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81.
(±)-Tryptoquivaline G was formally synthesized through shortened steps from tryptophan, in which oxidation with thallium(III) trinitrate(TTN) was effected at the crucial stage. The present work also constitutes the first synthesis of oxindole lactones carrying 2-alkyl quinazolinones. 相似文献
82.
Yoshitsugu Arai Shū-ichi Kuwayama Yoshio Takeuchi Toru Koizumi 《Tetrahedron letters》1985,26(50):6205-6208
The Diels-Alder reaction of a novel chiral dienophile, alkyl ()-2--tolylsulfinylacrylates 1 with anthracene and cyclopentadiene showed high diastereoselectivity under the chelation controlled condition. 相似文献
83.
The elemental analysis and morphology of individual particles indicate that the dominant suspended particles in river water are kaolin covered with hydrated iron(III) oxide which strongly sorbs humic substances. Suspended particles, about 1 mg, collected from 250 ml of water by centrifugation, are treated with 0.7 ml of 0.1M sodium hydroxide to desorb humic substances. Approximately 60% of copper and 30% of lead on or in suspended particles exist as humic complexes. 相似文献
84.
Growth of self-organized hierarchical ZnO nanoarchitectures by a simple In/In2S3 controlled thermal evaporation process 总被引:3,自引:0,他引:3
Novel hierarchical ZnO nanoarchitectures, such as microtrepangs, microbelts, nanoflowers, nanocombs, nanowheels, and nanofans assembled by ZnO nanocones, nanobowling pins, nanobottles, nanoarrows, and nanonails, have had their growth controlled by the thermal evaporation of Zn and a mixture of In and In2S3. Both the morphologies of the products and their construction units could be efficiently controlled by simple adjustment of the weight ratio of In/In2S3. The phase structure, morphologies, and photoluminescence properties of the ZnO products were investigated by X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, and photoluminescence spectroscopy. These novel hierarchical ZnO nanoarchitectures may be attractive building blocks for creating optical or other nanodevices. 相似文献
85.
Toshihiro Otsuki Masa-Aki Kakimoto Yoshio Imai 《Journal of polymer science. Part A, Polymer chemistry》1989,27(5):1775-1780
Wholly aromatic random copolyamides of high molecular weights were prepared by the high-temperature solution polycondensation of an aromatic diisocyanate, 4,4′-methylenedi(phenyl isocyanate) or 2,4-tolylene diisocyanate, with a mixture of isophthalic acid and 4,4′-oxydibenzoic acid. Glass transition temperatures of the polyamides and copolyamides were between 229 and 273°C; this depended on the combination of diisocyanates and dicarboxylic acids used. These aromatic copolyamides showed better solubility in various organic solvents and reduced crystallinity, compared to the corresponding homopolyamides. The copolyamides prepared from 2,4-tolylene diisocyanate had greater solubility and higher glass transition temperatures than those obtained from 4,4′-methylenedi(phenyl isocyanate). 相似文献
86.
Anna Miyazaki Yoshifumi Tachibana Eibai Lee Gyongyi Bokonyi Yuko Tsuda Yoshio Okada 《Tetrahedron letters》2004,45(33):6323-6327
It was reported that the somatostatin analog TT-232, d-Phe-c(Cys-Tyr-d-Trp-Lys-Cys)-Thr-NH2, exhibited a highly potent antitumor activity in vitro and in vivo. Using pyrazinone analogs and aliphatic amino acids instead of the disulfide bond, we prepared novel type somatostatin analogs including the sequence essential for antitumor activities, Tyr-d-Trp-Lys. These analogs exhibited antiproliferative effect on A431 tumor cells. 相似文献
87.
