共查询到20条相似文献，搜索用时 62 毫秒
1.
袁通全 《西南大学学报(自然科学版)》2015,37(9):106-109
以无限深方势阱中受击粒子为研究对象,详细分析了在参数变化情况下粒子的相空间轨道的形状.结果表明,该系统粒子的相空间轨道形成所谓的随机网区域与混沌区域共存,而且随着参数K的变化,随机网出现先破裂然后又恢复的有趣的现象. 相似文献
2.
在有限深势阱模型下,求出了考虑到电子-声子相互作用情况下量子线电子基态能、概率分布和禁带宽度,以HgS/CdS量子线为例,研究了电子-声子相互作用对它们的影响.结果表明:电子-声子相互作用会降低电子基态能,在对基态能的影响中以电子与界面光学支声子相互作用的影响最大,而与界面声学支声子相互作用影响最小;电子-声子相互作用的影响和电子由势阱透入有限高势垒的概率以及禁带宽度均随量子导线半径R的减小而增大;电子-声子相互作用不改变禁带宽度随R的变化趋势,仅使其数值减小.Abstract： Amodel of cylindrical quantum wires system with one core well,one shell barrier and finite deep potential well is founded.The body phonons,interface phonons,and their couplings with electron are investigated with the help of Green's function.The equations of electronic energy spectrum and wave function are obtained considering and neglecting the electron-interface interaction,and the correction of the electron ground level,electronic distribution and band gap to the well radius are giyen.Numerical calculations on a cylindrical HgS/CdS quantum wires system have been performed.The results show that the interaction of electron-interface phonons reduces the ground level and band gap.The smaller radius,the more reduced.Electron-interface optical phonons interaction plays the most influential,electron-interface acoustic phonon interaction impact ofthe minimum.The electron-interface phonon interaction does not change with changes in the law ofthe radius,just to changethe band gap variation in quantitative.The change increases with the decreases of well radius,which consistent with experimental. 相似文献
3.
在Hilbert空间中,给出关于寻找平衡问题解集和两族无限非扩张映射不动点集的公共元的Ishikswa迭代格式,并得出此迭代的弱收敛定理.Abstract： A new Ishikawa iteration scheme is proposed for finding a common element of the set of solutions of an equilibrium problem and the set of fixed points of two infinitely nonexpansive mappings in Hilbert space. A weak convergence theorem is established for this iteration. 相似文献
4.
建立了纳米粒子系统屏蔽效应的物理模型,应用电动力学理论求出了系统的电荷和电势分布以及屏蔽参量.以Cu和Al粒子为例,探讨了粒子线度和材料对纳米粒子系统的电荷、电势分布和屏蔽参量的影响.结果表明:两种不同金属纳米粒子构成的系统,其电荷密度和电势分布与单个带电粒子的电荷和电势分布不同,它们不仅与粒子的线度有关,而且还与粒子数密度、电子费米能、纳米粒子的分布范围等有关;两种粒子的电荷符号和密度分布不同:一种粒子的电荷密度为正且随离中心的距离增大而增大,而另一种粒子的情况相反;电荷密度随距离的变化快慢取决于粒子的线度,电荷密度的变化主要发生在两种粒子分布区域的分界面附近;系统的电势分布在两种粒子分布区域分界面处取极小值,其屏蔽参量要比块状晶体的值要小,与粒子线度、费米能、粒子数密度和分布范围等都有关.理论结果与文献给出的实验资料一致.Abstract： A physical model of the shielding effect in nanometric systems is constructed.Based on electrodynamics,the distribution of charge and electric potential and the parameters of the shield in nanometric systems are obtained.With Cu and Ag as samples,the influences of radius and material on the distribution of the charge and electric potential and the parameters of the shield in the nanometric system are discussed.The results show that in a system made up of two kinds of nanometric particles,the distribution of the charge density and electric potential are different from those of a single-particle system and that they are related not only to particle radius,but to the number density,Fermi-energy and distributive region of the nanometric particles as well.The values are consistent with experiment data from other sources in literature. 相似文献
5.
