延安地区马齿苋中总黄酮的提取与含量测定

采用超声波细胞破碎法和索氏提取法提取马齿苋中的总黄酮,用比色法测定总黄酮含量,通过正交试验确定超声波细胞破碎法的最佳提取条件。结果表明,超声波细胞破碎法提取的影响因素顺序为:料液比>乙醇浓度>提取时间;用超声波细胞破碎法提取马齿苋中总黄酮的最佳条件为:料液比为1 g∶20 mL、乙醇体积分数为90%、提取时间40 min。测得马齿苋中总黄酮含量为5.63%。     

正交实验法优选血三七药材提取工艺

通过正交实验,优选出血三七药材的最佳提取工艺.以干浸膏收率和槲皮素的含量作为考察指标,采用L9(34)正交表进行筛选,考察了乙醇的浓度、乙醇的用量、提取的时间、提取的次数、药材的粒径等因素以确定最佳的提取工艺.采用高效液相法测定血三七中槲皮素的含量,以C18柱为色谱柱,甲醇-0.4%磷酸溶液(49∶51)为流动相;检测波长为360nm.槲皮素标准品在1.13～9.04μg(r=0.9998)范围内呈良好的线性关系,优选提取工艺为血三七根茎粉碎成最粗粉,加90%的乙醇加热回流提取2次:第一次加6倍量90%乙醇,加热回流提取1.5h;第二次加4倍量90%乙醇,加热回流提取1h.     

高效液相色谱法测定银杏叶提取物中黄酮含量

银杏叶提取物具有多种生物活性.其中的黄酮是其主要药效成分.建立快速、高效、成本低廉的分析方法是非常必要的.在NANONSPACE SI-2型高效液相色谱仪上建立了测定银杏叶提取物(EGB)中总黄酮含量的方法.色谱条件:应用Shiseido MG C18色谱柱(1.5 mm×250 mm,5μm);流动相为甲醇∶0.5%磷酸(48∶52);流速200μL/m in;检测波长360 nm;进样量1μL.3种黄酮苷元有良好的分离度,并通过稳定性实验和加标回收实验,验证了方法的稳定性和可靠性.槲皮素浓度在40~200μg/mL;线性关系良好,r=0.999 8;槲皮素的平均回收率为99.2%.     

血三七药材提取工艺的优选研究

通过正交实验,优选出了血三七药材的最佳提取工艺.以干浸膏收率和槲皮素的含量作为考察指标,采用L9(34)正交表进行筛选,考察了乙醇的浓度和用量,提取的时间和次数,药材的粒径等因素以确定最佳提取工艺.采用高效液相法测定血三七中大黄素的含量,以C18柱为色谱柱,甲醇-0.1%磷酸溶液(体积比85∶15)为流动相;检测波长为254 nm.大黄素标准品在0.16～1.60μg(r=0.9999)范围内呈良好的线性关系,优选提取工艺为血三七根茎粉碎成最粗粉,加90%的乙醇加热回流提取2次:第一次加6倍量90%乙醇,加热回流提取1.5 h;第二次加4倍量90%乙醇,加热回流提取1 h为最佳提取工艺.     

辣椒叶片中类胡萝卜素组分分离及测定方法的研究

建立辣椒叶片中类胡萝卜素组分及其含量的分离测定方法.通过对提取溶剂、皂化温度、皂化时间、KOH-乙醇皂化液质量浓度、KOH-乙醇皂化液体积、料液比的选择,以及对流动相、柱温、柱流速等色谱条件的考察,研究提取辣椒叶片类胡萝卜素工艺流程.建立了提取辣椒叶片中类胡萝卜素的适宜工艺和分离测定辣椒叶片中类胡萝卜素组分及其含量的RP-HPLC工艺.技术关键是:以石油醚为提取溶剂、皂化温度为80℃、皂化时间为40min、皂化液质量浓度为20%、皂化液体积为10mL、料液比为1∶5;采用YMC-C30色谱柱(250mm×4.6mm i.d,5μm);检测波长450nm;柱流速1.0mL·min-1;柱温25℃;流动相A为乙腈:甲醇(V∶V=60∶40),流动相B为甲基叔丁基醚(100%),梯度洗脱.结果表明以外标法定量,叶黄素、玉米黄素和β-胡萝卜素各组分的线性关系良好,相关性系数在0.996 1~0.999 9之间;平均回收率在85.2%~95.1%之间.该方法为辣椒叶片中叶黄素、玉米黄素和β-胡萝卜素的分离与定量测定提供了方法保证.     

