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排序方式: 共有575条查询结果,搜索用时 46 毫秒
61.
Jian-Yu Zheng Shuichi Noguchi Kenjo Miyauchi Masahiro Hamada Kazushi Kinbara Kazuhiko Saigo 《Fullerenes, Nanotubes and Carbon Nanostructures》2001,9(4):467-475
A series of [60]fullerene bis-adducts having a π-electron-rich aromatic ring as a donor in a face-to-face arrangement were synthesized by the bis-cyclopropanation of [60]fullerene with tether-linked bis-malonates. One of the bis-adducts showed a photoinduced intramolecular electron transfer which caused the dramatic quenching of its fluorescence in a polar solvent. 相似文献
62.
To functionalize the surface of nanoparticles with phenyl groups for subsequent cross-linking with aromatic molecules by mutual interactions, we prepared functional nanoparticles (d = 3 nm) by silanization with phenyl-triethoxysilane. The nanoparticles had Fe(2)O(3) cores conjugated to phenyl groups; this was confirmed by Fourier transform infrared (FT-IR) spectroscopy and absorption spectrophotometry. The typical C-H and C-C peaks and the absorption at 240 nm, which corresponds to aromatic rings, were detected in the spectroscopic results for the phenyl group-modified nanoparticles. The nanoparticles could ionize aromatic (colchicine, reserpine, and bradykinin peptide) and nonaromatic (L-α-phosphatidylethanolamine,dioleoyl, and polyethylene glycol) molecules by nanoparticle-assisted laser desorption/ionization mass spectrometry. The nanoparticles worked as a selective trap and an ionization-assisting reagent in mass spectrometry for the aromatic molecular targets. 相似文献
63.
Variation of Fructooligosaccharides and their Metabolizing Enzymes in Onion Bulb (Allium cepa L. cv. Tenshin) During Long-term Storage 总被引:1,自引:0,他引:1
Noureddine Benkeblia Keiji Ueno Shuichi Onodera Norio Shiomi 《Journal of food science》2005,70(3):S208-S214
ABSTRACT: The objective of this study was to assess the status of fructooligosaccharides (FOS) in onion bulbs ( Allium cepa L. cv. Tenshin) and their metabolizing-enzymes—1-fructoexohydrolase (1-FEH), 1-kestose hydrolyzing enzyme (1-KH), fructan:fructan 1F -fructosyltransferase (1-FFT) and fructan:fructan 6G -fructosyltransferase (6G-FFT)—during storage at 15°C. Fructose varies slightly, whereas 1-kestose peaked after 6 wk and then decreased progressively during the last 18 wk of storage. Lower degree of polymerization (DP) 3 to 6) FOS, higher (DP 7 to 12) FOS, total FOS, and total carbohydrates showed similar and close patterns during 24 wk. They varied slightly at the beginning of the storage period; afterward they decreased progressively and regularly during the last 20 wk of storage. 1-FEH and 1-KH activities were low but peaked abruptly after 12 and 16 wk, respectively, after which they decreased to levels higher (1-FEH) or similar (1-KH) to those observed at the beginning of the storage. Surprisingly, 1-FFT activity showed similar pattern to the variation of 1-KH hydrolyzing activity; on the other hand, 6G-FFT, although higher, was stable during 16 wk but decreased after that. The results allowed us to associate FOS to the dormancy and sprouting states, and the peaks of the degrading enzymes were shown to signal the release of dormancy of onion bulb. 相似文献
64.
Takayuki Tomaru Shinji Miyoki Masatake Ohashi Kazuaki Kuroda Takashi Uchiyama Toshikazu Suzuki Akira Yamamoto Takakazu Shintomi Akitoshi Ueda Daisuke Tatsumi Shuichi Sato Koji Arai Masaki Ando Koji Watanabe Kenji Nakamura Masahiko Watanabe Kazuhiko Ito Izumi Kataoka Hiroaki Yamamoto Brett Bochner Yaron Hefetz 《Applied optics》2003,42(7):1306-1307
65.
Takashi Hirano Yuiko Kazahaya Akio Nakamura Toshihiro Miyao Shuichi Naito 《Catalysis Letters》2007,117(1-2):73-78
The effect of addition of In and Pb on the reduction of N2O by CO was studied over SiO2 supported Pd catalysts, using a closed gas circulation system as well as in-situ infrared spectroscopy. Formation of intermetallic
compounds such as Pd0.48In0.52, Pd3Pb and Pd3Pb2 was observed which caused a drastic enhancement of the rate of N2 formation. The infrared spectroscopic analyses revealed a weakening of the adsorption strength of CO on Pd metal by the formation
of intermetallic compounds, which is likely the main reason for the enhancement of the reaction rate. From a kinetic investigation
as well as in situ FT-IR observation during the N2O-CO reaction, a redox mechanism was proposed involving the oxidation of the surface by N2O followed by its reduction by CO. Over Pd/SiO2, the former process seems to be the rate limiting step because of the inhibition of N2O activation by strongly adsorbed CO. By adding In or Pb, the rate limiting step shifted to the latter process, which resulted
in a large enhancement in the rate of N2 formation. 相似文献
66.
