By applying degree theory and the lower and upper solutions method,it was obtained that in suitable conditions the existence of at least a solution to the third-order nonlinear differential systems as follow： {x′′′（t）＋f1（t,y（t）,x′（t）,x″（t））=0,0≤t≤1,y′′′（t）＋f2（t,x（t）,y′（t）,y″（t））=0,0≤t≤1.%利用拓扑度理论和上下解方法讨论了一类三阶微分方程组{x′′′（t）＋f1（t,y（t）,x′（t）,x″（t））=0,0≤t≤1,y′′′（t）＋f2（t,x（t）,y′（t）,y″（t））=0,0≤t≤1在适当的条件下解的存在性.
展开▼
