In the human cells , hundreds of molecular motors carry out various functions in the process of the contraction of muscles , cellular transportation , dna duplication and mitosis 细胞内部的上百种分子马达在肌肉收缩、细胞内部输运、遗传物质( dna )的复制、以及细胞的有丝分裂过程中执行着各种各样的生物功能。
Molecular motors are a kind of enzyme proteins which exist in the cell and play an important role in the process of the muscle contraction , intracellular transport , dna duplication , mitosis and so on 分子马达是广泛存在于细胞内部的具有马达功能的酶蛋白生物大分子。生命活动中的许多过程都是基于分子马达的运动。
In the third part , a more actual dynamic - chemical coupling model than two - state model , a dimensional v " j : ) t t periodic four - state kinetic hopping model , is established . the results are summarized as follows . 1 第三部分根据分子马达实际的力学化学耦合过程，建立起比两态模型更接近实际的模型?一维周期性四态随机跃迁模型。
Molecular motors in biological cells play important role , which carry out various life functions in the process of muscle contraction , intracellular transport , dna duplication , mitosis , and so on 分子马达在生命活动中起着十分重要的作用，它们在肌肉收缩、细胞内部输运、遗传物质dna的复制及细胞的有丝分裂过程中执行着各种各样的功能。
When the motion of the motors is coordinated , the macroscopic directed motion is brought . especially , kinesin , which has the feature of the directivity and stepping motion , has been focused on its particular dynamical mechanism 当分子马达的运动协调起来就产生了宏观的运动而做功，其中蕴含的动力学机制已成为众多研究者们关注的焦点。
An explicit solution for the probability distribution as a function of the time and position in the master equation is obtained when the substeps between arbitrary adjacent states in a single period are equal for the molecular motor 并取得了如下成果： 1计算了分子马达在等间距跃迁情况下，当给定初始分布时，任意位置任意时刻主方程中几率分布的解析表达式。
We can take molecular motor as a brownian particle in the case of ignoring the conformational changes . the interaction between motor and microtubule can be described by a special potential function and the effect of the environment can be simplified as a noise 在不考虑分子马达构象变化的情况下，通常把分子马达抽象为布朗粒子，用一个特定的势函数来表示轨道与马达的相互作用，环境的影响可以简化为特定形式的噪声激励。
4 . the theoretical curves v ( f , [ atp ] ) and r ( f , [ atp ] ) under the steady state are compared to experiments when a load acts on the molecular motor , the result is that these theoretical curves accord basically with experiments , which illustrates better the kinetic behaviors of a molecular motor 将分子马达拖动负载时的稳态速度v和随机参数r随atp浓度[ atp ]的理论变化拟合曲线同实验进行了比较，结果表明：拟合曲线与实验基本吻合，较好地说明了马达在拖动负载运动时的各种动力学行为。
The thesis includes three parts : firstly , previous study and latest advance of molecular motor in biology are outlined , including myosin ' s and kinesin ' s construction and function , the latest advance of molecular motor in constructional biology ; secondly , the latest advance of molecular motor in physics is reviewed , including the general view of brownian motor and two examples of molecular motor , one being related to two kinds of flashing potention energy , the other being related to electronical bipole ; and finally , the model on unidirectional motion of molecular motor is in detail come up with , and especially , the interact ion between two heads is taken into account , followed by the construction of langevin equation and fokker - planck equation involved in the model . by using solutions of fokker - planck equation , unidirectional motion mechanism of molecular motor is analyzed 本文内容包括：首先综述生物学领域分子马达研究的最新进展，内容安排为：肌球蛋白的结构和功能，驱动蛋白的结构和功能，肌球蛋白和驱动蛋白定向运动机制的结构生物学方面的最新进展；其次综述并分析了当前研究分子马达定向运动机制的几种物理模型，内容安排为：分子马达运动的基本观点和建构模型的一般方法，势垒的两态涨落诱导的分子马达运动模型，分子马达定向运动的偶极子模型；最后讨论双头相互作用的分子马达模型，内容安排为：先详细论述模型的构建，再建立langevin方程和fokker - planck方程，接着用差分的方法求解出fokker - planck方程的解，然后分析和研究分子马达定向运动的机制。
It is assumed that the particles experience several internal states in a single mechanical - chemical circle . in this model , the transition rates between different states are position - dependent which have the form of gaussian function . for any internal states , the probability distribution as a function of the time and position may be expanded near the transition points to any rank if necessary 我们认为马达在不同状态之间的跃迁不再局限于某些固定的跃迁点，也不是在各个位置都是等几率的，而是发生在某些点附近的一定宽度范围内，用跃迁宽度这一特征量表征跃迁范围的大小，能够较好地说明分子马达的动力学行为。
