Dynamics for a class of general hematopoiesis model with periodic coefficients

Sufficient conditions are obtained for the existence and global attractivity of a unique positive periodic solution x˜(t) of equation(∗)x′(t)=-a(t)x(t)+b(t)1+xn(t-τ(t)),t>0,where n > 1, a and b are continuous positive periodic function. Also, some sufficient conditions are established for oscillation of all positive solutions of (∗) about x˜(t). For the proof of existence and uniqueness of x˜(t), the method used here is better than contraction mapping principle.