Takao Yamamoto Shuichi Okuda Masatoshi Fujishiro 《Journal of Nuclear Materials》1988,160(2-3):247-252
A thin titanium layer with uniformly absorbed tritium (T/Ti ˜1.0) was bombarded by 390 keV D3+ ions (130 keV per deuteron). Bombardment was performed at low (111 K) and room temperatures up to fluences of 5.9 × 1018 D/cm2 and 3.0 × 1018 D/cm2, respectively. Depth profiles of tritium up to a depth of 0.8 mg/cm2 (˜1.8 μm) were measured and the change of the profile with fluence was investigated by means of the T(d, )n nuclear reaction. At both of the temperatures, a dip was formed on the depth profile of tritium at the depth around the projected range, indicating that the deuteron bombardment induced the migration of tritium against the concentration gradient. At the low temperature, the dip showed a gradual growth with fluence and saturation of the growth at the higher fluences, which could not be described by the existing model for isotope mixing. The spectrum of protons from the D(d, p)T reaction obtained in the same measurement suggested that the release of deuterium suddenly started at the final stage of the present bombardment. The dip formed at room temperature was larger than that at the low temperature. The migration of tritium induced by the bombardment is discussed on the basis of the experimental results obtained. 相似文献
67.
Shunichi Hasegawa Takahiro Nishiwaki Hitoe Habuchi Shoji Nitta Shuichi Nonomura 《Fullerenes, Nanotubes and Carbon Nanostructures》1995,3(2):163-178
CPM spectra of the fullerene film was measured to obtain the below gap absorption. The optical energy gap Eo was obtained by using the Tauc's plots. Eo did not change so much with the intercalated impurities. The absorption due to intercalated impurities was found below 1.6eV. 相似文献
68.
The basic characteristics and charge storage behavior of metal-alumina-silicon dioxide-silicon(MAOS) field effect transistors have been investigated as a function of the oxide thickness. The typical charge storage behaviors have also been measured on devices with SiO2 films of 50 Å and Al2O3 films of 700 Å and the results are interpreted in terms of electron and hole transport processes across thin SiO2 layer and electron injection from Al electrode by tunneling mechanism. In the MAOS structure, the shift of threshold voltage from initial state is within about 23 V and can be reversibly controlled, more than 106-times at least, by alternate electric fields under suitable stressing condition. It is considered that the charge storage time is practically infinite at room temperature and of the order of 106 hr at 150°C. The failure behaviors of device parameters under the repeated field stressing and cycles can be also accounted for in terms of electron accumulation within Al2O3 films and at interfaces between Al2O3 and SiO2 films. 相似文献
69.
The catalytic behavior of beryllia-supported Pd catalyst for the direct decomposition of NO was compared with that of silica supported one. The TOF of NO decomposition was one order of magnitude larger in the case of Pd/BeO. Over Pd/SiO2, the TOF was increased with the increase of the Pd particle size. On the contrary, over Pd/BeO smaller Pd particles exhibited higher TOF for NO decomposition suggesting some strong electronic or structural interaction between Pd and beryllia. TPD spectra of NO(a) over reduced catalysts indicated that NO was adsorbed on Pd/SiO2 more strongly than on Pd/BeO, and dissociation of NO(a) was easier on the former catalyst. FT-IR spectra of adsorbed NO at room temperature followed by the evacuation at elevated temperatures confirmed this. TPD spectra of O2 desorbed from oxidized surface indicated that adsorption strength of O(a) is one of the most important factors to determine the catalytic activity of NO decomposition over supported Pd catalysts. 相似文献
70.
The mechanism of acetaldehyde and ethanol formation from the CO + H2 reaction below atmospheric pressure has been investigated by combining infrared spectroscopic measurement and 13CO and C18O isotopic tracer studies with reaction kinetics. The rates of acetaldehyde and ethanol formation are markedly dependent on the nature of metal precursors employed. The addition of sodium cations depresses the total catalytic activity, while the selectivity for ethanol is increased by the addition of manganese cations. From the behavior of surface species under reaction conditions, it is concluded that acetaldehyde is formed through the following two steps: (i) CO insertion into C1 species which are reaction intermediates for not only hydrocarbons but also for the methyl group in acetaldehyde, and (ii) subsequent formation of acetate ions whose one oxygen atom is supplied from the support, finally producing acetaldehyde. Differences in 18O distribution in acetaldehyde and ethanol during the C18O + H2 reaction indicate that ethanol is not produced via direct hydrogenation of acetaldehyde. 相似文献