本文利用Krasnoselskii不动点定理,考虑了状态依赖时滞性微分方程x′(t) = −A(t, x(t))x(t) + B(x(t))F(x(t −  (t, x(t))))正周期解的存在性, 得到了该方程存在与不存在正周期解的充分条件.

In this paper ,we are concerned with the existence of positive periodic solutions to
the differential equations with state-dependent delay
x′(t) = −A(t, x(t))x(t) + B(x(t))F(x(t −  (t, x(t)))).
Using Krasnoselskii fixed point theorem, we establish some sufficient condition for the existence
and nonexistence of positive !-periodic solutions to the above equation .