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排序方式: 共有388条查询结果,搜索用时 218 毫秒
1.
Mineo Hashizume Hiroaki Inoue Kiyofumi Katagiri Atsushi Ikeda Jun-Ichi Kikuchi 《Journal of Sol-Gel Science and Technology》2004,31(1-3):99-102
Morphological characterization of the organic-inorganic vesicular nanohybrids, Cerasomes, was performed in aqueous media from two aspects. Firstly, a novel Cerasome-forming lipid having two triethoxysilyl groups in the head moiety was synthesized and the physical property of the Cerasome was investigated. While the morphological stability of the Cerasomes, as evaluated from the vesicular collapse behavior against a micelle-forming nonionic surfactant, Triton-X 100, was extremely higher than that of the conventional phospholipid liposome, the stabilities were comparable to each other for the Cerasomes derived from the dual- and single-head lipids. On the other hand, the surface property of the Cerasome formed with the dual-head lipid more closely resembled the colloidal silica particles rather than that derived from the single-head lipid, as suggested by zeta-potential measurements. Secondly, the effect of the media pH on the morphological stability of the Cerasome formed with the single-head lipid was evaluated and appeared as a time difference in obtaining the morphological stability of the Cerasome. These morphological characteristics of the Cerasomes could be mainly owing to the development of the siloxane network on the vesicular surface. 相似文献
2.
Yumi ShimadaMakoto Nakamura Toshimasa SuzukaJunji Matsui Ryo TatsumiKen Tsutsumi Tsumoru MorimotoHideo Kurosawa Kiyomi Kakiuchi 《Tetrahedron letters》2003,44(7):1401-1403
A new method for the construction of the AB-ring core of Taxol was developed utilizing a new skeletal transformation protocol as a pivotal step. The acid-catalyzed rearrangement of the cyclopentenone-allene photoadduct gave a bridged seven-membered ketone, which was easily transformed, using the intramolecular Suzuki reaction and the oxidative cleavage of the vicinal diol, to the bicyclic diketone. 相似文献
3.
Sachiko Yamada Keiko Nakayama Hiroaki Takayama Toshimasa Shinki Tatsuo Suda 《Tetrahedron letters》1984,25(30):3239-3242
(25)-25,26-Dihydroxy-23-oxovitamin D3 was synthesized efficiently and stereoselectively, and it was converted enzymatically to (25)-1α,25,26-trihydroxy-23-oxovitamin D3, a putative metabolite of 1α,25-dihydroxyvitamin D3. The spectral and chemical properties of (25)-25,26-dihydroxy-23-oxovitamin D3 and its 1α,hydroxylated derivative disagree with those reported for the isolated metabolite. 相似文献
4.
A quantum chemical study of interchain hopping model of negatively charged solitons in polyacetylene
Akitomo Tachibana Shigeru Ishikawa Yoshihiro Asai Hideki Katagiri Tokio Yamabe 《International journal of quantum chemistry》1992,41(3):461-474
Phonon-assisted interchain hopping of negatively charged solitons in polyacetylene has been studied using a local chemical reaction model CH + CH4 → CH4 + CH. Quantum chemical characteristics of the electron transfer process have been analyzed in terms of the dynamic electron density and the mutual polarization moment. The CH stretching vibrational motion of CH4, which is a local model of the sp3 defect, has been found to play a significant role for the electron transfer. The excitation of the corresponding vibrational mode of the sp3 defect would promote the interchain hopping of the charged soliton. The electron transfer process has also been studied in terms of the “regional” density functional theory. It has been shown that the driving force of the electron transfer is represented by the regional chemical potentials. 相似文献
5.
The enantioselective Reformatsky reaction of PhCHO was achieved by the use of trifluoromethylated amino alcohols as chiral ligands to afford the corresponding optically active β-hydroxy ester with up to 90% ee. 相似文献
6.
