昙花总黄酮提取工艺研究

研究昙花总黄酮的提取工艺条件.采用传统热回流浸提法,以乙醇为提取溶剂,考察溶剂体积分数、提取温度、提取时间以及料液比对昙花总黄酮含量的影响,并在单因素实验的基础上,通过正交试验,确定昙花总黄酮的最佳提取工艺.结果表明,乙醇体积分数、提取温度、提取时间以及料液比对昙花总黄酮的含量均有影响;单因素考察结果显示乙醇体积分数为80%,提取温度为80℃,提取时间为4 h,料液比为1∶40(g/m L)条件下昙花总黄酮含量较高;正交试验优化的昙花总黄酮的提取工艺为乙醇体积分数为80%,提取温度为90℃,提取时间为4 h,此条件下昙花总黄酮含量为1.18%.本工艺简单、可行,为昙花的进一步开发利用奠定基础.     

菟丝子总黄酮提取工艺的研究

优选水浴振荡提取方法,以菟丝子总黄酮质量分数为考察指标,研究提取溶剂浓度、提取温度、固液比、提取时间、提取次数等因素对总黄酮质量分数的影响.通过正交试验,确定菟丝子总黄酮提取的最佳工艺条件为:提取温度60℃,固液比1∶14,乙醇体积分数55%,提取时间2h,提取次数2次.     

大枣总黄酮的提取及百分含量测定

探讨大枣总黄酮的最佳提取工艺条件.选定乙醇体积分数、料液比、提取时间及提取温度4个因素,进行单因素考察和正交试验,再根据芦丁标准曲线,测定大枣中总黄酮百分含量,研究4个因素对总黄酮的影响,最终确定最佳工艺条件.大枣总黄酮的最佳提取工艺条件为乙醇体积分数70%、料液比1∶10、提取时间3 h、提取温度80℃,在此条件下,大枣总黄酮百分含量为0.875 5%.回流提取法提取总黄酮简便、快速、节省溶剂,且有较高的得率.     

沙棘果渣中总黄酮提取的研究

研究了从沙棘果渣中提取黄酮的工艺,考察了提取溶剂和果渣脱脂与否对提取效果的影响,在此基础上采用正交实验方法确定了沙棘果渣总黄酮的常规提取最佳条件：石油醚脱脂,质量分数为65%的乙醇溶液作为提取剂,提取温度为80 ℃,提取1 g果渣的每次溶剂用量为8 mL,提取次数为3次(每次为1h),在常规提取的最佳条件下沙棘果渣的总黄酮得率高达0.534 4%。尝试了超声辅助提取,结果表明提取前用超声预处理15 min,可以大大减少溶剂用量和提取时间,而黄酮得率保持不变。     

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%。     

维药药西瓜中总黄酮的提取工艺

维吾尔族传统民族药物药西瓜有多种药用功效,一直是国内学者的研究热点,但对药西瓜的研究主要集中在其药理活性和化合物的分离,对提取工艺的优化工作却是空白。本文对药西瓜中总黄酮的提取进行系统地工艺优化,以此为日后工业放大和黄酮类化合物单体的分离提供参考。通过单因素实验和正交实验,以温度、料液比、提取时间、溶剂体积分数作为工艺参数,分别采用回流提取和微波辅助2种方法在不同的提取条件下对维药药西瓜中的总黄酮进行提取,从而确定在2种方法下最佳的提取工艺。结果显示回流提取药西瓜中总黄酮的最佳工艺条件为:提取温度为90℃,提取时间为2h,乙醇体积分数为95%,料液比1∶80,在此条件下黄酮提取率为1.72%。微波辅助提取的最佳工艺条件为:提取温度为90℃,乙醇体积分数为95%,提取时间为提取时间为25 min,料液比为1∶90,在此条件下黄酮提取率为4.28%。对比2种提取方法,采用微波辅助技术提取,需要时间短,提取率更高,是更适宜的药西瓜黄酮提取的方法。     

超声法提取萹蓄总黄酮的正交试验研究

采用正交试验法优化篇蓄总黄酮的超声波提取工艺,系统考察了乙醇体积分数、料液比、超声温度、超声时间对总黄酮提取量的影响.篇蓄总黄酮的最佳提取工艺如下:料液比为1∶25,超声温度为45℃,超声萃取时间为25 min,乙醇体积分数为90％.此条件下总黄酮得率为12.012 mg/g.     

桂花总黄酮的提取及其抗氧化活性研究

利用乙醇为溶剂提取桂花中总黄酮类物质.通过单因素实验和正交试验确定桂花总黄酮最佳提取工艺条件,并对桂花总黄酮体外抗氧化性能进行系统评价.得出以乙醇为溶剂提取桂花中总黄酮最佳工艺条件为:乙醇体积分数60%,提取功率360 W,料液比1∶35,浸提时间2 min,在此条件下总黄酮得率可达18.18%;体外抗氧化性能研究结果表明,桂花总黄酮具备较好抗氧化活性,在相同的加入量下桂花总黄酮对DPPH自由基清除率明显优于BHT,低于Vc.     

芹菜籽中总黄酮提取工艺条件的研究

采用甲醇回流法进行提取,通过UV光谱法进行定量,分析各种不同条件下芹菜籽中总黄酮的提取率,确定芹菜籽中总黄酮的最佳提取条件为:提取次数为2次、提取温度为60 ℃、甲醇体积分数为40 %、料液比为1:40、回流时间为3 h,提取率为1.67 %.     

赶黄草总黄酮类化合物的提取纯化工艺研究

以赶黄草为原料,选择单因素和正交试验筛选了赶黄草回流提取和超声提取总黄酮的最佳工艺条件,并对提取出的总黄酮利用聚酰胺树脂进行纯化,筛选出纯化最佳条件.结果显示最佳回流提取条件为:料液比1:15、提取温度60℃、乙醇体积分数60％、提取时间1 h.超声最佳提取条件分别为料液比1:25,提取温度50℃,乙醇体积分数60％,提取时间50 min.聚酰胺树脂的纯化最优条件为:选择60～80目聚酰胺树脂、溶液pH值为4、装柱比例1:15、拌样比例1:3、洗脱溶剂pH值为8、乙醇体积分数为70％,并且乙醇用量需大于3倍量保留体积.通过实验对比和筛选赶黄草黄酮的提取工艺条件和树脂最佳纯化条件,为赶黄草黄酮未来的提取纯化类实验研究提供实验数据参考.     

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