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排序方式: 共有262条查询结果,搜索用时 31 毫秒
81.
Hisashi Yoshioka Hidenobu Matsumoto Shinpey Uno Fukuji Higashide 《Journal of polymer science. Part A, Polymer chemistry》1976,14(6):1331-1336
ESR spectra of methyl methacrylate (MMA) adsorbed on solid surfaces such as silica, alumina, and CPG-10 show a seven-line absorption due to monomer radicals when γ-irradiated at ?196°C. These spectra turn into conventional nine-line spectra by annealing at ?86°C as a result of polymerization. The intensity ratio of the four-line component to the five-line component changes with further polymerization. The ratio depends on the kind of solid and the smallest value is obtained in the spectra of alumina-MMA. The temperature of irradiation strongly affects the value in alumina-MMA. These results suggest that MMA is strongly adsorbed and deformed the conformation on alumina surface. 相似文献
82.
Ken Ohmori Mitsuru Kitamura Keisuke Suzuki 《Angewandte Chemie (International ed. in English)》1999,38(9):1226-1229
Two salient features —the stereoselectivity to give only the trans-diol, and the stereospecificity to transmit the axial chirality (in case the starting biphenyl is configurationally stable) onto two stereogenic centers of the product—characterize the pinacol cyclization of 2,2′-biaryldicarbaldehydes (see reaction). The accessibility of trans-9,10-dihydrophenanthrene-9,10-diols provides the new enantiopure C2-symmetric diol 1 , which shows potential utility in asymmetric synthesis. 相似文献
83.
84.
Akio Sugita Katsuhide Onose Yasuji Ohmori Mitsuho Yasu 《Fiber and Integrated Optics》1993,12(4):347-354
To enable alignmentfree optical fiber coupling to single-mode silica-based waveguides, fiber-guiding grooves are fabricated in the same substrate as waveguide circuits.These grooves are used successfully to couple optical fiber to Waveguides. An average, fiber-to-waveguide coupling loss of 0.6 dB per interface is obtained with eight arrayedguiding grooves, and it is expected that this will further be reduced to 0.2 dB per interface. The coupling loss varies by ±0.3 dB during thermal cycling between -10°C and +60°C. 相似文献
85.
This paper describes the peak shift in a Gaussian-like spectrum caused by the effects of spatial coherence and dispersive diffraction. The peak shift depends greatly on the ratio of the coherence areaA c produced by a primary incoherent source to the area лр2 of a circular aperture in the secondary source plane. The measured results are in reasonably good agreement with the numerical computational results. The peak shift is caused by a mixture of spatial coherence and dispersive diffraction in the region 0<A c/лр2<1. In the coherent limitA c/ лр2→∞, dispersive diffraction is most dominant and results in the maximum peak shift, whereas in the incoherent limitA c/л р2~0 no spectral change takes place. 相似文献
86.
Nakao H Hayashi H Iwata F Karasawa H Hirano K Sugiyama S Ohtani T 《Langmuir : the ACS journal of surfaces and colloids》2005,21(17):7945-7950
We report a simple method to functionalize DNA with pi-conjugated polymer, forming highly aligned and integrated arrays of pi-conjugated polymer nanowires of a few nanometers diameter. pi-conjugated polymer, polyphenazasiline, having alkylammonium salts on the N atom (PPhenaz-TMA), synthesized in this study can be directly attached to DNA, which can be organized along stretched and aligned DNA molecules on surfaces as a template. Furthermore, PPhenaz-TMA/DNA nanowires were stretched and aligned on surfaces, even when PPhenaz-TMA/DNA complexes formed in solutions. The resulting PPhenaz-TMA/DNA nanowires could be easily converted to oxidized states or metallic nanowires by using adequate oxidant or metal salts. The direct visualization of PPhenaz-TMA/DNA nanowires and its structural changes have been studied by atomic force microscopy and scanning near-field optical microscopy. 相似文献
87.
The undirectional solidification of the eutectic between α-Fe2Si5 and ?-FeSi was carried out. The temperature gradient at the liquid-solid interface was 70°C/cm. Microstructures of the aligned composite were fibrous and lamellar, for last and slow growth rates respectively. The growth direction of α and the preferred axial orientation relationships between α and ? were determined for both structures. 相似文献
88.
Ken Ohmori 《Tetrahedron》2004,60(6):1365-1373
Cationic metallocene species, generated from Cp2MCl2 and AgClO4 (M=Zr, Hf), were used for the glycosylation of catechin derivative 2, enabling a concise synthesis of a glycosyl flavonoid, astilbin (1). Further study revealed the efficiency of this Lewis acidic species for SN1-type activation of the C(4) position of catechin derivative 11, enabling selective substitution with various nucleophiles. 相似文献
89.
Ohmori N 《Chemical communications (Cambridge, England)》2001,(17):1552-1553
The highly functionalized core structure of phomoidride B (CP-263,114) was pursued by using intermolecular oxidopyrylium-alkene cyclization as one of the key steps. 相似文献
90.
Toward Naphthocyclinones: Doubly Connected Octaketide Dimers with a Bicyclo[3.2.1]octadienone Core by Thiolate‐Mediated Cyclization 下载免费PDF全文
Dr. Yoshio Ando Subaru Hori Takumi Fukazawa Prof. Dr. Ken Ohmori Prof. Dr. Keisuke Suzuki 《Angewandte Chemie (International ed. in English)》2015,54(33):9650-9653
A viable method is reported for the synthesis of the bicyclo[3.2.1]octadienone scaffold in naturally occurring octaketide dimers. The procedure employs a reductive cyclization reaction mediated by an unusual ethanedithiol monosodium salt. 相似文献