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KEIKO TAKAHASHI HIDEKI YOKOMIZO KATSURO ISHIYAMA MASAHIKO KITSUTA MEGUMI OHASHI 《Journal of inclusion phenomena and macrocyclic chemistry》2006,56(1-2):95-99
Asymmetric reduction of indol-3-pyruvic acid (IPA) with NaBH4 in aqueous solution in the presence of various cyclodextrins (α-, β-, γ-, mono-6-amino-6-deoxy-β- and di-6ABamino-6AB-deoxy-β-cyclodextrin) was investigated. From the NMR and circular dichroism spectral studies, the conformation of the CyD–substrate complexes is suggested; the part of carboxylic group stay in the cavity of α-CyD, whole of IPA in β-CyD, two molecules in a γ-CyD cavity, and IPA(s) is/are on the rim of the cavity of mono-6-amino-6-deoxy-β- and di-6ABamino-6AB-deoxy-β-CyD (AβCyD, DAβCyD) with electrostatic interaction between amino group and carboxylic group. This conformational difference provides in the difference in the optical selectivity of reduction. 相似文献
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KUNIMATSU NOBORU; SANO HIDEKI 《IMA Journal of Mathematical Control and Information》1998,15(4):317-330
This paper investigates the exponential stabilily of a modelof a heat exchanger of counterflow type, whose boundary conditionsare governed by boundary feedbacks. A theorem by F.L. Huangis applied to prove that the system satisfies the spectrum-determinedgrowth assumption. 相似文献
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Structural changes in never- dried, disintegrated bacteria l cellulose by treatment with aqueous NaOH were examined by electron microscopy, X-ray diffractometry and acid hydrolysis behaviour and compared with those of cotton cellulose. The microfibril kept its fibrillar morphology after treatment with NaOH solutions of less than 9% (w/w), but changed into irregular aggregates when treated with NaOH above 12% (w/w), corresponding to the crystal conversion to cellulose II. The crystallinity of the resulting cellulose II was very low after a brief alkali treatment, but was increased significantly by elongated treatment (up to 10 days). In contrast, cotton cellulose was converted to cellulose II of fairly high crystallinity by alkali treatment of as little as 3 min duration, and the crystallinity did not change with longer treatments. The leveling-off degree of polymerization (LODP) of bacterial cellulose was decreased from 150 to 50 by 18% (w/w) NaOH treatment, while that of cotton linter decreased from 260 to 70. These characteristic differences between cotton linter cellulose and bacterial cellulose can be ascribed to a basic difference in microfibrillar organization in these materials: the microfibrils in cotton cellulose are in close contact with neighbouring microfibrils having opposite polarity, and in bacterial cellulose are isolated from each other and require chain folding to form the antiparallel cellulose II crystal 相似文献
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HIDEKI KANDORI SINZI MATUOKA YOSHINORI SHICHIDA TÔCRU YOSHIZAWA 《Photochemistry and photobiology》1989,49(2):181-184
The primary photochemical reactions of cattle rhodopsin suspended in H2O or D2O were compared between excitation with both a weak and an intense picosecond laser pulse (wavelength, 532 nm; duration, 25 ps) at room temperature. The time-dependent change of absorbance at about 575 nm demonstrated that photohodopsin, a precursor of bathorhodopsin, was produced immediately after the excitation with a weak picosecond laser pulse. It decayed to bathorhodopsin with a time constant of 45 ps which is close to the value reported previously [Shichida et al., (1984) Photobiochem. Photobiophys., 7, 221-228]. No deuterium effect was observed in this process. Excitation with an intense laser pulse induced instantaneous increase of the absorbance at about 575 nm and remained at almost constant level on the picosecond time scale, which was in good agreement with the pioneering work [Busch et al., (1972) Proc. Natl. Acad. Sci., USA, 69, 2802-2806]. No deuterium effect was observed in this photochemical process. 相似文献
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Compression and decompression of clathrate hydrates have been carried out in order to investigate the onset pressures above which the crystalline forms begin to collapse at 0 K and do not revert back to the original structures upon decompression. Several proton-disordered structures of clathrate hydrate I encapsulating noble gases were subjected to compression, the steepest descent minimization of potential energy, the subsequent expansion to the original volume, and the steepest descent minimization. It was found that above the onset pressure, depending on guest species, even the fully occupied hydrates are compressed inelastically, and transformed into amorphous forms from which crystalline structures are no longer recovered by decompression at 0 K. 相似文献
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A structural member with rectangular cross-section is frequently encountered in civil, mechanical and ocean engineering applications. Structural loading in terms of steady and unsteady pressure fields, susceptibility to flow-induced instabilities, etc., for tall buildings, bridges, offshore platforms, marine risers and a wide variety of other configurations have been of interest to engineers. Recent progress in engineering materials and computer-aided design has led to structures with reduced stiffness, making them prone to wind, earthquake, as well as ocean-wave and current-excited oscillations. The present research is aimed at understanding these issues at a fundamental level through a comprehensive study of moving-surface boundary-layer control (MSBC) as applied to two-dimensional rectangular prisms with reference to drag reduction and suppression of flow-induced vibrations. Extensive wind-tunnel tests, complemented by quasisteady analysis and flow visualization study, suggest that the concept of MSBC represents a versatile tool for drag reduction and suppression of both vortex resonance and galloping type of instabilities. 相似文献
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Feedback control of semilinear diffusion systems: inertial manifolds for closed-loop systems 总被引:1,自引:0,他引:1
An approach via inertial-manifold theory is presented as a wayto study the problem of stabilizing semilinear diffusion systemsusing finite-dimensional controllers. It is shown that a Sakawatype of controller plays an important role in the constructionof an inertial manifold for the closed-loop (controlled) semilineardiffusion system. This means that the use of a Sakawa type ofcontroller reduces the stabilization problem for the closed-loopsystem to the one on the inertial manifold.
*This paper was partially presented at the 12th IFAC World Congress,Sydney, 1823 July 1993. 相似文献
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