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排序方式: 共有119条查询结果,搜索用时 32 毫秒
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Irina Piazza Antonio Cupane Emmanuel L. Barbier Claire Rome Nora Collomb Jacques Ollivier Miguel A. Gonzalez Francesca Natali 《Frontiers of Physics》2018,13(1):138301
With the aim of studying the effect of water dynamics on the properties of biological systems, in this paper, we present a quasi-elastic neutron scattering study on three different types of living cells, differing both in their morphological and tumor properties. The measured scattering signal, which essentially originates from hydrogen atoms present in the investigated systems, has been analyzed using a global fitting strategy using an optimized theoretical model that considers various classes of hydrogen atoms and allows disentangling diffusive and rotational motions. The approach has been carefully validated by checking the reliability of the calculation of parameters and their 99% confidence intervals. We demonstrate that quasi-elastic neutron scattering is a suitable experimental technique to characterize the dynamics of intracellular water in the angstrom/picosecond space/time scale and to investigate the effect of water dynamics on cellular biodiversity. 相似文献
3.
Julien Coulomb Victor Certal Dr. Marie‐Hélène Larraufie Cyril Ollivier Dr. Jean‐Pierre Corbet Dr. Gérard Mignani Dr. Louis Fensterbank Prof. Emmanuel Lacôte Dr. Max Malacria Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(39):10225-10232
A general and efficient method for the synthesis of cyclic sulfinates and sulfinamides based on intramolecular homolytic substitution (SHi) at the sulfur atom by aryl or alkyl radicals is described. Both alkyl and benzofused compounds can be accessed directly from easily prepared acyclic precursors. Enantiomerically enriched sulfur‐based heterocycles were formed through an SHi process with inversion of configuration at the sulfur atom. Cyclization of prochiral radicals proceeded with varying stereochemical outcomes, depending on the size of the incoming radical. 2‐Pyridyl and 2‐quinolyl radicals led to biaryl compounds, which result from attack onto the ortho position of the arylsulfinate rather than a thiophilic substitution. 相似文献
4.
Yann Ollivier 《Comptes Rendus Mathematique》2005,341(3):137-140
We show that random quotients of hyperbolic groups with ‘harmful’ torsion collapse at densities smaller than expected. To cite this article: Y. Ollivier, C. R. Acad. Sci. Paris, Ser. I 341 (2005). 相似文献
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Lise Crevier-Buchman Ollivier Laccourreye Jean-François Papon Dominique Nurit Daniel Brasnu 《Journal of voice》1997,11(2):232-237
We analyzed frequency and duration parameters of voice and speech in two men with adductor spasmodic dysphonia (SD). One was treated with botulinum toxin injection; the other received acupuncture therapy. Im provement after acupuncture therapy in terms of standard deviation of fundamental frequency, acoustic perturbation measurements, durational measurements of voice and speech, and spectrographic analysis was comparable to the results achieved with botulinum toxin injection. Voice and speech parameters were stable I year after acupuncture therapy. 相似文献
7.
M. Lamidi T. Martin-Lopez E. Ollivier F. Crespin-Maillard L. Nze Ekekang G. Balansard 《Chromatographia》1995,41(5-6):581-584
Summary A reversed-phase HPLC determination of 11 saponins and an alkaloid glycoside inNauclea diderrichii bark is described. Quantitative analysis of quinovic acid 3-0-α-L-rhamnopyranoside which is one of the main saponins was
determined, using Chrysanthelline A as internal standard. The complete separation was achieved in 47 minutes. The method of
quantification was validated. 相似文献
8.
Yuldashev P Ollivier S Averiyanov M Sapozhnikov O Khokhlova V Blanc-Benon P 《The Journal of the Acoustical Society of America》2010,128(6):3321-3333
The propagation of nonlinear spherically diverging N-waves in homogeneous air is studied experimentally and theoretically. A spark source is used to generate high amplitude (1.4 kPa) short duration (40 μs) N-waves; acoustic measurements are performed using microphones (3 mm diameter, 150 kHz bandwidth). Numerical modeling with the generalized Burgers equation is used to reveal the relative effects of acoustic nonlinearity, thermoviscous absorption, and oxygen and nitrogen relaxation on the wave propagation. The results of modeling are in a good agreement with the measurements in respect to the wave amplitude and duration. However, the measured rise time of the front shock is ten times longer than the calculated one, which is attributed to the limited bandwidth of the microphone. To better resolve the shock thickness, a focused shadowgraphy technique is used. The recorded optical shadowgrams are compared with shadow patterns predicted by geometrical optics and scalar diffraction model of light propagation. It is shown that the geometrical optics approximation results in overestimation of the shock rise time, while the diffraction model allows to correctly resolve the shock width. A combination of microphone measurements and focused optical shadowgraphy is therefore a reliable way of studying evolution of spark-generated shock waves in air. 相似文献
9.
D.I. Kolokolov H. Jobic A.G. Stepanov M. Plazanet M. Zbiri J. Ollivier V. Guillerm T. Devic C. Serre G. Férey 《The European physical journal. Special topics》2010,189(1):263-271
The low-frequency modes of MIL-47(V) and MIL-53(Cr) frameworks have been measured by inelastic neutron scattering. The librational
modes of benzene are very close in frequency in the two structures. First-principles calculations have been performed to assign
the measured spectra. The calculated values of the rotational barriers of the benzene rings are in reasonable agreement with
experimental data. The relatively large barriers (413–588 meV) explain the absence of quasi-elastic broadening on the neutron
time scale. 相似文献
10.
Panchaud P Chabaud L Landais Y Ollivier C Renaud P Zigmantas S 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(15):3606-3614
A novel reaction for the introduction of an azide moiety by means of a mild radical process is currently under development. Sulfonyl azides are suitable azidating agents for nucleophilic radicals, such as secondary and tertiary alkyl radicals. More electrophilic radicals, such as enolate radicals, do not react with sulfonyl azides. This feature allowed the development of efficient intra- and intermolecular carboazidations of olefins. Due to the versatility of the azido group, this reaction has an important synthetic potential, as already demonstrated by the preparation of the core of several alkaloids, particularly those containing an amino-substituted quaternary carbon center, such as FR901483. 相似文献