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[reaction: see text] We have developed an efficient copper-catalyzed allylation of carbonyl derivatives using allyl(2-pyridyl)silanes, in which the strong directing effect of the 2-pyridyl group was observed. A useful synthesis and allylation of substituted allyl(2-pyridyl)silanes is also described. 相似文献
23.
De-Qi Yuan Yuewei Zhao Makoto Fukudome Kahee Fujita 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):125-129
One or two coumarin units were incorporated to the primary face of γ-cyclodextrin (γ-CD), and the resultant coumarin derivatives
were employed to harvest the chemical energy generated in the reaction of bis(trichlorophenyl)oxalate with hydrogen peroxide.
In comparison with the coumarin without CD cavity for molecular recognition, the coumarin–CD conjugates demonstrated much
higher chemiluminescence inetensity, indicating that the CD moiety remarkably improves the chemical energy transfer. 相似文献
24.
Chisuzu Tokoh Keiji Takabe Junji Sugiyama Minoru Fujita 《Cellulose (London, England)》2002,9(3-4):351-360
Acetobacter
xylinum was cultured in Schramm–Hestrin medium containing pectin (pectin medium), xylan (xylan medium), or glucomannan (mannan medium). X-ray diffractometry revealed that xylan and glucomannan affected the size of the cellulose crystals and their d-spacing values. Solid-state cross polarization magic angle spinning carbon-13 nuclear magnetic resonance spectroscopy indicated that the ratio of cellulose I was reduced by the addition of polysaccharides. These effects were more remarkable on the cellulose in the mannan medium than that in the xylan medium, and were scarcely observed in the pectin medium. Electron diffraction analysis revealed that these effects on hemicelluloses along cellulose microfibrils are continuous in the mannan medium and discontinuous in the xylan medium. These findings suggest that the uronic acid in the polysaccharides prevents interactions with cellulose leading to alterations of the structure of the cellulose crystal. 相似文献
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N. Takahashi T. Shimoda Y. Fujita T. Itahashi H. Miyatake 《Zeitschrift für Physik B Condensed Matter》1995,98(3):347-351
Short-lived ions12B (beta-radioactive, T1/2=20.3 ms) sustaining nuclear spin polarization were introduced into superfluid helium at 1.7 K. It was found that the12B ions were transported as charged entities under a static electric field and that the nuclear polarization was maintained throughout the lifetime of12B nuclei. Polarization of12B was determined through beta-NMR method. Snowball, a singly charged microcluster of helium atoms formed around an impurity ion, is responsible for the behaviour and thus constitutes a suitable environment for preserving nuclear polarization of the core ions12B. In a separate experiment snowballs were produced by implanting8Li (T1/2=830 ms) into liquid helium and detected by means of alpha particles from the core ions to guarantee that the snowballs survive longer than the lifetime of12B. 相似文献
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Katsunori Wakabayashi Mitsutaka Fujita Koichi Kusakabe Kyoka Nakada 《Czechoslovak Journal of Physics》1996,46(4):1865-1866
Anoble mechanism of spin polarization is proposed for finite graphite sheet with edge. For graphite ribbon with zigzag edge, there appear peculiar ‘edge states’. These localized states comprise nearly flat band at the Fermi level, which easily causes magnetic instability. Magnetic structure is suggested from Hartree-Fock analysis of the Hubbard model, where huge magnetic moments are induced at around both of edges by weak HubbardU and are coupled antiferromagnetically with each other. 相似文献
30.
Fujita M Nakao Y Matsunaga S Seiki M Itoh Y Yamashita J Van Soest RW Fusetani N 《Journal of the American Chemical Society》2003,125(51):15700-15701
A novel MMP inhibitor, ageladine A (1) with antiangiogenic activity was isolated from a marine sponge Agelas nakamurai. Structure 1 was determined by a combination of spectroscopic and chemical methods to be an unprecedented structure of 4-(4,5-dibromo-1H-pyrrol-2-yl)]-1H-imidazo[4,5-c]pyridin-2-amine. 相似文献