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81.
The rhodium catalyzed isomerization of α-, β-, and γ-silylated allyl alcohols has been successfully applied to the selective synthesis of acylsilane, α-silyl ketones, and β-silyl ketones, respectively. 相似文献
82.
83.
The regioselective ring-opening reaction of α-methyl-β-propiolactone with 3,3-ethylene-dioxybutylmagnesium bromide in the presence of copper(I) catalyst afforded 2-methyl-6-oxoheptanoic acid, which was easily converted into (E)-3,7-dimethyl-2-2-octene-1,8-diol in good yield. 相似文献
84.
Hisashi Odani Masaki Uchikura Yukimasa Ogino Michio Kurata 《Journal of membrane science》1983,14(2):193-208
Diffusion and solution behavior of methanol vapor in two diblock copolymers, poly(2-vinylpyridine)—block—polyisoprene [P(2VPbI)] and poly(2-vinylpyridine)—block—polystyrene [P(2VPbS)], was studied by the weighing method at 25°C. The domain structure of films of both copolymers showed an alternating lamellar arrangement. Methanol is a good solvent for P2VP, but a nonsolvent for PI and PS. Methanol dissolved exclusively in the P2VP phase of the copolymers. For both copolymer systems, absorption and desorption processes of non-Fickian type were observed as characterized by a thickness anomaly. However, the magnitude of the deviations from purely Fickian behavior was small, and the integral diffusion coefficient, D?, was obtainable with reasonable accuracy. At low and medium concentrations, D? for P(2VPbI) was greater, by about one order of magnitude, than that for P2VP, while D? for P(2VPbS) was lower than that for P2VP. A similar trend was observed in plots of the permeability coefficient against the vapor pressure of methanol. The results indicate that the rubbery PI phase may facilitate the transport of penetrant molecules in the P(2VPbI) film. On the other hand, the glassy PS phase in the P(2VPbS) film merely interferes with the transport of methanol molecules. 相似文献
85.
Norio Kobayashi Tamotsu Fujisawa 《Journal of polymer science. Part A, Polymer chemistry》1972,10(9):2591-2600
Poly(sulfenyl thiocarbonates) have been prepared for the first time by the stepwise condensation of chlorocarbonylsulfenyl chloride with diols and dithiols. The polymers were obtained in high yield. Generally they were crystalline solids and were soluble in chlorinated hydrocarbons. On treatment with benzyl mercaptan in the presence of triethylamine, the polymers afforded a diol, carbonyl sulfide, and a disulfide compound. This reaction was extended to the preparation of alternating copolydisulfides. 相似文献
86.
87.
We have observed the Fano-Kondo antiresonance in a quantum wire with a side-coupled quantum dot. In a weak coupling regime, dips due to the Fano effect appeared. As the coupling strength increased, conductance in the regions between the dips decreased alternately. From the temperature dependence and the response to the magnetic field, we conclude that the conductance reduction is due to the Fano-Kondo antiresonance. At a Kondo valley with the Fano parameter q approximately 0, the phase shift is locked to pi/2 against the gate voltage when the system is close to the unitary limit in agreement with theoretical predictions by Gerland et al. [Phys. Rev. Lett. 84, 3710 (2000)]. 相似文献
88.
Observation of "partial coherence" in an Aharonov-Bohm interferometer with a quantum dot 总被引:1,自引:0,他引:1
We report experiments on the interference through spin states of electrons in a quantum dot (QD) embedded in an Aharonov-Bohm (AB) interferometer. We have picked up a spin-pair state, for which the environmental conditions are ideally similar. The AB amplitude is traced in a range of gate voltage that covers the pair. The behavior of the asymmetry in the amplitude around the two Coulomb peaks agrees with the theoretical prediction that the spin-flip process in a QD is related to the quantum dephasing of electrons. These results constitute evidence of "partial coherence" due to an entanglement of spins in the QD and in the interferometer. 相似文献
89.
Numao N Fujii H Fukazawa Y Hanagata N Tanaka K 《Chemical & pharmaceutical bulletin》2004,52(3):377-379
In the sequence Fourier analysis (SFA) of specific interactions such as those between fibroblast growth factors (FGFs)/FGF receptors (FGFRs), bone morphogenetic proteins (BMPs)/BMP receptors (BMPRs), or tumor repressor protein p53/mouse double minute 2 homolog (MDM2), the characteristic frequency peak(s) could be observed with the hydrophobic scale for 20 amino acids as well as 4 nucleotides as the physicochemical parameter, but not successfully with the absolute electronegativity scale. This result implies that these two independent scales should be appropriately selected in various specific ligand-protein interactions, though the critical difference has to be determined. 相似文献
90.
A series of trinuclear Cu(II)Ln(III)Cu(II) complexes with the bridging ligand 2,6-di(acetoacetyl)pyridine have been prepared by one-pot reaction with Cu(NO(3))(2).3H(2)O and Ln(NO(3))(3).nH(2)O in methanol. X-ray crystallographic studies for all the complexes indicate that two L(2)(-) ligands selectively sandwich two Cu(II) ions with the 1,3-diketonate entities and one Ln(III) ion with the 2,6-acetylpyridine entity to form a trinuclear CuLnCu core bridged by the enolate oxygen atoms. Cryomagnetic properties of the complexes are studied with respect to the electronic structure of the Ln ion. 相似文献