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排序方式: 共有15条查询结果,搜索用时 31 毫秒
1.
牛顿环实验测量结果的不确定度评定及其表示   总被引:3,自引:1,他引:2  
讨论了不等精度测量牛顿环曲率半径及牛顿环直径不确定度的评定及表示  相似文献
2.
Transport properties under the influence of finite friction   总被引:2,自引:0,他引:2  
Using the Langevin Monte Carlo method,the influence of friction on the directed motion of a Brownian particle driven by an external noise source is investigated.The results show that the exitence and change of the environment friction influence the establishment and development of the steady motion of a Brownian particle derived by nonequilibrium fluctuation.The most probable correlation time,which corresponds to the maximum current,is inversely proportional to the friction coefficient.The abnormal transition of the current with different friction appears because of the coupling between the effective ratchet potential and coloured noise intensity.  相似文献
3.
电路断路后火花产生过程的分析   总被引:1,自引:0,他引:1  
于慧  沈鼎权 《大学物理》2003,22(1):20-22,24
分析了小电阻大自感的直流电路中断开电源时回路中火花的形成及其规律,澄清了常见的电路断开时火花出现原因的不确切的解释。  相似文献
4.
It is well known that potassium ion channels have higher permeability than K ions, and the permeable rate of a single K ion channel is about 108 ions per second. We develop a hierarchical model of potassium ion channel permeation involving ab initio quantum calculations and Brownian dynamics simulations, which can consistently explain a range of channel dynamics. The results show that the average velocity of K ions, the mean permeable time of K ions and the permeable rate of single channel are about 0.92nm/ns, 4.35ns and 2.30 ×10^8 ions/s, respectively.  相似文献
5.
It has been proved recently that the spike timing can play an important role in information transmission, so in this paper we develop a network with N-unit FitzHugh--Nagumo neurons coupled by gap junctions and discuss the dependence of the spike timing precision on synaptic coupling strength, the noise intensity and the size of the neuron ensemble. The calculated results show that the spike timing precision decreases as the noise intensity increases; and the ensemble spike timing precision increases with coupling strength increasing. The electric synapse coupling has a more important effect on the spike timing precision than the chemical synapse coupling.  相似文献
6.
比较了铜掺杂钾钠铌酸锶钡(Cu∶KNSBN)和钾钠铌酸锶钡(KNSBN)两样品的晶格振动和d-d电子跃迁谱,对于拉曼(Raman)谱,A1(z)对称类的差别较小,E(xy)对称类的差别最大;对于红外反射谱,两对称类的均差别较大,认为Cu2+部分填充了晶格A位和C位,可见光范围内,d-d电子跃迁谱表明Cu2+在晶体中形成两个深能级2.50eV和2.64eV。  相似文献
7.
简要介绍了人类、模式生物基因组的测序计划以及生物大分子的数据库。并阐述了生物学的主要研究方向。  相似文献
8.
以修正后的Rapini-Papoular公式为基础,得到了有表面弹性能K13存在时,弱锚定向列液晶盒指向矢满足的方程和边界条件。用解析推导和数值计算的方法,详细研究了K13对阈值场强和饱和场强的影响。在理论上给出了检验K13是否存在的一种新方法及用沿面平行校列的弱锚定楔型液晶盒测定K13值的实验方案,并通过数值实验证实了本文所给方法的可行性。  相似文献
9.
用直拉单晶生长系统制备TbyDy1-x(Fe1-xTx)2(T=Al,Mn)单晶,并测量其磁致伸缩.用电弧炉合成多晶TbyDy1-y(Fe1-xTx)2(T=Al,Mn),并用X射线衍射方法测量拟合得到内禀磁致伸缩.结果表明,Al和Mn替代后饱和磁场降低,说明Al和Mn的替代明显地降低了各向异性能.随Al和Mn替代量的增加,总的趋势是材料的内禀磁致伸缩λ111降低.对Tb0.5Dy0.5(Fe0.9Mn0.1)2单晶,在不加压情况下的磁致伸缩效果并不明显,但当施加压力时,磁致伸缩变化显著,尤其在12—26MPa压力下,磁致伸缩变化很大,且低场效果很好.  相似文献
10.
张志东  于慧  李丽 《中国物理》2001,10(7):645-649
Equations are obtained for the surface tilt angle and the twist angle of the director in a twisted nematic liquid crystal cell under a high magnetic field. Under a zero pretilt angle, the two equations reduce to those obtained by Sugimura et al. This fact has also been demonstrated numerically. With finite field strength and nonzero pretilt angle, no saturation transition exists.  相似文献
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