排序方式: 共有57条查询结果,搜索用时 0 毫秒
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梁英 《理化检验(化学分册)》2005,41(1):57-57,61
镁和铁是人体必需的微量元素,具有重要的生理功能和营养作用,但若摄入超量会对人体产生毒性,造成潜在性危害,引起致畸及神经系统异常等,因此,研究镁铁的测定方法,了解头发中镁铁的含量,对预防镁致疾病,提高人体健康水平具有重要的意义。 相似文献
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A class of Hopfield neural network with time-varying delays and impulsive effects is concerned. By applying the piecewise continuous vector Lyapunov function some sufficient conditions were obtained to ensure the global exponential stability of impulsive delay neural networks. An example and its simulation are given to illustrate the effectiveness of the results. 相似文献
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Jian ZHUANG 《数学年刊B辑(英文版)》2011,32(2):161-186
Lateral inhibitory effect is a well-known feature of information processing in neural systems. This paper presents a neural
array model with simple lateral inhibitory connections. After detailed examining into the dynamics of this kind of neural
array, the author gives the sufficient conditions under which the outputs of the network will tend to a special stable pattern
called spatial sparse pattern in which if the output of a neuron is 1, then the outputs of the neurons in its neighborhood
are 0. This ability called spatial sparse coding plays an important role in self-coding, self-organization and associative
memory for patterns and pattern sequences. The main conclusions about the dynamics of this kind of neural array which is related
to spatial sparse coding are introduced. 相似文献
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采用数值模拟方法, 研究了由两个具有不同初始条件单向耦合的Hindmarsh-Rose神经元所组成系统的动力学行为. 研究结果表明, 耦合强度对两个神经元的同步具有重要的影响. 当两个神经元的控制参数取值不同时, 即在驱动系统和响应系统均处于混沌态及驱动系统处于周期振荡态, 响应系统处于混沌态两种情况下, 随耦合强度的增加其放电活动都能从不同步达到相位同步, 最后实现近似完全同步. 相似文献
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We investigate the dynamical response of the neuron system to a feeble external signal by using the Hindmarsh-Rose model, when the system is tuned below the first bifurcation point, which corresponds to the period-1 bursting state, and an external signal with a fixed period of about 170s is introduced to the system. It is found that to respond to the outside signal, the system changes from the period-1 state to a period-2 one with variation of the signal amplitude, indicating the occurrence of state-to-state transition (SST). Moreover, when a signal with different fixed periods is introduced, we can also find a similar transition between other states. Furthermore, the effect of the frequency of the signal on the transition is also discussed. These results may imply that SST plays a constructive role in information processing in neuron systems. 相似文献
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以甲基苯丙胺为代表的苯胺类中枢兴奋剂滥用问题日益突出,文章对甲基苯丙胺依赖的作用途径和机制进行了概述,包括中脑边缘系统多巴胺神经通路、多巴胺受体、多巴胺转运体及其他神经递质,最后提出了当前甲基苯丙胺成瘾治疗研究的主要方向. 相似文献
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We analyze the limiting behavior of a compressible two-pressure two-phase flow model as the Mach number tends to zero. Formal asymptotic expansions are derived for the solutions of compressible two-phase equations. Expansion coefficients through sec- ond order are evaluated in closed form. Underdetermination of incompressible pressures is resolved by information supplied from the weakly compressible theory. The incompressible pressures are uniquely specified by certain details of the compressible fluids from which they are derived as a limit. This aspect of two phase flow in the incompressible limit appears to be new, and results basically from closures which satisfy single phase boundary conditions at the edges of the mixing zone. 相似文献