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81.
Although methanolysis of [α-(trimethylsilyl)benzyl]ferrocene (I) and [p-methyl-α-(trimethylsilyl)benzyl]ferrocene (II) in the presence of anhydrous ferric chloride merely gave α-ferrocenylbenzyl methyl ether (III) and p-methyl-α-ferrocenylbenzyl methyl ether (IV), respectively, acid-catalyzed methanolysis of (I) and (II) in the presence of an equimolar amount of (III) or (IV) afforded 1,2-diferrocenyl-l,2-diarylethanes. It is suggested that one electron oxidation of [α-(trimethylsilyl)benzyl]ferrocene by α-ferrocenylbenzyl cation generated from α-ferrocenylbenzyl methyl ether, and subsequent methanolysis of the resulting substituted ferricenium ion may occur to give the two species of α-ferrocenylbenzyl radical, which in turn undergo an approximately statistical coupling. 相似文献
82.
K. Kondo H. Kawabata S. Ueda H. Hasegawa J. Inaba O. Mitamura Y. Seike Y. Ohmomo 《Journal of Radioanalytical and Nuclear Chemistry》2003,257(2):305-312
We investigated the distribution of aquatic plants and the absorption of radionuclides by them in the brackish Lake Obuchi, Japan, which is bordered by nuclear fuel cycle facilities. We studied 5 species of submerged plants: Zannichellia palustris, Ruppia maritima, Potamogeton pectinatus, Zostera japonica, and Z. marina. The plants contained many elements, including radionuclides. The concentrations of 238U, 137Cs, and 90Sr in Z. marina were 11.3-12.4, 0.000-0.144, and 0.151-0.202 Bq.kg-1 dw, respectively. Those in Z. japonica were 5.2-8.8, 0.000-0.267, and 0.081-0.175 Bq.kg-1 dw, respectively. The concentrations of these radionuclides in the plants tended to be higher in higher-salinity regions than in lower-salinity regions of the lake. We found a close relationship between photosynthetic activity and the absorption of stable Sr by plants in the laboratory. Salinity, illumination, and water temperature influenced the photosynthetic activity of the plants and the consequent absorption of elements. 相似文献
83.
Kondo M Miyazawa M Irie Y Shinagawa R Horiba T Nakamura A Naito T Maeda K Utsuno S Uchida F 《Chemical communications (Cambridge, England)》2002,(18):2156-2157
A coordination polymer [Zn(pyta)(OH)] (pyta = 4-pyridylthioacetate), was synthesized and structurally characterized; it is constructed by an alternating assembly of two types of homo-chiral helices, [Zn-OH] and [Zn-pyta], in which the sulfide moieties are fastened in the latter columns. 相似文献
84.
Abstract— The kinetics of enzymatic photoreactivation (PR) of u.v.-induced killing was compared among E. coli Bs-1, phage T1 in Bs-1 and phage T1 in irradiated Bs-1. The PR action spectrum showed no substantial difference between PR of Bs-1 and PR of T1 in Bs-1. The PR D37 (i.e. the PR dose required to reactivate all but 37 per cent of the reactivable lethal lesions) was found to decrease linearly with decreasing U.V. dose whether U.V. was given to produce pyrimidine dimers in Bs-1 DNA, which then compete with irradiated T1 DNA for PR enzyme, or to Bs-1 or T1 DNA to produce dimers serving as substrate for the PR enzyme. A generalized Michaelis-Menten formula was used to analyze the data and the following conclusions were drawn. (1) The number of PR enzyme molecules per cell available for PR of T1 DNA inside the Bs-1 host is only a quarter of the number available for PR of the Bs-1 host itself. (2) The Michaelis constant Km for reaction of host-DNA-damage and PR-enzyme becomes larger when the host damage acts as competitive inhibitor to PR of T1 DNA than when it is the substrate for PR enzyme. (3) PR enzyme retains almost all its initial catalytic efficiency even after about two-hundred rounds of catalytic functioning. Conclusions (1) and (2) suggest that PR enzyme is concentrated within the nuclear area surrounding the host DNA. 相似文献
85.
Keiichi Noguchi Hidekazu Kondo Yasushi Ichikawa Junichiro Washiyama Kenji Okuyama 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(8):o528-o530
The 20‐membered ring of the title compound, C16H24O8, adopts an approximately flat rectangular structure with three‐ and seven‐bond sides and lies across a crystallographic center of inversion. The corners of the ring occur at both ends of one of the planar ester segments. All of the carbonyl O atoms are involved in intermolecular C—H⋯O hydrogen bonds. 相似文献
86.
Copolyamides and copolyesters containing the phenoxasilin ring were prepared from 2,8-dichloroformyl-10,10-diphenylphenoxasilin, isophthaloyl chloride and m-phenylenediamine or bisphenol A by interfacial polycondensation in chloroform-aqueous alkali mixture. They were obtained in yields of 80% or above and at relatively high viscosities up to 1.30 dl/g. The copolymers with high phenoxasilin content were freely soluble in dimethylacetamide, dimethylformamide and N-methyl-2-pyrrolidone, but decreasing phenoxasilin content led to copolymers with slight solubilities in these solvents; the copolyesters also dissolved in chloroform, m-cresol and phenol-sym tetrachloroethane (60:40 in wt%). Flexible transparent films were obtained from chloroform solutions of the copolyesters, but the films cast from DMF solutions of the copolyamides became brittle as the phenoxasilin content decreased. The phenoxasilin-containing copolymers hardly degraded below 400° and had good thermal stability. Introduction of the phenoxasilin ring into the polymer backbones by copolycondensation did not reduce thermal stability. 相似文献
87.
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90.
Aiming to develop a high performance fiber reinforced rubber of SBR, a special technique using electron beam (EB) irradiation-induced graft-polymerization was applied to ultra-high molecular-weight polyethylene (UHMWPE) fibers. Although UHMWPE is chemically inert, N-vinyl formamide (NVF) could be graft-polymerized onto the UHMWPE fiber surface with this special technique. A maximum grafting percentage of 23.6% was achieved. The composite of SBR and grafted UHMWPE fibers with maximum grafting indicated a linear increase in the initial modulus and strength with the fiber content. At the fiber content of 10%, the initial modulus was improved about five times with respect to that of the pure SBR, while the strength was done about twice. At this moment, only a small reduction could be observed in the strain compared with that of pure SBR. The fiber reinforced rubber with a good performance was obtained in the system of SBR and grafted UHMWPE fibers. 相似文献