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121.
Two-degree-of-freedom Hamiltonian systems with an elliptic equilibrium at the origin are characterised by the frequencies of the linearisation. Considering the frequencies as parameters, the system undergoes a bifurcation when the frequencies pass through a resonance. These bifurcations are well understood for most resonances , but not the semisimple cases and . A two-degree-of-freedom Hamiltonian system can be approximated to any order by an integrable normal form. The reason is that the normal form of a Hamiltonian system has an additional integral due to the normal form symmetry. The latter is intimately related to the ratio of the frequencies. For a rational frequency ratio this leads to -symmetric systems. The question we wish to address is about the co-dimension of such a system in resonance with respect to left-right-equivalence, where the right action is -equivariant. The result is a co-dimension five unfolding of the central singularity. Two of the unfolding parameters are moduli and the remaining non-modal parameters are the ones found in the linear unfolding of this system. 相似文献
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Igor N. Karnaukhov 《Physics letters. A》2019,383(33):125951
A generalization of the Mattis-Nam model Mattis and Nam (1972) [7], which takes into account a correlated hopping and pairing of electrons, is proposed, its exact solution is obtained. In the framework of the model the stability of the zero energy Majorana fermions localized at the boundaries is studied in the chain in which electrons interact through both the on-site Hubbard interaction and the correlated hopping and pairing. The ground-state phase diagram of the model is calculated, the region of existence of topological states is determined. It is shown that low-energy excitations destroy bonds between electrons in the chain, leading to an insulator state. 相似文献
124.
Jorge Ferreira Raquel Zilz Igor S. Boeira Sabrina M. da Silva Adriana C.A. Casagrande Osvaldo L. Casagrande 《应用有机金属化学》2019,33(3)
A new set of Cr(III) complexes, {L}CrCl3(THF), based on thiophene–imine ( 2a , L = PhOC6H4(N═CH)‐2‐SC4H3; 2b , L = PhOC2H4(N═CH)‐2‐SC4H3; 2c , L = Ph(NH)C2H4(N═CH)‐2‐SC4H3; 2d , L = PhOC6H4(N═CH)‐2‐SC4H2‐5‐Ph; 2e , L = Ph(NH)C2H4(N═CH)‐2‐SC4H2‐5‐Ph) have been prepared and characterized using elemental analysis and infrared spectroscopy. Upon activation with methylaluminoxane, all the chromium complexes generated active systems affording a nonselective distribution of α‐olefins with turnover frequencies in the range 9500–93 500 (mol ethylene) (mol Cr)?1 h?1, and producing mostly oligomers (95.0–99.3 wt% of total products). Small amounts of polymer were produced in these oligomerization reactions (0.8–8.2 wt%). The catalytic activities were quite sensitive to the ligand environment. Moreover, the effects of oligomerization parameters (temperature, [Al]/[Cr] molar ratio, time) on the activity and on the product distribution were examined. 相似文献
125.
We present a study of resonant optical properties of gold‐protected silver nanoisland films. Silver nanoislands were grown on a glass substrate using out‐diffusion technique, the growth was followed by the deposition of nanometer‐thick gold coatings. Scanning electron microscopy and optical spectroscopy were used to characterize morphology and extinction spectra of the grown combined silver–gold nanostructures. Micro Raman spectroscopy of the combined nanoislands has demonstrated their signal enhancement factor exceeding that one of the initial silver nanoislands. 相似文献
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Galina A. Gazieva Yurii B. Vikharev Lada V. Anikina Tatyana B. Karpova Angelina N. Kravchenko Evgenii A. Permyakov Igor V. Svitanko 《Mendeleev Communications》2013,23(4):202-203
Target synthesis of substituted thioglycolurils possessing sedative activity predicted by preliminary 3D-QSAR simulation of bioactive structures has been carried out. 相似文献