142 resultados para 346.0922


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对乙酰氨基苯乙醚、氨基比林、乙酰氨基苯酚、氨基苯酚等4种有机物在玻碳电极上的伏安行为进行了研究.在0.1mol/L氢氧化钠溶液中得4个灵敏度和分辨率良好的阳极氧化峰,E_p分别为0.68,0.51,0.22,-0.06 V(vs.AgCl/Ag)左右,样品不需分离直接测定.20多种有机生化物质不干扰,方法简便快速.并对电极反应进行了探讨.

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吡喃酮类化合物是抗爱滋病的一类新药, 本文用CoMFA(Comparative Molecular Field Analysis)方法对19个吡喃酮类化合物的三维构效关系进行了研究, 较详细地探讨了分子的重叠方式, 并选用了其他有关的一些最优条件, 得到满意的结果。

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研究了在多官能团单体异氰尿酸三烯丙酯(TAIC)存在下,辐射对PP/BR共混体系的影响,并用SEM,DSC和动态力学性能等技术对其进行了表征。结果显示,辐射引发TAIC参与的界面反应改变了PP/BR的形态结构,增强了两相的界面粘接,改善了相容性,提高了力学性能。

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采用气相色谱/质谱(GC/MS)联用技术对山东泰山产单叶蔓荆子挥发油的化学成分进行了分析,分离出30多个峰,确认了其中28种成分,占总离子流的95%以上,并对挥发油的主要化学成分Δ3-蒈烯,用气相色谱/傅里叶红外光谱(GC/FTIR)法进行了验证。

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ESR和自旅捕捉技术用于研究活体动物犬心肌缺血再灌产生的自由基,PBN从冠状静脉血液中捕捉到了OH自由基,直接地证实了缺血再灌细胞膜损伤的活性氧自由基作用机制;实验还看到一种甾体皂甙药物具有保护心肌细胞.防止自由基损伤的功能.

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新型导电高分子材料的导电性与其结构的关系梁洪泽,宋永贤,丁黎明,綦玉臣,李丽霞,景遐斌,王佛松(中国科学院长春应用化学研究所,长春,130022)自Wright首次报道了聚环氧乙烷(PEO)-碱金属盐(MX)配合物的离子导电性以来,有关各种聚合物固体...

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从测得的竞聚率计算了单体链节在聚[苯乙烯-甲基丙烯酸β(甲基亚硫酰基)乙酯](PSM)中的序列分布。苯乙烯(S)或甲基丙烯酸β(甲基亚硫酰基)乙酯(M)的长序列的概率随着PSM中相应单体含量的增加而增加。对于S和M摩尔分数大致相等的PSM,单体链节的长序列分布函数值相接近。用与此结构相近的PSM合成的稀土金属络合物,其催化活性不佳。在M短序列分布和S长序列分布较高的情况下,络合物的催化活性最好。所得聚丁二烯的微观结构与PSM中单体单元的分布无关。

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Non-steady-state chronoamperometry of ultramicroelectrodes is a powerful method for the study of mass transport in polymer films. This method has many advantages over the conventional methods at a macroelectrode and the steady state method at an ultramicroelectrode, which yield the most information. The apparent diffusion coefficient, D(app), and the concentration of reactant in the film, c(f), can be determined from a single experiment without knowing the thickness of the film. We studied the transport of several species such as Ru(NH3)63+, Ru(bpy)3(2+), NR and MV2+ in Eastman-AQ polymer film coated ultramicroelectrodes by using this method.

