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971.
972.
Omar Foda Kenji Iohara Michio Jimbo Rinat Kedem Tetsuji Miwa Hong Yan 《Letters in Mathematical Physics》1994,32(3):259-268
An elliptic deformation of $\widehat{s1}_2 $ is proposed. Our presentation of the algebra is based on the relationRLL = LLR *, whereR andR * are eight-vertexR-matrices with the elliptic moduli chosen differently. In the trigonometric limit, this algebra reduces to a quotient of that proposed by Reshetikhin and Semenov-Tian-Shansky. Conjectures concerning highest-weight modules and vertex operators are formulated, and the physical interpretation ofR * is discussed. 相似文献
973.
Recent progress of the preparation of novel materials for catalysts utilizing metal-containing silsesquioxanes are reviewed
in the following categories: (i) activities of vanadium or titanium-containing silsesquioxanes as homogeneous catalysts for
oxidative reactions, (ii) preparation of immobilized or polymeric catalysts, and (iii) preparation of porous oxide catalysts
utilizing metal-containing silsesquioxanes. The present authors found that the liquid phase photo-oxidation of cyclohexane
in the presence of a vanadium-containing silsesquioxane as a homogeneous catalyst selectively afforded cyclohexanol and cyclohexanone
in high yields. Facile synthetic methods for group 4 metal-containing silsesquioxanes with functionalized silyl (or germyl)
groups are presented. Remarkably, titanocene(IV)-containing silsesquioxanes have been synthesized for the first time. The
presence of alkenylsilyl substituents shows a promotional effect on the epoxidation of cycloalkenes, which was found to be
more significant for titanium-bridged silsesquioxanes. By utilizing these silsesquioxanes, polymeric, starburst-like, and
dendritic silsesquioxanes were prepared as well as novel caged or macrocyclic molecules with organic–inorganic hybrid structures.
The controlled calcination of these metal-containing silsesquioxanes at around 823 K produces porous oxides with high BET
surface areas of 300–520 m2g−1 and uniformly-controlled micropores of 0.5–0.6 nm diameter. The oxides are found to include a well-dispersed metallic oxide
species. From group 13 elements-containing silsesquioxanes Br?nsted acidic oxides are produced. Among them, aluminum-containing
oxides show excellent activities for the cracking of cumene even at low temperature, 523 K, in spite of their amorphous nature. 相似文献
974.
Phospholipase D (EC 3.1.4.4.) and choline oxidase (EC 1.1.99.1.) are immobilized together on a hydrophobic agarose gel and used to convert the phospholipid to betaine and hydrogen peroxide, which is measured amperometrically at + 0.60 V vs. SCE. The response time of the sensor is 2 min, and the calibration curve for 0–3 g l-1 of phosphatidyl choline is linear. Different methods of insolubilizing the enzymes are compared. 相似文献
975.
Keitaro Ishii Takuya Sone Yukio Shimada Takahide Shigeyama Masahiro Noji Shigeo Sugiyama 《Tetrahedron》2004,60(48):10887-10898
The photochemical C,C-bond cleavage of N-benzyl β-aziridinylacrylonitrile 1 and acrylate 2 and the subsequent [3+2] cycloaddition with electron-deficient alkenes afforded head-to-head adducts selectively and efficiently. Irradiation of N-phenyl aziridine 3 with acrylonitrile gave adducts, but photoreaction of N-benzoyl aziridine 4 and thermal reactions of 3 and 4 with alkenes yielded C(γ),N-cleaved products instead of cycloadducts. N-trityl aziridine 5 also reacted with electron-deficient alkenes, affording 2,3-cis-pyrrolidine derivatives exclusively. A formal synthesis of a pyrrolizidine alkaloid, isoretronecanol (27), starting from 5 was achieved in a convenient manner. 相似文献
976.
(1R,5S,7S)-(+)-endo-Brevicomin (7-ethyl-5-methyl-6,8-dioxabicyclo[3.2.1]octane) and its (1S,5R),7(R)-(?)-isomer were synthesised employing the Sharpless asymmetric epoxidation as the key-step. 相似文献
977.
On treatment with anhydrous LiI, 2,6-lutidine and anhydrous methanol, an ester type glycosyl linkage of acidic tri- and di-terpenes was selectively cleaved without decomposition of a reducing terminal of the resulting sugar moiety to give an anomeric mixture of methyl glycosides along with an aglycone or a pro-aglycone in quantitative yield. In this reaction, no hydrolysis of any other glycoside linkages took place. 相似文献
978.
Enantioselective alkylation of lactams and lactones can be realized up to 98% ee by deprotonation with a chiral tetradentate lithium amide (4b) in the presence of lithium bromide, and subsequent alkylation with active alkylating agents in non-chelating solvents. 相似文献
979.
Supercritical carbon dioxide (scCO2) annealing enhances the hydrophobicity of the surfaces of asymmetric perfluorinated block copolymers. X-ray photoelectron spectroscopy (XPS) and contact angle measurement reveal that the surface domains of the fluorinated block (PF) of poly[styrene-block-4-(perfluorooctylpropyloxy)styrene] (PS-PF) become thicker than those annealed in a vacuum. Consequently, the contact angles of water on the surfaces of PS-PF block copolymers significantly increase after the scCO2 annealing compared to those annealed in a vacuum. The surface hydrophobicity enhanced by the scCO2 annealing is related to the thickness of the surface PF domain and the conformation of the PF block. 相似文献
980.
Tomohisa Nagamatsu Keiichi Kinoshita Kenji Sasaki Taiji Nakayama Takashi Hirota 《Journal of heterocyclic chemistry》1991,28(2):513-515
A simple and highly efficient methodology for the synthesis of 1,2,4,5-tetrahydro[1]benzothiepino[4,5-e]-imidazo[1,2-c]pyrimidine ( XI ) having a novel ring system via 4-substituted 5,6-dihydro[1]benzothiepino-[5,4-d]pyrimidines VII-X is described. The anti-platelet aggregation activity for it and its related compounds against collagen-induced aggregation of rabbit blood platelets in vitro was found. 相似文献