Existence of positive periodic solutions for a functional differential equation with a parameter Original Research Article

In this paper, we study the existence, multiplicity and nonexistence of positive ωω-periodic solutions for a kind of nonautonomous functional differential equation by employing the fixed point theorem in cones. Some new results are obtained. As an application of our results, we discuss the existence of a positive periodic solution for a class of models of blood cell production with a parameter, which has not been investigated by using previous methods.