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71.
Mariko Kitajima Mio Nakamura Hiromitsu Takayama Kazuki Saito Joachim Stöckigt Norio Aimi 《Tetrahedron letters》1997,38(52):1017-9000
The regeneration of plantlets was successful from Ophiorrhiza pumila callus cultures, from which a new glucosyloxy camptothecin, 9-β-glucosyloxycamptothecin, together with 15 metabolites including six camptothecin-related alkaloids was isolated. (3S)-Deoxypumiloside, one of the plausible biogenetic precursors of camptothecin, could not be found, whereas the (3R) epimer was isolated from the regenerated plants. 相似文献
72.
Structural evolution of the solution of tetraethoxysilane hydrolyzed with [H2O]/[Si(OC2H5)4] = 2 under acidic condition has been investigated by rheological measurements. It was found that the solution behaves as a Newtonian liquid up to a highly viscous state and shows spinnability before gelation when the evaporation of the solvent is allowed during gelation reaction. On the other hand, the solution behaved as a non-Newtonian liquid in the viscous state, showing no spinnability when the evaporation of the solvent was not allowed during the reaction. It was indicated from the Casson plots that the spinnable solution prepared in the open system has no yield stress up to highly viscous states, whereas the non-spinnable solution prepared in the closed system has a yield stress at viscous states. It was proposed that the increase in viscosity of the open system solution is attributable to the concentration of the sol particles whereas that of the closed system solution is attributable to the formation of the three dimensional network in the solution. 相似文献
73.
Kiyoshi Kitahara Hiromitsu Yanagimoto Namiko Nakajima Hisao Nishi 《Journal of heterocyclic chemistry》1992,29(1):167-169
The synthesis of 4,11-dialkylthioquinacridones and 5,12-dialkyl-4,11-dialkylthioquinacridone from o-alkylthioanilines and diethyl 2,5-dioxo-1,4-cyclohexanedicarboxylate is described. These compounds are easily soluble in organic solvents in contrast to unsubstituted quinacridone. 相似文献
74.
Yoshiaki Hidaka Takashi Taniguchi Takashi Kamesawa Hiromitsu Masaoka Koji Inami Hiroyuki Kawano 《国际化学动力学杂志》1993,25(4):305-322
Thermal decomposition of formaldehyde diluted with Ar was studied behind reflected shock waves in the temperature range of 1200–2000 K at total pressures between 1.3 and 3.0 atm. The study was carried out for compositions from the concentrated mixture, 4% CH2O, to the highly dilute mixture, 0.01% CH2O by using time-resolve IR-laser absorption and IR-emission, and a single-pulse technique. From a computer-simulation study, the mechanism and the rate-constant expressions that could explain all of our data and previously reported ARAS data were discussed. This data obtained over a wide concentration range from 50 ppm CH2O to 4% CH2O were satisfactorily modeled by a five-reaction mechanism. © 1993 John Wiley & Sons, Inc. 相似文献
75.
A trans type of doubly N-confused isomer of NCP (trans-N2CP) was synthesized via N-confused fused porphyrin (NcFP). The aromatic feature of trans-N2CP due to 18pi electronic system is contrasted to the weak aromaticity of cis-derivative. The solid-state structure of trans-N2CP exhibits pi-stacking column, while the Cu(III) complex shows 1-D rodlike hydrogen bonding chain comparable with the zigzag hydrogen-bonding chain of cis-derivatives. 相似文献
76.
Hiromitsu Maeda Prof. Dr. Yukio Kusunose Masahiro Terasaki Yoshihiro Ito Chikoto Fujimoto Rika Fujii Takashi Nakanishi Dr. 《化学:亚洲杂志》2007,2(3):350-357
X‐ray analysis of some 1,3‐dipyrrolyl‐1,3‐propanediones synthesized from pyrroles and malonyl chloride derivatives revealed 1D supramolecular networks formed by N? H???O?C interactions in the solid state. Micro‐ and nanometer‐scale morphologies of porous, fibrous, and sheet structures were fabricated by hydrogen‐bonding interactions and determined by fine‐tuning the substituents and the solvents used. Of the unique polymorphs, ordered 2D lamellar sheet structures of the derivatives with long alkyl chains (C16H33, C14H29, and so on) were constructed by van der Waals hydrophobic effects between aliphatic chains as well as hydrogen bonding. 相似文献
77.
