L-酪氨酸的合成研究

本文研究了L-酪氨酸的合成,采用有机合成法和酶转化法相结合的方法,主要原料为对羟基苯甲醛和海因,合成对羟基亚苄基苯丙酮酸粗品,再经过碱解得到对羟基苯丙酮酸,选取合适的酶对碱解液催化转氨,生成L-酪氨酸。含量达到99%以上。     

D-对羟基苯甘氨酸生产菌株的选育方法探讨

利用国际上通用的以底物--对羟基苯海因(HPH)为惟一氮源的培养基从69个土壤样品和3个水样中初步分离出238个菌株,然后利用双层琼脂法和微孔快速筛选法对分离到的菌株和实验室保藏的220多株茵进行反复筛选,最终获得D-海因酶阳性菌株54株.用茚三酮显色法及纸层析法从这54株茵中筛选到2株产N-氨甲酰水解酶的阳性菌株,从而获得了可同时产生D-海因酶(DHase)和D-氨甲酰水解酶(DCase)的菌株.     

Burkholderic cepecia 1003产海因酶固定化条件

海因酶是利用海因酶法制备手性氨基酸的关键酶.采用Eupergit C、Eupergit C250L及其氨基化后的载体作为固定化介质,对酶液pH值、蛋白浓度、固定化时间以及EDC用量等参数对海因酶固定化过程的影响进行研究,并在实验范围内,得到了上述参数的最优值.研究表明,环氧基载体的最适固定化条件为：酶液pH值为7.0,酶液蛋白质量浓度为0.4mg/mL,固定化时间为20 h;氨基载体最适固定化条件为：酶液pH值为8.0,酶液蛋白质量浓度为0.4 mg/mL,固定化时间为10 h,EDC用量：Eupergit C（-NH2）为70μL,Eupergit C250L（-NH2）为120μL.其中以Eupergit C250L为固定化载体,海因酶的活性回收率可高达87%,且固定化酶的稳定性也较好,酶活半衰期长达2 500h左右,具有较好的稳定性.     

高效液相色谱法测定D-对羟基苯甘氨酸

建立了反应体系中D－对羟基苯甘氨酸、N－氨甲酰－D－对羟基苯甘氨酸、DL－对羟基苯海因3者含量的测定方法。采用高效液相色谱法测定，以Kromasil-C18为固定相，ψ(乙腈）：ψ（磷酸（85％））＝10：90：0.01为流动相，紫外检测波长为210nm。3者回收率分别为99.5%,98.6%及99.6%,RSD为0.11%，0.13%和0.21%。     

易错PCR法定向进化D-海因酶的初步研究

D-海因酶是生物转化D-型氨基酸的关键酶,在一定浓度M n2 存在下,经易错PCR法重复扩增,产物构建成pET-HDT重组子,并建立突变体文库.经筛选获得了内源DNA序列变异的变异株.进化酶催化底物海因水解的活性为亲本重组酶的1.3倍,催化底物对羟基苯海因水解的活性为亲本重组酶的2.4倍.     

氧化—吸附法处理高浓度有机废水

探讨了氮化－吸附法处理对羟基苯海因生产中产生的高浓度有机废水,使用Fenton试剂、煤粉或煤渣对废水进行氧化、混凝、吸附处理、废水的色度可去除100％,COD可去除90％。通过实验,得出了两次组合处理的适宜工艺条件。     

固定化糖化酶性质及其应用的研究

以聚乙烯醇复合凝胶作为载体固定化糖化酶,最终酶活力达到1558μ/g干胶,酶活回收率为30.2%.用该固定化酶在pH4.6,45℃下进行连续操作.实验结果表明,10%～15%的淀粉液经过水解后,DE值均高于95%,产物转化率最高可达到98.2%,生产强度最高为28.9g/L·h,可连续使用24～28d.研究表明该固定化酶反应体系在高底物浓度下的操作稳定性和重复使用性较好.     

Galactomyces reessii转化β-甲基丁酸生产β-羟基-β-甲基丁酸

Galactomycesreessii可将 β-甲基丁酸 ( MBA)转化为 β-羟基 - β-甲基丁酸 ( HMB)。摇瓶实验表明发酵过程中提供生长因子的酵母萃取物浓度以 3 g/L较适宜。高浓度钠、铵离子对菌体生长有抑制作用 ,为保证转化 MBA所需 p H可采用混合碱 ( Na OH、KOH、NH4 OH)来调节 ,以防止单一阳离子浓度过高对菌体生长和产物形成的抑制。MBA对菌体生长有明显的抑制作用 ,1 0 g/L的MBA可使菌体浓度减少 3 0 %。分批补料发酵中 ,连续流加葡萄糖和 MBA,控制发酵液中葡萄糖浓度不超过 3 g/L,MBA浓度不超过 4g/L ,1 0 2 h时 HMB浓度达 2 9.0 g/L ,转化率达 5 7.3 % ,HMB平均生产率达 0 .0 98g/( L· h)。     

常压下制备乙内酰脲两种方法的比较

利用常压法制备乙内酰脲(海因)，产物收率高，纯度好，且具有很好的操作弹性。在常压下分别利用羟基乙腈、氨气和CO2，羟基乙腈和碳酸氢铵为原料，即双气法与碳铵法，分别制备出了海因，并得出了各自的最佳反应条件，其中双气法收率80．3％，碳铵法收率85.8％。双气法制备海因以往未见报道，碳铵法比以往高压制备提高了5个百分点：双气法与碳铵法成本低，收率高，均是工业化生产的好途径。     

分批补料合成纤维素酶扩大试验

研究了里氏木霉以纸浆为碳源分批补料制备纤维素酶。里氏木霉在10L发酵罐中以纸浆为碳源间歇式发酵合成纤维素酶,培养基中碳源浓度为15g/L时,滤纸酶活力、纤维二糖酶活力、酶产率和酶得率分别为2.15FPIU/mL、0.20IU/mL、16.3FPIU/(L·h)和143.3FPIU/g;碳源浓度提高到27.5g/L,采用分批补加碳源的方法,滤纸酶活力、纤维二糖酶活力、酶产率和每克纸浆酶得率分别为3.90FPIU/mL、0.35IU/mL、23.2FPIU/(L·h)和141.8FPIU。研究表明,提高培养基中碳源浓度,采用补料分批发酵技术,产酶时酶活力和酶产率随着培养基中碳源浓度的提高而提高,且保持酶得率不变,达到了降低产酶成本的目的。     

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