A delayed nonautonomous ratio-dependent predator-prey system is investigated. By using the continuation theorem of coincidence degree theory, sufficient conditions are derived for the existence of periodic solution in the system.

• 研究了一类基于比率和具有时滞的非自治的捕食者食饵系统。利用重合度理论,得到了该系统周期解存在性的充分条件。