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991.
Miwako Mori Katsutoshi Hori Masaya Akashi Masanori Hori Yoshihiro Sato Mayumi Nishida 《Angewandte Chemie (International ed. in English)》1998,37(5):636-637
Dry air is the source of molecular nitrogen for reactions with TiL4, Li, and TMSCl (L = Cl, OiPr; TMS = trimethylsilyl). The nitrogen–titanium complexes thus prepared can be used to synthesize indoles, pyrroles, and lactams from carbonyl compounds. Applying this method to 1 provides access to 2 , the key compound in the synthesis of (±)-lycopodine. 相似文献
992.
993.
We consider the local behavior of critical points of the functional as ε → 0. Here, W is a double-well potential and U is a regular domain in ℝn, n ≥ 2. Assuming that {uε}ε>0 is stable for n = 2 and locally energy-minimizing for n = 3, we show that the level sets of solutions converge in an average sense to a stationary (n − 1)-rectifiable varifold. Our study is based on estimates derived from the second variation formula and is entirely local. © 1998 John Wiley & Sons, Inc. 相似文献
994.
Shinji Watanabe Osamu Shishido Miki Murata Yuzuru Masuda 《Macromolecular rapid communications》1998,19(1):75-77
Polymer microspheres with mercapto groups were synthesized by polycondensation of 1,6-dibromohexane and 1,3-propanedithiol in the presence of a polystyrene latex and a nonionic surfactant. The sulfur content of the obtained particles is comparable with the one calculated according to the feed ratio, which shows that the polycondensation proceeds quantitatively in the particles. A higher molar ratio of dithiol against dibromide used in the polycondensation results in microspheres with higher mercapto group content. 相似文献
995.
Cong Wang Masayuki Nogami Yoshihiro Abe 《Journal of Sol-Gel Science and Technology》1999,14(3):273-279
Protonic conduction in 10P2O5·90SiO2 and 20P2O5·80SiO2 (mol %) glasses prepared by sol-gel processing was investigated as a function of the content of molecular water adsorbed in the pores. The results show that the electrical conductivity of the glasses containing adsorbed molecular water varies exponentially with the reciprocal absolute temperature and increases with the increase of the content of the adsorbed molecular water. The double-bonded oxygen and the high affinity of phosphorus for oxygen make protons easily to release and transfer, which is favorable to the protonic conductivity. 相似文献
996.
An efficient enantiospecific synthesis of the (R)‐ and (S)‐enantiomers of flavanone and 2‐methylchromanone is described. The key steps are a C,C‐bond formation by ring opening of a chiral epoxide with a dithiane anion, followed by a Mitsunobu cyclization. The products obtained have high enantiomeric purity. 相似文献
997.
998.
999.
Yoshihiro Sugiyama Yoshiaki Nakata Shunichi Muto Yuji Awano Naoki Yokoyama 《Physica E: Low-dimensional Systems and Nanostructures》2000,7(3-4)
We report on the two spectral holes in the photocurrent of InAs self-assembled quantum dots (SAQDs) embedded in a pin diode irradiated by two different lasers. The estimated homogeneous broadening (Γh) of 25 μeV for InAs SAQDs implies the possibility of high-density multiple wavelength-domain optical memory with the ratio of inhomogeneous broadening to Γh larger than 3300. The dependence of writing power, electric field, and temperature on the Γh was also investigated using hole burning spectroscopy. The Γh broadened not only as the writing power increased over a few W/cm2 but also as the applied field increased. The Γh showed linear dependence on temperature, and the spectral hole was observed up to 80 K. 相似文献
1000.
Yoshihiro Edo Shinnosuke Obi Sigeaki Masuda 《International Journal of Heat and Fluid Flow》2000,21(6)
The influence of Coriolis force on heat transfer in a rotating transitional boundary layer has been experimentally investigated. The experiments have been conducted for local Görtler numbers up to 150. Heat transfer measurements have been performed for a flat plate with nearly uniform heat flux applied to the surface, where the temperature was measured by the thermochromic liquid crystal method. The results indicate that heat transfer is enhanced when Coriolis force acts towards the wall, i.e., on the pressure surface. The velocity measurements under equivalent conditions show that Coriolis instability induces counter-rotating longitudinal vortices which augment the lateral transport of the fluid on the pressure surface. On the other hand, the heat transfer on the suction surface remains at the same level as compared to the case without system rotation. As a consequence, the heat transfer coefficient on the pressure surface is 1.8 times higher than that measured on the suction surface when averaged over the measured surface. 相似文献