武夷茶叶咖啡因含量研究及其聚类分析

建立高效液相色谱法测定武夷岩茶中不同产地、加工工艺过程中茶叶的咖啡因含量,采用Agilent Tc C_(18)柱(4.6 mm×150mm,5μm);流动相:乙腈和水;流速:1.000 mL/min;柱温:30℃;检测波长:274 nm;进样量:10μL进行测定.并讨论了溶剂种类、提取时间、提取功率、净化剂选择等因素对咖啡因的影响.实验结果表明:采用甲醇作为溶剂、超声波时间为25 min,提取功率720 W,采用无水Na_2SO_4和大孔树脂作为净化剂为提取茶叶中的咖啡因最佳提取条件,分析8个样品得知在不同产地、加工工艺过程中茶叶中咖啡因成分在含量上具有较大差异,且具有明显的地域特征.以茶叶中咖啡因含量变化为指标,可以作为区分武夷岩茶产地武夷岩茶品质之一的指标.     

超声波提取扁蓄总黄酮及测定

目的:从扁蓄中提取总黄酮并测定其含量.方法:选择乙醇为溶剂,用超声波技术从扁蓄中提取黄酮类物质,并对所提取的黄酮类物质进行验证,用分光光度法测定含量.结果:测得样品中总黄酮的平均含量为1.88%,平均回收率为100.95%.结论:运用超声波法从扁蓄中可以提取出黄酮类物质,加快提取速度,提高提取效率.     

水红花子总黄酮的超声波提取及抗氧化性研究

研究水红花子总黄酮的超声波辅助法提取工艺,并对水红花子总黄酮的抗氧化活性进行测定。结果表明:水红花子总黄酮的最佳提取工艺条件为浸泡16h、乙醇浓度55%(v/v)、料液比1:18(g.mL-1)、超声波功率100W、提取时间40min、提取温度70℃、提取次数2,此条件下总黄酮提取量为6.14g/100g;抗氧化实验证明水红花子总黄酮具有清除羟自由基的作用。     

水红花子总黄酮的超声波提取及抗氧化性研究

研究水红花子总黄酮的超声波辅助法提取工艺,并对水红花子总黄酮的抗氧化活性进行测定.结果表明:水红花子总黄酮的最佳提取工艺条件为浸泡16h、乙醇浓度55％(v/v)、料液比1∶18(g·mL-1)、超声波功率100W、提取时间40min、提取温度70℃、提取次数2,此条件下总黄酮提取量为6.14g/100g;抗氧化实验证明水红花子总黄酮具有清除羟自由基的作用.     

高效液相色谱同时测定何首乌中大黄酸、大黄素和大黄酚的含量

采用高效液相色谱法建立了同时测定何首乌中大黄酸、大黄素、大黄酚三种蒽醌类化合物的方法,样品采用超声波法提取,色谱柱为Phenomenex C18(250mm×4.6mm,5μm);流动相为甲醇-0.4%醋酸水溶液(80∶20);流速0.80mL/min;紫外检测波长254nm;柱温为35℃.结果:该方法对大黄酸、大黄素和大黄酚分别在0.0001~12.50μg/mL、0.0002~25.00μg/mL、0.00018~22.50μg/mL范围内线性关系良好,相关系数(r)均大于0.9999,定性检测限(S/N=3)依次是:0.0703ng/mL、0.0282ng/mL、0.0871ng/mL;样品回收率为88.39%~107.2%.结论:本法操作简单快速、定量准确、灵敏度高、成本低,为何首乌中蒽醌类化合物的检测分离及含量测定提供了一个有效的科学方法.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the