具Holling II型功能反应函数的捕食者一食饵模型的周期解存在性

摘要

通过引用重合度定理，给出具有HollingII型功能反应函数的三种群比率依赖的捕食者-食饵模型至少存在一个正周期解的充分条件．%Sufficient conditions for existing at least one positive periodic solution of a class of ratio-dependent predator-prey system with Holling type II functional response are established by using the coincidence degree theory.