微波辅助提取虎杖中白藜芦醇苷

用高效液相色谱法（HPLC）测定白藜芦醇苷的含量,并以白藜芦醇苷的提取率为参考指标,通过单因素实验及正交实验方法对微波辅助提取法（MAE）提取虎杖中白藜芦醇苷的最佳工艺进行研究。HPLC法的色谱分析条件为：ODS-C18色谱柱（长度×直径为200 mm×4.6 mm）,以40%（体积分数）的甲醇水溶液为流动相,流速为1 mL/min;检测波长为303 nm。研究结果表明,微波辅助提取白藜芦醇苷的最佳工艺条件为：10.000 g虎杖粗粉（2-3 mm）浸泡2 h,用70%（体积分数）乙醇水溶液提取2次,料液比为1-8,在功率650 W下微波辐射100 s,白藜芦醇苷的提取率达到91%。     

酶解法对提取虎杖中白藜芦醇的应用及工艺优化

在酶法提取虎杖中白藜芦醇的过程中,对原料经酶解处理后的乙醇提取工艺进行研究.研究结果表明,最佳提取工艺条件是:体积分数为40%乙醇,以液固比20:1,在40℃提取40 min,提取次数为1次.与原料未经酶解处理的直接醇提法的提取工艺条件比较,原料经酶解处理后,可以在较低的乙醇浓度、较低的温度下,提取较短的时间即可达到较好的提取效果.经HPLC分析,从虎杖中提取白藜芦醇的得率达13.85 mg/g,粗提物中白藜芦醇纯度达22.7%.     

虎杖中白藜芦醇的提取工艺

虎杖属于蓼科草本植物,具有多种药理作用。虎杖中的有效成分,具有改善血液微循环、强心、止咳平喘、防氧化、保肝、降三高的作用,对细菌和病毒也有抑制作用。为有效提取虎杖中白藜芦醇,采用乙醇回流法和超声波法进行研究,并进行溶剂(乙酸乙酯)萃取初步纯化和吸附树脂纯化条件筛选,考察不同单因素对虎杖中提取白藜芦醇的影响,并采用正交法对提取工艺进行优化,确定最佳提取工艺。结果表明:乙醇回流法优化提取工艺条件下白藜芦醇的提取率为1.30%,超声波辅助法最优提取条件下白藜芦醇的提取率为1.36%。针对超声波辅助工艺的溶剂萃取初步纯化,得到纯度为74.98%的白藜芦醇,经过大孔树脂分离纯化后,纯度达89.07%,收率为95.09%。经过萃取和大孔树脂吸附后,白藜芦醇的纯度明显提高。     

均匀设计法优选虎杖白藜芦醇的提取工艺

目的优选超声波法提取虎杖中白藜芦醇的最佳工艺。方法本研究以虎杖中白藜芦醇的提取量和吸光度值为考察指标，通过均匀设计法实验研究4个因素对提取效果的影响。结果实验得到从虎杖中提取白藜芦醇的最佳工艺为：100％乙醇-丙酮（1：1），料液比为（1：25），pH=6，浸泡时间24h，超声温度为30℃，提取时间为30min，平均2次提取，提取率为0．390％。结论该实验确定的最佳提取工艺简便易行。     

酶解法提取虎杖中的白藜芦醇

目的研究虎杖中白藜芦醇的最佳提取工艺。方法采用L9(34)正交实验,以白黎芦醇的提取率为评价指标。结果实验设计因素中酶解加水量、酶解时间和提取溶剂用量对白藜芦醇的提取率有显著影响。结论酶解法提取虎杖中白藜芦醇的最佳条件为:纤维素酶用量20mg/g,酶解加水量3倍,酶解时间6d,提取溶剂用量9倍。酶解法提高了虎杖中白藜芦醇的提取率。     

超声波辅助提取虎杖中白藜芦醇工艺研究

目的优选超声波辅助提取虎杖中白藜芦醇的最佳工艺。方法通过L16（4^5）正交实验研究5个因素不同水平对虎杖中白藜芦醇提取率的影响,采用紫外-可见分光光度法进行检测。结果经过正交实验得到从虎杖中提取白藜芦醇的最佳工艺为：以80％的CH3CH2OH＋CH3COCH3（体积比1：1）为提取剂,料液比1：10,pH=6,在30℃超声辅助提取50min,重复提取两次,虎杖中提取白藜芦醇的提取率可以达到1．83％。结论该实验确定的最佳提取工艺稳定性好且简便易行,且白藜芦醇的提取率高于有关报道。     

响应面法优化虎杖中反式白藜芦醇的提取工艺及抑菌活性

采用响应面分析法优化了虎杖中反式白藜芦醇的提取工艺,其最优提取工艺条件为:以体积分数79%乙醇为溶剂,53℃回流提取1.1h;此条件下白藜芦醇提取量为5.912mg/g,与理论值5.918mg/g接近。产物经红外和质谱鉴定为反式白藜芦醇(纯度99.8%)。考察了经分离纯化后的反式白藜芦醇对大肠杆菌、金黄色葡萄球菌的体外抑菌作用,结果表明所得反式白藜芦醇具有抑菌活性,10h后质量浓度为0.125mg/mL的反式白藜芦醇对金黄色葡萄球菌的抑菌率为80%,而质量浓度为1.00mg/mL的反式白藜芦醇对大肠杆菌的抑菌率为40%。     

花生壳中提取白藜芦醇的工艺研究

白藜芦醇是一种重要的活性天然产物,本实验以花生壳为原料,通过微波法和超声波法对白藜芦醇的提取工艺进行研究,分别考察了料液比,乙醇浓度,超声作用时间,微波时间、水浴时间、温度等对提取率的影响.通过单因素实验和正交实验分别确定微波法和超声波法提取花生壳中白藜芦醇的最佳工艺条件.实验结果表明:最佳工艺条件下,微波法和超声波法提取的得率分别是:0.0047%和0.0035%.微波法的得率略高于超声波法.     

微波辅助提取虎杖中白藜芦醇的工艺研究

试验以虎杖白藜芦醇的提取率为指标,选择乙醇浓度、微波处理时间、料液浸泡时间以及料液比4个因素分别进行单因素试验,得出各因素对提取率的影响大小依次为:料液比>微波处理时间>乙醇浓度,而浸泡时间在实验范围(1h)内基本无影响.对影响较大的三个因素采用L9(33)正交试验设计确定最佳提取工艺:乙醇浓度为60%,微波提取时间为80s,料液比为1:10(g:mL),在最佳工艺条件下虎杖白藜芦醇提取率最高可达0.423%.     

Research on the extraction technology of resveratrol from the peanut shells

白藜芦醇是一种重要的活性天然产物,本实验以花生壳为原料,通过微波法和超声波法对白藜芦醇的提取工艺进行研究,分别考察了料液比,乙醇浓度,超声作用时间,微波时间、水浴时间、温度等对提取率的影响.通过单因素实验和正交实验分别确定微波法和超声波法提取花生壳中白藜芦醇的最佳工艺条件.实验结果表明:最佳工艺条件下,微波法和超声波法提取的得率分别是:0.0047％和0.0035％.微波法的得率略高于超声波法.     

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。