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61.
Stereoselective synthesis of (±)-palitantin has been completed. 相似文献
62.
Stereoselective synthesis of (±)-senepoxyde and (±) crotepoxide is described starting from 2-hydroxymethyl-1, 4-benzoquinone through the retro-Diels-Alder reaction. 相似文献
63.
From 5-acetyl-4-hydroxy-6-methyl-α-pyrone, two phytotoxins, pyrenocine A and B, were synthesized and erroneous β-pyrone structure of the starting compound was corrected on the basis of spectroscopic data. 相似文献
64.
Masami Sawada Masaharu Ichihara Takashi Ando Yasuhide Yukawa Yuho Tsuno 《Tetrahedron letters》1980,21(51):4917-4920
A new set of σo values was determined for all positions of pyridyl and quinolyl groups, reliably excluding steric effect by perihydrogen, on the basis of the rates of the alkaline hydrolysis of substituted 2-methylbenzoates and pyridylmethyl and quinolylmethyl 2-methylbenzoates in 70% aq acetone. 相似文献
65.
Emmanuel Chasseigne Naoyuki Ichihara 《NoDEA : Nonlinear Differential Equations and Applications》2016,23(6):66
This paper is concerned with the ergodic problem for superquadratic viscous Hamilton–Jacobi equations with exponent \(m>2\). We prove that the generalized principal eigenvalue of the equation converges to a constant as \(m\rightarrow \infty \), and that the limit coincides with the generalized principal eigenvalue of an ergodic problem with gradient constraint. We also investigate some qualitative properties of the generalized principal eigenvalue with respect to a perturbation of the potential function. It turns out that different situations take place according to \(m=2\), \(2<m<\infty \), and the limiting case \(m=\infty \). 相似文献
66.
We give conditions assuring that the given section in a surface bundle over the circle is hyperbolic in terms of the ‘‘projection" in the fiber surface according to the Nielsen-Thurston types of the monodromies. 相似文献
67.
Junbo Deng Lu Pu Haibao Mu Guanjun Zhang Shigeyasu Matsuoka Akiko Kumada Kunihiko Hidaka 《Journal of Electrostatics》2013,71(4):739-745
The charge density distribution of the surface leader has never been measured before. Because the surface leader usually covers a long distance, and the surface potential caused by leader discharge is usually very high, this creates difficulties in measuring the potential distribution of the surface leader. In this paper, with a feedback type electrostatic probe based on a field-nullify technique, a charge density distribution scanning system is developed. A two-layer structure pipe is designed to lower the surface potential after discharge. In this way, the surface potential distribution caused by the residual charge of the leader discharge under the application voltage as high as to 40 kV can be measured. The surface charge density distribution including the leader and streamer is perfectly measured, which is in good agreement with the photograph. 相似文献
68.
Nobuhiko Sawaki Toshiki Hikosaka Norikatsu Koide Shigeyasu Tanaka Yoshio HondaMasahito Yamaguchi 《Journal of Crystal Growth》2009,311(10):2867-2874
Adopting anisotropy etching method, a (1 1 1) facet of Si is obtained on a Si substrate and selective area growth (SAG) of GaN is performed with metal-organic vapor phase epitaxy on the facet. The epitaxial lateral overgrowth of (1 1¯ 0 1), (1 1 2¯ 2) GaN is investigated on (0 0 1) and (1 1 3) Si substrate, respectively, and the incorporation properties of Si, C, and Mg elements are discussed in relation to the atomic configuration on the surface. Analyzing the optical and electrical properties of C-doped (1 1¯ 0 1) GaN layer, it is shown that carbon creates a shallow acceptor level. On the thus prepared (1 1¯ 0 1) GaN layer, a light emitting diode (LED) with a C-doped p-type layer is fabricated. 相似文献
69.
H. Nemoto I. Takekuma H. Nakagawa T. Ichihara R. Araki Y. Hosoe 《Journal of magnetism and magnetic materials》2008
A novel method of analyzing the switching field distribution (SFD) and magnetic correlation length of perpendicular magnetic recording media that uses major and minor magnetization loops is proposed. By applying the analysis to a series of capped perpendicular media, we found that a thick capping layer with a low saturation magnetization effectively reduced SFD without rapidly increasing the magnetic correlation length. Transmission electron microscope observation suggests that the SFD is narrowed by the increased uniformity of intergranular exchange coupling via the thick capping layer. Evaluations of recording characteristics demonstrated a close correlation between narrower SFDs and improved recording performance. Reducing exchange coupling dispersion is a clear solution for improving the performance of recording media. 相似文献
70.
Thermal decomposition behaviors of a fluororubber are observed with linear heating mode at constant rate, controlled rate mode and isothermal mode of TG/DTA, and, with isothermal mode of TG/mass-spectrometer. The results suggest that this material decomposes with, at least, three consecutive reactions. From the results of TG/DTA and TGMS in isothermal mode, it is considered that the first reaction is the first-order reaction, the second reaction is chain reaction and the last reaction is vaporization of residue. Supposing these three consecutive reactions, the decomposition behaviors of the rubber is simulated. The observed curves of fraction of mass loss, , against time, t, are well reproduced by the simulation. The relationship between d/dt and is reproduced also, though the differences between observed and the calculated values of d/dt are slightly larger than noise level of d/dt. 相似文献