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排序方式: 共有400条查询结果,搜索用时 31 毫秒
31.
32.
Daisuke Saio Toru Amaya Toshikazu Hirao 《Advanced Synthesis \u0026amp; Catalysis》2010,352(13):2177-2182
The hybrid consisting of gold nanoparticles and poly(2‐methoxyaniline‐5‐sulfonic acid), which works as a redox mediator for transferring protons and electrons, catalyzed the oxidation reaction of various alcohols in water under molecular oxygen. 相似文献
33.
Yuki Nakashima You Zhou Keisuke Tanabe Souhei Arima Kiyoshi Hirao Tatsuki Ohji Norimitsu Murayama Manabu Fukushima 《Journal of the American Ceramic Society》2023,106(2):1139-1148
Silicon nitride (Si3N4) was prepared from silicon by a sintered reaction-bonded silicon nitride method using yttria and magnesia as sintering additives. Post-sintering (PS) of nitrided compacts was carried out at 1850°C under a nitrogen pressure of 1 MPa. Effect of PS time on microstructure and dielectric breakdown strength (DBS) of the prepared Si3N4 ceramics was evaluated. The DBS was measured using specimens with four different thicknesses (0.30, 0.20, 0.10, and 0.05 mm) in order to examine the thickness dependence. The porosity of the sintered Si3N4 decreased by prolonging the PS time, and the full density could be achieved at the PS time of over 6 h. After full densification, rod-like β-Si3N4 grains grew up, and their maximum grain size increased from 45.1 to 154.7 μm by prolonging the PS time from 6 to 48 h. The DBS of the thick Si3N4 substrates (0.30 mm) showed little variation from 35.4 to 47.0 kV/mm, regardless of the PS time. On the other hand, that of the thin ones (0.05 mm) dramatically decreased from 99.5 to 9.8 kV/mm with increased the PS time from 6 to 48 h. Because the DBS sharply decreased at the thin substrate sintered for longer time in which some large-elongated grains might span the substrate thickness-wise throughout, it was inferred that the interface between β-Si3N4 grains and grain boundary phase/intergranular glassy films might be a path of the dielectric breakdown. 相似文献
34.
Shinsuke Takase Kazuo Kashiyama Seizo Tanaka Tayfun E. Tezduyar 《Computational Mechanics》2011,48(3):293-306
We show that combination of the Deforming-Spatial-Domain/Stabilized Space–Time and the Streamline-Upwind/Petrov–Galerkin formulations
can be used quite effectively for computation of shallow-water flows with moving shorelines. The combined formulation is supplemented
with a stabilization parameter that was originally introduced for compressible flows, a compressible-flow shock-capturing
parameter adapted for shallow-water flows, and remeshing based on using a background mesh. We present a number of test computations
and provide comparisons to theoretical results, experimental data and results computed with nonmoving meshes. 相似文献
35.
Jianrong Qiu Katsuhisa Tanaka Kazuyuki Hirao 《Journal of the American Ceramic Society》1997,80(10):2696-2698
Fluoroaluminate glasses containing various concentrations of Eu2+ were prepared under a reducing atmosphere for the present study, and the wavelength dependence of the Faraday rotation angle was examined. The magnitude of the Verdet constant (Vc ) increased as the concentration of Eu2+ increased. In addition, the Verdet constant of glasses containing 5 cat.% Eu2+ was larger than that of fluoroaluminate glasses containing the same concentration of Tb3+ in the wavelength region from 400 to 600 nm. The effective transition wavelength, λt , for glasses containing Eu2 + as well as those containing Tb3 + was evaluated based on the Van Vleck and Hebb theory. Factors dominating the Verdet constant of those glasses are discussed in this report. 相似文献
36.
Hideki Hyuga Mark I. Jones Kiyoshi Hirao Yukihiko Yamauchi 《Journal of the American Ceramic Society》2004,87(5):894-899
Si3 N4 /carbon fiber composites have been produced with and without seeding by an extrusion and sintering process. In both cases the carbon fibers were aligned along the direction of extrusion, but the Si3 N4 grains were only aligned in the seeded material. The mechanical properties of the specimens showed anisotropy with respect to the grain alignment, with both strength and toughness being highest in the direction parallel to the extruding direction. In this direction the seeded specimen, where both the Si3 N4 grains and the carbon fibers were aligned, showed both higher fracture toughness and higher fracture strength than the nonseeded specimen where only the fibers were aligned. 相似文献
37.
N Yamamoto K Hirao N Toshida H Nawata F Suzuki N Miyasaka K Hiejima 《Canadian Metallurgical Quarterly》1998,21(9):1724-1729
The right atrial posterior septum, including the coronary sinus (CS) ostium, is an important landmark in radiofrequency catheter ablation therapy for supraventricular tachycardia or atrial flutter. The anatomical findings around the CS ostium would be useful to determine a target site or line during catheter ablation. The aim of the study was to test the ability of the imaging catheter to identify structures in the posterior septal area of the right atrium and to evaluate the feasibility of guidance for catheter placement in the CS using a cardioscope that we recently developed. In 12 anesthetized dogs, the cardioscope, consisting of a deflectable 7 Fr fiberoptic endoscope with an inflatable and transparent balloon, was introduced into the right atrium via the femoral vein. The cardioscope was manipulated to observe the right atrial posterior septum. A deflectable electrode catheter was inserted via the jugular vein and positioned in the CS under cardioscopic guidance. In 10 of 12 dogs, the right atrial posterior septum, including the CS ostium, and the tendon of Todaro could be anatomically identified by cardioscopy. It was possible to position an electrode catheter in the CS in all 10 dogs under direct vision without fluoroscopy. But the CS ostium could not be detected in the remaining two dogs, although the cardioscope was placed at as many sites as possible. No complication occurred. The balloon-tipped cardioscope appears to be useful in observing the right atrialposterior septum and in guiding an electrode catheter into the CS. 相似文献
38.
K. Takahama M. Yokoyama S. Hirao S. Yamanaka M. Hattori 《Journal of Materials Science》1992,27(5):1297-1301
The interlayers of montmorillonite clay were pillared with silica-titania sol particles by ion exchange in aqueous solutions. The water in the pillared clay was substituted with ethanol which was in turn extracted with CO2 under supercritical conditions. This drying procedure avoids the formation of liquid-vapour interfaces which give rise to shrinkage of the swelled pillared structure. Highly porous structures with well developed card-house structures resulted. The pore structure was investigated and compared with that of samples prepared by conventional air-drying procedures. 相似文献
39.
Masahiko Hirao Hidekazu Fukuoka Yoshinori Murakami 《Research in Nondestructive Evaluation》1992,4(3):127-138
A computer-driven, swept-frequency measurement technique is developed on the basis of resonance birefringence acoustoelasticity to evaluate the stresses in thin plates. The resonance frequency depends on the thickness and the elastic wave velocity; they change with stress because of the Poisson effect and the acoustoelastic effect. The resonance frequency is obtained from the spectral response curve in the electric impedance of the piezoelectric transducer. The frequency displacement induced by acoustically coupling the transducer can be minimized by employing the resonance peak closest to the transducer fundamental frequency. To illustrate the method, the residual stress is measured in butt-welded aluminum alloy plates and is compared with the results of conventional methods. 相似文献
40.