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991.
Luis A. Sanchez 《Nonlinear Analysis: Real World Applications》2009,10(4):2151-2156
We give a global asymptotic stability result for the classical Goodwin system. The proof follows from a combination of the Poincaré–Bendixson property enjoyed by monotone cyclic feedback systems, the theory of compound matrices and comparison techniques from the theory of monotone systems. 相似文献
992.
The interaction of light pulses in passively mode-locked fiber lasers operating has been studied. The numerical simulation has been used to demonstrate that a narrow-band selector inserted in a laser cavity allows the character of the interaction to be changed: depending on the detuning of the selector passband from the center of the gain band, ultrashort pulses can both attract and repel one another. Peculiarities of the pulse interaction have been studied at different parameters of the laser system. 相似文献
993.
M. A. Aguero M. L. Najera J. A. Aguilar J. Sanchez 《International Journal of Theoretical Physics》2009,48(7):2098-2111
A model with interparticle inharmonic interaction under the Φ4 external potential is studied. Making use of the special relation of relevant parameters, in the continuous limit, it was
possible to obtain various non-classical soliton solutions, specifically, compact and peak-like solutions. The solutions undergo
a jump on their first derivatives at some points of the space-time manifold. These analytic solutions were obtained by considering
strong restrictions on their velocities and on the jump conditions. The energy concentrated in these solutions shows in several
cases a discrete spectrum. 相似文献
994.
A. P. Patiño‐Soto S. Sanchez‐Valdes L. F. Ramos‐deValle 《Journal of Polymer Science.Polymer Physics》2008,46(2):190-200
ABS/Clay nanocomposites were prepared using two ABS with different Acrylonitrile (AN) contents and four montmorillonite clays; a natural clay (CNa+) and three modified clays, Cloisites 10A, 20A, and 30B. The composites were prepared in a twin‐screw extruder. Results were analyzed considering the effect of clay and ABS type, on the clay dispersion, intercalation and exfoliation, as well as on the storage modulus and thermal stability of the nanocomposites. XRD and TEM confirm that when using an ABS with higher AN content (ABS2), a better dispersion and intercalation–exfoliation can be obtained. Cloisites 20A and 30B, respectively the one with greater initial intergallery spacing, but lower polarity and with smaller inter‐gallery spacing but greater polarity, produce the ABS nanocomposites with the greater intergallery spacing. Both ABS polymers have similar storage modulus and Tg and in both cases, the modulus increases with the 4 wt % clay. This increase is greater with the modified clays and slightly greater with the ABS2. Tg, from tan δ, increases very little with the 4 wt % clay, but again, this is slightly greater with ABS2. TGA and flammability tests show that the dispersed clay enhances the thermal stability and that the ABS with higher AN content produces a greater increase in fire retardancy. Tests also show that the better thermal stability and fire retardancy is obtained with the Cloisites 20A or 30B. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 190–200, 2008 相似文献
995.
Wilfried Nörtershäuser Andreas Dax Guido Ewald Stefan Götte Reinhard Kirchner H.-Jürgen Kluge Thomas Kühl Rodolfo Sanchez Agnieszka Wojtaszek Bruce A. Bushaw Gordon W. F. Drake Zong-Chao Yan Claus Zimmermann 《Hyperfine Interactions》2005,162(1-4):93-100
A novel method for the determination of nuclear charge radii of lithium isotopes is presented. Precise laser spectroscopic
measurements of the isotope shift in the lithium 2s → 3s transition are combined with highly accurate atomic physics calculation of the mass dependent isotope shift to extract the
charge-distribution-sensitive information. This approach has been used to determine the charge radii of 8,9Li for the first time. 相似文献
996.
M. Plaza L. Perez M.C. Sanchez A. Fernández-Pacheco J.M. De Teresa 《Solid State Communications》2009,149(45-46):2043-2046
In this work, we present Co-rich particles which have been successfully grown by high current electroplating. This technique produces particles with a Co–Cu core surrounded by an oxidized shell. This shell has two consequences: on the one hand, it electrically isolates the magnetic core and acts as a tunnel barrier; on the other hand, the ferromagnetic/antiferromagnetic structure causes an exchange bias coupling when cooling the particles in the presence of magnetic field. We also present magnetoresistance measurements up to 9 T. At low field, direct tunnelling between magnetic cores through the insulating layer properly explains the experimental observations, but, at high field, a linear contribution dominates the MR. The latter behaviour can be understood by assuming second-order tunnelling. 相似文献
997.
Photocatalytic Activity in the 2,4-Dinitroaniline Decomposition Over TiO2 Sol-Gel Derived Catalysts 总被引:3,自引:0,他引:3
Tessy Lopez R. Gomez E. Sanchez F. Tzompantzi L. Vera 《Journal of Sol-Gel Science and Technology》2001,22(1-2):99-107
Titania was prepared by the sol-gel method from titanium alkoxide. Depending on the pH of the gelling solution, specific surface areas between 88 and 10 m2/g were obtained. The band gap (E
g) of the samples was found between 3.05 and 3.32 eV. In samples gelled at pH5 and 9 and calcined at 400°C only anatase phase is observed, while for pH3 and pH7 brookite, anatase and rutile or anatase-rutile phases coexist. It was found that the photoactivity in the 2,4-dinitroanailine decomposition depends on the E
g and on the crystalline phases. The highest activity corresponds to the catalysts having the lowest E
g and more than one crystalline phases co-existing. 相似文献
998.
Journal of Statistical Physics - A lower bound on the grand partition function of a classical charge-symmetric system is adapted to the neutral grand canonical ensemble, in which the system is... 相似文献
999.
G. Hirankumar C. Iojoiu F. Alloin J. Y. Sanchez T. Pagnier 《Journal of Raman spectroscopy : JRS》2007,38(12):1570-1576
Organic solutions of lithium pentafluorobenzene sulfonate (C6F5SO3Li) with varying molalities in N,N‐dimethyl formamide (DMF) and triethyleneglycol dimethylether (triglyme) were investigated by Raman spectroscopy. Spectral decomposition in the νs(SO3) stretching region showed bands characteristic of free anions, ion pairs and various aggregates. The relative fraction of each species has been followed as a function of salt molality. In DMF, free anions dominate, while in triglyme ion pairs dominate, in accordance with the solvent dielectric constant. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
1000.
Jairo Quiroga Braulio Insuasty Rodrigo Abonia Diana Mejía Justo Cobo Manuel Nogueras Adolfo Sanchez John Nicolson Low 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(12):1457-1459
The molecules of the title compound, C12H17N3O, are linked by two N—H?O hydrogen bonds to form a three‐dimensional network. The N?O distances are 2.804 (3) and 2.766 (3) Å, both involving a common acceptor O atom. 相似文献