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991.
992.
Trizac E 《Physical review letters》2002,88(16):160601
We study the simplest irreversible ballistically controlled reaction, whereby particles having an initial continuous velocity distribution annihilate upon colliding. In the framework of the Boltzmann equation, expressions for the exponents characterizing the density and typical velocity decay are explicitly worked out in arbitrary dimension. These predictions are in excellent agreement with the complementary results of extensive Monte Carlo and molecular dynamics simulations. We finally discuss the definition of universality classes indexed by a continuous parameter for this far from equilibrium dynamics with no conservation laws. 相似文献
993.
994.
Plénat T Deshayes S Boichot S Milhiet PE Cole RB Heitz F Le Grimellec C 《Langmuir : the ACS journal of surfaces and colloids》2004,20(21):9255-9261
The mesoscopic organization adopted by two primary amphipathic peptides, P(beta) and P(alpha), in Langmuir-Blodgett (LB) films made of either the pure peptide or peptide-phospholipid mixtures was examined by atomic force microscopy. P(beta), a potent cell-penetrating peptide (CPP), and P(alpha) mainly differ by their conformational states, predominantly a beta-sheet for P(beta) and an alpha-helix for P(alpha), as determined by Fourier transform infrared spectroscopy. LB films of pure peptide, transferred significantly below their collapse pressure, were characterized by the presence of supramolecular structures, globular aggregates for P(beta) and filaments for P(alpha), inserted into the monomolecular film. In mixed peptide-phospholipid films, similar structures could be observed, as a function of the phospholipid headgroup and acyl chain saturation. They often coexisted with a liquid-expanded phase composed of miscible peptide-lipid. These data strongly suggest that primary amphipathic CPP and antimicrobial peptides may share, to some extent, common mechanisms of interaction with membranes. 相似文献
995.
996.
997.
[reaction: see text] An efficient synthesis of enone 4, representing the ABC ring motif of norzoanthamine, is presented. The crucial C22 quaternary center was introduced via a stereoselective methylation of enone 8. The trans-anti-trans relative configuration of the ABC framework of 4 was installed via a sequence of reactions that included a hydroboration and a modified Robinson annulation. 相似文献
998.
999.
1000.
Isolde Bachert Irene Bartusseck Pierre Braunstein Emmanuel Guillon Jacky Ros Guido Kickelbick 《Journal of organometallic chemistry》1999,580(2):3016
Heterometallic triangular platinum–cobalt, palladium–cobalt and palladium–molybdenum clusters stabilized by one or two bridging diphosphine ligands such as Ph2PNHPPh2 (dppa) or (Ph2P)2NMe (dppaMe) or by mixed ligand sets Ph2PCH2PPh2 (dppm)/dppa have been prepared with the objectives of comparing the stability and properties of the clusters as a function of the short-bite diphosphine ligand used and of the metal carbonyl fragment they contain. Ligand redistribution reactions were observed during the purification of [Co2Pd(μ3-CO)(CO)4(μ-dppa)(μ-dppm)] (4) by column chromatography with the formation of [Co2Pd(μ3-CO)(CO)4(μ-dppm)2] and the dinuclear complex [(OC)2
Cl] (5). The latter was independently prepared by reaction of [Pd(dppa-P,P′)2](BF4)2 with Na[Co(CO)4]. Attempts to directly incorporate the ligand (Ph2P)2N(CH2)3Si(OMe)3 (dppaSi) into a cluster or to generate it by N-functionalization of coordinated dppa were unsuccessful, in contrast to results obtained recently with related clusters. The crystal structure of [Co2Pt(μ3-CO)(CO)6(μ-dppa)] (1) has been determined by X-ray diffraction. 相似文献