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排序方式: 共有151条查询结果,搜索用时 15 毫秒
1.
Tamao K Asahara M Saeki T Toshimitsu A 《Angewandte Chemie (International ed. in English)》1999,38(22):3316-3318
Migration of NMe(2) from C(naphthyl) to Si and Si-Si and Si-C bond formation to give a 1,2-disilaacenaphthene skeleton occurred in the reaction of hypercoordinate dichlorosilanes bearing the 8-(dimethylamino)-1-naphthyl group with two equivalents of magnesium [e.g., Eq. (a)]. The intermediate was isolated as the 1-isopropoxy derivative after quenching the reaction mixture with isopropyl alcohol. 相似文献
2.
Makoto Kumada Koji Sumitani Yoshihisa Kiso Kohei Tamao 《Journal of organometallic chemistry》1973,50(1):319-326
The hydrosilylation of olefins catalyzed by nickel(II) chloride complexed with 1,2-bis(dimethylphosphino)-1,2-dicarba-closo-dodecaborane produces terminal and internal adducts in comparable amounts. This unusual feature of the reaction is explained in terms of the electron-accepting nature of the carboranyl group. 相似文献
3.
A bicyclic diphenyldisilane bearing two tetramethylene tethers reacts with lithium to form predominantly the disilanyllithium as a result of Si-CPh bond fission, while the pentamethylene homolog undergoes ordinary Si-Si bond cleavage to afford the expected phenylsilyllithium. The compressed Si-Si bond incorporated in the bicyclic ring system may be kinetically stabilized (compression effect), resulting in the unusual Si-C bond fission. When the reaction is carried out in the presence of chlorotrimethylsilane, a Calas-type reaction takes place on the phenyl rings. This result suggests that electron transfer to the phenyl group is the primary process in these bicyclic disilanes, followed by Si-Si or Si-C bond cleavage to afford the corresponding silyllithium species. 相似文献
4.
S Odake T Okayama M Obata T Morikawa S Hattori H Hori Y Nagai 《Chemical & pharmaceutical bulletin》1991,39(6):1489-1494
To develop a potent and specific collagenase inhibitor, a series of tetrapeptidyl hydroxamic acids were synthesized, based on the previous findings with tripeptidyl derivatives (Chem. Pharm. Bull., 38, 1007-1011, 1990). Among the series of tetrapeptidyl derivatives synthesized, R-Gly-Pro-Leu-Ala-NHOH and R-Gly-Pro-D-Leu-D-Ala-NHOH were found to be highly specific and potent inhibitors against vertebrate collagenase with an IC50 of 10(-6) M order, where R stands for Boc or acyl group. Analysis of their structure-activity relationships showed a characteristic feature of the substrate-binding site of collagenase as follows: 1) the S1 subsite forms a shallow hydrophobic pocket, although glycine residue corresponds to the subsite of the natural collagen substrate: 2) the S2 subsite constitutes a bulky pocket with less requirement for hydrophobicity: 3) the S3 subsite preferentially accommodates Pro residue: and 4) the accommodation of the P4-P1 subsites of peptidyl collagenase inhibitor to the S4-S1 subsites is required to form a tight binding of its hydroxamic acid moiety to the zinc ion at the catalytic site of the enzyme. The introduction of an enantiometric dipeptide unit, D-Leu-D-Ala, to the P2-P1 subsites demonstrated an increased binding capacity to the extended S4-S1 subsites of collagenase, thus providing proteinase-resistant inhibitor. 相似文献
5.
Attenuated total reflection spectrometry with a slab optical waveguide (SOWG) was explored for the simple, rapid and sensitive measurement of total anionic surfactants by the methylene blue active substance (MBAS) method. A fused-silica sheet used as a guiding layer was modified with trimethylsilane (TMS) to extract and concentrate the MBASs on the SOWG surface. Based on preliminary studies of the adsorption behavior and visible ATR spectrum of MB on the modified silica surface, a detection wavelength of 600 nm was chosen for the sensitive measurement of anionic surfactants. When the concentration of MB was set at 10 microM in the final measurement solution, the calibration curve for a typical anionic surfactant (sodium dodecylbenzenesulfonate) was linear up to 0.6 microM and the detection limit was 0.07 microM. The proposed method was applied to the determination of total anionic surfactants in river water. 相似文献
6.
A laser-induced fluorescence microscopic system based on optical parametric oscillation has been constructed as a tunable detector for microchip analysis. The detection limit of sulforhodamine B (Ex. 520 nm, Em. 570 nm) was 0.2 mol, which was approximately eight orders of magnitude better than with a conventional fluorophotometer. The system was applied to the determination of fluorescence-labeled DNA (Ex. 494 nm, Em. 519 nm) in a microchannel and the detection limit reached a single molecule. These results showed the feasibility of this system as a highly sensitive and tunable fluorescence detector for microchip analysis. 相似文献
7.
Hidetoshi Awata Satoru Odake Jun'ichi Shiraishi 《Communications in Mathematical Physics》1994,162(1):61-83
We construct a realization of the quantum affine algebra of an arbitrary level k in terms of free boson fields. In the q1 limit this realization becomes the Wakimoto realization of. The screening currents and the vertex operators (primary fields) are also constructed; the former commutes with modulo total difference, and the latter creates the highest weight state from the vacuum state of the boson Fock space.fellow of Soryushi ShogakukaiAddress after June 1: Department of Physics, Faculty of Liberal Arts, Shinshu University, Matsumoto 390, Japan 相似文献
8.
In the presence of palladium complexes as catalysts, fluorinated disilanes add to 1,3-dienes, metehyl vinyl ketone and p-benzoquinone to give mainly 1,4-addition products. 相似文献
9.
Tsuji H Terada M Toshimitsu A Tamao K 《Journal of the American Chemical Society》2003,125(25):7486-7487
On the basis of the UV absorption spectra of the anti,cisoid alternating oligosilanes, the first experimental clear-cut evidence was presented for the generally accepted idea that the sigma conjugation in polysilanes does not effectively extend through a tetrasilane fragment with a small dihedral angle such as a cisoid turn. 相似文献
10.