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141.
Choji Kashima Tadakuni Tajima Chihiro Higuchi Yoshimori Omote 《Journal of heterocyclic chemistry》1984,21(2):345-347
From the rate constants of the reaction with pyrrolidine, the reactivities of 3-(1-azolyl)-2-alken-1-ones with nucleophiles were evaluated to be rather high. Especially the reactivities of the quaternary salts of 3-(1-imidazolyl)-2-alken-1-ones were nearly equal to those of 3-chloro-2-alken-1-ones. In conclusion, 3-(1-imidazolyl)-2-alken-1-ones satisfied the practical requirements for the starting materials of the synthesis of 3-hetero-substituted 2-alken-1-ones. 相似文献
142.
Yoshinori Fujimoto Miki Kimura Akihiro Takasu Fathy A.M. Khalifa Masuo Morisaki Nobuo Ikekawa 《Tetrahedron letters》1984,25(14):1501-1504
Deuterated stigmasterols (10, 11 and 12) were chemically synthesized and fed to silk-worm larvae. GC-MS analysis of the metabolites, cholesterol (4) and desmosterol (6), indicates the migration of 25-hydrogen to C-24 position during stigmasterol dealkylation. 22,24(28)-Dienes(8a and 8b) were shown to be converted to 22,24-diene (5), desmosterol and cholesterol. 相似文献
143.
144.
Nobuhiro Kodama Kiyoaki Tanaka Taizo Utsunomiya Yoshio Hoshino Fumiyuki Marumo Nobuo Ishizawa Masanori Kato 《Solid State Ionics》1984,14(1):17-24
Integrated intensities of X-ray reflections from a barium chloride fluoride single crystal were measured at 24, 180, 289, 402, 467 and 610°C. The intensities were used for the determination of the anharmonic potential parameters up to the third order. Harmonic potential parameters for each ion were obtained from the temperature dependence of thermal parameters, and anharmonic potential parameters were determined by the least-squares procedures, utilizing the temperature factor formalism based on the cumulant expansion. As a result, it has been found that the Ba2+ and Cl? ions show an anharmonicity, while no significant anharmonic effect was detected for the F? ion. From the potential calculated around the Cl? and F? ions, it was found that both Cl? and F? ions diffuse more easily within the (001) plane than along the c axis. 相似文献
145.
At 4.2 K, MnSi has a helical spin structure with a period of 180 Å in the [111] direction. In magnetic fields greater than 4 kOe, a conical spin structure, whose screw axis coincides with the field direction and whose period is independent of the applied field is realized. 相似文献
146.
147.
Nobukatsu Nemoto Hiroji Ishii Manabu Ihara Nobuo Takamiya Koji Ikeda 《Journal of polymer science. Part A, Polymer chemistry》1994,32(13):2457-2467
The oxidation of hydroquinone catalyzed by pyridine-Cu(II) complexes attached to polyorganosiloxane was investigated in the mixed solvent of methanol/water (vol. ratio 2/1). The catalytic oxidation followed Michaelis-Menten-like kinetics. The large k2 term related to a turnover number indicated that the present polymeric catalysts have a remarkable effect on the activation process. The methylene number between the side-chain acid amido and pyridyl groups of the polymeric ligand was shown to be closely related to the appearance of hydrophobic effects in both the substrate-binding and the activation processes as deduced from the Michaelis constant and the thermodynamic and activation parameters. The binding parameters for 4-methoxyphenol with pyridyl-functionalized polyorganosiloxanes supported that the flexible backbone is also effective in the oxidation of hydroquinone. The Cu(II) complexes with pyridyl-functionalized polyorganosiloxane would have the structures distorted from square planar formation, which would promote the reduction of Cu(II) to Cu(I), as concluded from ESR spectroscopy and electrochemical measurement. © 1994 John Wiley & Sons, Inc. 相似文献
148.
On the basis of the heparin-like effect of phosphotungstate (PTA), we have shown that it is useful for the purification of hepatitis-B virus surface antigen (HBsAg) using heparin-Sepharose affinity chromatography. HBsAg was eluted with 0.2-0.6 M NaCl. HBsAg was also eluted with PTA at approximately 1 mM, and the HBsAg fraction thus obtained contained fewer impurities than the corresponding fraction eluted with NaCl. Moreover, PTA yielded HBsAg and hepatitis-B virus e-antigen simultaneously. PTA may specifically reduce the affinity of HBsAg for heparin as well as simply competing with heparin for an anion-binding site of HBsAg. Residual PTA in the eluate was easily decomposed by alkalization, which was useful for subsequent studies. 相似文献
149.
150.
Precise temperature and polarization dependences of Raman spectra have been investigated for fully oxygenated twin-free YBa2Cu3O7 single crystals. We have found a striking superconductivity-induced x−y anisotropy in the temperature behavior of the 340 cm−1 line: the magnitudes of the softening and broadening are quite different in the xx-and yy-polarizations. This anisotropy suggests a contribution of the CuO-chain superconductivity with a pairing symmetry different
from that for the CuO2 plane, or indicates that the superconducting gap amplitudes are different in the k
x and k
y directions. The d+s gap symmetry is the only realistic symmetry in the case of Δx≠Δy.
Fiz. Tverd. Tela (St. Petersburg) 40, 403–412 (March 1998)
Published in English in the original Russian journal. Reproduced here with stylistic changes by the Translation Editor. 相似文献