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排序方式: 共有178条查询结果,搜索用时 15 毫秒
41.
Twelve natural bis-spirolabdane-type diterpenoids, including eight new, named leoheteronones A-E, 15-epileoheteronones B, D, and E, and four known leopersin B, 15-epileopersin B, leopersin C, and 15-epileopersin C, together with hispanone and galeopsin were isolated from the aerial parts of the medicinal plant Leonurus heterophyllus SW. (Lamiaceae) grown in Vietnam. Their structures were determined by spectroscopic analyses. The current study emphasized the accumulation of C-15 oxygenated bis-spirolabdane-type diterpenoids of both 13R and 13S configurations in L. heterophyllus. 相似文献
42.
Ai Suzuki Katsuyoshi Nakamura Kotaro Okushi Nozomu Hatakeyama Hiromitsu Takaba Mark C. Williams 《Surface science》2009,603(20):3049-7652
The capability of theoretical durability studies to offer an efficient alternative methodology for predicting the potential performance of catalysts has improved in recent years. In this regard, multi-scale theoretical methods for predicting sintering behavior of Pt on various catalyst supports are being developed. Various types of Pt diffusions depending on support were confirmed by the micro-scale ultra accelerated quantum chemical molecular dynamics (UA-QCMD) method. Moreover, macro-scale sintering behavior of Pt/γ-Al2O3, Pt/ZrO2 and Pt/CeO2 catalysts were studied using a developed 3D sintering simulator. Experimental results were well reproduced. While Pt on γ-Al2O3 sintered significantly, Pt on ZrO2 sintered slightly and Pt on CeO2 demonstrated the highest stability against sintering. 相似文献
43.
44.
Wanas AS Matsunami K Otsuka H Desoukey SY Fouad MA Kamel MS 《Chemical & pharmaceutical bulletin》2010,58(12):1596-1601
From the EtOAc and 1-BuOH fractions, three new ursane-type and four new lupane-type triterpenes, along with nine known glycosides and glycosyl esters of lupane-type were isolated from the leaves of Schefflera actinophylla. All the isolated compounds were obtained for the first time from this plant. The structures of the new triterpenes were determined through a combination of spectroscopic and chemical analyses. 相似文献
45.
Miho Kawai Teppei Nogami Kyohei Takano Akinori Okumura Katsuyoshi Nakazato Masahiko Ikeuchi 《Molecular Crystals and Liquid Crystals》2014,603(1):248-255
This paper proposes a self-assembly fabrication method of microwells and investigates the effect of surface treatment for the cell trapping. The target cell is unicellular cyanobacterium Synechocystis sp. strain PCC 6803, which has been widely investigated as a model organism for photosynthesis. The self-assembly monolayer of polystyrene particles (3.0 μm diameter) etched by reactive-ion etching was used as a template of polydimethylsiloxane molds. The well diameter in the mold could be controlled by the etching time. The cell-trapping efficiency was discussed with the viewpoint of hydrophilically treatment and poly-L-lysine treatment on the well arrays. 相似文献
46.
Masakazu Nishida Yoshio Hayakawa Masaki Matsui Katsuyoshi Shibata Hiroshige Muramatsu 《Journal of heterocyclic chemistry》1991,28(2):225-229
The addition reaction of propionaldehyde to hexafluoro-2-butyne ( 1 ) under γ-ray irradiation gave trans-6,6,6-trifluoro-4-trifluoromethyl-4-hexen-3-one ( 2 ) and 4,5-bis(trifluoromethyl)octa-3,6-dione ( 3 ). The latter compound was treated with sulfuric acid to give 2,5-diethyl-3,4-bis(trifluoromethyl)furan ( 4a ). Several reactions, such as bromination, dehydrobromination and oxidation, were carried out to prepare derivatives of 4a . 相似文献
47.
Masakazu Nishida Yoshio Hayakawa Masaki Matsui Katsuyoshi Shibata Hiroshige Muramatsu 《Journal of heterocyclic chemistry》1992,29(1):113-116
Diels-Alder reaction of 2,5-dialkyl-3,4-bis(trifluoromethyl)furan with hexafluoro-2-butyne gave 1,4-dialkyl-7-oxa-2,3,5,6-tetrakis(trifluoromethyl)bicyclohepta-2,5-diene. Irradiation (uv) of 1,4-diethyl-7-oxa-2,3,5,6-tetrakis(trifluoromethyl)bicyclohepta-2,5-diene afforded 1-ethyl-2,3,4,5-tetrakis(trifluoromethyl)-1,4-cyclopentadiene, ethyl 3-[l-ethyl-2,3,4,5-tetrakis(trifluoromethyl)-1,4-cyclopentadienyl] ketone, and 2,7-diethyl-3,4,5,6-tetrakis(trifluoromethyl)oxepin. 相似文献
48.
Katsuyoshi Nishinari 《Macromolecular Symposia》2000,159(1):205-214
Sol‐gel transition of dispersions of biopolymers, which are used widely in food, cosmetics, biomedical and related industries, is classified by the temperature dependence of storage shear modulus. Sol‐gel transition of gellan gum solution is described well by a criterion of Winter‐Chambon. Too fast gelation of dispersions of konjac glucomannan in the presence of excessive amount of alkaline coagulant and/or at higher temperatures leads to a formation of gels with lower modulus. A solution of xyloglucan from which a certain amount of galactose residues is removed forms a gel on heating and reverts into a solution on further heating. The lower temperature transition of this xyloglucan solution is induced by hydrophobic interaction. 相似文献
49.
Ruth Knibbe Kazuhiro Nogita John Drennan Tsuneyuki Noguchi Katsuyoshi Tatenuma Pou Liu Fumihito Arai Eiji Yashima Michiru Nishiwaki Shigeki Kato 《Journal of nanoparticle research》2007,9(6):1201-1204
Multi-wall carbon nanotubes (MWNTs) have a great commercial potential as electron field emitters, but suffer from fundamental
problems such as stability and brightness. By depositing the MWNTs with nano-sized ruthenium dioxide (RuO2) particles, a new high performance emitter has been developed. When compared to MWNTs, the MWNTs impregnated with 1–2 nm
sized RuO2 have superior and more efficient electrical characteristics. MWNTs supported by a silicon substrate showed a reduction in
the onset voltage from 5.4 to 4 V/μm after RuO2 impregnation. The long-term stability of the impregnated MWNTs is also demonstrated with only a 20% increase in applied voltage
required after 700 h operation at 40 mA/cm2. 相似文献
50.
Minh Giang Phan Thi To Chinh Truong Tong Son Phan Katsuyoshi Matsunami Hideaki Otsuka 《Chemistry of Natural Compounds》2011,47(5):735-737
A new diarylheptanoid, a rare dammarane triterpenoid, and centrolobol were isolated from the leaves of Alnus nepalensis D. Don (Betulaceae). Their structures were determined by using spectroscopic analysis. 相似文献