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71.
采用络合溶胶-凝胶法制备出系列纳米级发光材料ASnO3(A=Ca,Sr,Ba): 1%Eu.并采用X射线衍射(XRD)、紫外光谱(UV-Vis)、透射电镜(TEM)、荧光光谱(PL)对所制备的纳米发光粉体进行表征.结果表明:所合成的物质均为具有确定结构的单一物相,并从结构上分析了其发光性质随碱土金属离子半径变化而变化的规律. 相似文献
72.
Ton Storcken 《International Journal of Game Theory》1997,26(2):235-248
The rather new notion of effectivity function is related to the notion of simple game. Every effectivity function is associated with a simple game. So theory about simple games may be applicable to effectivity functions. E.g. if the effectivity function is additive, then the associated simple game is weighted. Via a characterization of weighted simple games it is possible to characterize maximal additive effectivity functions.Finally we characterize additive effectivity functions and their associated simple games.I thank G.J. Otten for useful comments and stimulating conversations. 相似文献
73.
Ton That Thang Francois Winternitz Alain Lagrange Alain Olesker Gabor Lukacs 《Tetrahedron letters》1980,21(47):4495-4498
Appropriate precursors for the synthesis of D-vancosamine and L-evernitrose have been stereospecifically obtained from methyl 4,6-O-benzylidene-2-deoxy-α- and β-D-threo-hexopyranosid-3-ulose. 相似文献
74.
Ohne ZusammenfassungUnterstützt durch Air Force Office of Scientific Research, AF 49 (638)-253, S/A1. 相似文献
75.
76.
A simple theory is presented to explain the previously observed single-mode vibrational excitation of the spherical-top molecules CH4, CF4 and SF6 in collisions with H+ and Li+. The theory is based on a three-dimensional forced-oscillator model which has been modified to take account of many independent harmonic oscillators. For small-angle collisions the linear driving forces are the dipole-, polarizability- and quadrupole-derivatives taken from IR, Raman spectroscopy and simple estimates, respectively. To explain the results at larger angles near and beyond the rainbow it has been necessary to introduce short-range repulsive forces between the ions and the outer atoms of the molecule. For small angles both the predicted first moment of the energy transfer and the time-of-flight spectra agree quantitatively with the experimental results. At large angles, for which only the first moment of the energy is available, good qualitative agreement is obtained after a slight adjustment of the potential parameters. The energy transfer as a function of time is calculated and shows a different oscillatory behavior for the proton and Li+-ion systems. Also the effect of intra-mode coupling is investigated and shown to have only a small effect on the overall energy transfer. The paper closes with a discussion of the implications of these experiments and the possible role of rotational excitation. The field strengths in these ion scattering experiments are shown to be greater than in the strongest focused Q-switched laser pulses. 相似文献
77.
78.
A. Delijska Chr. Prǎvčeva N. Tončev 《Spectrochimica Acta Part B: Atomic Spectroscopy》1976,31(3):121-127
The reducing action of some aliphatic and aromatic hydrocarbon derivatives on the oxides of Me, W, Ti, Zr, Nb and Ta was compared to that of graphite powder. The investigation showed that among the organic compounds studied tetraethylammonium iodide gives a better separation of the volatile elements As, Te, Sn, Pb, Bi, Cd, Ag and In, which commonly occur in the above oxides as impurities, from the molybdenum and better line intensities than when using graphite powder. The possible reduction and iodide forming reactions which take place in the electrode cavity in the presence of tetraethylammonium iodide have been established by using calculated values for the change in the Gibbs free energy and the results of X-ray analyses of sample residues obtained after arcing. This reagent was also found to stabilize the are colunm temperature, a necessary condition for its successful application as a spectroscopic buffer. 相似文献
79.
Bui An Ton 《Journal of Mathematical Analysis and Applications》1975,49(3):713-720
The solution of the initial boundary-value problem u?′ ? ?D2u? + u?Du? = f on (a, b) x(0, T), u?(a, t) = u?(b, t) = 0 and u?(x, 0) = 0 on (a, b), is shown to converge to the solution of the limiting equation as the viscosity tends to zero. Estimates on the rate of convergence are given. 相似文献
80.
We introduce and experimentally demonstrate acousto-optic-assisted diffuse optical tomography (DOT) using a holography-based acousto-optic setup. The method is based on probing a scattering medium with a localized acoustical modulation of the phase of the scattered light. The optical properties of the scattering medium are recovered with ultrasound-limited resolution by applying DOT reconstruction methods on a set of the measured intensities of light, modulated at different locations throughout the medium. 相似文献