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71.
Shinichi Kitamura Kazuya Nakatani Takeshi Takaha Shigetaka Okada 《Macromolecular rapid communications》1999,20(12):612-615
Complex formation of large cyclodextrins(CDs) having DP 21–32 with iodine in aqueous KI solution was studied by isothermal titration calorimetry. The curves obtained for the titration of the CDs with iodine cannot be analyzed by a model based on a single set of identical sites, but, rather, by a model assuming 1 : 2 complex formation with identical interacting sites. For the two identical interacting sites, the binding constants K1 and K2 (K1 < K2), defined relative to the progress of saturation, lie in the range 0.7 to 7.3×103 M–1 and 3.0 to 62.6×103 M–1, respectively. The values of ΔH2 and T ΔS2 lie in the range –34.9 to –136.4 kJ·mol–1 and –15.5 to –112.8 kJ·mol–1, respectively. The largest values of –T ΔS2 obtained for a CD of DP 26 can, in part, be attributed to a large decrease in conformational flexibility of the CD which occurs during complex formation. 相似文献
72.
Nakamura S Ogasawara S Matuda S Saito I Fujimoto K 《Molecules (Basel, Switzerland)》2011,17(1):163-178
We demonstrated that 5-vinyldeoxyuridine ((V)U) and 5-carboxyvinyldeoxyuridine ((CV)U) can be used to photoligate a longer oligonucleotide (ODN) from smaller ODNs on a template. By performing irradiation at 366 nm, these artificial nucleotides make photoligated ODNs with high efficiency without any side reactions. Moreover, by performing irradiation at 312 nm, these photoligated ODNs were reversed to the original ODN. (V)U needs to be irradiated 366 nm for 6 h, but (CV)U needs to be irradiated at 366 nm for 15 min. Finally, we made a self-assembled structure with an ODN containing (CV)U and observed the photoligated ODN by photoirradiation. 相似文献
73.
α-Subslituted β-2-(5-nitrofuryl)viriylamines were synthesized from α-ary]-β-2-(5-nitrofuryl)-aeryloyl azides and N-[α-substituled β-2-(5-nitrofuryl)vinyl] pyridinium bromides. 相似文献
74.
Ion flotation is used to concentrate chromium(VI) in the range 3–70μg l-1 from 14 samples. The chromium(III)—diphenylcarbazone complex formed by reaction with diphenylcarbazide is floated efficiently with sodium lauryl sulfate, and the subsided foam is measured spectrophotometrically after simple dilution. Continuous flotation methods at solution flow rates of 2, 3 and 4 l h-1 are discussed. 相似文献
75.
Akira Tanaka Kenichi Yakushijin Shigetaka Yoshina 《Journal of heterocyclic chemistry》1977,14(6):975-979
4H-Furo[3,2-b]indole (III) was prepared from deoxygenation of 2-(2-nitrophenyl)furan (II) with triethyl phosphite and thermolysis of 2-(2-azidophenyl)furan (VI). 4H- or 4-alkylfuro [3,2-b]indole-2-carboxaldehydes (VIII, IXa-c) were obtained by Vilsmeier formylation of the corresponding furo[3,2-b]indoles (III, VIIa-c). 4H-Furo[3,2-b]indole-2-carboxaldehyde (VIII) was submitted to the Cannizzaro, Wittig and reduction reactions. The Shiff's bases were obtained by the reaction of 4-ethylfuro[3,2-b]indole-2-carboxaldehyde (IXb) with amines. J. Heterocyclic Chem., 14, 975 (1977) 相似文献
76.
Shigetaka Shimada Yasunori Takahasi Yusuke Sugino Shigeo Hara Katsuhiro Yamamoto 《Journal of Polymer Science.Polymer Physics》2004,42(9):1705-1714
The structural changes of polyethylene (PE) and photografted polyethylene‐g‐poly(hexyl methacrylate) (PE‐g‐PHMA) with the mechanical formation of pinholes were evaluated with differential scanning calorimetry, wide‐angle X‐ray scanning, and small‐angle X‐ray scanning. The crystallinity and the long period of the lamella increased with pricking under extremely high compression stress. The partial transformation of an orthorhombic crystal into a monoclinic one was also detected. The autonomic healing of pinholes in PE and PE‐g‐PHMA was studied in detail. The degree of healing increased with an increase in the grafting ratio of poly(hexyl methacrylate) (PHMA). Three mechanisms for the healing were investigated and related to the molecular motions of PE and PHMA grafted chains, which were evaluated with dynamic mechanical analyses. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1705–1714, 2004 相似文献
77.
Sulfoxides are reduced by a combination of sodium borohydride, a catalytic amount of cobalt(II) chloride hexahydrate, and chromatographic neutral alumina preloaded with a small amount of water (moist alumina) in hexane to produce the corresponding sulfides in good to excellent yields under mild conditions. An interesting structural influence of sulfoxides on their reactivity is observed.
78.
Shigetaka Yakabe 《合成通讯》2013,43(9):1339-1344
Reduction of epoxides with sodium borohydride, a catalytic amount of palladium(II) chloride, and chromatographic neutral alumina preloaded with a small amount of water (moist alumina) in hexane gave alcohols in good to excellent yields and good selectivity of the desired products under mild conditions. The reaction system was operationally simple and environmentally friendly. The alumina can be recovered simply and reused a number of times without any treatment and with good activity. 相似文献
79.
Shin-ichi Ninomiya Masakazu Ebie Atsushi Hakura Kohfuku Kohda Yutaka Kawazoe Takayuki Shioiri 《Tetrahedron letters》1984,25(50):5785-5788
The kinetics for hydrolysis and the chemoselectivity toward nucleophiles of mutagenic N-trimethylsilylmethyl-N-nitrosourea, a silicon analogue of N-neopentyl-N-nitrosourea, were studied. 相似文献
80.
Based on our recent finding regarding diverse biological activities of natural lignified materials, synthetic dehydrogenation homo- and copolymers were prepared using 3 p-hydroxylated cinnamic acids and coniferyl alcohol in order to explore the role of lignin skeleton in the activities displayed by natural lignins. The synthetic polymers stimulated polymorphonuclear cell iodination as potently as the natural lignified materials. 相似文献