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排序方式: 共有206条查询结果,搜索用时 15 毫秒
41.
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
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Quantitative structure-activity relationship (QSAR) analysis of 3-phenyl-1-indanamines, 1-amino-4-aryltetralins, and 6-phenylpyrrolo[2,1-a] isoquinolines has been performed for catecholamine-uptake inhibition activities. Similar equations were obtained for these series of congeners indicating a common tendency that the increase in hydrophobicity of the substituents on the primary phenyl ring (ring C) enhances the activity, and the important aromatic ring which interacts with the receptor is this ring C. It was also indicated that the effect of the introduction of the second N-methyl group differs depending on the series of congeners. These results were used to characterize a binding model for a pharmacophore, which comprised a phenyl ring and a basic nitrogen. This model defined the necessary three-dimensional features leading to the uptake inhibition, and degree of fitness with this model predicted the strength of the activity. Furthermore, it appeared likely that a substituent existing in a specific region of the inhibitor molecule causes a steric hindrance with the receptor site and reduces the activity. 相似文献
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Kozo Arai Shigeo Komine Michiharu Negishi 《Journal of polymer science. Part A, Polymer chemistry》1970,8(4):917-927
In order to elucidate the termination mechanism in the graft copolymerization of methyl methacrylate to unreduced and reduced wool fibers, graft copolymers were prepared by means of the LiBr–K2S2O8 redox sytem without homopolymer or with K2S2O8 only with homopolymer at 30°C. The graft polymers (PMMA) were isolated almost completely from the wool trunk by an HCI-digestion method, leaving a few amino acid residues on the end of the graft polymers. Dinitrophenylation of the isolated polymer was carried out by various methods. The spectral features were almost the same as for dinitrophenylated amino acids of the usual type such as valine, leucine, and methionine, with a maximum in ultraviolet light at 340–345 mμ. From colorimetric analysis of the number of dinitrophenylated amino acid endgroups and the measurement of the average molecular weight of the isolated polymers, the number of amino acid endgroups linked to the graft polymers was calculated to be about one and two per polymer chain in reduced and unreduced wool, respectively, independent of the reaction system, graft-on, and molecular weight of graft polymers. From these facts, it was suggested that the most of isolated polymers are the truly grafted polymers. Also, the termination reactions have been explained as follows. In the unreduced wool, the restriction of mobility of the radical end might be expected, for the confinement of growing chains in wool fibers. This would be favorable to termination by recombination rather than by the disproportionation, since the former has a lower activation energy than the latter. Thus, the formation of intra- or intermolecular crosslinks might be considered between polypeptide chains. On the other hand, in the reduced wool, the mobility of graft polymers might be considered to be greater than that of unreduced wool because of its open structure. Therefore, termination would be principally by disproportionation between graft polymer radicals. 相似文献
47.
Structural changes of graphite surfaces induced by femtosecond (fs) laser excitation at a fluence regime above 75 mJ/cm2 are reported. Direct imagings of excited surfaces by means of scanning tunneling microscopy have revealed that fs-excitations induce nanometer-scaled craters, together with sp3-type interlayer-bonded domains. The nano-craters are characterized by atomically-flat bottom and two atomic-steps in depth, indicating the exfoliation of fragmentary intact-sheets of double-layer of graphite. The theoretical simulation has shown that the required energy for the double-layer ablation is much lowered by the help of interlayer-bond formation, compared to the sequential removal of individual graphene layers. Based on the experimental and theoretical results, the exfoliation of double graphite layers, that is a novel mode of laser-ablation observed first, indicates clearly that the formation of strong interlayer bonds between the two atomic layers is a crucial step in the ablation process. 相似文献
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Inami Wataru Fukuta Masahiro Masuda Yuriko Nawa Yasunori Ono Atsushi Lin Sheng Kawata Yoshimasa Terakawa Susumu 《Optical Review》2015,22(2):354-358
Optical Review - A plastic scintillator film for use in an electron beam excitation-assisted (EXA) optical microscope is characterized. The thin film scatters an incident electron beam weakly and... 相似文献
50.
Gabyshev N Abe K Abe K Adachi I Aihara H Asano Y Aulchenko V Aushev T Bahinipati S Bakich AM Balagura V Barberio E Bartel W Bay A Bedny I Bitenc U Bizjak I Bondar A Bozek A Bracko M Browder TE Chen A Chen WT Cheon BG Chistov R Choi Y Chuvikov A Cole S Dalseno J Danilov M Dash M Drutskoy A Eidelman S Garmash A Gershon T Gokhroo G Golob B Haba J Hayasaka K Hayashii H Hazumi M Hokuue T Hoshi Y Hou S Hou WS Hsiung YB Ikado K Imoto A Inami K Itoh R Iwasaki M Iwasaki Y Kang JH Kawasaki T Khan HR 《Physical review letters》2006,97(20):202003
We report the first measurements of the doubly charmed baryonic B decays B --> Lambda c+ Lambda c- K. The B+ --> Lambda c+ Lambda c- K+ decay is observed with a branching fraction of (6.5(-0.9)(+1.0)+/-1.1+/-3.4)x10(-4) and a statistical significance of 15.4sigma. The B0 --> Lambda c+ Lambda c- K0 decay is observed with a branching fraction of (7.9(-2.3)(+2.9)+/-1.2+/-4.1)x10(-4) and a statistical significance of 6.6sigma. The branching fraction errors are statistical, systematic, and the error resulting from the uncertainty of the Lambda c+ --> pK- pi+ decay branching fraction. The analysis is based on 357 fb(-1) of data accumulated at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+ e- collider. 相似文献