三次项 meaning in English

cubic term
cubicterm

In the second chapter , we obtain the necessary and sufficient condition where the cubic kolmogorov type system is bounded if homogeneous polynomials of degree 3 are relatively prime . and we obtain there are only four behaviours of the trajectories near the equator of the bounded cubic system if the homogeneous polynomials of degree 3 are relatively prime . in the third chapter , we study the existence and nonexistence of limit cycle for a class of bounded cubic systems
第一章为引言；第二章，我们得到了齐三次项互素时三次kolmogorov型系统有界的充分必要条件及其在赤道上孤立奇点附近轨线的分布情况有且仅有四种；第三章，我们研究了一类有界三次kolmogorov型系统极限环的存在性与不存在性。