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排序方式: 共有128条查询结果,搜索用时 250 毫秒
31.
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Junichiro Makino 《Japanese Journal of Mathematics》2008,3(1):49-92
We overview our GRAPE (GRAvity PipE) and GRAPE-DR project to develop dedicated computers for astrophysical N-body simulations. The basic idea of GRAPE is to attach a custom-build computer dedicated to the calculation of gravitational interaction between particles to a general-purpose programmable computer. By this hybrid architecture, we can achieve both a wide range of applications and very high peak performance. GRAPE-6, completed in 2002, achieved the peak speed of 64 Tflops. The next machine, GRAPE-DR, will have the peak speed of 2 Pflops and will be completed in 2008. We discuss the physics of stellar systems, evolution of general-purpose high-performance computers, our GRAPE and GRAPE-DR projects and issues of numerical algorithms. 相似文献
33.
Tsuyoshi Oshima Iori Yamanaka Anupriya Kumar Junichiro Yamaguchi Taeko Nishiwaki‐Ohkawa Kei Muto Rika Kawamura Tsuyoshi Hirota Kazuhiro Yagita Stephan Irle Steve A. Kay Takashi Yoshimura Kenichiro Itami 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(24):7299-7303
The synthesis and functional analysis of KL001 derivatives, which are modulators of the mammalian circadian clock, are described. By using cutting‐edge C H activation chemistry, a focused library of KL001 derivatives was rapidly constructed, which enabled the identification of the critical sites on KL001 derivatives that induce a rhythm‐changing activity along with the components that trigger opposite modes of action. The first period‐shortening molecules that target the cryptochrome (CRY) were thus discovered. Detailed studies on the effects of these compounds on CRY stability implicate the existence of an as yet undiscovered regulatory mechanism. 相似文献
34.
A stereocontrolled total synthesis of both the (+)- and (-)-epolactaene ((+)- and (-)-1) enantiomers from tetrahydropyran-2-ol is described. The following reactions in this synthesis are particularly noteworthy: (1) the stereoselective construction of the conjugated (E,E,E)-triene by a combination of kinetic deprotonation and thermodynamic equilibration, (2) the E-selective Knoevenagel condensation of beta-ketonitrile 33 with a chiral 2-alkoxyaldehyde, (3) a diastereoselective epoxidation achieved using a bulky nucleophile (TrOOLi) and an appropriate protecting group, (4) the mild hydrolysis of an alpha-epoxy nitrile by silica gel on TLC facilitated by hydroxyl-mediated, intramolecular assistance. 相似文献
35.
Takamasa Ishigaki Shigeru Yamauchi Junichiro Mizusaki Kazuo Fueki Hiroyuki Naito Tatsuya Adachi 《Journal of solid state chemistry》1984,55(1):50-53
The tracer diffusion coefficient, , of oxide ions in LaFeO3 single crystal was determined over the temperature range of 900–1100°C by the gas-solid isotopic exchange technique using 18O as a tracer. For the determination of , the depth profile of 18O was measured by means of a secondary ion mass spectrometer (SIMS). The surface exchange reaction was found to be slow and the surface exchange rate constant, k, was determined together with . It was found that at 950°C is proportional to P?0.58O2, where PO2 is an oxygen pressure. The vacancy mechanism was determined for the diffusion of oxide ions from the PO2 dependence. The vacancy diffusion coefficient, DV, for LaFeO3 was nearly the same as that for LaCoO3 at the same temperature. The activation energy for migration of oxide ion vacancies was 74 kJ · mole?1 for both oxides. 相似文献
36.
Hayashi Y Shoji M Yamaguchi J Sato K Yamaguchi S Mukaiyama T Sakai K Asami Y Kakeya H Osada H 《Journal of the American Chemical Society》2002,124(41):12078-12079
The asymmetric total synthesis of (-)-azaspirene, an angiogenesis inhibitor, has been accomplished, establishing its absolute stereochemistry. The key steps are a MgBr2.OEt2-mediated, diastereoselective Mukaiyama aldol reaction, a NaH-promoted, intramolecular cyclization of an alkynylamide, and the aldol reaction of a ketone containing functionalized gamma-lactam moiety without protection of tert-alcohol and amide functionalities. 相似文献
37.
Kazami Yamamoto Junichiro Kamiya Michikazu Kinsho Ryuji Saeki Takeshi Toyama 《Applied Surface Science》2009,256(4):958-961
The J-PARC 3 GeV rapid-cycling synchrotron (RCS) is required to provide 1 MW pulsed protons to the spallation neutron target and the 50 GeV main ring. Since the RCS finally accelerates very high intensity beam such as 8.3 × 1013 ppp, the secondary electron cloud may affect the accelerator performance. We measured the secondary electron emission from the TiN coating surface and the ferrite sample. By using these measurement results, we estimated the effect of the electron cloud made by the emitted secondary electron at present beam parameters. 相似文献
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We report the observation of large (approximately 40%) laser-induced above-band-gap transparency in GaAs at room temperature. The induced transparency is present only during the pulse width of the driving midinfrared laser pulses and its spectral shape is consistent with a laser-induced blueshift of the band edge. Our simulations based on the dynamic Franz-Keldysh effect reproduce the salient features of the experimental results, demonstrating, in particular, that the amount of the band edge shift is approximately given by the ponderomotive potential. 相似文献