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排序方式: 共有162条查询结果,搜索用时 125 毫秒
41.
Imai Hiroaki Morimoto Hirotoki Tominaga Atsushi Hirashima Hiroshi 《Journal of Sol-Gel Science and Technology》1997,10(1):45-54
Structural changes in sol-gel derived thin films by exposure to water vapor were investigated using Fourier transform infrared absorption spectroscopy, ellipsometry and x-ray diffraction. We found that SiO2 gel films were densified with a decrease in OH groups by the exposure at 60°–180°C. The shrinkage and the peak frequency of 4 (TO) for the exposed films were comparable to those heated in a dry atmosphere at temperatures above 500°C. However, OH groups in the films were not completely removed by the water exposure. A subsequent annealing above 300°C changed the structure of the water-exposed SiO2 films with condensation of the remaining OH groups. Although the exposed SiO2 gel films were amorphous, TiO2 gel films were transformed to anatase with a decrease in OH groups by the treatments at 80°–180°C. 相似文献
42.
Kenji Yamagata Fumi Okabe Motoyoshi Yamazaki Yoshinobu Tagawa 《Monatshefte für Chemie / Chemical Monthly》2002,21(1):643-651
The reaction of 2-amino-4,5-dihydro-3-furancarboxamides with morpholine in the presence of acetic acid in pyridine or under
the influence of ammonium acetate gave the corresponding 3-diaminomethylene-4,5-dihydro-2(3H )-furanones; 4,5-dihydro-2-morpholino-3-furancarboxamides were not isolated. One of the former reacted with benzylamine to
give (E )- and (Z )-3-(amino-(benzylamino)-methylene)-4,5-dihydro-4-phenyl-2(3H )-furanones and 2-benzylamino-4,5-dihydro-4-phenyl-3-furancarboxamide. 相似文献
43.
Hiroshi Hirashima Seiji Kamimura Reiki Muratake Tetsuro Yoshida 《Journal of Non》1988,100(1-3):394-398
V2O5 gels containing up to 18 mol% of TiO2 were obtained through the simultaneous hydrolysis of alkoxides in ethanol solution. V2O5 gels containing Na2O or Li2O were obtained through the ion exchange method. The crystallization temperature, Tcr, of the gels increased and the H2O content of the gels decreased by the addition of TiO2 or Na2O. These additives seem to stabilize the amorphous state of the gels. On the other hand, Tcr and the H2O-content slightly varied with the addition of Li2O. No ionic polarization was observed in coating films of the gels dried at temperatures below Tcr. The dc conductivity of the films was anisotropic, and increased with the addition of Li2O or Na2O. However, it decreased with increasing TiO2 content. The fiber-like structure of gels was observed by TEM. The gels obtained from alkoxides were thin and short in comparison with the gels obtained through the ion exchange method. 相似文献
44.
45.
Takumi Mizuno Manabu Matsumoto Ikuzo Nishiguchi Tsuneaki Hirashima 《Heteroatom Chemistry》1993,4(5):455-458
Urea derivatives were readily synthesized in good yields under quite mild conditions, i.e., at ambient pressure and room temperature by sulfur-assisted carbonylation of primary amines with carbon monoxide followed by oxidation of the resulting ammonium thiocarbamates with molecular oxygen. 相似文献
46.
Kenji Yamagata Fumi Okabe Motoyoshi Yamazaki 《Monatshefte für Chemie / Chemical Monthly》2001,132(6):721-729
Summary. The reaction of 4-amino-2,5-dihydro-2- and -5-methyl-3-thiophenecarbonitriles with α-diazocarbonyl compounds in the presence
of rhodium(II) acetate gave regioselectively 4-cyano-2H-thiopyrans (C2-S insertion) in moderate to good yields; 5-cyano-2H-thiopyrans (C5-S insertion) were not isolated. The starting compounds were synthesized by reaction of tetrahydro-2- and -5-methyl-4-oxo-3-thiophenecarbonitriles
with morpholine, piperidine, and pyrrolidine in the presence of formic acid in ethanol.
Received November 13, 2000. Accepted December 12, 2000 相似文献
47.
Furuta T Sakai M Hayashi H Asakawa T Kataoka F Fujii S Suzuki T Suzuki Y Tanaka K Fishkin N Nakanishi K 《Chemical communications (Cambridge, England)》2005,(36):4575-4577
An artificial phospholipid, possessing saturated alkyl chains as a membrane anchor and protein recognition site as well as an Fe(III)-EDTA moiety as a protein cleavable polar head group, was designed and synthesized based on the amidite method for the purpose of examination of cleavage of integral membrane proteins. 相似文献
48.
Summary Analytical solutions are proposed for the stress and displacement fields in a quasi three-dimensional elastic anisotropic body containing an elliptic cavity or rigid inclusion. The directions of the principal elastic axes are allowed to be inclined arbitrarily with respect to the axes of the elliptic cavity. As an application, expressions for the stress intensity factors are formulated when the cavity reduces to a colinear crack. 相似文献
49.
Kosuke Nakashima Shin-ichi Hirashima Masahiro Kawada Yuji Koseki Norihiro Tada Akichika Itoh Tsuyoshi Miura 《Tetrahedron letters》2014
The novel pyrrolidine-diaminomethylenemalononitrile organocatalyst 7 promotes the asymmetric conjugate addition of a carbonyl compound to a nitroalkene to afford the corresponding adduct in high yield with up to 99% ee, under solvent-free conditions. 相似文献
50.
Keita Suzuki Jun‐Ichi Oku Kenichi Izawa Hiro‐Fumi Okabayashi Isao Noda Charmian J. O'Connor 《Journal of Polymer Science.Polymer Physics》2004,42(18):3447-3460
The three‐step polymerization of a well‐defined polymeric silane coupling agent, triethoxysilyl‐terminated polystyrene, catalyzed by acid (H3PO4), was traced as a function of the reaction time with gel permeation chromatography (GPC). Time‐resolved GPC traces collected during the polymerization process were then used to construct two‐dimensional (2D) correlation maps via generalized 2D correlation analysis. The results demonstrated that the synchronous and asynchronous 2D correlation GPC spectra directly reflected the dynamic variation of aggregate–aggregate interactions during each step of the polymerization. In particular, it was found that the formation of aggregates among the cyclic trimers (or tetramers) and monomers was critical for the preferential production of pentamers in the reaction system. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3447–3460, 2004 相似文献