一类三次Kolmogorov系统的极限环存在性和唯一性

Existence and Uniqueness of Limit Cycle of Cubic Kolmogorov's Differential System

研究一类三次Kolmogorov系统:x=x（A0+A1x-A3x2+A2y+A4xy）,y=y（-1+x2-y）（＊）.当A1>0,A2<0,A4<0时得到:当A0-A2>A02.x＊>x＊时,系统（＊）在第一象限内存在极限环;当A0>（A1A2）/A4,A3>A3时,系统（＊）在第一象限内存在唯一的极限环.

The cubic kolrnogorov differential. System is considered, the conditions for existence and uniqueness of limit cycle are obtained.