THE POSITIVE PERIODIC SOLUTIONS OF PERIODIC RFDEs WITH INFINITE DELAY

This paper is concerned with the periodic retarded functional differential equati-ons(RFDEs) with infinite delay. The sufficient conditions for the existence of noncon-stant positive periodic solutions are established by combining the theory of monotone semiflows generated by RFDEs with infinite delay and the fixed point theorems of solution operators. A nontrivial application of the results obtained here to a well-known nonautonomous Lotka-Volterra system with infinite delay is also presented.     

POSITIVE ALMOST PERIODIC SOLUTIONS OF n DIMENSIONAL NONAUTONOMOUS LOTKA-VOLTERRA COMPETITIVE SYSTEMS

In this paper,we study some n dimensional nonautonomous Lotka-Volterra competitive ecological systems.We then obtain permanence of such systems, as well as the existence,uniqueness and global asymptotic stability of almost periodic positive solutions to these systems.     

Periodic solution and almost periodic solution for a nonautonomous Lotka-Volterra dispersal system with infinite delay

This paper studies a nonautonomous Lotka-Volterra dispersal systems with infinite time delay which models the diffusion of a single species into n patches by discrete dispersal. Our results show that the system is uniformly persistent under an appropriate condition. The sufficient condition for the global asymptotical stability of the system is also given. By using Mawhin continuation theorem of coincidence degree, we prove that the periodic system has at least one positive periodic solution, further, obtain the uniqueness and globally asymptotical stability for periodic system. By using functional hull theory and directly analyzing the right functional of almost periodic system, we show that the almost periodic system has a unique globally asymptotical stable positive almost periodic solution. We also show that the delays have very important effects on the dynamic behaviors of the system.     

Periodic solution of neutral Lotka-Volterra system with periodic delays

A nonautonomous n-species Lotka-Volterra system with neutral delays is investigated. A set of verifiable sufficient conditions is derived for the existence of at least one strictly positive periodic solution of this Lotka-Volterra system by applying an existence theorem and some analysis techniques, where the assumptions of the existence theorem are different from that of Gaines and Mawhin's continuation theorem [R.E. Gaines, J.L. Mawhin, Coincidence Degree and Nonlinear Differential Equations, Springer-Verlag, Berlin, 1977] and that of abstract continuation theory for k-set contraction [W. Petryshyn, Z. Yu, Existence theorem for periodic solutions of higher order nonlinear periodic boundary value problems, Nonlinear Anal. 6 (1982) 943-969]. Moreover, a problem proposed by Freedman and Wu [H.I. Freedman, J. Wu, Periodic solution of single species models with periodic delay, SIAM J. Math. Anal. 23 (1992) 689-701] is answered.     

周期二维Lotka—Volterra系统的一些新结果

该文研究周期二维Lotka－Volterra捕食食饵系统解的有界性，持续生存性以及正周期解的存在性和全局稳定性．并将结果推广到食饵有补充的周期二维Lotka－Volterra竞争系统上去，得到了一系列新的结果，改进和推广了文[1—3]的主要结论．     

时滞Lotka-Volterra竞争型系统的概周期解

研究具有离散时滞的N-种群Lotka-Volterra竞争型系统，得到了系统存在唯一性概周期解的一组充分条件。     

一类无穷时滞周期Lotka-Volterra型系统的正周期解

该文研究一类无穷时滞周期Ｌｏｔｋａ Ｖｏｌｔｅｒｒａ型系统正周期解的存在性．应用Ｓｃｈａｕｄｅｒ不动 点定理得到了一个比较一般的正周期解存在定理．文献［１,２］中的主要结果被改进和推广．     

非自治Kolmogorov竞争系统的严格正解

In this paper, the existence of strictly positive solutions for N species normutonomous Kolmogorov competition systems is studied. By applying the Schauder‘s flxed pointtheorem some new sufficient conditions are established. In particular, for the almost periodicsystem, tile existence of strictly positive almost periodic solutiorts is obtained, Some previousresults are improved and generalized.     