Turpan is one of the major high-quality grape production bases in the world for years because its climate is so special (hot, dry, and windy). The grape market needs the varieties with high yield, quality, and environmental adaptability. ‘Xinyu’ is a new variety bred by crossing selection of E42-6 (a self-pollinated inbred of Vitis vinifera cv. ‘Red Globe’) as female and Vitis vinifera cv. ‘Rizamat’ as male parents and registered in the Crop Varieties Registered Commission of Xinjiang Uygur Autonomous Region in 2005. In this study, we determined the impacts of environmental factors on its photosynthesis. The results showed the climate in Turpan was characterized by long-time intensive sunshine, high temperature and relatively low humidity. The peak value of photosynthetic available radiation (PARi) was 1 454 μmol·m-2·s-1, and the minimum and average values were 111 μmol·m-2·s-1and 938.889 6 μmol·m-2·s-1, respectively. Air temperature and sunlight intensity reached the highest values during 1 p.m. to 4 p.m. Net photosynthetic rate (Pn) of Xinyu increased stably before 11 a.m. and there was a midday depression during 11 a.m. to 2 p.m. The minimum value of Pn appeared at noon (2.77 μmol·m-2·s-1). It was concluded that as a new grape cultivar, “Xinyu” could withstand extreme climate conditions in Turpan. 相似文献
6.
通过对一维无限深势阱的量子运动严格的解析计算表明,经典极限下,量子力学中的物理量在等权波包下的期望值,趋于经典力学量的傅立叶级数的Fejér平均值,而不是傅立叶级数本身.而且,当等权波包中叠加的本征态的数目N等于量子数n的平方根时,等权波包的不确定性最小. 相似文献
7.
主要说明带乘法白噪音的随机Kuramoto-Sivashinsky方程能够求解,并且它的唯一的解可生成一个随机动力系统,在区间I的长度L满足一定条件时,这个系统在L2(I)中有一个紧的随机吸引子.Abstract： It is shown that the stochastic Kuramoto-Sivashinsky equation with multilicative white noise can be solved pathwise and the unique solution generates a random dynamical system S. This system S possesses a compact random attractor in (L)2 (I) under the assumptions with respect to the length L of internal I. 相似文献
8.
分析了超导高梯度磁分离污水处理技术的基本原理,介绍了超导高梯度磁分离技术在纸厂污水处理中的应用及设备,讨论了利用等离子体聚合薄膜制备具有强捕捉能力磁性粒子的工艺.Abstract： Superconducting magnetic separation is a new candidate method for purifying wastewater produced by paper factories owing to its compactness in volume and effectiveness in treatment. In this paper,the principles of wastewater purification with superconducting high gradient magnetic separation are analyzed, its usage and equipment in wastewater purifying factories are presented and the process of preparation of the magnetic particles having high scavenging capabilities with plasma polymerization polymer thin film is described. 相似文献
9.
应用指数函数法,借助计算机代数系统获得了包括五阶KdV方程、Sawada-Kotera方程和Kaup-Kupershmit方程在内的一类五阶非线性演化方程的广义孤立波解和周期解.结果表明,指数函数法结合符号计算已成为解决数学物理中非线性演化方程的强有力工具.Abstract： In this paper,the exp-function method is used to obtain generalized solitary wave solutions and periodic solutions for a class of fifth-order nonlinear evolution equations,which include different forms of fifth-order KdV equations,Sawada-Kotera equations and Kaup-Kupershmit equations.The results show that the exp-function method,with the help of symbolic computation,provides a powerful mathematical tool for solving nonlinear evolution equations in mathematical physics. 相似文献
10.
