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排序方式: 共有161条查询结果,搜索用时 78 毫秒
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In this paper, linear stability analysis is applied to an exponential discrete Lotka–Volterra system, which describes the competition between two identical species. Conditions for the Turing instability are obtained and the emergence of spiral patterns is demonstrated by means of numerical simulations in the vicinity of the bifurcation point. Moreover, the impact of crucial system parameters on the stability and coherence of spiral patterns is illustrated on several examples. 相似文献
63.
The mechanism of adsorption and desorption of ethyl cellulose (EC) on and from silver powder was studied. After analysis with DSC, XPS and dynamic FT-IR, which could be heated by a program-controlled heater, applied to observe the states of pure EC and of EC adsorbed on silver powder, and also the thermal decomposition of EC from silver powder, the chemisorption bonding bridge between the oxygen atoms of EC and the silver atoms investigated. The differences in thermal decomposition between pure EC and EC adsorbed in silver powder were also studied. It was concluded that the chemisorption bonding between the oxygen atoms of EC and the silver atoms mainly involved the lone-pair electrons of the oxygen atoms on the EC chain and the outer empty 5 sp3 hybrid orbital of the silver. Because of the formation of this bridge, the bonds between neighboring carbon and oxygen atoms are weakened. As a result of this effect, the C-O bonds in the EC chain are broken more easily than the C-H bonds, which leads to the observation of -C-H- fragments in the upper space when EC adsorbed on silver is heated. When the same experiments were carried out on pure EC, almost all kinds of broken fragments of the EC molecule, including -C-H-, -C=O- and -C-O- appeared simultaneously. 相似文献
64.
应用溶胶-凝胶法制备TiO2薄膜.在薄膜中掺杂了Ce和La离子,并对其微结构和光催化特性作了分析。结果表明:这两种元素的加入量和热处理的温度能使薄膜的晶体结构产生重人改变,从而影响到TiO2的催化性能。当掺杂量和热处理温度适当时,能够获得光催化性能最好的TiO2薄膜。 相似文献
65.
利用洛伦兹力沿径向的保守性引入势函数方便地计算刚性导线在均匀磁场中绕定轴转动时的动生电动势. 相似文献
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Hui Fang 《Czechoslovak Mathematical Journal》2003,53(3):561-570
In this paper, we employ some new techniques to study the existence of positive periodic solution of n-species neutral delay system N
i
= N
i
(t)[
i
(t) —
ij
(t)N
j
(t) —
b
ij
(t)N
j
(t—
ij
(t))—
c
ij
(t)N
j
(t—
ij
(t))].As a corollary, we answer an open problem proposed by Y. Kuang. 相似文献
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70.