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31.
S. F. Biagi M. Bourquin R. M. Brown H. J. Burckhart Ch. Doré P. Extermann M. Gailloud C. N. P. Gee W. M. Gibson R. J. Gray P. Jacot-Guillarmod P. W. Jeffreys W. C. Louis T. Modis P. Mühlemann R. C. Owen J. Perrier K. J. S. Ragan Ph. Rosselet B. J. Saunders P. Schirato H. W. Siebert V. J. Smith K. -P. Streit J. J. Thresher R. Weill A. T. Wood C. Yanagisawa 《Zeitschrift fur Physik C Particles and Fields》1985,28(4):495-507
In an experiment performed in the CERN SPS hyperon beam we have obtained a value for the branching ratio $${{\Sigma ^ + \to p\gamma } \mathord{\left/ {\vphantom {{\Sigma ^ + \to p\gamma } {\Sigma ^ + \to p\pi }}} \right. \kern-\nulldelimiterspace} {\Sigma ^ + \to p\pi }}^0 of\left( {2.46_{ - 0.35}^{ + 0.30} } \right) \times 10^{ - 3} ,$$ corresponding to a branching ratio $${{\Sigma ^ + \to p\gamma } \mathord{\left/ {\vphantom {{\Sigma ^ + \to p\gamma } {\Sigma ^ + \to all}}} \right. \kern-\nulldelimiterspace} {\Sigma ^ + \to all}}of\left( {1.27_{ - 0.18}^{ + 0.16} } \right) \times 10^{ - 3} .$$ This result is discussed in the context of present understanding of hyperon radiative decays. 相似文献
32.
Gilbert Weill 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(13-14):1769-1780
33.
34.
Abstract Optical measurements in the diamond anvil cell (DAC) as well as thermodynamics, show cubic GaAs I to be unstable at 300 K, at 13 GPa. The thermodynamic phase line from GaAs I to the high pressure (H.P.) form(s) is at 11 ± 2 GPa. Large hyteresis makes the actual I→II transition observable only at 17.5 ± 1 GPa. 相似文献
35.
Isotopically labelled (CH)x samples have been studied to probe the influence of nuclear spin diffusion on the relaxation mechanisms of polyacetylene. The results are discussed in terms of two spin species: those relaxing by direct interaction with solitons and those diffusing by mutual flip-flop towards this well relaxed core. Predictions are made for the time dependence of magnetization recovery and for the frequency dependence of long T1. 相似文献
36.
One novel and three known hydroxycinnamic acid derivatives having antioxidant activities were isolated from a Brazilian bee pollen. They were identified as kaempferol 3-O-[2-O-p-coumaroyl]-alpha-L-arabinopyranoside, N(1), N(5), N(10)-tri-p-coumaroyl spermidine, N(1), N(5), N(10), N(14)-tetra-p-coumaroyl spermine, and monocaffeoyl-tri-p-coumaroyl spermine, respectively. The structure of the kaempferol glycoside was established on the basis of spectroscopic and chemical investigations. Among the isolated compounds, monocaffeoyl-tri-p-coumaroyl spermine showed the strongest free radical-scavenging activity, which was almost identical to that of alpha-tocopherol. On the other hand, the antioxidant effect of tri-p-coumaroyl spermidine on autooxidation of linoleic acid was strongest and nearly equal to that of alpha-tocopherol. 相似文献
37.
D. Maring M. Wilhelm H. W. Spiess B. Meurer G. Weill 《Journal of Polymer Science.Polymer Physics》2000,38(20):2611-2624
Following an earlier study of the 1H relaxation and NMR line shapes, we have carried out selective one‐dimensional and two‐dimensional 13C solid‐state NMR studies that yield to detailed interpretation of the dynamics in form I, II, and III polymorphs of isotactic poly‐1‐butene. A specific defect diffusion along the side group is proposed to account for the temperature dependence of the 13C spectra in form I. The backbone of the helix in forms II and III is shown to undergo large angle motions above the glass‐transition temperature. High‐resolution solid‐state 13C two‐dimensional exchange NMR under magic‐angle spinning with cross‐polarization techniques demonstrates the existence of slow rotational jumps of the helices in form III with typical jump rates of about 10 s−1. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2611–2624, 2000 相似文献
38.
T. Lachhab C. Weill 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,9(1):59-69
Mechanical properties of packings of deformable spheres of polyelectrolyte gel are studied experimentally. These particles
are plunged into a brine. They have the property to swell and shrink when the concentration of salt of the solution is varied.
An oedometric compression is performed imposing cycles of deformation at constant speed and constant salinity Cs. Under many different conditions, we study the laws of deformation relating the macroscopic compression force F, to the macroscopic strain . We find empirical non linear relations of the type . The values of this exponent m are discussed and compared to the results of measurements on a single sphere compressed on
a plane as well as to the results of experiments and simulations on dry model granular assemblies. The swelling and deswelling
properties of the spheres are used to perform isotropic compression tests. In this situation we determine the relation between
the force at equilibrium and the macroscopic strain . The results are compared with those obtained in the oedometric compression tests.
Received 27 January 1998 相似文献
39.
We report the first isolation of the alkaloid aaptamine from the Philippine marine sponge Stylissa sp. Aaptamine possessed weak antiproliferative activity against HCT116 colon cancer cells and inhibited the proteasome in vitro at 50 µM. These activities may be functionally linked. Due to its known, more potent activity on certain G-protein coupled receptors (GPCRs), including -adrenergic and -opioid receptors, the compound was profiled more broadly at sub-growth inhibitory concentrations against a panel of 168 GPCRs to potentially reveal additional targets and therapeutic opportunities. GPCRs represent the largest class of drug targets. The primary screen at 20 µM using the -arrestin functional assay identified the antagonist, agonist, and potentiators of agonist activity of aaptamine. Dose-response analysis validated the -adrenoreceptor antagonist activity of aaptamine (ADRA2C, IC50 11.9 µM) and revealed the even more potent antagonism of the -adrenoreceptor (ADRB2, IC50 0.20 µM) and dopamine receptor D4 (DRD4, IC50 6.9 µM). Additionally, aaptamine showed agonist activity on selected chemokine receptors, by itself (CXCR7, EC50 6.2 µM; CCR1, EC50 11.8 µM) or as a potentiator of agonist activity (CXCR3, EC50 31.8 µM; CCR3, EC50 16.2 µM). These GPCRs play a critical role in the treatment of cardiovascular disease, diabetes, cancer, and neurological disorders. The results of this study may thus provide novel preventive and therapeutic strategies for noncommunicable diseases (NCDs). 相似文献
40.
Vincent Pessey Rosa Garriga Francois Weill Bernard Chevalier Jean Etourneau François Cansell 《高压研究》2013,33(1-6):289-298
Abstract The chemical transformation of metallic precursors in a supercritical fluid is a new route for obtaining nanometric homogeneous powders. In this paper we present a technique to produce metal, oxide or nitride submicronic particles, with a spherical morphology and mean diameters from a few microns to a few tens of nanometers. Metallic copper, oxides (Cu2O, Fe3O4, Ga2O3) and nitrides (Cu3N, Fe4N) have been prepared. This process consists in solubilizatiw and subsequent thermal decomposition of acetylacetonates of metals in a supercritical fluid, either a mixture of CO2/C2H5OH or NH3. 相似文献