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141.
Yasuhiro Takagi Naoko Saeki Akira Tsubouchi Hisashi Murakami Yoshinao Kumagai Takeshi Takeda 《Journal of polymer science. Part A, Polymer chemistry》2002,40(15):2663-2669
The preparation of lustrous conducting polyacetylene films by the polymerization of acetylene with vinyltitanium species as initiators was studied. Organotitanium species were generated by the alkylation of titanium vinylcarbene complexes with tert‐butyl chloride. Solid‐state 13C NMR and IR analyses of the obtained polyacetylene indicated that polyacetylene with a trans configuration was produced. The use of titanocene(II) species Cp2Ti[P(OEt)3]2 and titanium vinylcarbene complexes for the preparation of polyacetylene films was also studied. The morphology of the films and the mechanisms of polymerization are discussed. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2663–2669, 2002 相似文献
142.
Tanaka N Hasan Z Hartog AF van Herk T Wever R Sanders RJ 《Organic & biomolecular chemistry》2003,1(16):2833-2839
Nonspecific acid phosphatases share a conserved active site with mammalian glucose-6-phosphatases (G6Pase). In this work we examined the kinetics of the phosphorylation of glucose and dephosphorylation of glucose-6-phosphate (G6P) catalysed by the acid phosphatases from Shigella flexneri (PhoN-Sf) and Salmonella enterica (PhoN-Se). PhoN-Sf is able to phosphorylate glucose regiospecifically to G6P, glucose-1-phosphate is not formed. The K(m) for glucose using pyrophosphate (PPi) as a phosphate donor is 5.3 mM at pH 6.0. This value is not significantly affected by pH in the pH region 4-6. The K(m) value for G6P by contrast is much lower (0.02 mM). Our experiments show these bacterial acid phosphatases form a good model for G6Pase. We also studied the phosphorylation of inosine to inosine monophosphate (IMP) using PPi as the phosphate donor. PhoN-Sf regiospecifically phosphorylates inosine to inosine-5'-monophosphate whereas PhoN-Se produces both 5'IMP and 3'IMP. The data show that during catalysis an activated phospho-enzyme intermediate is formed that is able to transfer its phosphate group to water, glucose or inosine. A general mechanism is presented of the phosphorylation and dephosphorylation reaction catalysed by the acid phosphatases. Considering the nature of the substrates that are phosphorylated it is likely that this class of enzyme is able to phosphorylate a wide range of hydroxy compounds. 相似文献
143.
Preparation of visible-light-responsive TiO2-xNx photocatalyst by a sol-gel method: analysis of the active center on TiO2 that reacts with NH3 总被引:5,自引:0,他引:5
Kuroda Y Mori T Yagi K Makihata N Kawahara Y Nagao M Kittaka S 《Langmuir : the ACS journal of surfaces and colloids》2005,21(17):8026-8034
Active reaction centers for ammonia on titanium oxyhydroxide were explored to direct the search for an efficient sol-gel method for the synthesis of a titanium oxynitride (TiO2-xNx) sample with an efficient responsiveness to the visible light constituting a main part of the solar spectrum. The results lead to the conclusion that the site giving IR bands at around 2195 cm(-1) for the adsorbed CO molecules at 300 K is a reactive site and behaves as Lewis acid site in the coordination environment of distorted five-coordinate Ti4+ ions. Ammonia molecules are adsorbed on such a site to form -NH2 and -OH species during the heat treatments at a temperature above 373 K, and they are ultimately incorporated into the TiO2 lattice as nitride through the dehydration at higher temperatures of up to 723 K, resulting in the formation of an anatase type of TiO2-xNx. 相似文献
144.
Manabe Eichi Hirano Morio Takano Hiroyuki Ishikawa-Doi Naoko Sode Koji Matsunaga Tadashi 《Applied biochemistry and biotechnology》1992,(1):273-281
Changes in growth and fatty acid content ofSpirulina platensis were examined after transferring cells into media containing various concentrations of ammonium chloride. Photosynthetic
O2 evolution rate decreased with increasing ammonium chloride concentration. Therefore, the algal growth was interrupted by
ammonium chloride addition. On the other hand, total fatty acid content markedly increased after addition of ammonium chloride
to a concentration of 15–50 mM and was maximized 40–48 h after addition of 25 mM ammonium chloride. The increases in palmitic
and oleic acid content were especially remarkable. However, this began to decrease 48 h after the addition of 25 mM of ammonium
chloride. Also, γ-linolenic acid content increased continuously during a 72-h incubation. As a result,Spirulina platensis cells containing about 2% γ-linolenic acid were obtained by ammonium chloride treatment, representing an increase of 1.5–2-fold
compared to untreated cells. 相似文献
145.
Nobuhiro Sato Naoko Miwa Hiroko Suzuki Tohru Sakakibara 《Journal of heterocyclic chemistry》1994,31(5):1229-1233
Deoxydative acetoxylation of 3-methoxy-, 3-phenyl-, 3-methyl-, 3-chloro-, and 3-methoxycar-bonylpyrazine 1-oxides furnished predominantly 2-acetoxy-6-substituted pyrazines, some of which were more selectively prepared by addition of zinc bromide and triethylamine to the reaction. Regioselectivity of the acetoxylation is discussed based upon heat of formation by AMI and AMI-COSMO for all possible isomers of each set. 相似文献
146.
147.
[reaction: see text] An intermolecular aza-double Michael reaction leading to functionalized piperidin-2-ones from simple starting materials has been developed. The method allows alpha,beta-unsaturated amides to be used as a synthon of the piperidine nucleus. In addition, the utility of this methodology is demonstrated by its application to a formal synthesis of the indolo[2,3-a]quinolizidine alkaloids, (+/-)-deplancheine, (+/-)-tacamonine, and the antidepressant paroxetine. 相似文献
148.
Morisaki N Kobayashi H Yamamura Y Morisaki M Nagasawa K Hashimoto Y 《Chemical & pharmaceutical bulletin》2002,50(7):935-940
Steroidal allylic alcohols formed Na+ adduct ion peaks [M+Na]+ by the addition of NaCl in FAB mass spectrometry. A comparison of the intensities of the adduct ion peaks of allylic alcohols with those of the corresponding saturated alcohols and olefin suggested that the olefinic double bond and the proximal hydroxyl group had coordinated to Na+. The adduct ion was stable and did not undergo dehydroxylation. We suggest that the Na+ adduction will be useful for the molecular weight determination of allylic alcohols which are susceptible to dehydroxylation under FAB mass spectrometric conditions. Na+ adduct ions of alpha,beta-unsaturated carbonyl compounds were also investigated. 相似文献
149.
Morisaki N Kobayashi H Nagasawa K Baba Y Sodeoka M Hashimoto Y 《Chemical & pharmaceutical bulletin》2003,51(11):1341-1344
The FAB mass spectrum of the Ca(2+) salt of RK-682 (1, MW 368), a potent protein tyrosine phosphatase inhibitor, shows a complex pattern due to Ca(2+) adduct ions with multimers of 1 and their decomposition ions. Addition of LiCl greatly simplified the FAB mass spectrum, providing a prominent Li(+) adduct ion of 1 at m/z 381 [M+2Li-H](+). The addition of LiCl also greatly simplified the FAB mass spectrum of calcium pantothenate. This approach may be generally useful for molecular weight determination of multivalent metal salts of organic compounds, or organic compounds that can form Li salts, by FAB mass spectrometry. 相似文献
150.