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排序方式: 共有67条查询结果,搜索用时 31 毫秒
1.
Kohji Chihara Takeshi Takemura Tsuguo Yamaoka N. Yamamoto Arnold Schaffer Ralph S. Becker 《Photochemistry and photobiology》1979,29(5):1001-1008
Abstract— The absorption and emission spectra, lifetimes and quantum yields of all-trans retinol have been examined as a function of solvent and temperature. In addition, the spectroscopy of retinyl ether and 2 other polyene alcohols have been determined. Based on the results obtained, we conclude that the singlet excited state of retinol and retinyl cther is of a forbidden character and of the type loosely called 1 A- g . Retinol forms a dimer in an alkane solvent when cooling from 298 to 77 K. A general structure for the dimer is proposed. 相似文献
2.
A linear correlation between the NQR frequency of the terminal iodine atom and the corresponding I-I bond length in I3? was found in several compounds containing triiodide anions. A simple extended Huckel MO calculation suggested that such a correlation can be used to check the validity of wavefunctions of iodine. 相似文献
3.
Abstract— All- trans - and 13- cis -14,15-dideuterioretinal were synthesized and their solution photochemistry examined. Quantum yields of trans → cis or cis → trans photoisomerization and the number and ratio of primary photoproducts, determined by high pressure liquid chromatographic analysis, are essentially identical to that of their corresponding retinal isomer. The C-14, C-15 carbon-hydrogen modes play no particularly important role in the deactivation of electronically excited linear polyenes related to retinal. 相似文献
4.
Suzuki N Aihara N Takahara H Watanabe T Iwasaki M Saburi M Hashizume D Chihara T 《Journal of the American Chemical Society》2004,126(1):60-61
Five-membered metallacyclic alkynes that have no substituents adjacent to the triple bond have been synthesized, isolated, and structurally characterized. Zirconocene dichlorides, Cp'2ZrCl2 (Cp' = C5H5, C5H4-t-Bu), reacted with 1,4-dichlorobut-2-yne in the presence of magnesium to give 1-zirconacyclopent-3-yne compounds (5 (a) Cp' = C5H5, (b) Cp' = C5H4-t-Bu) that have a -CH2CCCH2- moiety in good yields. They are stable enough to be isolated in a pure form, despite the absence of substituents. 5a reacted with an equimolar amount of Cp2Zr(but-1-ene)(PMe3) to produce a bimetallic complex in which the zirconacyclopentyne coordinates to the other zirconocene moiety as an alkyne. 相似文献
5.
Sayoko Nagashima Shota Furukawa Satoshi Kamiguchi Ryu Kajio Hiroshi Nagashima Aritomo Yamaguchi Masayuki Shirai Hideki Kurokawa Teiji Chihara 《Journal of Cluster Science》2014,25(5):1203-1224
A series of molecular rhenium sulfide clusters [Re6S8(OH)6?n (H2O) n ](4?n)? (n = 0, 2, 4, 6) catalyze dehydrogenation of alcohols, and hydrogenation of ketones and olefins in a hydrogen stream at 350 °C. The catalytic activities of the dianionic and neutral clusters (n = 2, 4) are lower than those of tetraanionic and dicationic clusters (n = 0, 6) for all the reactions. When 1,4-butanediol is allowed to react over K4[Re6S8(OH)6], dehydrogenation proceeds to yield 2-hydroxytetrahydrofuran and successively γ-butyrolactone above 300 °C. Over [Re6S8(H2O)6]SO4 dehydration proceeds to yield tetrahydrofuran above 250 °C. The thermal activation mechanisms of these clusters were studied by powder X-ray diffraction analyses, Raman spectrometry, extended X-ray absorption fine structure spectrometry, thermogravimetry, and differential thermal analyses. The catalytically active site of K4[Re6S8(OH)6] is an uncoordinated metal site (Lewis acid site) developed by the loss of a water molecule from two hydroxo ligands. The active site of [Re6S8(H2O)6]SO4 is a Brønsted acid site; the anhydrous aqua cluster dication disproportionates to a hydroxo cluster monocation and a proton. Both of the octahedral cluster frameworks are retained up to 500 °C. 相似文献
6.
Hiroyuki Chihara 《Mathematische Annalen》1999,315(4):529-567
We discuss local existence and gain of regularity for semilinear Schr?dinger equations which generally cause loss of derivatives.
We prove our results by advanced energy estimates. More precisely, block diagonalization and Doi's transformation, together
with symbol smoothing for pseudodifferential operators with nonsmooth coefficients, apply to systems of Schr?dinger-type equations.
In particular, the sharp G?rding inequality for pseudodifferential operators whose coefficients are twice continuously differentiable,
plays a crucial role in our proof.
Received: 14 December 1998 相似文献
7.
We discuss a short-time existence theorem of solutions to the initial value problem for a third order dispersive flow for closed curves into a compact almost Hermitian manifold. Our equations geometrically generalize a physical model describing the motion of vortex filament. The classical energy method cannot work for this problem since the almost complex structure of the target manifold is not supposed to be parallel with respect to the Levi-Civita connection. In other words, a loss of one derivative arises from the covariant derivative of the almost complex structure. To overcome this difficulty, we introduce a bounded pseudodifferential operator acting on sections of the pullback bundle, and eliminate the loss of one derivative from the partial differential equation of the dispersive flow. 相似文献
8.
9.
[3]Rotaxane containing two Pd centers in the cyclic compounds catalyzes a Mizoroki-Heck reaction of substrates with two iodophenyl groups with bisacrylate. Formation of the cyclic products is enhanced by the rotaxane catalyst more smoothly than Pd(OAc)(2). 相似文献
10.