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121.
Tsutomu Kumagai Kazuo Shimizu Haruki Tsuruta Toshio Mukai 《Tetrahedron letters》1981,22(49):4965-4968
The valence isomerization reaction of bicyclo[3.2.2]nona-2,6,8-triene (), which photoisomerized to two homologues of semibullvalene, was discussed with the photoreactions of its dihydro-dreivatives, bicyclo[3.2.2]nona-6,8-diene () and bicyclo[3.2.2]nona-2,6-diene (). 相似文献
122.
A new entry to oxacycles via base-catalyzed endo mode cyclization of allenyl sulfoxides and sulfones
[reaction: see text]. Treatment of the allenyl sulfoxides and sulfones possessing a proper delta-hydroxy appendage at the C-1 position with potassium tert-butoxide effected endo mode ring closure at the sp-hybridized carbon center of the allenyl moiety to provide the five- to eight-membered oxacycles in high yields. 相似文献
123.
The photochemical reactions of tetracyclic azo compounds () giving and via diazoethane derivatives () were investigated in addition to the nitrogen extrusion reactions leading to tetracyclo[4.3.0.02,9.05,7nonenes (). 相似文献
124.
Abstract— The pathways and quantum yields of direct photoisomerization of unprotonated and pro-tonated n-butylamine Schiff bases (SB and PSB) of isomeric retinylideneacetaldehyde (C22 aldehyde) were determined in n-hexane, acetonitrile and methanol for the former and in acetonitrile and methanol for the latter. The results are compared with those of the Schiff bases of isomeric retinal (C20 SB and C20 PSB) reported previously (Koyama et al., Photochem. Photobiol. 54 , 433–443, 1991). The isomerization pathways and quantum yields of C22 SB are more or less similar to those of C20 SB, but conspicuous differences in the isomerization pathways are found between C22 PSB and C20 PSB. The homogeneous (exclusive) isomerization of the retinylidene chromophore from all-trum to 11-cis in retinochrome is rationalized not by C22 PSB but by C20 PSB.
Almost complete one-way isomerization from cis to trans of C22 SB (in n-hexane) is ascribed to isomerization via the T1 state, while mutual isomeritation between cis and tram of C22 PSB is ascribed to isomerization via the S1 (Bu ) state. The TI potential of C22 SB and the S1 potential of C22 PSB are discussed based on photostationary state compositions. 相似文献
Almost complete one-way isomerization from cis to trans of C22 SB (in n-hexane) is ascribed to isomerization via the T
125.
Monolithic silica gel microhoneycombs, which have an array of straight macropores within their structure and developed micro/mesopores inside their walls, were prepared using pseudosteady state growth of ice crystals which occurs during the unidirectional freeze-gelation of freshly gelled aqueous silica hydrogels, followed by a pore-protecting drying method, freeze drying. 相似文献
126.
Kishimoto K Yoshio M Mukai T Yoshizawa M Ohno H Kato T 《Journal of the American Chemical Society》2003,125(11):3196-3197
A flexible self-standing film with layered nanostructures was obtained by in situ photopolymerization of a new smectic liquid-crystalline monomer containing a tetra(oxyethylene) moiety, which forms a macroscopically oriented complex with lithium salts. The resultant films show two-dimensional ionic conductivity. 相似文献
127.
T. Nozaki M. Iwamoto K. Usami K. Mukai A. Hiraiwa 《Journal of Radioanalytical and Nuclear Chemistry》1979,52(2):449-459
Oxygen in silicon nitride films on silicon wafers was analyzed by activation with the16O(3He, p)18F reaction. By3He bombardment of samples propertly arranged under consideration of the18F recoil effect, total oxygen was reliably determined and its predominant part was estimated to be located whether on film
surface, in film interior, or on film-substrate interface. Sample films with 0.1 to 2 μm thicknesses were found to contain
0.2 to 2 μg/cm2 of oxygen in locations varying with preparation conditions. This method has been compared with ESCA and other methods for
surface analysis. 相似文献
128.
Treatment of the 3,4-dioxygenated-9-hydroxy-1-nonyn-5-one derivative, derived from diethyl l-tartrate, with a palladium catalyst in methanol under a CO atmosphere effected an intramolecular acetalization and a stereoselective construction of the (E)-methoxycarbonylmethylidene functionality resulting in formation of the core framework of the diacetylenic spiroacetal enol ether natural products. Chemical transformations of the 1,6-dioxaspiro[4.5]decane derivative thus formed led to the first total synthesis of (-)-AL-2. [reaction: see text] 相似文献
129.
In vivo imaging of brain dopaminergic neurotransmission system in small animals with high-resolution single photon emission computed tomography. 总被引:6,自引:0,他引:6
Hideo Saji Yasuhiko Iida Hidekazu Kawashima Mikako Ogawa Youji Kitamura Takahiro Mukai Seiichiro Shimazu Fumiro Yoneda 《Analytical sciences》2003,19(1):67-71
High-resolution single photon emission computed tomography (SPECT) provides a unique capability to image the biodistribution of radiolabeled molecules in small laboratory animals. Thus, we applied the high-resolution SPECT to in vivo imaging of the brain dopaminergic neurotransmission system in common marmosets using two radiolabeled ligands, [123I]2beta-carbomethoxy-3beta-(4-iodophenyl)tropane (beta-CIT) as a dopamine transporter (DAT) ligand and [123I]iodobenzamide (IBZM) as a dopamine D2 receptor (D2R) ligand. Specific images of the striatum, a region with a high density of dopaminergic synapses, were obtained at 240 min and 60 min after injection of [123I]beta-CIT and [123I]IBZM, respectively. Furthermore, a significantly low accumulation of [123I]beta-CIT in the striatum was observed in MPTP-treated animals compared with results for a control group, and a similar accumulation in the control group was observed with the pretreatment of deprenyl in the MPTP-treated animals. However, the striatal accumulation of [123I]IBZM showed no changes among the control, MPTP-treated, and deprenyl-MPTP-treated groups. These SPECT imaging results agreed well with those of DA concentration and motor behavior. Since MPTP destroys nigrostriatal dopamine nerves and produces irreversible neurodegeneration associated with Parkinsonian syndrome, SPECT imaging data in this study demonstrated that deprenyl shows its neuroprotective effect on Parkinsonism by protecting against the destruction of presynaptic dopamine neurons. 相似文献
130.
Hossain MZ Machida S Yamashita Y Mukai K Yoshinobu J 《Journal of the American Chemical Society》2003,125(31):9252-9253
One of the fundamental points of interest on the Si(100) surface is how the spatial localization of electron density on the buckled silicon dimer controls the site-specific reaction toward different Lewis acid and Lewis base molecules. We have investigated the adsorption of trimethylamine (TMA) on Si(100)c(4x2) using scanning tunneling microscopy (STM) at 80 K. The adsorbed TMA appears as a triangle-shaped bright protrusion in the occupied-state STM image. The triangle-shaped protrusion is ascribed to three methyl groups in the adsorbed TMA. The center of the protrusion is located on the down atom site, which indicates that the adsorption of TMA occurs only on the down dimer atom. Thus, TMA adsorption on Si(100)c(4x2) is found to be purely site-specific on the down dimer atom and can be categorized in Lewis acid-base reaction. 相似文献