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排序方式: 共有461条查询结果,搜索用时 15 毫秒
101.
Tomoko Yajima Ishrat Jahan Takayuki Tonoi Manami Shinmen Aya Nishikawa Kanako Yamaguchi Izumi Sekine Hajime Nagano 《Tetrahedron》2012,68(34):6856-6861
Photoinduced radical perfluoroalkylation of various simple electron-deficient olefins was achieved in the presence of an aqueous Na2S2O3 solution. The reactions proceeded smoothly to give addition or addition–elimination products. The ability of the products to be used as radical precursors or Michael acceptors was also demonstrated. 相似文献
102.
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104.
Keisuke Sekine Dai Akaishi Kakeru Konagaya Prof. Dr. Shigekazu Ito 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(32):e202200657
Optically active cyclopropanes have been widely investigated especially from the views of pharmaceutical and agrochemical industries, and substituting one of the methylenes with the difluoromethylene unit should be promising for developing novel biologically relevant compounds and functional materials. In this paper, the copper-catalyzed enantioselective hydrosilylation of gem-difluorocyclopropenes to provide the corresponding chiral gem-difluorocyclopropanes is presented. The use of copper(I) chloride, chiral ligands including bidentate BINAPs and monodentate phosphoramidites, and silylborane Me2PhSi-Bpin accompanying sodium tert-butoxide in methanol was appropriate for the enantioselective hydrosilylation of the strained C=C double bond, and the resultant chiral difluorinated three-membered ring was unambiguously characterized. Subsequent activation of the silyl groups in enantio-enriched gem-difluorocyclopropanes showed substantial reduction of the enantiopurity, indicating cleavage of the distal C−C bond leading to the transient acyclic intermediates. 相似文献
105.
Ayako Sekine Noriaki Seko Masao Tamada Yoshio Suzuki 《Radiation Physics and Chemistry》2010,79(1):16-21
A fibrous adsorbent for Hg ions was synthesized by radiation-induced emulsion graft polymerization of glycidyl methacrylate (GMA) onto a nonwoven cotton fabric and subsequent chemical modification. The optimal pre-irradiation dose for initiation of the graft polymerization of GMA, which minimized the effects of radiation damage on the mechanical strength of the nonwoven cotton fabric, was found to be 10 kGy. The GMA-grafted nonwoven cotton fabric was subsequently modified with ethylenediamine (EDA) or diethylenetriamine (DETA) to obtain a Hg adsorbent. The resulting amine-type adsorbents were evaluated for batch and continuous adsorption of Hg. In batch adsorption, the distribution coefficients of Hg reached 1.9×105 and 1.0×105 for EDA- and DETA-type adsorbents, respectively. A column packed with EDA-type adsorbent removed Hg from 1.8 ppm Hg solution at a space velocity of 100 h?1, which corresponds to 16,000 times the volume of the packed adsorbent. The adsorbed Hg on the EDA-type adsorbent could be completely eluted by 1 M HCl solution. A microbial oxidative degradation test revealed that the EDA-type adsorbent is biodegradable. 相似文献
106.
Nobuko Yoshimoto Osamu Shimamura Takuya Nishimura Minato Egashira Maiko Nishioka Masayuki Morita 《Electrochemistry communications》2009,11(2):481-483
A novel polymeric electrolyte based on a self-assembled copolymer moiety has been prepared by a simple method of photo-induced radical polymerization of a mixture consisting of stearylmethacrylate (SMA) and poly(ethylene glycol)-monomethacrylate (PEM) that dissolves LiBF4 as the electrolytic salt. The SMA moiety work as mechanically stable backbone and the PEM unit dissolving the salts serves as ion-conducting path in the polymeric composite. Solid-state NMR measurements indicated that the resulting polymer composite consists of PEM-rich and SMA-rich phases, each of which exists within several nanometers apart. The ionic conductivity of the polymer electrolyte with the composition of PEM/SMA = 7/3 (by mass ratio) was 2.8 × 10?5 S cm?1 at 50 °C, which was significantly higher than that of the polymer electrolyte based on cross-linked PEM copolymer without SMA. 相似文献
107.
A stepwise synthetic method for 9,10-dihydro-9,10-diboraanthracene was developed, and the optical and electrochemical properties as well as the molecular structure of the 9,10-dihydro-9,10-diboraanthracene were elucidated. The 9,10-dihydro-9,10-diboraanthracene exhibited high complexation ability against fluoride ion, and the complexation was accompanied by the enhancement of photoluminescence emission, probably due to intramolecular charge transfer between the two boron atoms. 相似文献
108.
109.
110.
K. Sekine 《Colloid and polymer science》1999,277(4):388-393
Using the finite-element method (FEM), the frequency dependence of conductivity and relative permittivity was calculated
for a heterogeneous specimen in which a sphere was placed in a medium. The FEM calculations were made for the whole system
in which the specimen was located in a measuring cell comprising two parallel electrodes and a spacer with a cylindrical sample
cavity, as in practical measurements. Values of the conductivity and the permittivity of the sphere and the medium were chosen
so as to simulate specimens of water-in-nitrobenzene (W/N) and oil-in-water (O/W) types. When the volume ratio of the sphere
to the sample cavity p was below 0.1, the frequency dependence of conductivity and permittivity was in good agreement with that described by Wagner's
theory for both the W/N and O/W specimens. When p was greater than 0.1, deviations from Wagner's theory were found for limiting values of the conductivity and permittivity
at low and high frequencies for both the W/N and O/W specimens, and for the relaxation time for the W/N specimens.
Received: 15 July 1998 Accepted in revised form: 5 November 1998 相似文献