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401.
Toshihiko Nishimoto 《Studies in Applied Mathematics》1979,60(1):11-26
For density waves in a certain simplified model of a disk shaped galaxy, the dominant term of the basic equation (governing density waves) may be represented by a cubic polynomial, in which the stability parameter Q is allowed to be somewhat less than unity near corotation. For such a differential equation, an asymptotic form of the global dispersion relation is presented. It is shown that there exist discrete complex roots of the dispersion relation with small negative imaginary parts. The real parts and the imaginary parts of these roots represent approximately the angular speeds and the growth rate of the amplitudes of the density waves, respectively. It is proved that there exist only a finite number of unstable normal modes of density waves. 相似文献
402.
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405.
Toshihiko Masuda 《Proceedings of the American Mathematical Society》1999,127(7):2053-2057
Using the continuous decomposition, we classify strongly free actions of discrete amenable groups on strongly amenable subfactors of type III, . Winsløw's fundamental homomorphism is a complete invariant. This removes the extra assumptions in the classification theorems of Loi and Winsløw and gives a complete classification up to cocycle conjugacy.
406.
Atsushi Miyagawa Shunya Takeuchi Shinji Itoda Sanami Toyama Kenta Kurimoto Hatsuo Yamamura 《合成通讯》2016,46(22):1790-1795
2-Deoxy sugars are attractive compounds in synthetic chemistry with regard to reactivity and stereoselectivity. Moreover, their ability to inhibit enzymes and metabolism is significant in biology. In this study, uridine-5′-diphosphate (UDP)-2-deoxy glucose (11) and galactose (12) were synthesized chemically. These sugar donors for glycosyltransferases were obtained α-selectively via phosphorylation using thioglycosides, coupling reaction with uridine-5′-monophosphate (UMP)-morpholidate, and moderate deacetylation. Isolation was carried out by sequential silica-gel chromatography using two kinds of developing solvents in a refrigerator. The structures were elucidated from the NMR results. Investigation of stability showed that the synthesized UDP-2-deoxy sugars were hydrolyzed much faster in buffer (pH 4) than the natural UDP sugars. 相似文献
407.
To extract effectively the absorber information embedded in a homogeneous scattering medium in the transmission geometry, a method of taking the ratio of the output intensity in a measured medium to that in a reference medium is evaluated. The reference medium is a virtual one with the same scattering coefficient distribution as that of the measured medium, but with a uniform absorption coefficient distribution. Numerical results show that the proposed method can enhance the output signal by extracting the ballistic-like component. We also apply a backprojection method to reconstruct the single absorber using many pairs of input and output intensity ratio distributions. The reconstruction position error and the quantitative measurement of absorption coefficient are discussed. 相似文献
408.
To clarify the electronic spectral properties of uranyl(V) complexes systematically, we measured absorption spectra of three types of pure uranyl(V) complexes: [U(V)O2(dbm)2DMSO]-, [U(V)O2(saloph)DMSO]-, and [U(V)O2(CO3)3]5- (dbm = dibenzoylmethanate, saloph = N,N'-disalicylidene-o-phenylenediaminate, DMSO = dimethyl sulfoxide). As a result, it was found that these uranyl(V) complexes have characteristic absorption bands in the visible-near-infrared (NIR) region, i.e., at around 640, 740, 860, 1470, and 1890 nm (molar absorptivity, epsilon = 150-900 M(-1).cm(-1)) for [U(V)O2(dbm)2DMSO]-, 650, 750, 900, 1400, and 1875 nm (epsilon = 100-300 M(-1).cm(-1)) for [U(V)O2(saloph)DMSO]-, and 760, 990, 1140, 1600, and 1800 nm (epsilon = 0.2-3.6 M(-1).cm(-1)) for [U(V)O2(CO3)3]5-. These characteristic absorption bands of the uranyl(V) complexes are attributable to the electronic transitions in the U(V)O2+ core because the spectral features are similar to each other despite the differences in the ligands coordinated to the equatorial plane of the U(V)O2+ moiety. On the other hand, the epsilon values of [U(V)O2(CO3)3]5- are quite smaller than those of [U(V)O2(dbm)2DMSO]- and [U(V)O2(saloph)DMSO]-. Such differences can be explained by the different coordination geometries around the center uranium in these uranyl(V) complexes. Consequently, the absorption bands of the uranyl(V) complexes in visible-NIR region were assigned to f-f transitions in the 5f1 configuration. 相似文献
409.
Satoshi Okazaki Hiroyuki Sasatani Hiroyuki Hatano Tooru Hayashi Toshihiko Nagamura 《Mikrochimica acta》1988,96(1-6):87-95
Instrumentation of a high-resolution optical scanning fluorescence microscope is presented. This instrument provides a fluorescent image of the structural surface of various kinds of thin membrane samples with high resolution on the molecular scale. For this instrument, a new excitation optical tip and a three-dimensional scanning unit have been designed. The optical tip consists of a sharpened optical fibre covered with evaporated aluminium in vacuo, on which the top has a pinhole. The optical tip is mounted in the centre of a crosslinked piezoelectric scanning head. On thez-axis, a piezoelectric positioner is equipped with a differential micrometer mechanism. All operations are controlled with a micro-computer system.The scanning area in this instrument is 4000*4000 nm2 for measurements of biological specimens. Several optical scanning microscopic images as well as the STM image are presented. 相似文献
410.
Toshihiko Kondo Mitsutoshi Tanimoto Masakatsu Matsumoto Katsunori Nomoto Yohji Achiba Katsumi Kimura 《Tetrahedron letters》1980,21(17):1649-1652
Experimental COOC dihedral angles are used to support the relation proposed by Coughlin et al. for correlating the observed photoelectron splitting n(O)+- with the dihedral angle around the peroxide bond in cyclic peroxides. 相似文献