Masami Sawada Yasuo Okumura Hitoshi Yamada Yoshio Takai Shigetoshi Takahashi Takahiro Kaneda Keiji Hirose Soichi Misumi 《Journal of mass spectrometry : JMS》1993,28(12):1525-1528
Using fast atom bombardment (FAB) mass spectrometry (MS), cross-chiral relationships were confirmed for the first time for the diasteromeric host-guest complexations between the chiral crown ether host (1) and the chiral organic ammonium ion guest (2) on the basis of the relative peak intensities (RPI). Both host–guest combinations (R, R, R, R) – 1, (R) – 2 and (S, S, S, S) – 1, (S) – 2 obviously provided larger RPI values than the combination of both (R, R, R, R) – 1, (S) – 2 and (S, S, S, S) – 1, (R) – 2 by a factor of 1.6 as an averaged value: 1.87 (n = 4)/1.16 (n = 4) = 1.6. These results are consistent with the expected stabilities of the host-guest complexations by CPK model examinations. Successfully observed cross-chiral examinations strongly suggest a potentially useful FABMS/RPI methodology for rapidly searching newly designed and synthesized crown ether-like host compounds with a higher degree of enantioselectivity. 相似文献
88.
Jun Suzuki Kenjiro Fujimoto Toshiyuki Mori Mamoru Watanabe Yoshio Hasegawa 《Journal of Sol-Gel Science and Technology》2000,19(1-3):775-778
The photocatalytic reduction of nitrogen monoxide (NO) with ethane on the hollandite type catalyst (K2Ga2Sn6O16KGSO) was investigated. Using a closed-gas circulating system equipped with a Q-MASS detector and in-situ diffuse reflectance FT-IR spectroscopy. The reactant gases of NO and 13C2H6 decreased with the increasing irradiation time. In contrast, the N2 yield increased proportionally to the conversion of 13C2H6. Nitrogen oxides such as N2O did not reach their detectable levels. The NO adsorbed on KGSO was found to change to its activated species by UV irradiation. The oxidized products of C2H6 such as CH3CHO increased in proportion to the reaction time. The present results strongly suggest that KGSO has remarkable photocatalytic activity for the reduction of NO with C2H6. 相似文献
89.
The effects of excipients on the protein stability during lyophilization as well as the storage stability of lyophilized bilirubin oxidase (BO) and beta-galactosidase (GA) formulations were studied using four polymer excipients: dextran, polyvinylalcohol (PVA), poly(acrylic acid) (PAA), and alpha, beta-poly(N-hydroxyethyl)-L-aspartamide (PHEA). Denaturation of BO and GA during lyophilization largely depended on the excipient used. Dextran appeared to cause severe damage to proteins, whereas PHEA protected proteins effectively from denaturation. Storage stability of BO and GA formulations also depended on the excipients, such that the formulations containing dextran and PAA were relatively unstable. Storage stability was improved by absorption of a small amount of water for all the formulations studied. Absorption of a larger amount of water, however, decreased the storage stability of the formulations containing PVA, PAA or PHEA. In contrast, the storage stability of formulations containing dextran did not decrease noticeably with increasing water. This may be because formulations containing dextran have a higher glass transition temperature than formulations containing PVA, PAA or PHEA when a large amount of water is absorbed. 相似文献
90.
Mitsuru Ueda Masami Takahashi Yoshio Imai Charles U. Pittman 《Journal of polymer science. Part A, Polymer chemistry》1982,20(10):2819-2828
The kinetics of α-methylene-γ-butyrolactone (α-MBL) homopolymerization was investigated in N,N-dimethylformamide (DMF) with azobis(isobutyronitrile) as initiator. The rate of polymerization (Rp) was expresed by Rp = k[AIBN]0.54[α-MBL]1.1 and the overall activation energy was calculated as 76.1 kJ/mol. Kinetic constants for α-MBL polymerization were obtained as follows: kp/kt1/2 = 0.161 L1/2 mol?1/2·s?1/2; 2fkd = 2.18 × 10?5 s?1. The relative reactivity ratios of α-MBL(M2) copolymerization with styrene (r1 = 0.14, r2 = 0.87) were obtained. Applying the Q–e scheme led to Q = 2.2 and e = 0.65. These Q and e values for α-MBL are higher than those for MMA 相似文献