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991.
Trypanocidal constituents of Pogostemon cablin were investigated. Activity guided isolation of the acetone extract resulted in isolation of three new sesquiterpene hydroperoxides 1-3, together with a known sesquiterpene, patchouli alcohol (4). In vitro minimum lethal concentrations of the hydroperoxides 1-3 against epimastigotes of Trypanosoma cruzi were 0.84 microM (1), 1.7 microM (2) and 1.7 microM (3). The activity of the corresponding alcohols and patchouli alcohol was very weak (MLC>200 microM). 相似文献
992.
Kondo M Hayakawa Y Miyazawa M Oyama A Unoura K Kawaguchi H Naito T Maeda K Uchida F 《Inorganic chemistry》2004,43(19):5801-5803
A new two-dimensional coordination polymer with cobalticinium 1,1'-dicarboxylate (ccdc) incorporated in the framework has been prepared, the ccdc functioning as unique monoanionic dicarboxylate ligands. The compound shows a high redox activity based on the ccdc units. 相似文献
993.
A new regression structure is introduced to several families of distributions, including the Generalized Extreme Value (GEV) distribution, which are available to explain the distribution of the maximum pit depth of a small sample. This regression structure depends on sample sizes, but under a simple assumption it is also available in the case of unknown sample sizes. GEV with the proposed regression structure provides us with a new extrapolation model for time. Compared to ordinary GEV models, effectiveness of our GEV model is demonstrated for our real data set. Also, comparisons are made with GEV and other two families of distributions with respect to the proposed regression structure. 相似文献
994.
Kawasaki K Yoshida T Tarui M Nakagawa H Yano H Ishikawa O Hata T 《Physical review letters》2004,93(10):105301
We have investigated the transition phenomena of superfluid 3He in thin 0.8 microm slabs with a cw-NMR method. We found that, just below the phase-transition temperature, only the A phase appeared at any pressure. At lower temperatures, the phase transition to the B phase occurred between 0.3 and 2.74 MPa. We obtained a universal critical thickness delta as a function of pressure. When the reduced slab thickness, d/xi(T), is smaller than delta, only the A phase becomes stable. 相似文献
995.
Three-dimensional (3D) relativistic electromagnetic subcycle solitons were observed in 3D particle-in-cell simulations of an intense short-laser-pulse propagation in an underdense plasma. Their structure resembles that of an oscillating electric dipole with a poloidal electric field and a toroidal magnetic field that oscillate in phase with the electron density with frequency below the Langmuir frequency. On the ion time scale, the soliton undergoes a Coulomb explosion of its core, resulting in ion acceleration, and then evolves into a slowly expanding quasineutral cavity. 相似文献
996.
Esirkepov TZh Bulanov SV Nishihara K Tajima T Pegoraro F Khoroshkov VS Mima K Daido H Kato Y Kitagawa Y Nagai K Sakabe S 《Physical review letters》2002,89(17):175003
In order to achieve a high-quality, i.e., monoenergetic, intense ion beam, we propose the use of a double-layer target. The first layer, at the target front, consists of high-Z atoms, while the second (rear) layer is a thin coating of low-Z atoms. The generation of high-quality proton beams from the double-layer target, irradiated by an ultraintense laser pulse, is demonstrated with three-dimensional particle-in-cell simulations. 相似文献
997.
Abe K Abe K Abe T Adam I Akimoto H Aston D Baird KG Baltay C Band HR Barklow TL Bauer JM Bellodi G Berger R Blaylock G Bogart JR Bower GR Brau JE Breidenbach M Bugg WM Burke D Burnett TH Burrows PN Calcaterra A Cassell R Chou A Cohn HO Coller JA Convery MR Cook V Cowan RF Crawford G Damerell CJ Daoudi M de Groot N de Sangro R Dong DN Doser M Dubois R Erofeeva I Eschenburg V Fahey S Falciai D Fernandez JP Flood K Frey R Hart EL Hasuko K Hertzbach SS Huffer ME Huynh X Iwasaki M Jackson DJ 《Physical review letters》2002,88(15):151801
The parity violation parameters A(b) and A(c) of the Zb(b) and Zc(c) couplings have been measured directly, using the polar angle dependence of the polarized cross sections at the Z(0) pole. Bottom and charmed hadrons were tagged via their semileptonic decays. Both the electron and muon analyses take advantage of new multivariate techniques to increase the analyzing power. Based on the 1993-1998 SLD sample of 550,000 Z(0) decays produced with highly polarized electron beams, we measure A(b) = 0.919+/-0.030(stat)+/-0.024(syst), and A(c) = 0.583+/-0.055(stat)+/-0.055(syst). 相似文献
998.
We observed and measured the relative carrier-envelope phase difference per round trip between synchronized femtosecond Ti:sapphire and Cr:forsterite mode-locked lasers. The relative carrier-envelope phase slip was directly recorded by heterodyning of the Cr:forsterite laser with the supercontinuum from the Ti:sapphire laser. We also obtained another phase relation by superimposing the third harmonic of the Cr:forsterite laser with the second harmonic of the Ti:sapphire laser. In the latter case we obtained a stable beat signal with a signal-to-noise ratio larger than 30 dB and found a dependence of the beat frequency on the cavity length. 相似文献
999.
Racemic indanofan [(+/-)-1] was efficiently converted to enantiopure (S)-indanofan [(S)-1] by a combination of enzymatic resolution and chemical inversion techniques. An additional important technique is the use of an o-xylene complex of a hemiketal (S)-3c as a precursor, which can be quantitatively converted to (S)-indanofan and easily purified by recrystallization from o-xylene. 相似文献
1000.
PtI(2)(PPh(3))(2) catalyzes hydrosilylation of 2,2-diphenyl-1-methylenecyclopropane with HSiEt(3), HSiPh(3), HSiEt(2)Ph, HSiPhCl(2), and HSiCl(3) under solvent-free conditions at 140 degrees C to produce the silyl compounds with a (2,2-diphenylcyclopropyl)methyl substituent in moderate to high yields without ring-opening of the substrate. PtI(2)(PPh(3))(2) is converted by the reaction into PtH(I)(PPh(3))(2), which also catalyzes the hydrosilylation of the methylenecyclopropanes. The reaction of 2-phenyl-1-methylenecyclopropane, 2-methyl-2-phenyl-1-methylenecyclopropane, 2,2-diphenethyl-1-methylenecyclopropane, and alkylidenecyclopropanes with HSiEt(3) catalyzed by PtI(2)(PPh(3))(2) causes addition of hydrosilane to the substrate accompanied by ring-opening. 2,2-Diphenyl-1-methylenecyclopropane undergoes ring-opening isomerization in the presence of HSi(OEt)Me(2) and Pt(PEt(3))(3) catalyst to give 1,1-diphenyl-1,3-butadiene. The pathways for the hydrosilylation and the isomerization are discussed. 相似文献