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91.
Koichiro Koyama Yusuke Hirasawa Tomohiro Hoshino Norimichi Nakahata 《Tetrahedron》2005,61(15):3681-3690
Seven new Lycopodium alkaloids, lannotinidines A-G (1-7), have been isolated from the club moss Lycopodium annotinum and L. annotinum var. acrifolium. Stereochemistry of 1-7 was elucidated by combination of NOESY correlations and chemical transformation. Lannotinidines B-E (2-5) elevated NGF mRNA expression. 相似文献
92.
Ogata M Kaneya D Shin-Ya K Li L Abe Y Katoh H Seki S Seki Y Gonda R Urano S Endo T 《Chemical & pharmaceutical bulletin》2005,53(9):1167-1170
Many researchers have stated that eugenol might inhibit lipid peroxidation at the stage of initiation, propagation, or both, and many attempts have been made to elucidate the mechanism of its antioxidant activity. Nevertheless, details of its mechanism are still obscure. This study was carried out to investigate the trapping effect of eugenol on hydroxyl radical generated from L-3,4-dihydroxyphenylalanine (DOPA) in MiliQ water and the generation mechanism of the hydroxyl radical by this system which uses no metallic factor. This was studied by adding L-DOPA and 5,5-dimethyl-1-pyrroline N-oxide (DMPO) to phosphate buffered saline (PBS) or MiliQ water, and the generation of hydroxyl radical was detected on an ESR spectrum. By this method, the effect of antioxidants was detected as a modification of ESR spectra. We found that the eugenol trapped hydroxyl radicals directly, because it had no iron chelating action, did not trap L-DOPA semiquinone radical and inhibited hydroxyl radicals with or without iron ion. 相似文献
93.
Ohno H Ando K Hamaguchi H Takeoka Y Tanaka T 《Journal of the American Chemical Society》2002,124(51):15255-15266
The base-mediated intramolecular amination of bromoallenes having an axial chirality is described. The treatment of (4S,aR)-4-alkyl-4-[N-(arylsulfonyl)amino]-1-bromobuta-1,2-dienes with NaH in DMF affords 2,3-cis-2-ethynylaziridines in good to excellent selectivity (2,3-cis:trans = 92:8-99:1). The reaction of (4S,aS)-bromoallenes with NaH/DMF also gives 2,3-cis-2-ethynylaziridines selectively (79:21-91:9). These experimental results have been rationalized by B3LYP density functional calculations together with the 6-31+G(d) basis set and the Onsager solvation model. The transition structures for cis-aziridine formation of both (4S,aR)- and (4S,aS)-bromoallenes in DMF are favored over the corresponding trans transition structures by 4.35 and 1.41 kcal/mol, respectively. Furthermore, the calculations predicted that a less polar solvent gives higher cis selectivity for (4S,aS)-bromoallenes. In fact, improvement of the cis selectivity to 99:1 has been realized by using a less polar solvent such as THF. The cyclization of bromoallenes bearing a beta- or gamma-amino group also affords four- and five-membered azacycles in a highly cis-selective manner. 相似文献
94.
Yoko Nambu Takeshi Endo Makoto Okawara 《Journal of polymer science. Part A, Polymer chemistry》1985,23(1):223-230
A lipoamide (LAm) structure was introduced into a polymeric membrane by chemical modification of poly(γ-methyl-D -glutamate) (PMG). A. redox reaction proceeded across the membrane mediated by pendant LAm groups as solid carriers. It is suggested that the electron transport process in the membrane is derived from the exchange reaction between reduced LAm (thiol) and LAm (disulfide). 相似文献
95.
Kazuhiro Endo Hideo Ihara Kazuhiro Watanabe Shun-Ichi Gonda 《Journal of solid state chemistry》1981,39(2):215-218
Transition-metal trisulfides, TiS3, NbS3, and TaS3, with a quasi-one-dimensional structure are investigated by X-ray photoelectron spectroscopic (XPS) measurements to obtain information on the valence band structures. The band structures at the Fermi level of these compounds correspond well to their transport properties. A shoulder is observed at the top of the valence band in NbS3 and TaS3, suggesting that this band is made up of the metal dz2 electrons. The dz2 band is occupied in NbS3 and TaS2 and empty in TiS3. The characteristic features at the top of the valence band in NbS3 imply the occurrence of dz2 band separation, which leads to a semiconducting nature. 相似文献
96.
Kondo M Irie Y Shimizu Y Miyazawa M Kawaguchi H Nakamura A Naito T Maeda K Uchida F 《Inorganic chemistry》2004,43(20):6139-6141
Reversible construction of a nanoporous framework from a nonporous framework has been found in the zinc(II) coordination polymer with 4,4'-oxybis(benzoate) (oba). [Zn(2)(oba)(2)(dmf)(2)].2DMF (1), which has 1 nm scale channels, transforms to the nonporous coordination polymer [Zn(oba)(H(2)O)] (2) with the loss of the open framework. Compound 2 on treatment with DMF reversibly yields nanoporous compound 1. 相似文献
97.
98.
Hiroyuki Nakazumi Takashi Endo Toshiyuki Nakaue Teijiro Kitao 《Journal of heterocyclic chemistry》1985,22(1):89-92
3-Amino-4H-1-benzothiopyran-4-one (3-aminothiochromone) was easily prepared by reaction of 3-bromo-thiochromen-4-one with sodium azide in methanol-water. Condensation of 3-aminothiochromone with diethyl ethoxymethylenemalonate and with dimethyl acetylenedicarboxylate gave intermediates, which were thermally cyclized to give 4,10-dihydro-4,10-dioxo-1H[1]benzothiopyrano[3,2-b]pyridinecarboxylates. 3-Formyl-thiochromone was condensed with o-phenylenediamine to give 7-oxo-7,13-dihydro[1]benzothiopyrano[2,3-b]-1,5-benzodiazepine. 相似文献
99.
Yoshiaki Yoshida Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2018,56(19):2255-2262
Polyaddition of various diisothiocyanates and dithiols was achieved with triethylamine in dimethylformamide at 25 °C for 12 h under nitrogen, and then the corresponding polydithiourethanes (PDTUs) were obtained with high yield and molecular weight without depending on the monomer structures, although the dithiol monomer of the low nucleophilicity was unsuitable for polyaddition in this system. The chemical and physical properties of the obtained PDTUs such as solvent solubility, glass transition temperature, thermal stability, transparency, refractive index, and tensile strength, were analyzed in detail by gel permeation chromatography, nuclear magnetic resonance, Fourier transform infrared–attenuated total reflection, ultraviolet–visible, differential scanning calorimetry, thermogravimetric analysis, and tensile testing measurements. These results proved that PDTUs and their cast films having the aliphatic diisothiocyanate and dithiol moieties exhibited excellent chemical and physical properties compared to that of the aromatic PDTUs. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2255–2262 相似文献
100.
Defect turbulence described by the one-dimensional complex Ginzburg–Landau equation is investigated and analyzed via a birth–death process of the local structures composed of defects, holes, and modulated amplitude waves (MAWs). All the number statistics of each local structure, in its stationary state, are subjected to Poisson statistics. In addition, the probability density functions of interarrival times of defects, lifetimes of holes, and MAWs show the existence of long-memory and some characteristic time scales caused by zigzag motions of oscillating traveling holes. The corresponding stochastic process for these observations is fully described by a non-Markovian master equation. 相似文献