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71.
72.
Joo F. Mano Natlia T. Correia Joaquim J. Moura Ramos Anabela C. Fernandes 《Journal of Polymer Science.Polymer Physics》1995,33(2):269-277
The technique of thermally stimulated depolarization currents was used to study the dipolar relaxation mechanisms in two side-chain liquid-crystalline polysiloxanes. The studied polymers have the same mesogenic side-group, but they differ in the number (or density) of side groups attached to the main chain. In both cases three different relaxations were observed: one in the vitreous state, one in the liquid crystalline phase, and the glass transition relaxation. The features of those thermally stimulated discharges are discussed and some suggestions are made concerning the attribution of those discharges at the molecular level. © 1995 John Wiley & Sons, Inc. 相似文献
73.
We generalize previous stochastic classical trajectory-ghost atom calculations for describing palladium deposition onto the Ni(111) surface between 0.1 and 0.5 monolayers. The growth evolves through two-dimensional islands. The islands are formed following the downward funneling mechanism. Surface temperature does not affect the island growth. 相似文献
74.
Jennifer A Rust Joaquim A Nóbrega Clifton P Calloway Bradley T Jones 《Analytical sciences》2005,21(8):1009-1013
A continuum-source tungsten coil electrothermal atomic absorption spectrometer has been assembled, evaluated, and employed in four different applications. The instrument consists of a xenon arc lamp light source, a tungsten coil atomizer, a Czerny-Turner high resolution monochromator, and a linear photodiode array detector. This instrument provides simultaneous multi-element analyses across a 4 nm spectral window with a resolution of 0.024 nm. Such a device might be useful in many different types of analyses. To demonstrate this broad appeal, four very different applications have been evaluated. First of all, the temperature of the gas phase was measured during the atomization cycle of the tungsten coil, using tin as a thermometric element. Secondly, a summation approach for two absorption lines for aluminum falling within the same spectral window (305.5-309.5 nm) was evaluated. This approach improves the sensitivity without requiring any additional preconcentration steps. The third application describes a background subtraction technique, as it is applied to the analysis of an oil emulsion sample. Finally, interference effects caused by Na on the atomization of Pb were studied. The simultaneous measurements of Pb and Na suggests that negative interference arises at least partially from competition between Pb and Na atoms for H2 in the gas phase. 相似文献
75.
For a nonautonomous dynamics with discrete time given by a sequence of linear operators Am, we establish a version of the Grobman-Hartman theorem in Banach spaces for a very general nonuniformly hyperbolic dynamics. More precisely, we consider a sequence of linear operators whose products exhibit stable and unstable behaviors with respect to arbitrary growth rates ecρ(n), determined by a sequence ρ(n). For all sufficiently small Lipschitz perturbations Am+fm we construct topological conjugacies between the dynamics defined by this sequence and the dynamics defined by the operators Am. We also show that all conjugacies are Hölder continuous. We note that the usual exponential behavior is included as a very special case when ρ(n)=n, but many other asymptotic behaviors are included such as the polynomial asymptotic behavior when ρ(n)=logn. 相似文献
76.
77.
78.
The results of a calculation of transport properties of the A phase of superfluid 3He are reported. The temperature dependence of the normal fluid density, viscosity, thermal conductivity, and nuclear spin relaxation time are given. 相似文献
79.
We study removable sets of solutions of locally solvable partial differential operators with smooth coefficients and characterize
them in terms of capacity in the sense of Harvey and Polking. For operators of order one we are able to give a geometric characterization
of removable sets in terms of orbits in the sense of Sussmann.
Oblatum 2-IX-1995 & 14-V-1996 相似文献
80.
Michael H. Abraham Asadollah Nasehzadeh Joaquim J. Moura Ramos 《Tetrahedron letters》1981,22(20):1929-1932
From standard Gibbs energies of transfer, corrected for cavity or nonelectrostatic effects, it is concluded that the solvolysis of methyl perchlorate takes place through a looser-than-usual SN2 transition state with a charge separation of about 0.52 units. 相似文献