Okamoto Y Kawano M Kawabata T Kubota T Hiromitsu I 《The journal of physical chemistry. B》2005,109(1):288-296
The elucidation of a molecular structure of the active sites (i.e., the Co-Mo-S phase) of Co-Mo hydrodesulfurization catalysts has received extensive attention. In the present study, we unambiguously determined, for the first time, the NO adsorption behavior and magnetic property of the Co-Mo-S phase by preparing unique Co-Mo/Al(2)O(3) catalysts (CVD-Co/MoS(2)/Al(2)O(3)), in which all the Co atoms are present as the Co-Mo-S phase. The catalysts were characterized by NO adsorption (pulse technique and FTIR), Co K-edge XANES, and the magnetic susceptibility and effective magnetic moment of Co. Nitric oxide molecules were adsorbed on 33% of the Co atoms in CVD-Co/MoS(2)/Al(2)O(3) after sulfidation and on only half of the Co atoms even after an H(2)-treatment of the sulfided catalyst at 573-673 K. The Co atoms in CVD-Co/MoS(2)/Al(2)O(3) exclusively exhibited an antiferromagnetic property, indicating that even-numbered Co atoms are interacting with each other in the Co-Mo-S phase. A Co-Mo/Al(2)O(3) catalyst, prepared by a conventional impregnation technique, was composed of the antiferromagnetic Co sulfide species as observed in CVD-Co/MoS(2)/Al(2)O(3) in addition to Co(9)S(8). On the basis of the NO adsorption behavior and magnetic property, it is empirically proposed that the structure of the Co-Mo-S phase is represented as a Co sulfide dinuclear cluster located on the edge of MoS(2) particles. The magnetic property of Co/Al(2)O(3) sulfide catalysts depended on the preparation method. 相似文献
78.
Yong Jin Lim Sung Hoon Kim Hiromitsu Hamano Toru Takagishi Nobuhiko Kuroki 《Journal of polymer science. Part A, Polymer chemistry》1986,24(3):503-510
Powdered Nylon 66 was prepared as a model of amorphous polymers. The resultant powder polyamide was composed of only amorphous regions. The extent of uptake of the acid azo dyes, a homologous series of methyl orange derivatives, by the polymer was measured in an aqueous solution. The first binding constants and the thermodynamic parameters in the course of the binding were evaluated. The thermodynamic behaviors obtained are very similar to those of crosslinked polyvinylpyrrolidone. The favorable free energy of the binding is accompanied by an entropy gain and an exothermic enthalpy change. The shorter the alkyl chain of the dyes, the more negative is the enthalpy change and, hence, the smaller is the entropy change. The thermodynamic data for butyl orange showed that the binding process is athermal and is wholly an entropic effect. The binding of the dyes to the matrix is entropically favorable as a result of the operation of the hydrophobic effect. In addition, an electrostatic force is operative between the sulfonate group on the dyes and the terminal amino groups on the polyamide. 相似文献
79.
The RBCC (RING finger, B-box type zinc finger, coiled-coil domain) motif family contains a large number of proteins implicated in many cellular processes, including vesicle exocytosis. The acrosome reaction, the sperm exocytotic event that is required for fertilization, involves essentially the same process of intracellular membrane fusions as vesicular exocytosis in somatic cells. We have previously isolated a haploid-germ-cell-specific gene designated haprin, which encodes a RBCC motif protein that plays a role in the acrosome reaction of sperm by mediating protein complex formation via the RBCC motif. In this review, we describe the potential role of Haprin in the molecular mechanisms of acrosome reaction, as compared with some other RBCC proteins. The conserved structure and localization of the Haprin protein in human and mouse suggest an indispensable role for Haprin in the functioning of mammalian sperm. 相似文献
80.
Kitajima M Fujii N Yoshino F Sudo H Saito K Aimi N Takayama H 《Chemical & pharmaceutical bulletin》2005,53(10):1355-1358
Two new monoterpene glucosides, demethylsecologanol and 3'-O-glucosylsenburiside II, were isolated from Ophiorrhiza liukiuensis (Rubiaceae) together with 23 known compounds, including camptothecins and beta-carboline-type alkaloids. Their structures were determined by spectroscopic analysis. 相似文献