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排序方式: 共有363条查询结果,搜索用时 15 毫秒
71.
72.
Kentaro Yonesato Hiroyasu Ito Daisuke Yokogawa Kazuya Yamaguchi Kosuke Suzuki 《Angewandte Chemie (International ed. in English)》2020,59(38):16361-16365
Small Agn nanoclusters (n<10) have been emerging as promising materials as sensing, biolabeling, and catalysis because of their unique electronic states and optical properties. However, studying synthesis, structure determination, and exploration of their properties remain major challenges as a result of the low stability of small Ag nanoclusters. Herein, we synthesized an atomically precise face‐centered‐cubic‐type small {Ag7}5+ nanocluster supported by a novel triangular hollow polyoxometalate (POM) framework [Si3W27O96]18?. The cluster showed unique {Ag7}5+‐to‐POM charge transfer bands in both visible and UV light regions. Furthermore, this small {Ag7}5+ nanocluster exhibited an unprecedented ultrastability in solution, despite having exposed Ag sites that can be accessed by small molecules, such as O2, water, and solvents. 相似文献
73.
74.
Quantification of ultrasonic intensity based on the decomposition reaction of porphyrin 总被引:3,自引:0,他引:3
Hiroyasu Nomura Shinobu Koda Keiji Yasuda Yoshihiro Kojima 《Ultrasonics sonochemistry》1996,3(3):1007-S156
A simple method is proposed for quantification of the effective ultrasonic intensity in the reaction vessel based on the decomposition reaction of 5,10,15,20-tetrakis(4-sulfotophenyl) porphyrin (H2TPPS4−). The change of concentration of porphyrin in solution irradiated by the ultrasound wave depends on the irradiation time and the output power of ultrasound generator. The decomposition ratio of porphyrin is defined as the ratio of the concentration of porphyrin after ultrasonic irradiation to that before ultrasonic irradiation. A linear relationship between the decomposition ratio of porphyrin and the concentration Fe3+ in the Fricke solution under sonication was obtained. The decomposition ratio was related to the absorption dose in radiation chemistry. 相似文献
75.
Chuzo Tanaka M.D. Shoji Naruse M.D. Yoshiharu Horikawa M.D. Kimiyoshi Hirakawa M.D. Kazuo Yoshizaki M.D. Hiroyasu Nishikawa M.D. 《Magnetic resonance imaging》1986,4(6):503-508
Proton nuclear magnetic resonance (NMR) spectra were successfully measured in human brain tumor tissues and experimental rat brain tumors. The investigation was performed on clinical materials which consisted of tissue from one normal brain and 36 brain tumors. Normal rat brain tissue and rat glioma implanted in the brain were also analysed. NMR measurements were carried out at the resonance frequency of 99.54 MHz. The proton NMR spectrum of the normal brain consisted of one broad component and eight superimposed sharp peaks. The sharp peaks obtained from the brain tumors varied from those of the normal brain. A decrease in the signal intensity from N-acetyl aspartate was the most common finding in all tumors. Spectral patterns were similar within the same histological types, but varied among the different types. Therefore, 1H-NMR spectra might indicate the metabolism characteristic of each tumor type which would be invaluable for clinical differential dagnosis of brain tumors. 相似文献
76.
Koichi Aoki Hiroyasu Kamo Jingyuan Chen Yoshimasa Hoshino 《Journal of Electroanalytical Chemistry》1997,420(1-2)
A new tetranuclear ruthenium complex in which a metal was bridged radially to three identical metals with acetylene links showed a mixed-valence state in cyclic voltammograms. The peak potential difference for the mixed-valence state was twice the potential difference for a mixed-valence state of the corresponding binuclear complex. This fact suggests stabilization of the mixed-valence state twice by configurational modification of redox centers. However, this is inconsistent with the prediction from the additive pair model of the redox interaction. A quantum chemical model of the redox interaction was presented, in which the potential difference was expressed by the overlap integral S and the nearest neighbor interaction energy between the reduced center and the oxidized one. Application of the theory gave a negative value of S, which demonstrated reasonably the stabilization of the mixed-valence state from a quantum chemical viewpoint. 相似文献
77.
