In this paper, we study the existence of infinitely many positive periodic solutions to a class of second order functional differential equations which cannot be applied directly to the fixed point theorem in cone. With suitable deformations, we construct the operator whose fixed point is closely related to the periodic solution of the original equation and show that the problem has infinitely many positive periodic solutions under appropriate conditions.

中文翻译：

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二阶函数微分方程的无限多正周期解


在本文中，我们研究了一类二阶函数微分方程存在无限多的正周期解，这些解不能直接应用于圆锥中的不动点定理。在合适的变形下，我们构造了不动点与原始方程的周期解密切相关的算子，并证明该问题在适当条件下具有无限多的正周期解。