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排序方式: 共有175条查询结果,搜索用时 15 毫秒
21.
Katsuya Sako Toshiaki Kakehi Shota Nakano Hiroyuki Oku Xu Feng Shen Tetsuo Iwanaga Manami Yoshikawa Kouta Sugahara Shinji Toyota Hiroyuki Takemura Teruo Shinmyozu Michito Shiotsuka Hitoshi Tatemitsu 《Tetrahedron letters》2014
Two novel redox-active 1,3-dithiole (DT) ring-fused 4,5-diazafluorene ligands with crown ether moieties (L1 and L2) were synthesized and characterized. The crystal structure of L1 was studied. The electrochemical and spectroscopic properties of these new ligands, as well as the corresponding bis(bipyridine)ruthenium(II) complexes [4: Ru L1(bpy)2 and 5: Ru L2(bpy)2], were also been investigated. 相似文献
22.
Oku N Krishnamoorthy R Benson AG Ferguson RL Lipton MA Phillips LR Gustafson KR McMahon JB 《The Journal of organic chemistry》2005,70(17):6842-6847
The absolute stereochemistry of the three unresolved structural components in neamphamide A (1) was determined to be (R)-beta-methoxy-L-tyrosine, (2R,3R,4S)-4-amino-7-guanidino-2,3-dihydroxyheptanoic acid, and (2R,3R,4R)-3-hydroxy-2,4,6-trimethylheptanoic acid. Stereochemical assignments were made by chemical degradation of 1, derivatization of the resulting products, and then spectroscopic and chromatographic comparison of the derivatives with synthetically prepared standards. Using the same analytical protocol developed for 1, the beta-methoxytyrosine residue in papuamide B (2) was found to be (R)-beta-methoxy-D-tyrosine. This represents a rare example of divergent stereochemistry in an unusual amino acid residue that is present in two closely related classes of peptides. 相似文献
23.
Boron nitride (BN) nanohorns were synthesized by arc-melting YB6 powders. Method, and atomic structure models for BN nanohorns encaging Y@B36N36 were proposed from high-resolution electron microscopy. The molecular mechanics calculation indicated that BN clusters with metal atoms would be stabilized by being encaged in double-walled BN nanohorns. 相似文献
24.
Albrecht H Binder U Harder G Lembke-Koppitz I Philipp A Schmidt-Parzefall W Schröder H Schulz HD Wurth R Donker JP Drescher A Matthiesen U Scheck H Spaan B Spengler J Wegener aD Gabriel JC Schubert KR Stiewe J Waldi R Weseler S Brown NN Edwards KW Frisken WR Fukunaga C Gilkinson DJ Gingrich DM Goddard M Kapitza H Kim PC Kutschke R MacFarlane DB McKenna JA McLean KW Nilsson AW Orr RS Padley P Patel PM Prentice JD Seywerd HC Stacey BJ Yoon T Yun JC Ammar R Coppage D Davis R Kanekal S Kwak N 《Physical review letters》1986,56(6):549-552
25.
S. Nakajima M. Kikuchi Y. Syono K. Nagase T. Oku N. Kobayashi D. Shindo K. Hiraga 《Physica C: Superconductivity and its Applications》1990,170(5-6):443-447
The Tc and oxygen content of TlBa2CaCu2Oy have been investigated by quenching experiments, in which the heat-treated samples were dropped into liquid nitrogen. The oxygen loss, v, of TlBa2CaCu2Oyo − v was determined by thermogravimetry in a nitrogen atmosphere using an oxygen-annealed specimen of TlBa2CaCu2Oyo and also by measurements of the weight differences before and after quenching. Tc increased from 80 K of the oxygen-annealed specimen up to about 110 K with increasing oxygen loss up to v = 0.035 by annealing at 500°C in a nitrogen atmosphere. Judging from the high Tc above 110 K achieved by a small oxygen loss about v = 0.035, the as-sintered oxygen-annealed TlBa2CaCu2Oyo specimen was in the over-doping state and probably has an oxygen vacancy of 7 − yo0. 相似文献
26.
Kichinosuke Hirokawa Shigeru Suzuki Kenji Abiko Hiroshi Kimura Masaoki Oku 《Journal of Electron Spectroscopy and Related Phenomena》1981,24(2):243-253
A method is proposed for semi-quantitative determination of the thickness or composition of a covering layer on a solid by XPS or by micro-AES using neither a series of standard samples nor argon-ion etching. In the case of XPS, the thickness or relative composition of the covering layer is calculated by means of the intensity ratio between one element and another in a specimen and using physical parameters such as inelastic mean free paths of electrons and photoionization cross-sections.In the case of AES, the physical parameters for the quantification can be eliminated by using the ratio of the relative intensity for two elements in the sample to that in a suitable, comparable reference. 相似文献
27.
The thermal decomposition of dialkali metal salts of β- and γ-hydroxyketone tosyl-hydrazones in refluxing DME produced pyrazoles and pyridazines, respectively. 相似文献
28.
Quantitative ESCA has been used for studying the surface of mixed precipitates. When the precipitation is complete and homogeneous, as with titanium and zirconium hydroxides, almost complete correlation is found between the atomic ratio of the elements in the precipitate and that estimated by the Hirokawa-Ebel method, but not for incomplete mixed precipitation, as with copper and silver hydroxides. When precipitated copper and silver are reduced to the metals with iron or zinc, the surface is enriched in copper. 相似文献
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