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41.
J.J.?RomeroEmail author M.R.B.?Andreeta E.R.M.?Andreeta L.E.?Bausá A.C.?Hernandes J.?García Solé 《Applied Physics A: Materials Science & Processing》2004,78(7):1037-1042
The growth from ceramic pedestals of single crystal fibers of strontium barium niobate (SBN), doped with different Nd concentrations, was studied. High-quality fibers were grown for Nd doping levels of up to 4.2 at.%, and doping levels as high as 9.9 at.% were reached. No signs of core effects were observed, even for the highest concentration samples. The emission spectra of Nd3+ ions in the fibers did not differ from those obtained from bulk SBN crystals, showing very broad bands due to the typical disorder of the crystallographic tungsten-bronze structure. Fluorescence quenching was clearly observed for Nd doping levels above 2 at.%. PACS 81.10.Fq; 78.55.-m 相似文献
42.
Hildebrando?M.?RodriguesEmail author J.?Solà-MoralesEmail author 《Journal of Dynamics and Differential Equations》2004,16(3):767-793
As a continuation of a previous work on linearization of class C1 of diffeomorphisms and flows in infinite dimensions near a fixed point, in this work we deal with the case of a saddle point with some non-resonance restrictions for the linear part. Our result can be seen as an extension of results by Hartman [Boletin de la Sociedad Matematica Mexicana 5(2), 220–241 (1960)] and Aronson, Belitskii and Zhuzhoma [Introduction to the Qualitative Theory of Dynamical systems on surfaces, AMS Transl. Math. Monog. vol.153, pp. 268–277 (1996)] in dimension two. We also present an application to a system of nonlinear wave equations.AMS Subject Classifications: Primary: 35B05, 34G20. Secondary: 35B40, 34D05.Dedicated to Professor Shui-Nee Chow on the occasion of his 60th birthday 相似文献
43.
R.?V.?SoléEmail author 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,35(1):117-123
The dynamics of cancer evolution is studied by means of a simple quasispecies model involving cells displaying high levels of genetic instability. Both continuous, mean-field and discrete, bit-string models are analysed. The string model is simulated on a single-peak landscape. It is shown that a phase transition exists at high levels of genetic instability, thus separating two phases of slow and rapid growth. The results suggest that, under a conserved level of genetic instability the cancer cell population will be close to the threshold level. Implications for therapy are outlined.Received: 22 April 2003, Published online: 22 September 2003PACS:
87.10.+e Biological physics: General theory and mathematical aspects - 87.23.Kg Dynamics of evolution - 87.23.-n Ecology and evolution - 89.75.Fb Structures and organization in complex systems 相似文献
44.
M.?Grether M.?de Llano M.?A.?SolísEmail author 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,25(3):287-291
Normal behavior of the thermodynamic properties of a Fermi gas in d > 2 dimensions, integer or not, means monotonically increasing or decreasing of its specific heat, chemical potential or isothermal sound velocity, all as functions of temperature. However, for 0 < d < 2 dimensions these properties develop a "hump" (or "trough") which increases (or deepens) as d? 0 d\rightarrow 0 . Though not the phase transition signaled by the sharp features ("cusp" or "jump") in those properties for the ideal Bose gas in d > 2 (known as the Bose-Einstein condensation), it is nevertheless an intriguing structural anomaly which we exhibit in detail. 相似文献
45.
Tom Schoonjans Antonio Brunetti Bruno Golosio Manuel Sanchez del Rio Vicente Armando Solé Claudio Ferrero Laszlo Vincze 《Spectrochimica Acta Part B: Atomic Spectroscopy》2011,66(11-12):776-784
This work presents the recent developments of xraylib, an ANSI C library that provides convenient access to a large number of X-ray related databases, with a focus on quantitative X-ray fluorescence applications. The enhancements include improved X-ray fluorescence production cross sections that take into account cascade effects and M-lines, as well as revised line energies, atomic level widths, Compton broadening profiles etc. A full overview of the complete application programming interface is presented. 相似文献
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Over the past 50 years, pentafluorobenzaldehyde has received much attention due to its unique chemical and physical properties as well as its real or potential applications in chemistry of porphyrines, additives, drug delivery and in analytical chemistry. Pentafluorobenzaldehyde is multifunctional aromatic compound containing five atoms of fluorine and one aldehydic function. That is why it can provide nucleophilic substitutions of all or some atoms of fluorine, nucleophilic additions of aldehydic function, “haloform reaction” and some cyclization reactions. This year, it is being the 50th year, since the first synthesis of this compound was published. 相似文献
49.
Within a lattice model describing a binary mixture with fixed concentrations of the species we discuss the relationship between the surface tension of the mixture and the concentrations. 相似文献
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