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991.
992.
993.
Kenji Wada Yasuhiko Satomura Hiroshi Kamie Takafumi Kiuchi Hiromichi Horinaka Yoshio Cho Tokuo Umeda Kenji Nakamura 《Optical Review》2000,7(5):432-435
Aiming at the realization of optical computed tomography (optical CT), a compact system comprised of two cw-lasers and a detector was proposed for the extraction of quasi-straightforward propagating photons from scattered light transmitting through a scattering medium. The extraction ability of the system based on the sum-frequency generation technique was investigated using a standard scattering medium of Intralipid-10% aqueous solution and was found to be 78 dB in dynamic range. The optical CT image of absorbers placed in the scattering medium was successfully obtained with high contrast using the proposed system. 相似文献
994.
In order to investigate the relationship between ionic conductivity and liquid crystallinity, we prepared the main‐chain type polyester having 1,4‐bisstyrylbenzene units and ethyleneoxide chain in the repeating unit. The main‐chain type polyester with lithium salt at the ratio of 0.04 per polymer repeating unit exhibited a smectic phase. However, the polyester with lithium salt (0.11) showed a nematic phase. The ionic conductivity of the polyester with lithium salt increased with increasing lithium salt concentration. The trans‐type polyester exhibited a liquid crystalline phase, while the cis‐type polyester did not show any mesophase. We found that the ionic conductivity of the trans‐type polyester with lithium salt (0.11) was larger than that of the cis‐type polyester with lithium salt (0.11). However, a liquid crystalline phase was found in the side‐chain type polyether with alkoxy chain length of below 12. A smectic phase was induced for the non‐mesomorphic polyethers with lithium salt. The layer spacing of the smectic A phase for the non‐mesomorphic polyether with lithium salt decreased from 55 to 41 Å with increasing temperature. The ionic conductivity of the polyether with lithium salt increased with decreasing the layer spacing. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
995.
Application of 2-(3,5,6-trifluoro-2-hydroxy-4-methoxyphenyl)benzoxazole and -benzothiazole to fluorescent probes sensing pH and metal cations. 总被引:3,自引:0,他引:3
2-(3,5,6-Trifluoro-2-hydroxy-4-methoxyphenyl)benzoxazole (3) and benzothiazole analogue (4) are prepared by the two-step procedures from the corresponding 2-(pentafluorophenyl)benzazoles. Benzoxazole 3 is applicable to a fluorescent probe sensing magnesium cation, and 4 is suitable for sensing zinc cation. Both fluorophores 3 and 4 are sensitive to the pH change at pH 7-8, resulting in large fluorescence enhancement under basic conditions. Their high sensitivity to pH and selectivity in metal cations are ascribed to the high acidity of the fluorophenol moiety. 相似文献
996.
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
997.
Kenji Takahashi Katsutoshi Fujii Sadashi Sawamura Charles D. Jonah 《Radiation Physics and Chemistry》1999,55(5-6):579-581
The Stokes shifts of coumarin 153 (C153) in CF3H, CO2 and C2H6 have been measured at several reduced densities (0.3–1.8). For C153 in CF3H, the shifts increase with a decrease in reduced density and show a maximum value at a reduced density of 0.5. In non-polar solvents, the shifts are not dramatically altered as a function of reduced density but slightly increase with a decrease in the reduced density. 相似文献
998.
The reactions of N-(5,6-dihydro[1]benzothiepino[5,4-d]pyrimidin-4-yl)amidines or its amide oxime derivatives with hydroxylamine hydrochloride under basic condition gave abnormal cyclization products via a ring cleavage of pyrimidine component accompanied with a ring closure of [1,2,4]oxadiazole. 相似文献
999.
It is found numerically that the time-bandwidth product (TBP) of optical pulse from a gain-switched semiconductor laser operating under a sufficient gain saturation condition increases monotonously with increasing modulation amplitude. This enhancement of the TBP becomes remarkable for longer-wavelength semiconductor lasers (1.3, 1.55 μm) having large value of the gain compression factor ε (∼ 10−23 m3), making the pulse chirp estimation using the TBP difficult. 相似文献
1000.