Several Types Of Existence Of Periodic Solution Of Functional Differential Equations

This dissertation is mainly concerned with the existence of periodic solutions for some kinds of functional differential equations.In Chapter 1, the development of periodic solutions for functional differential equations and some knowledge about degree theory are presented.In Chapter 2, the existence of periodic solutions for such a kind of nonlinear neutral functional differential equationis discussed. Based on coincidence degree theory, we establish some new sufficient conditions which significantly improve and enrich the relevant results in existing literature.In Chapter 3, the existence of periodic solutions of such a kind of p-Laplacian differential equation with distributed delay is studiedWe give the new prior estimate of solutions by some analysis skills, and then obtain a new conclusion by using the coincidence degree theory.In Chapter 4, through investigating the positive periodic solutions of a general semi-ratio-dependent system with the nonmonotonic functional response and delaywe obtain a new sufficient condition for the existence of positive periodic solutions under the weaker conditions, which improve and extend the relevant results in existing literature greatly.