液晶用羊毛脂胆固醇的精制研究

本文研究了液晶用羊毛脂胆固醇的精制方法,确定了影响羊毛脂胆固醇精制的各种因素及其最佳工艺条件,采用此工艺羊毛脂胆固醇的含量可达99%,达到了液晶用羊毛脂胆固醇的标准要求。     

从青霉菌丝体中提取核糖核酸的研究

文中研究了从青霉菌丝体中提取纯化核糖核酸的工艺条件。采用盐碱法破碎细胞,调抽提液 pH值至4.6以沉淀部分蛋白质,然后用中性蛋白酶AS1.398处理分级沉淀后的上清液,详细考察了蛋白酶用量、反应温度、初始pH值和反应时间对核酸纯度的影响。酶解液经截留相对分子质量为6.0×10⁴的超滤膜过滤后,核糖核酸的纯度和得率分别是72.1%和0.42%。     

钛白废盐制备高纯MnO_2纳米棒

以钛白生产中产生的废盐为原料,采用水热法合成制备了高纯MnO2纳米棒,研究了不同反应条件对产品纯度和产率的影响.以纯度和产率为指针,确定了制备高纯MnO2纳米棒的最佳工艺条件,并对样品进行了XRD、FT-IR、SEM、ICP表征.研究结果表明,MnO2纳米棒的纯度随水热反应pH增大而增大,当pH为2.0时,制得的MnO2纳米棒纯度最大,继续增大pH,样品纯度下降,MnO2纳米棒的产率随水热反应pH增大而增大,当pH为4.0时,产率最大,继续增大pH,产率下降;当NaCl的加入量为0.08 g时,纯度和产率同时达到最大;MnO2纳米棒纯度几乎不随NaClO3加入量的变化而变化,而产率随着NaClO3加入量的增加而增加.     

药用植物单面针中总黄酮的制备

为获得纯度较高的单面针总黄酮,对影响单面针总黄酮制备的工艺条件进行了研究,采用超声提取法,通过正交试验优化总黄酮提取条件。优选AB-8型大孔树脂用于总黄酮的分离纯化,并考察静态和动态吸附与解吸附影响因素。结果表明:采用15倍量(m L/g)的70%乙醇50℃超声1.5 h,提取2次,可得最大提取量为4.78 mg/g;上样液质量浓度为1.5 mg/m L,pH值为6.0,流速为2.0 m L/min,解吸时采用140 m L 70%乙醇,2.0m L/min进行动态解吸附,得到总黄酮纯度为69.57%。     

氧化法纯化回收Lyocell纤维纺丝溶剂NMMO的研究

研究用H2O2氧化回收含有NMMO的lyocell纤维的纺丝凝固浴,并使之纯化脱色,应用正交实验方法研究各种参数对氧化法的影响,探索适合实际工业生产的最佳工艺条件。在实验中,用溶液在450nm的吸光度来跟踪反应的进行,通过测量溶液的吸光度、pH值、过氧化氢的残余量来指示反应的绺和结果。研究结果表明影响氧化法纯化回收凝固浴的主要因素是温度和H2O2的加入量。最佳工艺条件是再生温度为70℃、H2O2的加入量为溶液质量的1.0%、溶液的pH值为8。     

两步纯化溶液法制备高纯氢氧化铝粉

以工业氢氧化铝和硫酸为原料,采用两步纯化溶液法制得了纯度为99.99%的氢氧化铝粉.此外,对活性炭和离子交换树脂对溶液的纯化效果,以及有屏蔽剂A存在时pH值对铁离子平衡浓度的影响进行了研究.研究结果表明:活性炭、吸附树脂、强碱性、弱碱性阴离子交换树脂纯化溶液的效果较差,螯合树脂Da纯化溶液的效果最好,其饱和容量大约是树脂体积的6倍;当没有屏蔽剂存在时,约有80%的铁离子以沉淀析出;当有屏蔽剂A存在时,在pH值为5时只有4.02%的铁离子以沉淀析出,在pH值为6.5时有16.41%的铁离子以沉淀析出,达到了用屏蔽剂阻止杂质离子析出的二次纯化的目的.     

莪术多糖的分离纯化

研究莪术多糖分离纯化的最佳条件,优化莪术多糖的提取纯化工艺,为进一步探讨莪术多糖的生物活性奠定基础.莪术经热水提取,酒精沉淀,脱色,脱蛋白得粗多糖.粗多糖用50%、75%乙醇分级沉淀得2个级分CZ1、CZ2,进行DEAE-纤维素柱层析.调节DEAE-纤维素的pH值,比较洗脱曲线的不同.CZ1经DEAE-纤维素柱层析得到1个组分,CZ2在酸性、中性条件下层析得2个组分,在碱性条件下得1个组分,随pH升高,回收率降低,纯度增高.各纯化得到的多糖组分经纸层析、琼脂糖凝胶电泳鉴定为单一成分.实验证明,pH是影响层析的一个重要因素,因此莪术多糖的最佳纯化pH值为7.0.     

大孔吸附树脂分离纯化菟丝子黄酮工艺的研究

研究了大孔吸附树脂纯化菟丝子黄酮的方法.以菟丝子总黄酮含量考察纯化后黄酮纯度,对可能影响纯化的因素进行单因素试验,确定纯化的最佳工艺条件为:选用H-103型大孔吸附树脂,吸附液pH值为3～4,洗脱剂浓度60%,动态吸附流速为0.5 ml/min,吸附时间60min,洗脱剂量与树脂比为8.     

抗肿瘤溶栓嵌合蛋白制备工艺研究

对抗肿瘤溶栓嵌合蛋白在重组大肠杆菌中高效表达作了研究.以装液量、接菌量和初始pH值三因素设计正交试验,确定其最佳培养条件.结果表明:抗肿瘤溶栓嵌合蛋白制备工艺的最佳培养条件是装液量100 m L、接菌量2%、初始pH值7.5.在优化后的培养条件下,1 L发酵液可以得到0.987 mg蛋白,比优化前蛋白量提高了一倍,较高的表达量为进一步研究该蛋白的纯化和性质提供了基础.     

重组Hepcidin融合蛋白的金属螯合亲和层析纯化

在大肠杆菌中表达的重组Hepcidin融合蛋白以包涵体形式存在,其N端带有6个组氨酸。以Ni²⁺-IDA-Sepharose Fast Flow为层析介质,在变性条件下以不同的咪唑和pH值洗脱方式对Hepcidin融合蛋白的纯化效果进行了比较,确定了该融合蛋白的金属螯合层析纯化条件。以60mmol/L咪唑洗脱杂蛋白,然后将pH值降至4.0洗脱融合蛋白,纯化后的融合蛋白纯度大于95%,而且不含咪唑,有利于下一步Hepcidin的制备。金属螯合层析中融合蛋白收率不低于90%。Ni²⁺-IDA-Sepharose Fast Flow对该融合蛋白的吸附量为30.4mg /mL。     

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