Jeong Y Friggeri A Akiba I Masunaga H Sakurai K Sakurai S Okamoto S Inoue K Shinkai S 《Journal of colloid and interface science》2005,283(1):113-122
The structure of a dual-component organogel consisting of methyl 4,6-O-(p-aminobenzylidene)-alpha-D-glucopyranoside and methyl 4,6-O-(p-nitrobenzylidene)-alpha-D-glucopyranoside in diphenyl ether was investigated with small-angle X-ray scattering (SAXS). The individual components gelatinized the solvent to yield a colorless gel and the gel fiber consisted of the crystal, providing the crystalline peaks at the same diffraction angles as those of the solid samples. When the components were mixed in equimolar ratio and dissolved in diphenyl ether, a yellow gel was formed and the crystalline peaks disappeared. For all compositions, the SAXS profiles were well fitted by a cylinder model. The cross-sectional radius of gyration, r(c), was determined from the cross-sectional Guinier plot (qI vs q(2), where I and q are the scattering intensity and the magnitude of the scattering vector). The value of r(c) reached a minimum of 3.0 nm at the equimolar composition. By correcting the data for the thermal scattering background, we obtained the entire SAXS profile for the equimolar dual-component gel. From this profile, the radial electron density distribution was determined and the radius of the cylinder was estimated to be 2.6 nm. The electron density distribution thus obtained revealed that four gelator molecules are packed in the sectional direction. This model was consistent with the size of the gelator molecules. 相似文献
78.
Adduct formation on the oxygen of a bridging carbonyl causes a very small perturbation of metal—metal stretching frequencies of polynuclear carbonyls. This small shift contrasts with the large change in v(MM) when carbonyl groups are redistributed between terminal and bridging positions; therefore, using low frequency Raman spectroscopy, it is possible to infer the structural relation of C- and O-bonded adduct to the parent carbonyl. Structural inferences for Fe3(CO)12 · AlBr3, Ru3(CO)12 · AlBr3 and Fe2(CO)9 · AlBr3 are given. 相似文献
79.
Takayuki Chujo Isao Saraoka Shinobu Kato Hiroyasu Sato Koichi Fukuhara Hiroatsu Matsuura 《Journal of inclusion phenomena and macrocyclic chemistry》1995,22(1):41-58
Three sodium complexes (bromide, iodide and thiocyanate) of 4,13-diaza-18-crown-6 were studied using Raman and IR spectroscopy and normal coordinate calculations to probe the stoichiometry of the complexes and the variation in the conformation of azacrown moiety on complex formation. complex formation is accompanied by characteristic shifts of the bands, especially of those in the 800–900 cm–1 region. Complexes of both 11 and 21 stoichiometry were observed. Normal coordinate calculations showed the reduction of symmetry of azacrown moiety toC
i
, in contrast to theC
2h
symmetry known for the parent azacrown and potassium thiocyanate complex. 相似文献
80.
The first luminescent rhenium(I)-gold(I) hetero organometallics, Re{phenAu(PPh3)}(CO)3Cl (3) and Re{(PPh3)AuphenAu(PPh3)}(CO)3Cl (4), have been prepared using the gold(I) complex AuCl(PPh3) (PPh3 = triphenylphosphine) and the novel rhenium(I) complexes Re(phenH)(CO)3Cl (5) (phenH = 3-ethynyl-1,10-phenanthroline) or Re(HphenH)(CO)3Cl (6) (HphenH = 3,8-bis(ethynyl)-1,10-phenanthroline). All the present rhenium(I) complexes 3-6 were revealed to possess a facial configuration (fac-isomer) with respect to the three carbonyl ligands. The main frameworks for these new gold(I) organometallics were constructed by the Au-C σ-bonding (with the η1-type coordination) between the ethynylphenanthrolines and the Au(I) phosphine unit. Re(I)-Au(I) heterometallics 3 and 4 have shown single phosphorescence from the 3MLCT excited state and this observation can be interpreted in terms of the efficient intramolecular energy transfer from the Au(I) unit to the Re(I) unit. 相似文献