不同方法提取荸荠皮中总黄酮类物质,在不同条件下对荸荠皮中的总黄酮物质进行提取,用正交优选法选出适宜的条件。结果表明:采用超声波辅助提取方法得到的总黄酮提取物最多,该方法的适宜提取工艺为:提取时间为50 min,乙醇浓度为50%,提取温度为60℃,料液比为1∶30,该条件下,荸荠皮中总黄酮的得率为2.483%;其次是微波辅助法提取,该方法的适宜提取工艺为:功率为420 W,料液比为1∶30,乙醇浓度为50%,提取时间为5 min,该条件下,荸荠皮中总黄酮的得率为2.455%;加热提取的最少,适宜提取工艺为:提取温度为60℃,乙醇浓度60%,料液比为1∶30,提取时间为4 h,该条件下,荸荠皮中总黄酮的得率为1.618%。比较3种提取方法各有优劣,在实际工作中可以根据情况选择不同的提取方法。     

咖啡中绿原酸高效液相色谱法测定及不同提取工艺的比较研究

用正交设计对水浸提法、水浸提+超声波法、乙醇浸提法、乙醇浸提+超声波法进行比较,以咖啡提取物中绿原酸的含量为评判指标,考察时间、温度、乙醇浓度对提取物有效成分绿原酸含量的影响.采用高效液相色谱法测定该成分的含量.最佳提取工艺为乙醇浸提+超声波法,最佳提取条件为超声提取30 min、温度60℃、乙醇浓度70%,此条件下提取绿原酸的含量最高.影响提取的主次因素为:超声时间温度乙醇浓度.     

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。