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21.
Smaoui S Mellouli L Lebrihi A Coppel Y Fguira LF Mathieu F 《Natural product research》2011,25(8):806-814
Thirty litres of fermentation broth was extracted from the newly isolated Streptomyces sp. strain TN17 and various separation and purification steps led to the isolation of three pure bioactive compounds (1-3). Compound 1: cyclo (L-Leu-L-Arg), a diketopiperazine 'DKP' derivative; 2: di-(2-ethylhexyl) phthalate, a phthalate derivative; and 3: cyclo 1-[2-(cyclopentanecarbonyl-3-phenyl-propionyl]-pyrrolidine-2-carboxylic acid (1-carbamoyl-propyl)-amide, a cyclic tetrapeptide derivative. The chemical structure of these three active compounds was established on the basis of spectroscopic studies (MS and NMR) and by comparison with data from the literature. According to our biological studies, the pure compounds (1-3) possess antibacterial and antifungal activities. 相似文献
22.
Periodica Mathematica Hungarica - We discuss the rational solutions of the Diophantine equations $$f(x)^2 \pm f(y)^2=z^2$$ . This problem can be solved either by the theory of elliptic curves or by... 相似文献
23.
Amine Asselah Fabienne Castell 《Annales de l'Institut Henri Poincaré (B) Probabilités et Statistiques》2007,43(2):163
We consider a random walk in random scenery {Xn=η(S0)+?+η(Sn),n∈N}, where a centered walk {Sn,n∈N} is independent of the scenery {η(x),x∈Zd}, consisting of symmetric i.i.d. with tail distribution P(η(x)>t)∼exp(−cαtα), with 1?α<d/2. We study the probability, when averaged over both randomness, that {Xn>ny} for y>0, and n large. In this note, we show that the large deviation estimate is of order exp(−ca(ny)), with a=α/(α+1). 相似文献
24.
Amine El Sahili 《Comptes Rendus Mathematique》2002,335(11):859-861
Consider two maps f and g from a set E into a set F such that f(x)≠g(x) for every x in E. What is the maximal cardinal of a subset A of E such that the images of the restriction of f and g to A are disjoint? Mekler, Pelletier and Taylor have shown that it is card(E) when the set E is infinite; in the finite case, we have proved that it is greater than or equal to card(E)/4. In this paper, using graph theoretical technics, we find these results as a direct application of a lemma of Erdös. Moreover, we show that if , then there exists a countable partition {En}n?1 of such that f(En)∩g(En)=φ, for every n?1. To cite this article: A. El Sahili, C. R. Acad. Sci. Paris, Ser. I 335 (2002) 859–861. 相似文献
25.
This paper presents a theoretical formulation in which the stream-tube method (STM) is examined through a variational approach for solving solid strain and fluid flow problems with finite elements. The analysis considers a reference domain, used as computational domain, related to the physical domain by an unknown transformation function to be determined numerically. Mass conservation is automatically verified by STM. The variational approach leads to eliminate the pressure in fluid problems and avoids to set up a mixed displacement–pressure procedure in the case of incompressible solids. Examples are given for fluid flows, applications and comparisons are also provided in the bending problem in elasticity. 相似文献
26.
Ion conductive characteristics of cross-linked network polysiloxane-based solid polymer electrolytes
Z. C. Zhang J. J. Jin F. Bautista L. J. Lyons N. Shariatzadeh D. Sherlock K. Amine R. West 《Solid State Ionics》2004,170(3-4):233-238
A series of cross-linked network polysiloxanes containing oligoethylene oxide units, (OCH2CH2)n, as internal free chains have been synthesized by performing hydrosilylation of partially PEO-substituted polysiloxane precursor with , ω-diallyl terminated poly(ethylene glycol). The polymer electrolytes were formed by complexing with LiN(CF3SO2)2 electrolyte salt and exhibited superior conductive property. The σRT of the network polymer electrolytes is in the range of 2.50×10−5 to 1.62×10−4 S/cm and depends on the cross-linking density (in terms of Si–H amount of the siloxane precursor), repeating unit number of internal oligoethylene oxide and chain length of the cross-linker. The significant enhancement of the conductivity was observed when low molecular weight dimethyl poly(ethylene glycol) was added as plasticizer. The temperature dependence of the ionic conductivity was also studied, following the Vogel–Tamman–Fulcher (VTF) equation. 相似文献
27.
Amine Makkouk 《Mathematische Annalen》1973,204(3):199-201
Sans résumé 相似文献
28.
Amine Fawaz 《Central European Journal of Mathematics》2007,5(3):493-504
We compute the energy of conformal flows on Riemannian manifolds and we prove that conformal flows on manifolds of constant
curvature are critical if and only if they are isometric.
相似文献
29.
Elmouloudi Ed-Dari Mohamed Amine Khamsi 《Proceedings of the American Mathematical Society》2006,134(7):2019-2025
We give a partial answer to the problem of computing the numerical index of for .
30.
Amine Asselah 《Journal of statistical physics》2010,138(4-5):619-644
We consider a randomly charged polymer. Each monomer carries a random charge, and only charges on the same site interact pairwise. We study the lower tails of the energy, when averaged over both randomness, in dimension three or more. As a corollary, we obtain the correct temperature-scale for the Gibbs measure. 相似文献