Kosuke Katagiri Yukina Yamamoto Yuui Takahata Ryoga Kishibe Naoki Fujimoto 《Tetrahedron letters》2019,60(30):2026-2029
Anthracenyl(diphenyl)phosphine oxide and dianthracenylphenylphosphine oxide as photoactive compounds have been synthesized. Anthracenyl group of these compounds indicate the multi-functional roles such as an emission component, a photodimerization component, and a leaving group. When the light irradiation was performed under an oxygen atmosphere, photo-oxidative PC bond cleavage to leave the antharacenyl group was observed. Moreover, phosphonyl radical was produced and then PP bond formation to form diphosphane was observed. 相似文献
7.
Masatoshi Sakae Masanori Katsurada Mayumi Watanabe Fumio Yoneda Sadao Nishigaki Toshimasa Ishida 《Journal of heterocyclic chemistry》1997,34(1):157-160
The reaction of 2-bromoethylamine 1 with methylisothiocyanate 2 under mild condition gave 2-methyl-amino-2-thiazoline 3 as the major product together with two kinds of byproducts, 3-(N-methylthiocar-bamoyl)-2-methyliminothiazolidine 4 and N,N′-dimethyl-N-(2-thiazolin-2-yl)thiourea 5. Thermal isomer-ization of 5 to 4 was observed. The structures of the byproducts were confirmed by X-ray crystallography. 相似文献
8.
High-performance liquid chromatographic procedure for the simultaneous determination of norfloxacin, fenbufen and felbinac in rat plasma 总被引:1,自引:0,他引:1
Y Katagiri K Naora N Ichikawa M Hayashibara K Iwamoto 《Chemical & pharmaceutical bulletin》1989,37(10):2858-2860
A high-performance liquid chromatographic method for the simultaneous determination of norfloxacin, fenbufen and felbinac extracted from 50 microliters of rat plasma is described. Chromatography was performed on a reversed-phase column with ultraviolet detection. By the present method, quantitative and reproducible determinations were possible for norfloxacin, fenbufen and felbinac over the concentration ranges of 0.2-20, 0.2-120 and 0.4-40 micrograms/ml, respectively. The recoveries of norfloxacin, fenbufen and felbinac added to plasma were nearly 100% with a coefficient of variation of less than 8.0%. This method was found to be applicable to pharmacokinetic studies of each drug after the concomitant administration of norfloxacin and fenbufen. 相似文献
9.
Shogo Mitsuhashi Junko Kawai Tomofumi Santa Toshimasa Toyo’oka 《Analytica chimica acta》2006,562(1):36-43
Kynurenic acid (KYNA), an endogenous antagonist of ionotropic glutamate and α7 nicotinic receptors, was fluorometrically determined by column-switching high-performance liquid chromatography (HPLC) with fluorescence detection. The HPLC system consists of two octadecyl silica (ODS) columns, both of which are connected with an anion-exchange column (trapping column). Following sample injection onto the HPLC column, KYNA was separated on the first ODS column with a mobile phase of H2O/acetonitrile (95/5) containing 0.1% acetic acid. The peak fraction of KYNA was trapped on the anion-exchange column by changing the position of a six-port valve and then introduced into the second ODS column. Subsequently, KYNA was detected fluorometrically as a fluorescence complex formed with zinc ion which was pumped constantly. Instrumental limit of detection was approximately 0.16 nM, which corresponded to 8.0 fmol (per 50 μl injection, signal to noise ratio 3), and the limit of quantification was 0.53 nM (signal to noise ratio 10). Intra- and inter-day relative standard deviations were 1.1-3.9% (n = 3) and 3.0-5.3% (n = 3), respectively. The peak of KYNA in rat plasma was clearly detected by the proposed column-switching HPLC system after a facile pretreatment procedure. Intra- and inter-day relative mean errors were −1.6-1.4% (n = 3) and −2.4 to −0.4% (n = 3), respectively, with a satisfactory precision (within 5.0%). A calibration curve for the determination of KYNA showed a good linearity (r2 > 0.999) in the range of 25-200 nM. The KYNA concentrations in the plasma of male Sprague-Dawley rats (8-week-old) were 44 ± 5.5 nM (mean ± S.E., n = 5). In ketamine-treated rats, which are animal models of schizophrenia, the plasma KYNA concentrations were significantly increased compared with those in the control rats (p < 0.05). 相似文献
10.