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介绍了p-n结电容测量方法。通过测量C-V特性研究了Cds太阳电池的热处理及上栅过程,分析并讨论了p-n结的变化与电池不稳定的关系。初步研究了扩散电位的测定问题。

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用X射线光电子能谱(XPS)和二次离子质谱仪(SIMS)等表面分析方法对稀土-6063铝合金进行了研究,发现稀土铝合金的表面为金属铝和铝的氧化物两种形态。稀土及镁两者的协同作用,可以缓和铝合金的氧化程度。SIMS结果表明,加入适量稀土,可以抑制镁在稀土-6063铝合金的表面偏析作用。

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用ESR方法研究了CoO-MgO固溶体作为多相氧载体的可逆吸氧性质。发现CoO-MgO表面的Co~(2+)可以以两种方式与分子氧可逆结合,一种形成Co~(2+)-O_2,它给出了与MgO晶格中Co~(2+)相似的各向同性的信号(g=4.2);一种形成Co~(2+)-O_2~-,它给出轴对称的信号(g_‖=2.141,A_‖=30G,g_⊥_=1.980,A_⊥=15G)。我们认为Co~(2+)-O_2是表面Co_(5c)~(2+)与O_2结合产生的,而Co~(3+)-O_2~-是由表面Co_(4c)~(2+)或Co_(3c)~(2+)与O_2结合形成的。

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Sulfide: quinone oxidoreductase (SQR) is a flavoprotein with homologues in all domains of life except plants. It plays a physiological role both in sulfide detoxification and in energy transduction. We isolated the protein from native membranes of the hyperthermophilic bacterium Aquifex aeolicus, and we determined its X-ray structure in the "as-purified,'' substrate-bound, and inhibitor-bound forms at resolutions of 2.3, 2.0, and 2.9 angstrom, respectively. The structure is composed of 2 Rossmann domains and 1 attachment domain, with an overall monomeric architecture typical of disulfide oxidoreductase flavoproteins. A. aeolicus SQR is a surprisingly trimeric, periplasmic integral monotopic membrane protein that inserts about 12 angstrom into the lipidic bilayer through an amphipathic helix-turn-helix tripodal motif. The quinone is located in a channel that extends from the si side of the FAD to the membrane. The quinone ring is sandwiched between the conserved amino acids Phe-385 and Ile-346, and it is possibly protonated upon reduction via Glu-318 and/or neighboring water molecules. Sulfide polymerization occurs on the re side of FAD, where the invariant Cys-156 and Cys-347 appear to be covalently bound to polysulfur fragments. The structure suggests that FAD is covalently linked to the polypeptide in an unusual way, via a disulfide bridge between the 8-methyl group and Cys-124. The applicability of this disulfide bridge for transferring electrons from sulfide to FAD, 2 mechanisms for sulfide polymerization and channeling of the substrate, S2-, and of the product, S-n, in and out of the active site are discussed.

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Arthrospira (Spirulina) (Setchell& Gardner) is an important cyanobacterium not only in its nutritional potential but in its special biological characteristics. An unbiased fosmid library of Arthrospira maxima FACHB438 that contains 4300 clones was constructed. The size distribution of insert fragments is from 15.5 to 48.9 kb and the average size is 37.6 kb. The recombination frequency is 100%. Therefore the library is 29.9 equivalents to the Arthrospira genome size of 5.4 Mb. A total of 719 sample clones were randomly chosen from the library and 602 available sequences, which consisted of 307,547 bases, covering 5.70% of the whole genome. The codon usage of A. maxima was not strongly biased. GC content at the first position of codons (46.9%) was higher than the second (39.8%) and the third (45.5%) positions. GC content of the genome was 43.6%. Of these sequences, 287 (47.7%) showed high similarities to known genes, 63 (10.5%) to hypothetical genes and the remaining 252 (41.8%) had no significant similarities. The assigned genes were classified into 22 categories with respect to different biological roles. Remarkably, the high presence of 25 sequences (4.2%) encoding reverse transcriptase indicates the RT gene may have multiple copies in the A. maxima genome and might play an important role in the evolutionary history and metabolic regulation. In addition, the sequences encoding the ATP-binding cassette transport system and the two-component signal transduction system were the second and third most frequent genes, respectively. These genomic features provide some clues as to the mechanisms by which this organism adapts to the high concentration of bicarbonate and to the high pH environment.