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961.
Taizo Hatta Muneob Kawano Hironori Maeda Otohiko Tsuge 《Journal of heterocyclic chemistry》1997,34(2):579-583
The reaction of 5-bromomethyl-3-(p-bromomethylphenyl)isoxazole with o-, m-, and p-bis(mercap-tomethyl)benzenes gave the corresponding dithia- and/or tetrathiaisoxazolophanes, whose relative yields strongly depended upon the nature of the mercaptomethyl compound. The above isoxazole dibromide reacted with the bis(mercaptomethyl)isoxazole to afford a mixture of two isomeric dithiaisoxazolophanes. 相似文献
962.
Quantum state and dynamics of muon and proton in crystalline silicon have been studied by solving one‐particle Schrödinger equations for the impurities. The ground state wavefunctions and energies are determined as a function of local distortion of the host Si lattice, where the Si–H interaction we used is that parameterized by Ramírez and Herrero following the results of earlier pseudopotential‐density‐functional calculation. It is shown that quantum zero‐point motion of muon induces an effective potential barrier between the tetrahedral‐symmetry (T) site and the bond‐center (BC) site, which ensures bistability of muonium states observed in experiments. It is also shown that, if we fully consider the quantum effect with the present model potential, the BC site becomes less stable than the T site on the contrary to the experiments and former theoretical calculations. 相似文献
963.
Luminescence of rare-earth ions in perovskite-type oxides: from basic research to applications 总被引:3,自引:0,他引:3
Luminescence of a rare-earth ion in SrTiO3 or other perovskite-type oxides was used as a probe of physical properties of a host crystal, but not as a phosphor because observed luminescence efficiency was low. Recent investigations have shown that the luminescence efficiency of SrTiO3:Pr3+ is intensified up to 200 times by addition of Al ions. This paper reviews experimental results on this phenomenon and discusses mechanism of the Al-addition effect. A survey was made to find other materials, the efficiency of which can be improved by the impurity addition. Host-to-activator energy transfer by a coupling of the band-edge recombination energy and an allowed transition of a rare-earth ion is essential to provide a high efficiency. A red phosphor, Al-added SrTiO3:Pr3+, is promising for display applications. 相似文献
964.
Shinji Nohara Hajime Wada Naoji Furukawa Hiroshi Inoue Chiaki Iwakura 《Research on Chemical Intermediates》2006,32(5):491-496
An electric double-layer capacitor (EDLC) was assembled with the polymer hydrogel electrolyte prepared from cross-linked potassium
poly(acrylate) (PAAK) and KOH aqueous solution, and the self-discharge characteristics were investigated. The EDLC cell with
the polymer hydrogel electrolyte showed lower voltage decay on open circuit than that with a KOH aqueous solution. Moreover,
it was found that the leakage current of the EDLC cell was markedly suppressed by using the polymer hydrogel electrolyte.
The suppression was enhanced with increasing PAAK content in the electrolyte. These results strongly suggest that the PAAK
plays an important role in the suppression of self-discharge. 相似文献
965.
A compact beam-shaping device with a reflective aspherical surface is proposed. The device converts a circular symmetric Gaussian
beam from a laser into a uniform distribution on a target plane. The device consists of a laser, a reflective aspherical surface
formed on the base plane inclined by 45° against the optical axis, and a spacer. The surface is designed for an optical device
used as a transmitter of indoor wireless optical communication, which is one of the promising applications. The designed surface
is obtained by approximation using polynomial. Beam shaping of a simulated surface and a uniform intensity distribution on
the target plane is obtained. The intensity distribution generated by the surface is numerically simulated and evaluated if
the surface is misaligned. It is clarified that the generated distribution is tolerable for the misalignment. 相似文献
966.
967.
With the aim of constructing a comprehensive design optimization procedure of axial flow hydraulic turbine, an improved quasi‐three‐dimensional inverse method has been proposed from the viewpoint of system and a set of rotational flow governing equations as well as a blade geometry design equation has been derived. The computation domain is firstly taken from the inlet of guide vane to the far outlet of runner blade in the inverse method and flows in different regions are solved simultaneously. So the influence of wicket gate parameters on the runner blade design can be considered and the difficulty to define the flow condition at the runner blade inlet is surmounted. As a pre‐computation of initial blade design on S2m surface is newly adopted, the iteration of S1 and S2m surfaces has been reduced greatly and the convergence of inverse computation has been improved. The present model has been applied to the inverse computation of a Kaplan turbine runner. Experimental results and the direct flow analysis have proved the validation of inverse computation. Numerical investigations show that a proper enlargement of guide vane distribution diameter is advantageous to improve the performance of axial hydraulic turbine runner. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
968.
Shinji Kamisuki Yoshiyuki Mizushina Kouji Kuramochi Kengo Sakaguchi Tadashi Nakata 《Tetrahedron》2004,60(27):5695-5700
The first total synthesis of dehydroaltenusin, a natural enzyme inhibitor, is described. The key step involves Suzuki-coupling reaction of an aryl triflate prepared from 2,4,6-trihydroxybenzoic acid with a catechol-derived boronic acid or boronic ester. The synthetic product was evaluated as a potent inhibitor against eukaryotic DNA polymerase α and other DNA polymerases. 相似文献
969.
The intermolecular reductive coupling of aromatic imines with acylimidazoles was effected by electroreduction in the presence of chlorotrimethylsilane and gave α-amino-α-aryl ketones. This method was also effective for the synthesis of α-amino-α-aryl esters using methoxycarbonylimidazole as an electrophile. 相似文献
970.
Tetsuya Miki Katsuyasu Kawano Nobuo Nakajima Naoto Kishi Masaru Miyamoto Tetsu Aoki 《光学学报》2003,23(Z1)
A novel Radio On Fiber(ROF) access is proposed and demonstrated which enables the pico-cell Base Station (BS) for high-speed wireless communications to eliminate external electric power supply facilities. We demonstrated 2.4-GHz band radio signal transmission through the BS without external electric power supply. The electrical power used for BS circuit is feeded by optical power over optical fiber from central station. 相似文献