淡竹叶中茶多酚的微波辅助提取

以淡竹叶为原料,采用乙醇作为提取溶剂,研究了在微波辐射下提取茶多酚的工艺条件。探讨了茶多酚的提取方法及相应的提取条件;对微波功率、溶剂浓度、料液比、提取时间和提取级数等影响因素进行了研究,按照GB/T8313-2002标准,用UV-9200型分光光度计对茶多酚的吸光度进行了测定,同时对提取得到的茶多酚收率进行了分析。结果表明,微波辅助法从淡竹叶中提取茶多酚的适宜工艺条件为:淡竹叶在60%乙醇溶液中浓度为0.125g/mL,3级提取,提取功率320W,提取时间4min。此条件下茶多酚收率为1.43%。     

茶多酚提取与含量测定方法的比较

通过对茶多酚的分析和解释,着重介绍了茶多酚的提取技术、茶多酚的含量测定方法,并对不同的提取工艺与检测手段加以对比,指出茶多酚是一种对健康有益的物质,用途广泛,随着技术的更新,对茶多酚的提取将更加简便、廉价。     

微波法从绿茶中提取茶多酚的工艺研究

为了得到成本低、提取效率高、环保、节约的绿茶中茶多酚提取方法,以乙醇为提取剂,采用微波加热法从低档绿茶中提取茶多酚。研究了提取剂浓度、料液比、微波提取功率、微波提取时间、提取级数几个因素对茶多酚提取率的影响,获得了微波法提取绿茶中茶多酚的最佳提取条件。结果表明,采用50%乙醇溶液为提取剂,料液比(g/mL)为1∶9,提取功率设定为320W,提取时间18s,微波浸提2次,此提取条件下,绿茶中茶多酚提取率较传统提取法高,可达23.4%。该方法较传统提取方法工艺简单、成本低、提取时间短、节约能源,可广泛用于提取绿茶中的茶多酚。     

茶灰中提取搞氧化剂工艺研究

本文介绍了由茶厂废弃物－－茶灰中提取天然抗氧化剂茶多酚的两种实用工艺。工艺Ｂ利用现代提取技术，可以价廉、方便地制取茶多酚。     

响应曲面法优化醇提茶多酚工艺研究

在单因素试验的基础上,利用响应曲面法对茶多酚醇提工艺参数进行优化研究.选择乙醇浓度、提取时间以及提取温度为自变量,茶多酚提取率为响应值,采用Box-Behnken设计方法,研究各自变量及其交互作用对茶多酚提取率的影响.利用Design Expert软件对数据进行回归分析,得到二次多项式回归方程的预测模型.结果表明,茶多酚醇提的优化工艺条件为:乙醇浓度取20%,提取时间30 min,提取温度76℃.在此工艺条件下茶多酚提取率理论值为18.75%.     

普洱茶中茶多酚和茶多糖的提取工艺研究

以普洱茶为材料、水为提取溶剂,通过正交设计考察了浸提温度、浸提时间、溶剂用量、浸提次数4个因素对其所含茶多酚和茶多糖提取得率的影响,优化茶多酚和茶多糖综合提取工艺.结果表明,最佳提取工艺条件为浸提温度80℃,浸提时间1 h,溶剂用量(固液比)1∶10,浸提次数1次.在优化的提取工艺条件下,提取物干物质得率为20.65%,其中茶多酚含量为30.47%,茶多糖含量为57.26%,且该提取物作用于高脂饮食小鼠降脂效果显著.     

从茶叶中提取茶多酚的工艺探讨

用正交实验方法探讨了茶叶中茶多酚的最佳提取工艺.研究结果表明:用4倍于叶重体积的水溶液加热回流提取4次,每次提取20min,用2倍于提取水溶液体积的乙酸乙酯萃取3次,茶叶中茶多酚提取效果最好,其平均浸出率可达86.3%.     

天然抗氧化剂茶多酚的提取及抗氧化试验

开发利用天然抗氧化剂是当前食品科技发展的趋势。茶叶中富含的茶多酚是一种天然抗氧化剂,本文采用了较为先进的茶多酚提取工艺,并将其产品茶多酚与BHA、VE在猪油中的抗氧化能力进行比较,得到了较为满意的结果。     

从茶叶中提取茶多酚的工艺探讨

用正交实验方法探讨了茶叶中茶多酚的最佳提取工艺。研究结果表明：用4倍于叶重体积的水溶液加热回流提取4次，每次提取20min，用2倍于提取水溶液体积的乙酸乙酯萃取3次，茶叶中茶多酚提取效果最好，其平均浸出率可达86．3％。     

油茶皂素和多酚的综合提取工艺研究

以油茶枯为研究对象,研究油茶枯中油茶皂素和油茶多酚的综合提取工艺。采用醇-水提取,以得率为考察指标,考察提取时间、提取温度、料液比及乙醇浓度对油茶皂素和多酚得率的影响,并通过正交试验确定最优综合提取工艺。实验结果表明:油茶皂素及多酚的最优综合提取工艺为提取时间2h、提取温度80℃、料液比1∶12、乙醇体积分数60%,在此工艺下,油茶皂素的得率为15.26%,油茶多酚的得率为0.52%(以山奈酚计)。     

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.     

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.     

Jane Eyre——A Feminist In The 19th Century

In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.     

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     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of