共查询到20条相似文献,搜索用时 15 毫秒
1.
N-phenoxyacetylribonucleosides were prepared efficiently from the reaction of ribonucleosides with phenoxyacetylchloride and 1,2,4-triazole(for adenosine and cytidine) or 1-hydroxybenzotriazole (for guanosine). 相似文献
2.
The use of zinc/silver couple for preparation of the o-quinodimethane from 3, 6-dimethyl-1, 2-bis (bromomethyl) benzene, 1, is described. 相似文献
3.
《Analytical letters》2012,45(7):539-554
Abstract An improved method for the conjugation of Fab' to B-D-galactosidase from Escherichia coli was developed. The enzyme with thiol groups was treated with excess of N, N'-o-phenylene-dimaleimide to introduce maleimide groups, and the maleimide-enzyme was reacted with thiol groups in the hinge of Fab' to form Fab'-B-D-galactosidase conjugate. Gel filtration of Fab' was required only once, and the recovery of Fab' in the conjugate was 71–81%, while in the previous method, gel filtration was required twice and the recovery was 31–38 %. Although the enzyme activity was decreased slightly (8–12%) by the dimaleimide treatment, the conjugate was as useful for sandwich enzyme immunoassay as that obtained by the previous method. 1gG also could be conjugated to B-D-galactosidase more efficiently in the present method than in the previous one. 相似文献
4.
正戊醛合成方法的改进刘瑞蓝,南志祥,郭治安(西北大学化学系西安710069)关键词正戊醛,一步氧化法,共沸蒸馏,精馏醛类化合物的使用相当广泛,尤其在香料工业中越来越受到人们重视,但由于易氧化与易聚合,在加热条件下合成难度大,产率低,我们在过去研究工作... 相似文献
5.
6.
4,5-Diaminochrysazin was prepared from chrysazin by ethylation and nitration followed by reaction with hydroiodic acid (HI). Treatment of 1,8-diethoxy-4,5-dinitroanthraquinone with HI resulted not only in O-deethylation, but also in reduction of nitro groups with more than 95% yield. This is a unique finding and is reported for the first time with a definite improvement over literature methods and is suitable for scale-up. 相似文献
7.
8.
Time series data can provide valuable insight into the complexity of biological reactions. Such information can be obtained by mass-spectrometry-based approaches that measure pre-steady-state kinetics. These methods are based on a mixing device that rapidly mixes the reactants prior to the on-line mass measurement of the transient intermediate steps. Here, we describe an improved continuous-flow mixing apparatus for real-time electrospray mass spectrometry measurements. Our setup was designed to minimize metal–solution interfaces and provide a sheath flow of nitrogen gas for generating stable and continuous spray that consequently enhances the signal-to-noise ratio. Moreover, the device was planned to enable easy mounting onto a mass spectrometer replacing the commercial electrospray ionization source. We demonstrate the performance of our apparatus by monitoring the unfolding reaction of cytochrome C, yielding improved signal-to-noise ratio and reduced experimental repeat errors. 相似文献
9.
对烷氧基苯甲醛合成方法的改进 总被引:3,自引:0,他引:3
对烷氧基苯甲醛合成方法的改进董恒山杨世琰*殷元骐(中国科学院兰州化学物理研究所兰州730000)关键词对烷氧基苯甲醛,Wiliamson醚合成,Cannizzaro反应1996-04-18收稿,1996-08-09修回对烷氧基苯甲醛是合成液晶材料和有... 相似文献
10.
酞菁氧钛的合成及晶型转化 总被引:4,自引:0,他引:4
酞菁氧钛以联环己烷为溶剂,以邻苯二脂及四氯化钛直接反应生成。其优点是便于分离及纯化。同时对各晶型的获得及晶型间的相互转化进行了研究,并以X-射线粉末衍射及FT-IR进行了表征,并记录了不同晶型的酞菁氧钛在室温硫化硅橡胶中的吸收光谱。 相似文献
11.
12.
An improved method for the preparation of β-substituted cyclohexenones is reported. Conditions were defined to effectuate the key desulfonylation-deketalization step in a mild manner. Several cyclohexenones bearing acid and/or base sensitive β-substituents were prepared by the modified method in moderate to good yields. 相似文献
13.
A straightforward way for the preparation of the energetic 5‐aminotetrazolium and 1, 5‐diaminotetrazolium salts is reported. The energetic salts were readily synthesized by the reaction of 5‐aminotetrazolium nitrate or 1, 5‐diaminotetrazolium nitrate with ammonium 5‐nitroiminotetrazolate, ammonium 1‐methyl‐5‐nitroiminotetrazolate, bis(ammonium) ethylene bis(5‐nitroiminotetrazolate), and diammonium iminobis(5‐tetrazolate), respectively, in water under mild conditions. All products were recovered as highly crystalline materials in excellent yields and purities, and were fully characterized by IR spectroscopy, 1H and 13C NMR spectroscopy, DSC measurements as well as elemental analyses. 相似文献
14.
16.
《Analytical letters》2012,45(3):209-218
Abstract A sensitive and specific fluorimetric assay for 6-mercaptopurine (6-MP) is described. The method consists of enzymatic (xanthine oxidase) conversion of 6- MP to the oxypurine derivatives, followed by oxidation with acidic chromate to the corresponding 6-sulfonate. The fluorescent product has excitation and emission maxima at 330 and 400 nm, respectively. The good recovery and reproducibility were obtained. The sensitivity (the smallest amount detectables) was about 22 pg/ml for 6- MP in water. Different spiked serum samples containing 6-MP and azathioprine (AZA) were also analyzed and the sensitivity for 6-MP was about 2.2 ng/ml. 相似文献
17.
建立了一种基于增压电渗泵驱动、整体柱分离和紫外检测相结合的电动流动分析系统。研究了载流溶液中甲醇的体积分数对电渗泵空载流量、输出压强、移动相流量和分离度的影响。在4950V的外加电压下,以含0.5mmol/L六亚甲基四胺的45%甲醇溶液为泵载流,电渗泵的流量和输出压强分别为0.58mL/min和0.79MPa,以泵载流为流动相,该系统对苯和萘进行了反相色谱分离。电动流动分析系统设备简单、操作方便、功能多样。对苯和萘的分离结果表明,电动流动分析系统可用于样品的色谱分离。 相似文献
18.
19.
IntroductionThe human immunodeficiency virus(HIV)is thecausative agent of acquired immunodeficiency syndrome(AIDS).Since HIV protease is essential for the repli-cation and maturation of HIV,the inactivation of HIVprotease by either mutation or chemical in… 相似文献
20.
N-methylimidazole (NMI) is used as the base in the triflic anhydride (Tf2O)–mediated formation of oxadiazoles from diacyl hydrazines. This reagent is superior to pyridine-derived bases in terms of cost and reaction profile. 相似文献