排序方式: 共有57条查询结果,搜索用时 15 毫秒
11.
We develop a model of CA3 neurons embedded in a resistive array to mimic the effects of electric fields from a new perspective. Effects of DC and sinusoidal electric fields on firing patterns in CA3 neurons are investigated in this study. The firing patterns can be switched from no firing pattern to burst or from burst to fast periodic firing pattern with the increase of DC electric field intensity. It is also found that the firing activities are sensitive to the frequency and amplitude of the sinusoidal electric field. Different phase-locking states and chaotic firing regions are observed in the parameter space of frequency and amplitude. These findings are qualitatively in accordance with the results of relevant experimental and numerical studies. It is implied that the external or endogenous electric field can modulate the neural code in the brain. Furthermore, it is helpful to develop control strategies based on electric fields to control neural diseases such as epilepsy. 相似文献
12.
13.
铅的危害 总被引:4,自引:0,他引:4
《广东微量元素科学》2001,8(9):29-29
铅和铅的化合物都有毒 ,而且是积累性的。它积蓄在人体各组织中 ,特别是动脉管、胰、脾、肾、肺、骨骼和神经系统中 ,而其中又以骨骼积蓄量最多 ,约占体内积蓄铅的 85 %~ 90 %。铅中毒损害的器官主要是骨髓造血系统和神经系统。对男性的生殖腺也有一定的损害。损害骨髓造血系统 ,能引起贫血。因为血红素合成过程中 ,需要许多酶的催化作用 ,而铅会使这些酶的活力下降 ,从而造成血红素减少 ;同时 ,铅还能使红细胞膜上三磷酸腺苷酶失去作用。本来这种酶能控制细胞膜内外的钾、钠离子和水的分布 ,当铅抑制这种酶之后 ,红细胞内外的钾、钠离子和… 相似文献
14.
Artificial neural networks are trained to forecast the plasma
disruption in HL-2A tokamak. Optimized network architecture is obtained.
Saliency analysis is made to assess the relative importance of different
diagnostic signals as network input. The trained networks can successfully
detect the disruptive pulses of HL-2A tokamak. The results obtained show the
possibility of developing a neural network predictor that intervenes well in
advance for avoiding plasma disruption or mitigating its effects. 相似文献
15.
16.
随着人们生活水平的日益提高,越来越多的人开始关注健康,吸烟已成为人们最重视的问题之一。由于种植环境的影响,烟草中含有一定量的重金属元素,主要有铅和镉。铅容易导致贫血以及神经系统和消化系统的损伤;镉会造成肾功能损伤, 相似文献
17.
DUPei-ge QIUFang-ping ANLi-ping WANGYan LUGang 《高等学校化学研究》2005,21(3):291-293
TPP- Ⅰ (tripeptidyl peptidase- Ⅰ ) protein turnover was studied by observing the role of rat TPP- Ⅰ in neuromedin B(NMB) and other neuropeptides degradations in some physiological situations. The mixtures of rat TPP- Ⅰ with each of NMB. other neuropeptides and Ala-Ala-Phe-MCA were made respectively under the same conditions. The reaction was observed at different timeand monitored by means of high performance liquid chromatography (HPLC) and time-of-flight mass spectrometry (TOF-MS) in vitro. NMB was broken down at the same degree as Ala-Ala-Phe-MCA by rat TPP- Ⅰ and Gly-Asn-Leu was released within 16 h, but other neuropeptides were not digested within 24 h. TPP- Ⅰ is the predominant proteolytic enzyme responsible for the intracellular degradation of neuromedin B. NMB has recently been found to be a good natural substrate for rat lysosomal TPP-Ⅰ. 相似文献
18.
19.
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