研究了具有年龄结构的无穷时滞的捕食生态系统.运用比较定理,得到了系统持续生存和捕食者灭绝的充分条件.

The singularly perturbation for there points boundary value problem of nonlinear third order equation is studied in this paper by means of differential inequality theories and the method of boundary layer correction.Under suitable assumptions,the author constructs specific upper and lower solutions,proves the existence of the solutions,and obtains the uniformly valid asymptotic expansion of the solutions.

By using the directly expanding method of the perturbation theory,the author discusses the equation ef(x)=g(x,e),where e is a positive small parameter.The asymptotic approximation of roots can be given according to the single root or multiple root of its reduced equation.

The permanence of a two-prey one-predator ecosystem with stage structure is considered in this paper.By analyzing the right functions of the ecosystem and using the standard comparison the-orem,some sufficient conditions are obtained for the permanence of the ecosystem and non-perma-nence of predators.