基于Richardson外推法提出了一种求解三维扩散方程的高阶紧致差分方法.该方法首先利用截断误差为O(τ2+h4)的四阶紧致交替方向隐式(ADI)差分格式在不同尺寸的网格上对原方程进行求解,然后利用Richardson外推技术外推一次,得到了三维扩散方程具有O(τ4+h6)精度的数值解.数值实验验证了该方法的高阶精度及有效性.Abstract： A high-order compact difference method based on the Richardson extrapolation technique is proposed to solve the unsteady three-dimensional diffusion equations. For a particular implementation, firstly, numerical results are obtained on meshes of different sizes using a high order alternating direction implicit (ADI) difference scheme, which are fourth order in space and second order in time. Then, the Richardson extrapolation method is used to get an accuracy solution for three-dimensional problems, which is six order in space and fourth order in time. Numerical experiments are made to demonstrate the high accuracy and validity of this method. 相似文献
11.
12.
Bailes M Bates SD Bhalerao V Bhat ND Burgay M Burke-Spolaor S D'Amico N Johnston S Keith MJ Kramer M Kulkarni SR Levin L Lyne AG Milia S Possenti A Spitler L Stappers B van Straten W 《Science (New York, N.Y.)》2011,333(6050):1717-1720
Millisecond pulsars are thought to be neutron stars that have been spun-up by accretion of matter from a binary companion. Although most are in binary systems, some 30% are solitary, and their origin is therefore mysterious. PSR J1719-1438, a 5.7-millisecond pulsar, was detected in a recent survey with the Parkes 64-meter radio telescope. We show that this pulsar is in a binary system with an orbital period of 2.2 hours. The mass of its companion is near that of Jupiter, but its minimum density of 23 grams per cubic centimeter suggests that it may be an ultralow-mass carbon white dwarf. This system may thus have once been an ultracompact low-mass x-ray binary, where the companion narrowly avoided complete destruction. 相似文献
13.
Action at a distance along a DNA 总被引：35，自引：0，他引：35
A number of ways are known by which an event at one location on a DNA molecule can affect an event at a distant location on the same molecule. Three classes of mechanisms are described for such distal actions: tracking or translocation of a protein along a DNA, the association of two proteins bound at separate sites to form a DNA loop in between, and distal interactions that are affected by the topology of the DNA. The basic characteristics of each type of mechanism are discussed in terms of the known physicochemical properties of DNA. The various modes of action at a distance are often interrelated. Examples include the formation of positively and negatively supercoiled DNA loops by tracking and the strong effects of DNA topology on looping. 相似文献
14.
15.
16.
17.
18.
When the sensory fiber of a Pacinian corpuscle (in cat mesentery) is transected (at the inferior mesenteric nerve) transduction fails within 30 hours: the nerve ending produces no generator potentials in response to mechanical stimulation. Electrically elicited nerve impulse conduction continues for at least another 18 hours. A transducer mechanism develops on a regenerating nerve fiber when this fiber enters the denervated corpuscle. Such transducer development takes place on myelinated fibers from the inferior mesenteric nerve, which normally supplies corpuscles, as well as on myelinated hypogastric nerve fibers, which normally do not go to corpuscles, including fibers larger than the original corpuscle afferents. 相似文献
19.
Pathways for the reduction of protein disulfide bonds are found in all organisms and are required for the reductive recycling of certain enzymes including the essential protein ribonucleotide reductase. An Escherichia coli strain that lacks both thioredoxin reductase and glutathione reductase grows extremely poorly. Here, we show that a mutation occurring at high frequencies in the gene ahpC, encoding a peroxiredoxin, restores normal growth to this strain. This mutation is the result of a reversible expansion of a triplet nucleotide repeat sequence, leading to the addition of one amino acid that converts the AhpC protein from a peroxidase to a disulfide reductase. The ready mutational interconversion between the two activities could provide an evolutionary advantage to E. coli. 相似文献
20.
研究了离散型三维竞争系统的模型结构与稳定性,得到了这类竞争系统中各类平衡点的坐标及其性质,获得了系统在某些边界上的平衡点渐近稳定的充分条件和不稳定的充分条件,并由此得到了系统中的某群体在竞争过程中竞争获胜淘汰所有对手的条件和参与竞争的各个群体永不和谐的充分条件. 相似文献