对于一类六次一致等时系统, 得到了原点为中心的充要条件, 并证明从细焦点至多可分支出7个小振幅极限环. 对于一类五次一致等时系统, 给出其具有6个小振幅极限环的具体实例.

For a class of six order rigid systems, the necessary and sufficient conditions for the origin to be center are obtained, and the maximal number of limit cycles bifurcating from the weak focus is proved to be 7. For a class of qintic rigid systems, a concrete example of the systems is given, which exhibits six amplitude limit cycles around the origin.