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951.
铜锌超氧化物歧化酶(Cu2Zn2SOD)在汞电极上的吸附研究 总被引:8,自引:0,他引:8
金属氧化还原蛋白质的电化学行为作为生物电化学领域中一个重要的研究内容,受到了广泛的关注犤1~3犦,生物体系一些重要的反应均与基本电荷运动有关,如生物催化、神经传导、光合作用以及呼吸作用等均涉及到一些重要氧化还原蛋白质的氧化还原过程。利用电化学的基本原理和实验方法,不但能在生命体系和有机组织的整体水平上,更主要是能在分子和细胞水平上研究氧化还原蛋白质体系中的电子转移以及氧化态转化的化学本质和规律。铜锌超氧化物歧化酶(Cu2Zn2SOD)是一个二聚体,由两个等同的亚单位组成,每一个亚单位含有咪唑桥联的铜?和锌?离子,催… 相似文献
952.
Charge-discharge Behavior of Surface-coated LiMn2O3.95F0.05 Cathode Materials at High Temperature 总被引:1,自引:0,他引:1
ZhaoYongCHEN YanRongLI ZuoLongYU 《中国化学快报》2003,14(12):1296-1298
With inorganic salts such as LiNO3, Li2CO3, surface-coated LiMn2O3.95F0.05 were prepared by melt-impregnation method. When these surface-coated LiMn2O3.95F0.05 were used as cathode materials, their charge-discharge characters were carefully compared. As a result, they exhibited good charge-discharge properties at 50℃ high temperature. Especially, LiNO3 surface-coated LiMn2O3.9F50.05 retained nearly 80% initial reversible capacity after 130 cycles at 50℃. 相似文献
953.
人参挥发油的提取和分析 总被引:7,自引:0,他引:7
应用GC-MS-DS联机分析人参挥发油是当前较好的方法,但人参挥发油的提取方法和GC-MS条件的选择明显影响人参挥发油这一复杂天然混合物的分离和鉴定。本工作严格控制提取条件,提高了挥发油收率,达0.95%;选择最佳GC-MS条件,鉴定出76种化合物,该法稳定重现性好。 相似文献
954.
955.
956.
(S)-和(R)-普萘洛尔的不对称合成 总被引:3,自引:0,他引:3
普萘洛尔是一种临床上广泛使用的β受体阻断剂, 介绍了一种不对称合成(S)-和(R)-普萘洛尔的方法. 以手性Salen-CoIII催化剂水解动力学拆分外消旋环氧氯丙烷得到高光学纯度的(S)-环氧氯丙烷和(R)-3-氯-1,2-丙二醇, 以(S)-环氧氯丙烷为手性原料先水解得(S)-3-氯-1,2-丙二醇, 其与1-萘酚反应得(S)-3-(1-萘基)-丙烷-1,2-二醇, 再与氯化亚砜反应得环状亚硫酸酯, 最后和异丙胺作用得(S)-普萘洛尔, 总收率80.9%, 光学纯度大于99%; 而同样以(S)-环氧氯丙烷为手性原料直接与1-萘酚反应得(2R)-3-(1-萘氧基)-1,2-环氧丙烷, 再与异丙胺作用得(R)-普萘洛尔, 总收率74.5%, 光学纯度大于99%. 相似文献
957.
958.
WANG Yan ZENG Xiao-Lan SHEN Sai-Jun 《结构化学》2007,26(7):767-772
The mechanism, catalytic effect and solvent effect of the hetero-Diels-Alder reac- tions between 3-pyridinedithioesters and 1-phenylsulfanylbutadiene have been studied theoretically using density functional theory (DFT) at the B3LYP/6-31G(d) level. The results show that all of these reactions proceed in a concerted but asynchronous way. In some reactions the formation of C-S bond is prior to that of C-C bond and the opposite results are found in other reactions. The BF3 catalyst may lower the activation barriers by changing the energies of LUMO for 3-pyridine- dithioester. THF solvent has trivial influence on the potential energy surface of these reactions. With the BF3-catalyzed reactions, regioselectivity and stereoselectivity observed experimentally were predicted correctly by calculations and these results originate probably from C-H···F interaction in two transition states. 相似文献
959.
Nanosized aluminum nitride hollow spheres were synthesized by simply heating aluminum nanoparticles in ammonia at 1000 °C. The as-synthesized sphere shells are polycrystalline with cavity diameters ranging from 15 to 100 nm and shell thickness from 5 to 15 nm. The formation mechanism can be explained by the nanoscale Kirkendall effect, which results from the difference in diffusion rates between aluminum and nitrogen. The Al nanoparticles served as both reactant and templates for the hollow sphere formation. The effects of precursor particle size and temperature were also investigated in terms of product morphology. Room temperature cathode luminescence spectrum of the nanosized hollow spheres showed a broad emission band centered at 415 nm, which is originated from oxygen related luminescence centers. The hollow structure survived a 4-h heat treatment at 1200 °C, exhibiting excellent thermal stability. 相似文献
960.
Interference-free determination of Sudan dyes in chilli foods using second-order calibration algorithms coupled with HPLC-DAD 总被引:1,自引:0,他引:1
This paper presents a new method for the determination of Sudan dyes contained in hot chilli samples. The method employs second-order calibration algorithms to handle the recorded data. The second-order calibration algorithms are based on the popular parallel factor analysis (PARAFAC), alternating trilinear decomposition (ATLD) and self-weighted alternating trilinear decomposition (SWATLD), respectively. These chemometric methodologies have the second-order advantage, which is the ability to get accurate concentration estimates of interested analytes even in the presence of uncalibrated interfering components. The results on a set of spiked chilli test shows that low contents of Sudan I and Sudan II in complex chilli mixtures can be accurately determined using the new method. The sample preparation was based on solvent extraction, and internal standard was not required. Quantification was carried out with simple mobile phase. 相似文献