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排序方式: 共有137条查询结果,搜索用时 46 毫秒
41.
Stinville J.C. Francis T. Polonsky A.T. Torbet C.J. Charpagne M.A. Chen Z. Balbus G.H. Bourdin F. Valle V. Callahan P.G. Echlin M.P. Pollock T.M. 《Experimental Mechanics》2021,61(2):331-348
Experimental Mechanics - Background: Advancements in the Digitial Image Correlation (DIC) technique over the past decade have greatly improved spatial resolution. However, many processes, such as... 相似文献
42.
Loïc Bourdin 《Journal of Difference Equations and Applications》2013,19(9):1417-1436
We derive the discrete version of the classical Helmholtz's condition. Precisely, we state a theorem characterizing second-order finite difference equations admitting a Lagrangian formulation. Moreover, in the affirmative case, we provide the class of all possible Lagrangian formulations. 相似文献
43.
Najeh Rekik Dr. Houcine Ghalla Dr. Henryk T. Flakus Prof. Magdalena Jabłońska Dr. Paul Blaise Brahim Oujia Prof. 《Chemphyschem》2009,10(17):3021-3033
Polarized IR spectra of the hydrogen bond in 2‐thiophenic acid crystals, isotopically neat and of mixed H/D isotopic content, are measured at 298 and 77 K in the “residual” νO? H and νO? D band frequency ranges. This crystalline system provides spectra in these band frequency ranges that differ considerably in intensity distribution from the spectra of other H‐bonded centrosymmetric dimeric species. This change in the spectral properties of the crystals is probably due to the influence of the sulfur atoms from the thiophene aromatic rings, which are directly linked to the (COOH)2 or (COOD)2 cycles. The magnitude of this effect correlates with the net electronic charge distribution at the 2‐ and 3‐positions of substituted thiophene rings, which in a different way influences the electron charge density in the hydrogen bonds of the two thiophenic acid isomers. The experimental results for spectral structures are compared to predictions obtained with theoretical calculations involving the combined effects of anharmonicities, Davydov coupling, Fermi resonances, and direct and indirect relaxations within the framework of the linear response theory. Numerical results show that mixing of all these effects allows satisfactory reproduction of the main features of the experimental IR line shapes of crystalline H‐ and D‐bonded 2‐thiophenic acid at room and liquid‐nitrogen temperatures. 相似文献
44.
A new method is reported for the determination of aluminium in wine by HPLC, involving derivatisation with 8-hydroxyquinoline (oxine) in the presence of micelles resulting in the formation of a fluorescent derivative. The complex is separated on a C18 column using a mobile phase of oxine - SDS - 35% acetonitrile, in a pH 7 buffer. The method was validated in the range 0.125-2 mg/l in a synthetic wine. The method was applied to the determination of aluminium in white, rosé and red wines and results compared with those obtained by atomic absorption (GFAA). Aluminium concentrations found by HPLC in white wines were greater than those found in red wines. Further investigation using a polyphenol-enriched white wine revealed a statistically significant inverse relationship between wine polyphenol content and the aluminium concentration determined by HPLC. The method may therefore be envisaged for the determination of unbound aluminium in wine. 相似文献
45.
P.H. Fries E. Belorizky N. Bourdin F. Cinget D. Gagnaire W. Goreckic M. Jeannin Ph. Vottero 《Journal of Molecular Structure》1995,330(1-3):335-345
The paramagnetic dipolar spin-lattice relaxation of nuclear spins is expressed in terms of the geometrical and dynamical parameters of the molecules and used to analyze the intra- and intermolecular microdynamics. The possible conformational changes of a TEMPOL nitroxide-labelled sugar in deuterated chloroform are studied and then the intermolecular processes are considered. The influence of the discrete polar natures of acetonitrile, chloroform, and methanol on the TEMPOL solvation dynamics is recognized. The importance of the water structure on the collisional approach of two attractive ions is emphasized. Finally, the attractive effects of the dipole-dipole electrostatic forces are shown for the water/TEMPOL pair. Diffusion and jump analytical theories, integral equations of statistical mechanics, and Monte-Carlo simulations of the diffusion are combined to treat the anisotropic interactions and the many-body effects. 相似文献
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Hailong Yuan Florian Massuyeau Nicolas Gautier Antoine Blaise Kama Eric Faulques Fei Chen Qiang Shen Lianmeng Zhang Michael Paris Romain Gautier 《Angewandte Chemie (International ed. in English)》2020,59(7):2802-2807
Near‐UV‐pumped white‐light‐emitting diodes with ultra‐high color rendering and decreased blue‐light emission is highly desirable. However, discovering a single‐phase white light emitter with such characteristics remains challenging. Herein, we demonstrate that Mn doping as low as 0.027 % in the hybrid post‐perovskite type (TDMP)PbBr4 (TDMP=trans‐2,5‐dimethylpiperaziniium) enables to achieve a bright pure white emission replicating the spectrum of the sun's rays. Thus, a white phosphor exhibiting an emission with CIE coordinates (0.330, 0.365), a high photoluminescence quantum yield of 60 % (new record for white light emission of hybrid lead halides), and an ultra‐high color rendering index (CRI=96, R9=91.8), corresponding to the record value for a single phase emitter was obtained. The investigation of the photoluminescence properties revealed how free excitons, self‐trapped excitons, and low amount of Mn dopants are coupled to give rise to such pure white emission. 相似文献
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50.
John G. Conway Earl F. Worden Jean Blaise Pierre Camus Jean Vergès 《Spectrochimica Acta Part B: Atomic Spectroscopy》1977,32(2):101-106
The spectrum of 249Bk, excited in an electrodeless lamp, has been recorded between 3700 and 12,000 cm?1 on a Fourier-transform spectrometer. The strongest 90 lines are listed along with the classification for 77 of them. The lowest levels of the 5f96d7s, 5f97s7p, 5f97s8s, 5f86d7s2 , 5f87s27p and 5f86d7s7p configurations of Bk I and of the 5f96d and 5f97p configurations of Bk II have been identified. Lists of the energies and hfs data of the Bk I levels involved in the i.r. transitions are also included. 相似文献