Exisitence Of Positive Periodic Solutions For Delayed Functional Differential Equations

In this paper,we are devoted to establish the existence of positive periodic solutions to first-order delay functional differential equations with disturbance.It is proved that such a problem has at least oneω-periodic positive solution under our reasonable conditions. Our nonlinearity may be with disturbance.The proof relies on Leray-Schauder fixed point theorem.It is well known that the functional differential equation with delay includes many mathematical ecological equations.In this paper,we apply the main result to study the Nicholson's blowflies model.