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51.
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
52.
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
53.
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
54.
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
55.
Saito Y Ichihara M Okamoto Y Gong X Kuroda C Tori M 《Natural product communications》2012,7(4):423-426
Four new eremophilane-type sesquiterpenoid alcohols were isolated from Cremanthodium helianthus collected in China and their structures established on the basis of spectroscopic analyses. All of them had 9-en-8-one partial structures with one more double bond either delta11, delta11(13), or delta7(11). Two of them had a hydroxy group at C-1 position. 相似文献
56.
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
57.
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
58.
Osamu Shimomura Keisuke Maeno Atsushi Ohtaka Shunro Yamaguchi Junko Ichihara Kiyoko Sakamoto Ryôki Nomura 《Journal of polymer science. Part A, Polymer chemistry》2014,52(13):1854-1861
The reaction of glycidyl phenyl ether (GPE) with 1‐aminoalkanes‐intercalated α‐zirconium phosphate (α‐ZrP·1‐aminoalkane): 1‐aminoalkanes 1‐aminopropane (α‐ZrP·Pr), 1‐aminobutane (α‐ZrP·Bu), 1‐aminooctane (α‐ZrP·Oct), and 1‐aminohexadecane (α‐ZrP·Hed) was carried out at varying temperatures for 1 h periods. Reaction progress was not observed until the reactants were heated to 80 °C or above. On increasing the temperature, the conversion factors increased such that, at 140 °C, conversions of 62% (α‐ZrP·Pr), 60% (α‐ZrP·Bu), 67% (α‐ZrP·Oct), and 64% (α‐ZrP·Hed) were obtained. The thermal stabilities as latent initiators were tested: GPEs reacted with α‐ZrP·Pr, α‐ZrP·Bu, and α‐ZrP·Oct at 40 °C for 360 h achieved conversions of 83, 55, and 59%, respectively. In contrast, the reaction in the presence of α‐ZrP·Hed did not proceed at 40 °C. The order of the thermal stability of GPE in the presence of α‐ZrP·1‐aminoalkane intercalation compounds was: α‐ZrP·Hed > α‐ZrP·Bu ≈ α‐ZrP·Oct > α‐ZrP·Pr. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1854–1861 相似文献
59.
The thermoelectric power of linear chain synthetic metals Nb3X4 (with X=S, Se and Te) was measured from 5 to 300 K. The thermopower is negative indicating a dominant transport by electrons. Common to three compounds, in lower temperature regions the thermopower rises linearly with temperature but soon saturates. With respect to Nb3S4 and Nb3Se4 we have found no special anomaly of the thermopower except for a little higher magnitude.With respect to Nb3Te4 anomalies in the thermopower vs temperature appear at about 80 and 20 K which are explained in terms of the charge- density-wave phase transition from the simultaneous measurement of the resistivity and the observation of the electron diffraction patterns. 相似文献
60.