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排序方式: 共有337条查询结果,搜索用时 15 毫秒
71.
72.
X.-M. Su P. Dong J.-Y. Gao K. Muraoka 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,12(1):193-196
Electromagnetically induced transparency in a non-uniform plasma is investigated. We discuss the possible frequency ranges
in which a weak beam below cutoff can propagate transparently in this plasma with the presence of a strong high frequency
field. We also analyze the effect of driving intensity on the frequency range of the probe.
Received 3 March 2000 and Received in final form 21 April 2000 相似文献
73.
74.
Morikawa T Pan Y Ninomiya K Imura K Yuan D Yoshikawa M Hayakawa T Muraoka O 《Chemical & pharmaceutical bulletin》2010,58(10):1403-1407
Three iridoid glycosides, kankanosides L, M, and N, and two acyclic monoterpene glycosides, kankanosides O and P, were isolated from fresh stems of Cistanche tubulosa (Orobanchaceae) together with eight iridoid glycosides, five acyclic monoterpene glycosides, three phenylpropanoid glycosides, and four lignan glycosides. Their structures were elucidated on the basis of chemical and physicochemical evidence. 相似文献
75.
An efficient algorithm is proposed for finding all solutions of systems of n nonlinear equations. This algorithm is based on interval analysis and a new strategy called LP narrowing. In the LP narrowing strategy, boxes (n-dimensional rectangles in the solution domain) containing no solution are excluded, and boxes containing solutions are narrowed so that no solution is lost by using linear programming techniques. Since the LP narrowing is very powerful, all solutions can be found very efficiently. By numerical examples, it is shown that the proposed algorithm could find all solutions of systems of 5000-50,000 nonlinear equations in practical computation time. 相似文献
76.
Jun-Ichi Yamaura Shigeki Yonezawa Yuji Muraoka Zenji Hiroi 《Journal of solid state chemistry》2006,179(1):336-340
We report the single-crystal X-ray analysis of the structure of the pyrochlore oxide superconductor KOs2O6. The structure was identified as the β-pyrochlore structure with space group and lattice constant at : the K atom is located at the 8b site, not at the 16d site as in conventional pyrochlore oxides. We found an anomalously large atomic displacement parameter at for the K cation, which suggests that the K cation weakly bound to an oversized Os12O18 cage exhibits intensive rattling, as recently observed for clathrate compounds. The rattling of A cations is a common feature in the series of β-pyrochlore oxide superconductors AOs2O6 (A=Cs, Rb and K), and is greatest for the smallest K cation. 相似文献
77.
Toshio Morikawa Xuezheng Li Eriko Nishida Seikou Nakamura Kiyofumi Ninomiya Hisashi Matsuda Yoshimi Oda Osamu Muraoka Masayuki Yoshikawa 《Helvetica chimica acta》2010,93(3):573-586
The MeOH extract from the flowers of Bellis perennis was found to show pancreatic‐lipase inhibitory activity (IC50 455 μg/ml). From the extract, seven new triterpene saponins named perennisaponins G ( 1 ; IC50 163 μM ), H ( 2 ; 137 μM ), I ( 3 ; 147 μM ), J ( 4 ; 148 μM ), K ( 5 ; 223 μM ), L ( 6 ; 81.4 μM ), and M ( 7 ; 195 μM ) were isolated as pancreatic lipase inhibitors. The stereostructures of 1 – 7 were elucidated on the basis of chemical and spectroscopic evidence. 相似文献
78.
Tetsu Tsubogo Yuichiro Kano Koki Ikemoto Yasuhiro Yamashita Shū Kobayashi 《Tetrahedron: Asymmetry》2010,21(9-10):1221-1225
The first catalytic asymmetric 1,4-addition reactions of azlactones with acrylic esters have been developed. A chiral coordinative calcium catalyst was found to be effective for these reactions, and the desired 1,4-adducts were obtained in good yields and enantioselectivities. The product was converted to the corresponding α-alkylated glutamic acid by acid hydrolysis. 相似文献
79.
80.
Muraoka T Kinbara K Kobayashi Y Aida T 《Journal of the American Chemical Society》2003,125(19):5612-5613
The first example of "light-driven chiral molecular scissors" (1), which consists of 1,1',3,3'-tetraarylferrocene as a pivot part and azobenzene as a driving part, was synthesized. Absorption, circular dichroism (CD), and 1H NMR spectral studies on the photoinduced isomerization process of an enantiomer of 1 agreed well with a prediction by a DFT calculation, where a motion of the handles via light-driven contraction/expansion of the connecting azobenzene strap was transformed, through a pivotal motion of the ferrocene unit, into an open-close motion of the blade parts. 相似文献