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41.
42.
1-Alkoxy-3-trimethylsilylmethyl- and 1-alkoxy-3-trimethylsilyl-l,3-butadienes () were newly prepared. The cycloaddition reactions of with various dienophiles including heterodienophiles were found to proceed very smoothly in a perfectly regiospecific mode. 相似文献
43.
44.
Nagaoka Y Inoue H el-Koussi N Tomioka K 《Chemical communications (Cambridge, England)》2002,(2):122-123
Upon treatment with lithium diisopropylamide achiral and chiral alpha,beta,psi,omega-unsaturated bisphosphine oxides underwent lithiation-conjugate addition tandem cyclization to afford the corresponding endo-alpha,beta-unsaturated cyclic bisphosphine oxides; sequential stereoselective reduction of the cyclized bisphosphine oxide gave the corresponding trans- and cis-bisphosphines that were successfully applicable in a catalytic asymmetric hydrogenation as chiral bisphosphine ligands. 相似文献
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46.
Aihara H Alston-Garnjost M Avery RE Barbaro-Galtieri A Barker AR Barnes AV Barnett BA Bauer DA Bengtsson H Bintinger DL Bobbink GJ Bolognese TS Bross AD Buchanan CD Buijs A Cain MP Caldwell DO Clark AR Cowan GD Crane DA Dahl OI Derby KA Eastman JJ Eberhard PH Eisner AM Enomoto R Erné FC Fujii T Gary JW Gorn W Hauptman JM Hofmann W Huth JE Hylen J Kamae T Kaye HS Kees KH Kenney RW Kerth LT Ko W Koda RI Kofler RR Kwong KK Lander RL Langeveld WG Layter JG Linde FL Lindsey CS Loken SC Lu A Lu X 《Physical review letters》1986,57(8):945-948
47.
Abou El-Nasr EA Fujii A Yahagi T Ebata T Mikami N 《The journal of physical chemistry. A》2005,109(11):2498-2504
Geometric structures and excited-state proton dislocation of size-selected salicylic acid clusters (salicylic acid and 5-methoxysalicylic acid) with water were studied by using laser spectroscopic techniques. Fluorescence excitation, dispersed fluorescence, and infrared (IR) spectra of those clusters in supersonic jets were examined for both the electronic ground (S0) and first excited (S1) states. The geometric structures of the clusters were determined on the basis of the IR spectra of the OH stretch region with the help of quantum chemical calculations. The hydroxyl group of the water moiety in the clusters forms a ring involving the carboxylic group of the salicylic acid moiety. The IR spectra in S0 show that the intramolecular hydrogen bond in the salicylic acid moiety is still held upon cluster formation, but the phenolic OH stretch band intensity is remarkably weaken in the clusters. The IR spectra in the S1 state and dispersed fluorescence spectra indicated that the intramolecular excited state proton dislocation is hardly affected by the microsolvation with water, in contrast with the strong suppression of the dislocation in the self-solvation. 相似文献
48.
A quantum chemical study of interchain hopping model of negatively charged solitons in polyacetylene
Akitomo Tachibana Shigeru Ishikawa Yoshihiro Asai Hideki Katagiri Tokio Yamabe 《International journal of quantum chemistry》1992,41(3):461-474
Phonon-assisted interchain hopping of negatively charged solitons in polyacetylene has been studied using a local chemical reaction model CH + CH4 → CH4 + CH. Quantum chemical characteristics of the electron transfer process have been analyzed in terms of the dynamic electron density and the mutual polarization moment. The CH stretching vibrational motion of CH4, which is a local model of the sp3 defect, has been found to play a significant role for the electron transfer. The excitation of the corresponding vibrational mode of the sp3 defect would promote the interchain hopping of the charged soliton. The electron transfer process has also been studied in terms of the “regional” density functional theory. It has been shown that the driving force of the electron transfer is represented by the regional chemical potentials. 相似文献
49.
Hideki Namba Okihiro Tokunaga Tadashi Tanaka Yoshimi Ogura Shinji Aoki Ryoji Suzuki 《Radiation Physics and Chemistry》1993,42(4-6):669-672
The fundamental research work with simulated coal-fired flue gas was performed in JAERI to get basic data for electron beam treatment of flue gas from thermal power plants in Japan. The standard condition of the experiments was set to be the same as that of next large scale pilot test in Nagoya. The concentrations of NOx and SOx were 225 ppm and 800 ppm, respectively. The temperature of the system was 65°C. The effect of multiple irradiation was observed for NOx removal. The target SOx and NOx removals (94% and 80%, respectively) with low NH3 leakage (less than 10 ppm) were achieved at 9 kGy irradiation with 0.9 NH3 stoichiometry during 7 hours continuous operation. The facility for the pilot plant (12,000 Nm3/hr) has just built at the site of Shin-Nagoya power plant of Chubu Electric Power Company and will be started in full operation in November 1992. 相似文献
50.
Takeo Ito Hideki Shirakawa Sakuji Ikeda 《Journal of polymer science. Part A, Polymer chemistry》1974,12(1):11-20
A direct method of simultaneously polymerizing and forming acetylene monomer to produce uniformly thin films of polyacetylene was investigated in terms of catalyst system, catalyst concentration, and polymerization temperature. The best catalyst was a Ti(OC4H9)4–Al(C2H5)3 system (Al/Ti = 3–4) and the critical concentration was 3 mmole/l. of Ti(OC4H9)4. Below the critical concentration, only a solid or a powder was obtained. The configuration of the polymers obtained depends strongly upon the polymerization temperature. Thus an all-cis polymer was obtained at temperatures lower than ?78°C, whereas an all-trans polymer resulted at temperatures higher than 150°C. Observations either in an electron microscope by direct transmission or in a scanning electron microscope showed that the film is composed of an accumulation of fibrils about 200–300 Å in width and of indefinite length. 相似文献