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1.
Miao-Kun Wang Yu-Ming Chu Song-Liang Qiu Yue-Ping Jiang 《Journal of Approximation Theory》2012,164(7):928-937
In this paper, we present several bounds for the perimeter of an ellipse, which improve some well-known results. 相似文献
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《Physics letters. A》2002,306(1):57-61
The structures and energies of a Ga5N5 cluster have been calculated using a full-potential linear-muffin-tin-orbital (FP-LMTO) method, combined with molecular dynamics technique. Twenty-four structures for a Ga5N5 cluster have been obtained. The most stable structure is a C1 planar structure with a N3 subunit. The Ga5N5 clusters show a preference for a N3 subunit, revealing the same behavior as in the Ga3N3 and Ga4N4 clusters. The existence of strong N–N bonds dominates the structure of a Ga5N5 cluster. Through the calculation of the density of states we found that the most stable structure of Ga5N5 clusters presented semiconductor-like properties. 相似文献
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《Physics letters. A》2001,288(1):41-44
Using full-potential linear-muffin-tin-orbital molecular-dynamics (FP-LMTO-MD) method, we have performed calculations on the fullerene cage structures and the binding energies of Si36 cluster. It is found that their atomic arrangement tends towards tetrahedral geometry. The distorted structures are very stable. In addition, we have also investigated a stacked structure by tricapped trigonal prisms (TTP). The stacked structure is slightly more stable than the distorted fullerene cages. Their electronic states suggest that they present different electric properties. 相似文献
7.
采用固定床微反应器、利用 XRD及 TPR技术研究了载体对负载于 γ- Al2 O3、Si O2 和HZSM- 5分子筛上的 Co催化剂的 CH4/ CO2 重整制合成气反应性能的影响 .结果表明 ,金属与载体之间的相互作用是影响催化剂活性和稳定性的重要因素 .HZSM- 5是一种优良载体 ,但硅铝比较低易积炭 ;Co/ Si O2 及低负载量的 Co/ Al2 O3催化剂活性较低易失活 ,其失活原因前者为 Co0 晶粒的烧结 ,后者为 Co0 向 Co Al2 O4的转变 .探讨了金属 -载体相互作用与催化剂性能之间的关系 相似文献
8.
Highly efficient and chemoselective N‐heterocyclic carbene palladium complexes‐catalyzed multicomponent carbonyltive Suzuki reaction with sodium tetraphenylborate used as phenylating reagent has been demonstrated in this article. Both electron‐rich and electron‐deficient aryl iodides gave unsymmetric aryl ketones in excellent yields. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
9.
We describe maximal regular subsemibands of the singular transformation
semigroup Singn on the set Xn = {1, 2, . . . n} and obtain their complete classification
We show that Singn has n(n + 1)/2 maximal regular subsemibands,
and formulate the cardinal number of such subsemigroups. 相似文献
10.
《Chaos, solitons, and fractals》2007,31(3):631-638
In this paper, impulsive control and synchronization for the newly presented Lorenz systems family are systematically investigated. Some new and more comprehensive criteria for global exponential stability and asymptotical stability of impulsively controlled Lorenz systems family are established with varying impulsive intervals. In particular, several simple and easily verified criteria are derived with equivalent impulsive intervals. An illustrative example is also provided to show the effectiveness and feasibility of the impulsive control method. 相似文献