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Nobuo Nakabayashi Gerhard Wegner Harold G. Cassidy 《Journal of polymer science. Part A, Polymer chemistry》1969,7(5):1269-1274
Redox polyurethanes, polyesters, and alternate copolyurethanes and copolycarbonates from two kinds of benzoquinonyl glycol were prepared based on 2-(duroquinonyl)-propan-1,3-diol. The oxidized polymer is stable. When the fully reduced polymer in solution is exposed to air the durohydroquinonyl residues are oxidized to the quinone form while the less substituted hydroquinonyl glycol residues remain stable in the reduced form. There is thus prepared polymer with oxidized and reduced groups alternating along the chain. 相似文献
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A Mössbauer study was performed to find the fraction of non-bridging oxygens in potassium borate glasses containing a small amount of iron. The borate glasses with alkali contents of 15, 20, 25, 30 and 40 mol% were irradiated with 60Co-γ rays at room temperature in a nitrogen atmosphere. The Mössbauer absorption area for the irradiation-induced Fe2+ increased with the total γ-ray dose in the range of 1 × 106 ?2 × 108 R, and became constant after irradiation ranging from 2 × 108 R ? 1 × 109 R. The absorption area for the Fe2+ at the saturated region was correlated with the difference in the glass structure, i.e., the fraction of the non-bridging oxygens was estimated from the increased absorption area for the Fe2+ as a function of the alkali content of the glasses. The fraction of the non-bridging oxygen increased with the alkali content of the glasses in the alkali region above 20 mol%, and about 14% of the fraction was obtained for an alkali content of 40 mol%. 相似文献
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Irradiation of α-bisulfenylated keto compounds in acetonitrile affords the cis-fused dihydrobenzothiophenes which are dehydrated to benzothiophenes in high yields. 相似文献
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A. Kimura H. Kobayashi M. Nishida P. Valentin 《Journal of Quantitative Spectroscopy & Radiative Transfer》1985,34(2):189-215
Average radiative transition probabilities for argon atoms have been calculated for transitions between 24 levels in two groups characterized by the atomic core terms 2P1/2 and 2P3/2 by using the method of Bates and Damgaard. The results are compared with data in the NBS tables (Wiese et al.) and with those of Katsonis and Drawin. We find satisfactory agreement for the order of magnitude, even for transitions between lower lying levels. Parameters, which appear in Drawin's semiempirical cross-section expressions for electronic excitation of optically allowed and parity-forbidden transitions, are determined with the multipole expansion method proposed by Sobel'man for transitions between the specified levels. Most of these are easily obtained, but the method must be improved for transitions between levels having the same azimuthal quantum number because the summation over the constituent terms does not converge. 相似文献