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61.
Junji Furukawa Eiichi Kobayashi Morio Nakamura 《Journal of polymer science. Part A, Polymer chemistry》1974,12(8):1851-1859
The terpolymerization of sulfur dioxide, butene-1 and acrylonitrile affords terpolymers containing equimolar amounts of sulfur dioxide and butene-1 with various acrylonitrile contents. Ultraviolet irradiation was found to accelerate the polymerization and decrease the acrylonitrile content in the polymer. This fact is interpreted by a mechanism through a copolymerization of sulfur dioxide–butene-1 complex and acrylonitrile, whereby the polymerizability of sulfur dioxide–butene-1 complexed monomer may be accelerated by ultraviolet light. In fact, a binary system of sulfur dioxide and butene-1 was found to be accelerated by ultraviolet irradiation, and it affords a maximum rate at a 1:1 composition of feed monomer. Ultraviolet light of 250–300 mμ wavelength is effective for the initiation and the propagation. This may be ascribed to the ultraviolet absorption of the sulfur dioxide–butene-1 complex. The temperature coefficient was measured in both dark and ultraviolet irradiation reactions. The ultraviolet irradiation enhances the reactivity of sulfur dioxide–butene-1 complexed monomer at low temperature. In the terpolymerization with sulfur dioxide, isoprene, and butadiene, the ratio of isoprene and butadiene in the terpolymer was not altered by ultraviolet irradiation because both monomers from complexes with sulfur dioxide, perhaps having the same temperature coefficient for the polymerization. 相似文献
62.
Jeong-Chang Lee Ken Nakajima Takayuki Ikehara Toshio Nishi 《Journal of Polymer Science.Polymer Physics》1997,35(16):2645-2652
Miscibility behavior of poly(3-hydroxybutyrate) [PHB]/poly(vinylidene chloride-co-acrylonitrile) [P(VDC-AN)] blends have been investigated by differential scanning calorimetry and optical microscopy. Each blend showed a single Tg, and a large melting point depression of PHB. All the blends containing more than 40% PHB showed linear spherulitic growth behavior and the growth rate decreased with P(VDC-AN) content. The interaction parameter χ12, obtained from melting point depression analysis, gave the value of −0.267 for the PHB/P(VDC-AN) blends. All results presented in this article lead to the conclusion that PHB/P(VDC-AN) blends are completely miscible in all proportions from a thermodynamic viewpoint. The miscibility in these blends is ascribed to the specific molecular interaction involving the carbonyl groups of PHB. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 2645–2652, 1997 相似文献
63.
An efficient enantiospecific synthesis of the (R)‐ and (S)‐enantiomers of flavanone and 2‐methylchromanone is described. The key steps are a C,C‐bond formation by ring opening of a chiral epoxide with a dithiane anion, followed by a Mitsunobu cyclization. The products obtained have high enantiomeric purity. 相似文献
64.
Shigeo Matsuda Akira Ishikubo Akinori Kuzuya Morio Yashiro Makoto Komiyama 《Angewandte Chemie (International ed. in English)》1998,37(23):3284-3286
Even in the presence of a large excess of Zn II ions , sequence-selective RNA hydrolysis is achieved by DNA conjugates involving a dinuclear ZnII complex (shown schematically). This is because the cooperation of two ZnII ions is essential for the RNA scission. 相似文献
65.
Yoshiyuki Dobashi Takashi Hirano Morio Hirano Yasukazu Ohkatsu 《Journal of photochemistry and photobiology. A, Chemistry》2008,197(2-3):141-148
Catechins are studied vigorously, in particular, concerning the antioxidant ability as polyphenol, which is generally considered responsible for photo-antioxidant natures of catechins. In this study, the antioxidant and photo-antioxidant abilities of (+)-catechin, (−)-epicatechin, and epigallocatechin have been investigated kinetically and discussed in detail. As a result, this study clarifies that a strong antioxidant is not always a good photo-antioxidant as well as that catechins show a high antioxidant ability in an initial oxidation process and acquire a photo-antioxidant ability with the progress of photo-oxidation. In particular, (+)-catechin and (−)-epicatechin convert into quercetin to show a remarkable photo-antioxidant ability almost comparable to quercetin. In this case, (−)-epicatechin has a higher photo-antioxidant ability than (+)-catechin, although they differ only in the configurations. These facts are explained by the direct conversion of the catechins into quercetin. 相似文献
66.
Characterization of Full-WDM-Band Photodiode Modules Using Raman Amplifiers in the U Band at 40 Gb/s
We present the characteristics of a full-WDM-band photodiode module in 40 Gb/s U-band operation using a Raman amplifier. This module is suitable for wide-band transmission systems with the additional new channels in the U band. 相似文献
67.
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69.
E Otsuka M Ubasawa S Morioka M Ikehara 《Journal of the American Chemical Society》1973,95(14):4725-4733
70.
On the basis of the data obtained from 13C NMR spectra of 8,2′-S-cycloadenosine 3′,5′-cyclic phosphate and other nucleoside 3′,5′-cyclic phosphate analogues, it is suggested that the published assignments of the C-3′ and C-4′ signals in nucleoside 3′,5′-cyclic phosphates should be reversed. According to the revised assignments, C-4′, which is fixed very closely to the diesterified phosphate group is markedly shielded (?12.5 to ?15 ppm), and the C-3′ signal shows a downfield shift (+6 to +8 ppm) which is comparable to that for the C-5′ signal, for all compounds so far measured when compared with the chemical shifts for the corresponding nucleosides. The 3′,5′-cyclic phosphates of thymidine and 8,2′-S-cycloadenosine, which have no α-OH group on C-2′, show similar chemical shift changes for the corresponding sugar carbons which are different from those observed for ribonucleoside derivatives. 相似文献