The non - existence of radially non - increasing positive solutions is derived for a system of quasi - linear elliptic differential equations first of all 摘要首先得到一类拟线性椭圆型方程组正解的先验界估计和衰减性质，从而推出该方程组的径向非增正对称解的不存在性结果。
In chapter 3 , we study cauchy problem of a class of abstract nonlinear systems with damping : the existence and non - existence of the global solution are proved by potential well method 在第三章中，利用位势井方法研究一类具阻尼的抽象非线性双曲型方程的cauchy问题的整体弱解的存在与不存在性
In chapter two , some integral identities on groups of heisenberg type are established . a nonexistence result for posotive solutions of semilinear sub - laplace equations on groups of heisenberg type is obtained 第二章建立了h型群上的一些积分恒等式，得到了h型群上半线性次椭圆laplace方程正解的一个不存在性结果。
In chapter 1 , the author first study the two - stage confidece intervals for the variance of a normal distribution , then work out the optimal sample size of the first stage by numerical computations and establish a proof for the non - existence of fixed - size sampling 在第1章里，作者首先研究了正态总体方差的两步置信区间，并用数值计算的方法给出了第一步的最优抽样量，且证明了固定样本抽样的不存在性。
Assume that . in this paper , we will discuss the existence , the non - existence and the uniqueness of limit cycle system ( * ) . the methods employed are poincare - bendixsion theorem , method of dulac function and zhang zhifen ' s uniqueness theorem . our main results are as follows : theorem 1 对的情形,我们讨论了系统（ * ）极限环的存在性、不存在性和唯一性。主要利用环域定理、 dulac函数法和张芷芬的唯一性定理等手法。
In this paper we study the existence uniquness and the asymptotic behavior of global solutions and the nonexistence of the global solutions for the initial boundary value problems , cauchy problem and abstract cauchy problem to some nonlinear evolution equations of higer order 本文讨论几类非线性高阶发展方程(组)初边值问题、 cauchy问题和抽象初值问题整体解的存在唯一性、解的渐近性以及整体解的不存在性，主要结果有以下五部分内容
In the second chapter , we obtain the necessary and sufficient condition where the cubic kolmogorov type system is bounded if homogeneous polynomials of degree 3 are relatively prime . and we obtain there are only four behaviours of the trajectories near the equator of the bounded cubic system if the homogeneous polynomials of degree 3 are relatively prime . in the third chapter , we study the existence and nonexistence of limit cycle for a class of bounded cubic systems 第一章为引言；第二章，我们得到了齐三次项互素时三次kolmogorov型系统有界的充分必要条件及其在赤道上孤立奇点附近轨线的分布情况有且仅有四种；第三章，我们研究了一类有界三次kolmogorov型系统极限环的存在性与不存在性。
In the first part of the thesis , we study two one - dimensional dynamical systems with negative schwarzian derivative . by using the non - existence of attractive periodic orbits and wandering intervals , a theorem is obtained that the forward invariant compact sets of the two dynamical systems are uniform hyperbolic 本文第一部分主要考虑两类具有负schwarz导数的单峰映射的动力学性质，利用吸引周期轨道和游荡区间的不存在性等，证明了其正向不变紧集的一致双曲性。
