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131.
132.
133.
Organometallic compounds of general formula (RAsO)α are associated as trimers (R = C2H5, C3H7, C4H9) or even as a tetramer (R = CH3). Their physicochemical properties show them to be cyclic, the oxygen atoms being located in the bridging position. A “limited” electron delocalization may occur in these rings. 相似文献
134.
135.
Marcel Brelot 《Journal d'Analyse Mathématique》1960,8(1):273-288
Sans résumé
Ces recherches ont fait l'objet d'exposés, d'abord au Séminaire de théorie du potential (Paris, javier 1960). 相似文献
136.
137.
Quantum systems with quadratic Hamiltonians are considered. Some results about the time evolution of homogeneous polynomials and of quantum correlation functions are given. The image of arbitrary orbit of Weyl–Heisenberg group under this time evolution is shown to be again an orbit of this group. For quantum free particle it is shown that its time evolution intersects arbitrary such orbit at most once. A result about existence of more orbits having the same dispersion of some quantum position is presented.PACS: 02.20.Qs, 02.30.Sa 相似文献
138.
We present a stable regime of asymmetric bound states for spiral pairs in a generic numerical model of a homogeneous excitable medium. In this regime, one spiral tip (slave) rotates around the other (master). Master-slave dynamics occur for both same-chirality and opposite-chirality spiral pairs in a range of parameters and initial conditions. We study the dependency of master-slave characteristics on the medium's excitation threshold and present a phenomenological model that accounts for the qualitative properties of master-slave dynamics. 相似文献
139.
We present a single curve that describes the decay in average growth velocity for microtubules in response to a mechanical force. Curves obtained at two new and one previously studied tubulin concentrations coalesce when normalized with the growth velocity at zero load. This scaling provides direct evidence for a force-independent molecular off rate, in agreement with Brownian ratchet models. In addition, microtubule length changes were measured with a precision up to 10 nm, revealing that microtubules under load abruptly switch between different growth velocities. 相似文献
140.
Pisula W Kastler M Wasserfallen D Pakula T Müllen K 《Journal of the American Chemical Society》2004,126(26):8074-8075
The substitution of a hexa-peri-hexabenzocoronene by bulky, space-demanding, 2-decyltetradecyl side chains proved to be an effective procedure to influence the thermal and self-aggregation behavior. The extremely large steric requirement of the introduced side chains modulated the aggregation and resulted in a dramatic lowering of the isotropization temperature and a higher solubility. As an additional consequence of the exceptional, long-range self-aggregation of the discotic molecule, spherulite formation was observed during crystallization by polarized light microscopy. Macroscopic self-assembly was induced by zone crystallization of the material, leading to aligned columnar superstructures as revealed by 2D-WAXS experiments. These extraordinary properties have not yet been reported for a discotic columnar material, making this compound very promising for application in electronic devices. 相似文献