周期捕食被捕食系统正周期解存在的充要条件

研究周期环境下的Lotka-Volterra捕食被捕食系统。采用分歧理论和微分不等式方法,建立了关于正周期解存在的一个充分必要判别准则,总结和推广了文[1—4]中的主要结果。     

一类滞后型非自治的捕食者-食饵系统的周期解

本文研究了一类滞后型三种群捕食者-食饵Lotka-Volterra系统.利用重合度理论 建立了这类系统正周期解的存在性判据.     

Positive Periodic Solution for a Nonautonomous Delay Differential Equation

In this paper, by using the Krasnoselskii fixed point theorem, we study the existence of one or multiple positive periodic solutions of a nonautonomous delay differential equation. We also give some examples to demonstrate our results.     

具有限时滞的非自治三种群扩散捕食系统的周期解

主要讨论了具有限时滞的非自治三种群扩散捕食系统的周期解的存在性.方法是运用Yoshizawa型周期解定理的推广,得出该系统至少有一个ω周期解.     

PERMANENCE,PERIODIC AND ALMOST PERIODIC SOLUTIONS OF NONAUTONOMOUS STAGE STRUCTURED POPULATION DYNAMICS WITH TIME DELAY AND DIFFUSION

A nonautonomous stage-structured two species model with time delay anddiffusion is considered. It is shown that the system is uniformly persistent undersome conditions. By discussing the independent subsystem, more brief sufficientconditions are drawn for a unique positive periodic solution which is globallyattractive and the existence of the positive almost periodic solution which isuniformly asymptotically stable by the Razumikhin function method.     

具有时滞的周期Lotka-Volterra型系统的全局渐近稳定性

考虑一般具有时间依赖时滞和连续分布时滞的Ｎ－种群周期Ｌｏｔｋａ－Ｖｏｌｔｅｒｒａ型系统。通过使用Ｌｉａｐｕｎｏｖ函数方法得到了关于正周期解的存在性和全局渐近稳定性的充分条件。这些条件改进和推广了最近被Ｗａｎｇ,Ｃｈｅｎ,Ｌｕ「２」和Ａｈｌｉｐ,Ｋｉｎｇ「４」得到的相应结果。     

一类具有阶段结构的非自治捕食-食饵系统的持久性与周期解

研究了一类具有阶段结构的非自治的捕食-食饵系统的渐近性质,得到了在适当条件下该系统的持久性,对应周期系统正周期解的存在性、唯一性以及全局渐近稳定性.     

一类Lotka-Volterra互惠扩散系统的概周期解和全局稳定性

In this paper a nonautonomous two-species n-patches system is studied.Within each patch,there are two cooperative species and their dynamics are described by the LotkaVolterra model.Each species can diffuse independently and discretely between its interpatch and intrapatch.By constructing a suitable Liapunov function,some sufficient conditions are obtained for the existence of a unique globally asymptotically stable positive almost periodic solution.     

中立型时滞Lotka-Volterra系统正周期解的存在性

本文研究了具有m个捕食者n个食饵的中立型时滞Lotka-Volterra系统,并 利用重合度理论中的连续性引理,得到了该系统正周期解存在性的充分条件.     

一类Lotka-Volterra捕食-竞争扩散系统的概周期解

研究了一类带扩散项的n种群Lotka-volterra非自治捕食-竞争系统，应用Liapunov泛函方法得到系统持久生存和存在唯一全局渐近稳定正概周期解的新的充分条件，并举例说明定理的应用．     

Existence of positive periodic solution of n-dimensional Lotka-Volterra system with delays

With the help of a continuation theorem based on coincidence degree, easily verifiable criteria are established for the existence of positive periodic solutions of n-D Lotka-Volterra system with delays. And sufficient conditions are obtained for the persistence of the delay system. Finally, computer simulations are presented to illustrate the conclusions.     

POSITIVE PERIODIC SOLUTIONS OF IMPULSIVE LATKA-VOLTERRA EQUATIONS

By using the continuation of coincidence degree theory, we study the periodic Lotka-Volterra equations with impulses, and some sufficient onditions for the existence of positive periodic solutions are obtained.