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1.
地衣芽孢杆菌α-乙酰乳酸脱羧酶的纯化及酶学性质   总被引:3,自引:0,他引:3  
地衣芽孢杆菌(Bacillus licheni formis)AS10106α-乙酰乳酸脱酸酶经硫酸沉淀,聚乙二醇沉淀,DEAE-Sepharose Fast Flow离子交换,Gigapite K-100S柱层及SephadexG-100分子凝胶过滤柱等分离纯化步骤,得到SDS-PAGE电泳纯,α-乙酰乳酸脱羧酶的比活提高了53.5倍。对该酶性质的研究表明,酶单亚基分子量为32Kda,等电点为4.5;该酶的最适反应温度为40℃,最适反应pH为6.0,对热(40℃以上)敏感。在pH5.0-6.5之间稳定。酶活不需要金属阳离子,Cu^2 、Co^2 强烈抑制酶的活性。摇瓶实验表明,纯化的地衣芽孢杆菌α-乙酰乳酸脱羧酶能明显降低双乙酰的形成并缩短其还原时间。  相似文献   

2.
报导了添加剂CaCl3在天青石还原焙烧中的反应行为;并从试验中寻找出了使用该添加剂的最佳反应条件。实验结果表明:CaCl2用量为0.5%-1%,反应温度为1150-1200℃,反应时间为30min,矿:煤为1:0.6,矿、煤粒度为20-40目时,可使SrCO3生产的转化率最高。  相似文献   

3.
TiSiW12O40/TiO2催化合成丙酸正丁酯   总被引:6,自引:2,他引:4  
首次以固载杂多酸盐TiSiW12O40/TiO2为多相催化剂,通过丙酸和正丁醇反应合成了丙酸正丁酯,并探讨了诸因素对酯化率的影响,实验表明,TiSiW12O40/TiO2具有良好的催化活性,醇酸物质的量比为1.3:1,催化剂用量为反应物料总量的1.5%,反应时间1.0h,反应温度116-128度,酯化率可达71%。  相似文献   

4.
TiSiW12O40/TiO2催化合成氯乙酸正丁酯   总被引:3,自引:0,他引:3  
首次以固载杂多酸盐TiSiW12O40/TiO2为多相催化剂,通过氯乙酸和正丁酸反应合成了氯乙酸正丁酯,并探讨了诸因素对产率的影响。实验表明:TiSiW12O40/TiO2具有良好的催化活性,醇酸物质的量比为1.4:1,催化剂用量为反应物料总量的2.0%,反应时间0.5h,反应温度130-139℃,产率可达66.51%。  相似文献   

5.
pH为4.4~7.6,温度为40℃,离子强度为0.1mol·dm-3(NaClO4)条件下,研究了[Cr(NTA)(H2O)(H2O)/(OH)-]与染料3-苯基偶氮-5-磺基水杨酸(PASSA)的混配络合物的生成反应动力学.拟1级速率常数为kobs,反应符合Eigen机理.因速率常数(k1,k2)大于水交换速率(kex),故此反应可归属于交换缔合机理。  相似文献   

6.
在ESR-GC-Computer联机的动态装置下,用固定床微型石英催化反应器,研究不同硅含量SAPO-5(22),SAPO-5(19),SAPO-5(5)及AlPO4-5和HY分子筛对异丙苯裂化反应的催化活性、ESR幅值特征.并测定催化剂的积炭量.结果表明,催化剂的催化活性、ESR幅值及积炭量大小之排序一致,均为HY》SAPO-5(22)>SAPO-5(19)>SAPO-5(5)》AlPO4-5.在SAPO-5和AlPO4-5催化剂上,异丙苯反应前后吸附吡啶的IR谱证实,异丙苯在SAPO-5催化剂上的裂化反应是在B酸中心进行的.  相似文献   

7.
用考察考察了氧化亚锡、钛酸四丁酯和六水合三氯化铁等3种非质子酸催化剂在石油酸酯化反应中的催化性能。结果表明,在180-230℃下,石油酸与一元醇的摩尔比为0.5,氧化亚锡或钛酸四丁酯用量占石油酸用量的1%-2%,反应3-4h4后都可使石油酸的酯化反应率达99%。在石油酸与二元醇的摩尔比为2.2时,氧化亚锡用量占石油酸用量的2%,反应4h可使二元醇烃基的酯化率达99%。氧化亚锡可重复使用,且酸液的后处理工艺简单。在120-140℃下,石油酸与一元醇的摩尔比为0.33-0.40,六水合三氯化铁的用量占石油酸用量的21%,反应4h可使石油酸的酯化率达到98%。  相似文献   

8.
N-苯基-2,2,6,6-四氯环己亚胺的催化合成   总被引:1,自引:0,他引:1  
以2,2,6,6-四氯环己酮为原料,在催化剂存在下,合成了N-苯基-2,2,6,6-四氯环己亚胺,通过对催化剂、溶剂用量、反应时间、反应温度等因素的考察,得到了适宜的工艺条件;在n(酮):n (苯胺):n(催化剂)=1:5:1.5(摩尔比),反应温度为10-20℃,反应时间为3.5h手枪扌,收率为80%。  相似文献   

9.
以硅胶为载体,制备了负载型的Cs2.5H0.5PWl2O40催化剂,将该催化剂用于乙酸与1—丁烯的酯化反应和叔戊烯与甲酵的醚化反应,考察了其活性组分负载量、载体硅胶性质和焙烧温度对催化剂性能的影响.研究了催化剂用量、反应温度、反应压力、n(1—丁烯)/n(乙酸)、反应时间等反应条件对酯化反应中乙酸转化率的影响.与其他类型催化剂的醚化活性进行了对比,并进行了Cs2.5H0.5PWl2O40/SiO2催化剂的醚化稳定性实验.结果表明,以低钠硅胶为载体,在活性组分负载量为40%,焙烧温度为300—400℃时制备的Cs2.5H0.5PWl2O40/SiO2催化剂具有较高的催化活性.随着负载量增大,催化剂孔径、孔容和比表面积减小,而催化活性先增加后减小.在反应温度120℃、压力1.5MPa、n(1—丁烯)/n(乙酸)比3.0、催化剂用量4%、反应时间7h的条件下进行酯化反应,乙酸的转化率为87.36%.在反应温度80℃、压力1.0MPa、n(甲酵)/n(叔戊烯)比1.1、LHSV为1h^-1的条件下进行醚化反应,叔戊烯的转化率为68.57%.制备的新型Cs2.5H0.5PWl2O40/SiO2催化剂对于乙酸与1—丁烯的直接酯化反应和叔戊烯与甲酵的醚化反应具有良好的活性与选择性,催化剂寿命长.因此,Cs2.5H0.5PWl2O40/SiO2是一种理想的乙酸与烯烃直接酯化和叔戊烯与甲酵醚化反应的催化剂.  相似文献   

10.
用短路混合模型确定沥青汽化炉的工艺条件   总被引:1,自引:0,他引:1  
采用短路混合模型,预测了沥青汽化炉工艺条件变化对反应结果的影响,模拟结果表明,最佳氧沥青比约在0.78-0.80之间,相应的每公斤沥青有效气(CO+H2)产率约为2.5m3(标准状态),而蒸气沥青比则以0.40左右为宜。  相似文献   

11.
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.  相似文献   

12.
何延凌 《科技信息》2008,(4):258-258
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.  相似文献   

13.
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。  相似文献   

14.
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.  相似文献   

15.
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-  相似文献   

16.
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-  相似文献   

17.
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  相似文献   

18.
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  相似文献   

19.
<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with  相似文献   

20.
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