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排序方式: 共有217条查询结果,搜索用时 619 毫秒
91.
Yoshika Imai Yuko Tamai Youichi Kurokawa 《Journal of Sol-Gel Science and Technology》1998,11(3):273-278
Cellulose acetate gel film impregnated with fine Ag particles has been prepared by a counter diffusion method. Surface-enhanced Raman scattering (SERS) of benzoic and thiosalicylic acids was observed using the impregnated films. It seems likely that these acids adsorb dissociatively on the surface of impregnated films. The impregnated film can be used as a highly sensitive substrate for Raman scattering. 相似文献
92.
Murakami D Takata Y Matsubara H Aratono M Takiue T 《The journal of physical chemistry. B》2005,109(47):22366-22370
The interfacial tension of the hexane solution of 1H,1H-perfluorononanol (FDFC9OH) and its omega-hydrogenated analogue, 1H,1H,9H-perfluorononanol (HDFC9OH), against water was measured as a function of the total molality and composition of the mixture at 298.15 K under atmospheric pressure. The existence of omega-dipole in HDFC9OH makes the interfacial density larger in the gaseous and expanded states and smaller in the condensed state compared to FDFC9OH. The phase diagram of adsorption (PDA) was constructed, and the excess Gibbs energy of adsorption (gH,E) was calculated at each state in order to discuss quantitatively the miscibility of FDFC9OH and HDFC9OH in the adsorbed film. We found that the gH,E value is negative in the gaseous state, while it is positive and increases with decreasing interfacial tension in the condensed state. These results are explained mainly by the balance of two effects induced by mixing of two alcohols: (1) Reduction of repulsive interaction between omega-dipoles aligning parallel in the adsorbed film because of the increase in mean distance between HDFC9OH molecules. (2) The loss of effective dispersion interaction between hydrophobic chains due to the fact that the oblique orientation of HDFC9OH molecules at the interface is mixed with the perpendicular one of FDFC9OH. We concluded that the factor (2) is negligible compared to the factor (1) in the gaseous and expanded films and exceeds the factor (1) in the condensed film, in which molecules are closely packed. 相似文献
93.
Nishibayashi Y Yoshikawa M Inada Y Hidai M Uemura S 《Journal of the American Chemical Society》2002,124(40):11846-11847
A novel ruthenium-catalyzed propargylation of aromatic compounds with propargylic alcohols has been found to afford the corresponding propargylated aromatic products in good yields with complete regioselectivity. The catalytic reaction provides a potential usefulness for practical application in organic synthesis, because the selective propargylation of aromatic compounds with an aromatic C-H bond cleavage is generally difficult. 相似文献
94.
Nishibayashi Y Yoshikawa M Inada Y Hidai M Uemura S 《Journal of the American Chemical Society》2004,126(49):16066-16072
A simple method for the preparation of fused polycyclic compounds by an intramolecular cyclization of propargylic alcohols bearing an alkene moiety at a suitable position has been developed, where the presence of both Ru and Pt catalysts promotes a sequence of catalytic cycles in the same medium. This sequential system can be applied to an intermolecular reaction between a propargylic alcohol and an alkene to obtain the corresponding bicyclo[3,1,0]hex-2-ene derivative. These sequential reactions provide a conceptually new type of cycloaddition system between propargylic alcohols and alkenes. 相似文献
95.
Hiroyuki Hatayama Taku Swabe Youichi Kurokawa 《Journal of Sol-Gel Science and Technology》1996,7(1-2):13-17
Urease was entrap-immobilized on composite gel fibre of cellulose acetate and TiO2. The immobilization can be easily performed under mild conditions. The gel fibre is stable in high ionic solutions and in phosphate solutions with a range of pH 6–8.The pH and thermal stabilities of immobilized urease were higher than those of the native one. 相似文献
96.
Takata Y Matsubara H Kikuchi Y Ikeda N Matsuda T Takiue T Aratono M 《Langmuir : the ACS journal of surfaces and colloids》2005,21(19):8594-8596
The line tension of an air/hexadecane/aqueous solution of an dodecyltrimethylammonium bromide (DTAB) system was measured as a function of the molality of DTAB at 298.15 K by means of a newly constructed apparatus. It was estimated to be on the order of 10(-10)-10(-12) N, which is comparable to the theoretical estimation. Furthermore, its sign was reversed from positive to negative in the vicinity of the wetting transition concentration. The reversal of the sign was examined on the basis of our experimental findings on the wetting transition and the theory of Indekeu. 相似文献
97.
R. Sawada T. Karaki J. Watanabe 《Applied Physics A: Materials Science & Processing》1983,31(2):109-114
Distribution and morphology for dislocations introduced in (001) Si wafers subjected to bending stress at 800°, 900°, and 1100°C were investigated. For wafers bent around a [110] axis at 900° and 1100°C, straight dislocations appeared along the [110] direction only near the neutral plane, and were absent at the surfaces where bending stress is greatest. However, for wafers bent at 800 °C, such straight dislocations were not formed. Dependence of the dislocation distribution and morphology on heat treatment temperature is explained on the basis of interaction between bending stress and SiO2 precipitates introduced in bulk. Also, it was found that the straight [110] dislocations remained still near the neutral plane, even when additional reverse bending stress was applied around an axis parallel to the dislocations, but were transfered toward the tensile surface by bending around an axis normal to the dislocation direction. 相似文献
98.
[reaction: see text] A catalytic one-pot triarylation on the C=C core of vinylboronate pinacol ester (1) produces extended pi-systems based on a multisubstituted olefin structure very rapidly. We established an efficient protocol for the Pd-catalyzed double C-H arylation of 1 with aryl halides, which was successfully integrated with C-B arylation with aryl halides (cross-coupling) in one pot. By using this method, several highly fluorescent materials with a wide range of color variations (blue to red) were discovered. 相似文献
99.
Takashi Mino Youichi TanakaYutaka Sato Akio SaitoMasami Sakamoto Tsutomu Fujita 《Tetrahedron letters》2003,44(25):4677-4679
New type chiral ligands 3, which have a chiral carbon center and stable C(aryl)-N(amine) axial chirality, were prepared from chiral prolinol-derived aminophosphine oxide 4. Pd-catalyzed asymmetric allylic alkylation of 1,3-diphenyl-2-propenyl acetate (6) with a dimethyl malonate-BSA-LiOAc system was successfully carried out in the presence of 3d resulting in a good yield with good enantioselectivity (up to 95% ee). 相似文献
100.
Aratono M Kashimoto K Matsuda T Muroi S Takata Y Ikeda N Takiue T Tanida H Watanabe I 《Langmuir : the ACS journal of surfaces and colloids》2005,21(16):7398-7404
The mole fraction of chloride ion of dodecyltrimethylammonium bromide (DTAB) and dodecyltrimethylammonium chloride (DTAC) mixture in the adsorbed film XHC was estimated not only by the thermodynamic analysis of the surface tension data but also by analyzing the Br K-edge jump of the XAFS spectrum under the total reflection condition (TRXAFS method). The phase diagrams of adsorption (PDA) at several surface tensions from the two methods were in good agreement. On the basis of the PDA obtained, it was clearly shown that the criterion of an ideal mixing for the DTAB-DTAC system is not given by the linear relation between the total molality of surfactant mixture m and XHC, m = m0B + (m0C - m0B)XHC, but by the one between m2 and XHC, m2 = (m0B)2 + [(m0C)2 - (m0B)2]XHC. Furthermore, it was demonstrated that the theoretical approach that provides the latter relation draws a distinction between the criteria for an ionic surfactant mixture without a common ion and that for an ionic surfactant mixture with a common ion. 相似文献