枇杷叶总黄酮的提取及其脂质体的抗氧化活性

采用乙醇回流法提取枇杷叶中黄酮类物质,制备黄酮脂质体,并考察其抗氧化活性及各因素对总黄酮提取率的影响.优化总黄酮脂质体制备处方,并测定其抗氧化活性.优化结果表明:最佳提取工艺中乙醇体积分数为70%,料液比为1:60,提取温度为80℃,提取时间为1.5h;黄酮脂质体最佳处方中卵磷脂与胆固醇的质量比为4∶1,卵磷脂与黄酮的质量比为20∶1,磷酸盐缓冲液pH值为5.8.体外抗氧化结果显示:不同质量比的黄酮及其脂质体对猪油都具有一定的抗氧化作用,且随着其剂量的增加而增强;质量分数相同时,黄酮脂质体的抗氧化效果优于黄酮溶液,且与抗坏血酸有较好的协同抗氧化增效作用.     

紫鸭跖草总黄酮提取工艺优化及抗氧化研究

以紫鸭跖草为研究材料,采用溶剂提取法对紫鸭跖草进行总黄酮的提取和体外抗氧化研究.经单因素和正交试验得出紫鸭跖草黄酮最佳提取工艺为:料液比1∶70,提取时间2h,提取温度90℃,乙醇体积分数80%,在最佳提取工艺条件下黄酮得率为4.59%,该工艺稳定可行.紫鸭跖草黄酮对于试验中所选取的自由基在测定范围内,清除作用均随着质量浓度的增加呈现出正相关的效应,体现出较强的抗氧化作用;对DPPH自由基的清除能力较强并和相同质量浓度的VC清除效果基本相当,对羟自由基的清除作用在所试范围内效果弱于VC.     

响应面法优化枇杷花黄酮提取工艺研究

采用超声波辅助提取法对枇杷花黄酮的提取工艺进行了研究.在单因素实验的基础上,采用四因素三水平的响应面法优化枇杷花黄酮提取工艺条件.结果表明,枇杷花黄酮提取的最佳工艺条件为:乙醇体积分数为64%,料液比为1∶44(g ∶mL),超声温度为59 ℃,超声时间为38 min.在此条件下,枇杷花黄酮得率为106.422 mg/g     

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。     

虎尾轮根部黄酮类化合物的提取及其抗氧化性能研究

以虎尾轮根为原料,采用乙醇水溶液浸提法提取黄酮类化合物,并研究该类提取物的抗氧化性能.结果表明,虎尾轮根部黄酮最佳的提取工艺条件为:乙醇溶液体积分数为70%,料液比为1(g)∶25(mL),浸提温度为60℃,浸提时间为4h,此条件下黄酮提取量可达到48.44mg·g-1,同时发现虎尾轮根部黄酮提取物对超氧阴离子自由基具有一定的清除能力,半抑制质量浓度(ρIC50)为2.43mg·L-1,强于维生素C,表现出较好的体外抗氧化性.     

柚皮总黄酮的提取及其抗氧化活性研究

通过考察柚皮总黄酮的最佳提取工艺,研究其抗氧化活性.该方法以柚皮中的总黄酮得率为指标,并采用正交实验.结果显示,最佳提取工艺为:乙醇浓度为60%,物料比为1∶25,提取温度为50℃,提取时间为3 h,此条件下得到的柚皮总黄酮的提取率为0.986%.认为柚皮总黄酮对超氧自由基的抑制率随着黄酮浓度的增加而增大,其IC50为2.165 mg/mL.     

原花青素的抗氧化活性研究

以脱脂葡萄籽为原料提取原花青素,选择了清除超氧阴离子自由基、对亚油酸体系的保护、以及对猪油自氧化的抑制等三方面对原花青素的抗氧化活性进行评定,同时考察了原花青素与合成抗氧化剂的复合使用效果及与有机酸、Vc的协同效应.结果表明,原花青素具有很强的清除O2-.的能力,其抑制邻苯三酚自氧化率可高达91.5%;其对亚油酸抗氧化的最适范围是在pH值为7.0的环境中;0.03%原花青素的抗氧化活性接近于0.01%BHT,0.02%原花青素的抗氧化活性优于0.01%茶多酚,0.01%原花青素与0.01%PG的复合使用效果最佳,可使猪油的货架期在20℃下由8.5个月延长到23.9个月.     

茶树花黄酮的提取及对羟自由基的清除效果

通过对茶树花物料粒度、不同提取剂和提取方式的比较,研究茶树花黄酮的最佳提取工艺;并比较不同提取方法获得的茶树花黄酮提取物对羟自由基(·OH)的清除效果.结果表明:乙醇热回流提取的最佳工艺条件为:体积分数95%的乙醇,料液比1∶15,80℃下批次提取90 min;超声波振荡提取最佳工艺为:体积分数95%的乙醇,料液比1∶30,提取温度45℃,批次提取80 min.超声波结合热提法获得的茶树花黄酮提取物对·OH的清除效果最好.     

超声波辅助提取刺梨籽黄酮工艺优化及其体外抗氧化活性研究

以恩施市野生刺梨籽为原料,借助超声波为辅助的提取方法,对野生刺梨的刺梨籽黄酮的提取工艺进行优化研究,在此基础上初步探索刺梨籽黄酮的抗氧化活性.提取工艺响应面优化结果为:提取剂乙醇体积分数(v/v)81. 36%,超声功率403.54 W,超声时间55.76 min,液料比21.94∶1,响应面模型预测刺梨籽黄酮提取最大得率为82. 27 mg/g.以优化后的提取条件进行黄酮提取验证,其得率为80.16 mg/g,与模型预测值的误差为2.56%.通过体外抗氧化活性试验,表明刺梨籽黄酮提取物具有一定的抗氧化活性.该试验结果为刺梨籽黄酮的提取以及黄酮的性质研究提供了一定的试验基础.     

超声辅助提取黑芝麻油脚卵磷脂及其抗氧化活性研究

以黑芝麻油脚为实验原料,研究超声辅助乙醇溶液提取其卵磷脂的工艺.以卵磷脂得率为考核指标,在单因素实验基础上,通过正交试验优化研究提取黑芝麻油脚卵磷脂的最佳工艺条件,并采用DPPH自由基清除法研究最佳工艺条件下得到的卵磷脂粗提物的抗氧化活性.实验结果表明,黑芝麻油脚卵磷脂的最佳提取工艺条件为:乙醇的体积分数为95%,料液比为1:12,超声温度为40℃,超声时间为40min.在此最优提取工艺条件下,黑芝麻油脚卵磷脂的得率为11.98%.由体外抗氧化活性实验结果可知,黑芝麻油脚卵磷脂对DPPH自由基的清除能力在一定范围内随着浓度的增加而增加,其IC50值为0.46 mg/mL,表明其具有一定的抗氧化活性,但与对照品维生素C的抗氧化性能相比较弱.     

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.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

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