反相高效液相色谱法分离测定3,4,6,7,9,10-6H-3,3,6,6-四甲基-9-对氟苯基-10-N-对甲基苯基吖啶-1,8-二酮

通过比较各种分析柱的分离效果 ,建立了用 Nucleosil C18柱为固定相 ,2 5 4 nm紫外检测 ,分析 3,4 ,6 ,7,9,10 - 6 H- 3,3,6 ,6 -四甲基 - 9-对氟苯基 - 10 - N-对甲基苯基吖啶 - 1,8-二酮的液相色谱方法 ,并对流动相的组成比例和p H值进行了优化 ,确定用甲醇∶ 0 .0 0 1mol/L磷酸 (75∶ 2 5 v/v p H=3.2 0 )作流动相为最佳条件 .该方法的最低检测量为 4 .99ng,方法的重复性测定其相对标准偏差低于 4 .2 % ,分析时间为 2 0 mi     

The biogenesis and function of eukaryotic porins

Summary Like most other mitochondrial proteins porin is synthesized in the cytosol and imported posttranslationally into the outer mitochondrial membrane. This transport follows the general rules for mitochondrial, protein import with a few aberrations: a) porin contains an,uncleaved NH₂-terminal signal sequence, b) also its carboxyterminus might be involved in the import process, and c) this transport does not seem to require a membrane potential , although it is ATP-dependent. Most likely the actual import step occurs at contact sites between the outer and the inner mitochondrial membrane and involved at least one receptor protein.Although porin is known to be the major gate through the outer mitochondrial membrane, its absence only causes transient respiratory problems in yeast cells. This could mean a) that there is a bypass for some mitochondrial functions in the cytosol and/or b) that there are alternative channel proteins in the outer membrane. The first idea is supported by the overexpression of cytosolic virus-like particles in yeast cells lacking porin and the second by the occurrence of residual pore activity in mitochondrial outer membrane purified from porinless mutant cells.     

Formation of 4,4′-methylene-bis(2-chloroaniline)-DNA adducts in yeast expressing recombinant cytochrome P450s

N-Oxidation of 4,4-methylene-bis(2-chloroaniline) (MBOCA) may lead to formation of DNA adducts. To determine if cytochrome P450s are involved in the formation of MBOCA derived-DNA adducts, yeast strains expressing rodent P450s were exposed to MBOCA, and³²P-postlabelling of nucleotides from yeast genomic DNA was done. Chromatographic analysis on PEI cellulose showed that, upon exposure to MBOCA for 1 h, nine DNA adducts were formed in yeast expressing phenobarbital-inducible rabbit P450 2B5. With a 4-h-exposure, all adducts increased in parallel. In cell-free experiments, the incubation of MBOCA with phenobarbital-induced rat microsomal fraction followed by incubation with thymus DNA, led to the formation of more than ten DNA adducts. When yeast expressing 3-methylcholanthrene-inducible rat P450 1A1 was exposed to MBOCA, one major and two minor adducts were formed. No adducts were detected in control yeast. These results show that recombinant rabbit P450 2B5 exhibits a potential activation of MBOCA and that rat P450 1A1 has some effect. The use of yeast expressing recombinant P450s and the technique of³²P-postlabelling facilitates a simple search for chemicals with carcinogenic potential.     

La2Mo2O9氧离子导体的合成及XPS研究

采用溶胶-凝胶法制备了La2Mo2O9氧离子导体,并利用XRD、X射线光电子能谱对其制备条件和氧物种进行了分析.研究表明,凝胶前驱体在600℃焙烧可以形成La2Mo2O9晶相.提高焙烧温度,有利于晶粒生长和致密化.XPS分析表明,La2Mo2O9中金属离子均处于其最高价态,只有晶格氧物种存在,没有吸附态的氧物种.高温相中各元素的结合能均较低温相高,可能归结于高温相立方结构中金属和氧的键合程度高于其在低温相的键合程度.     

Oracle9i数据库的性能优化方法

介绍数据库性能优化的基本原则,并从设计阶段和运行阶段论述了O racle9 i数据库性能优化的方法,结合实例,给出O racle9 i数据库对系统全局区、磁盘输入输出和SQL语句的优化过程。O racle9 i数据库优化前后的效果比较表明,优化后的查询效率和CPU占用率明显改善,SQL语句执行时间减少。     

甘草废渣中抗菌抗氧化剂的提取及其化学组成

进行了用有机溶剂从甘草废渣中提取抗菌抗氧化剂的研究．考察了两种有机溶剂对抗菌抗氧剂提取率的影响，提取得到的抗菌抗氧化剂的有效成分主要为黄酮类化合物．并首次从甘草废渣提取物中鉴定出了具有生理活性的亚麻酸乙酯．     

盐生盐杆菌S9营养条件及紫膜分离的初步研究

目的　为获得紫膜,研究了盐生盐杆菌(Halobacteriumhalobium)S9的最适营养条件和紫膜的分离。方法通过该菌的培养特征、不同培养基、细胞色素的测定等,利用正交试验法对NaCl、酪蛋白氨基酸、MgSO4·7H2O和甘油这4个重要因素进行了优化。结果　最适营养和浓度分别是:NaCl200g/L,酪蛋白氨基酸10g/L,MgSO4·7H2O25g/L,甘油10g/L。该菌株在光照条件下,38℃摇瓶培养6d,可用高速冷冻离心、透析袋、蔗糖密度梯度纯化、超速离心等得到紫膜。结论优化了盐生盐杆菌S9的最适营养条件,并确定了所获紫膜的基本性质,可指导用于分子电子器件,今后将继续对其作定量研究。     

1Cr18Ni9Ti热喷涂层在含硫油品中的耐蚀性研究

针对含硫油对石油炼制设备腐蚀严重的实际 ,研究了热喷涂 1 Cr1 8Ni9Ti层对设备进行腐蚀防护 .测定了涂层的孔隙率以及不同温度、不同硫浓度下 1 Cr1 8Ni9Ti涂层的腐蚀速率 .用化学反应动力学理论模型模拟了此腐蚀过程 ,求出了反应过程的反应活化能、反应速率常数和反应速率方程 ;并用三电极电化学研究系统测试了 1 Cr1 8Ni9Ti涂层在含硫油中的极化曲线 ,认为 1 Cr1 8Ni9Ti涂层在含硫油中的腐蚀为电化学腐蚀控制过程 .     

紫外线吸收剂UV－9生产工艺的改进

用混和酸作催化剂,三氯甲基苯和间苯二酚在水相中缩合成中间体2,4-二羟基二苯基甲酮.然后在相转移催化剂的作用下,用硫酸二甲酯醚化为目的产物UV-9.     

新型液晶材料主链聚缩醛螺胞二醚的合成

在催化剂的作用下利用苯甲醛与季戊四醇,合成了聚缩醛螺胞二醚的模型化合物3,9 二苯基 2,4,8,10 四氧杂螺[5·5] 十一烷,并在此基础上利用1,4 苯二甲醛与季戊四醇在催化剂的作用下成功地合成了标题化合物.考察了催化剂、反应物的摩尔比、带水剂、反应温度等对反应的影响,利用FTIR、HNMR对模型化合物及标题化合物的结构进行了表征,标题产品的最高收率可达8500以上.