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941.
942.
DAI XiongPing 《中国科学 数学(英文版)》2011,(2)
In this paper, we simply prove, in the framework of Liao, the hyperbolicity of C 1 -star invariant sets of C 1 -class differential systems on a closed manifold of dimension≤ 4, without using the C 1 -connecting lemma and even the ergodic closing lemma. 相似文献
943.
944.
研究了一类具两条不连续相交线的平面系统的闭轨.利用微分包含理论和点变换的方法,获得了一些有趣的结果,包括滑模解,同宿解和闭轨的存在性.同时给出了闭轨存在的必要条件. 相似文献
945.
946.
Using a dynamical Langevin equation coupled with a statistical decay model, we calculate the excess of the pre-scission neutron multiplicities over its standard statistical-model values as a function of the nuclear dissipation strength for the three nuclei 190Os, 200Hg, and 210Po which have the same neutron-to-proton ratio N/Z. We find that by decreasing the size of the fissioning nuclei, the effects of nuclear dissipation on the excess of the pre-scission neutron multiplicity are substantially amplified, and that the sensitivity of this excess to the nuclear friction strength is considerably increased as well. We suggest that for those fissioning systems with the same N/Z that are populated in fusion reactions, to obtain a more accurate information of the nuclear dissipation strength by measuring the pre-scission neutron multiplicity, it is best to choose a system with a small size. 相似文献
947.
A Preliminary Study of Diastereoselectivity in the PdII‐Catalyzed C(sp3)‐H Alkoxylation of Cyclic Systems
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Xinglin Yang Tian‐Yu Sun Prof. Yu Rao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(10):3273-3277
Primary mechanism of a PdII‐catalyzed 8‐aminoquinoline‐directed C?H alkoxylation was investigated. It was understood that the PdII‐catalyzed C(sp3)?O bond formation proceeded through a concerted reductive elimination from the PdIV intermediate in the cyclic system. Deuteration experiments and related computational studies elucidate that intrinsic conformation determined the diastereoselectivity of the PdII‐catalyzed C?H alkoxylation of cyclic carboxylic acids. 相似文献
948.
949.
In this Letter, a novel method is developed for generating grid multi-scroll chaotic attractors using switching piecewise linear controller. First, a third-order linear system is designed to ensure that its unique equilibrium point belongs to a saddle-focus type with index 2 and the corresponding eigenvalues satisfy Shilnikov conditions. Then, by three different types of switching control strategies, the equilibrium point can be extended along both xy plane and z axis direction, so as to generate grid multi-scroll chaotic attractors. The dynamical behaviors are further analyzed. Moreover, an improved module-based circuit is designed for realizing 5×3 and 4×4 grid scroll chaotic attractors, and the experimental results are also obtained, which is consistent with the numerical simulations. 相似文献
950.
We give a geometric analysis of relaxation oscillations and canard cycles in a singularly perturbed predator–prey system of Holling and Leslie types. We discuss how the canard cycles are found near the Hopf bifurcation points. The transition from small Hopf-type cycles to large relaxation cycles is also discussed. Moreover, we outline one possibility for the global dynamics. Numerical simulations are also carried out to verify the theoretical results. 相似文献