本刊英文版Vol.34(2018),No.5论文摘要（英文）

来源：数学学报(中文版), 2018, 61(04): 705-707.

<正>Global Phase Portraits of Quadratic Systems with a Complex Ellipse as Invariant Algebraic Curve Jaume LLIBRE Claudia VALLS Abstract In this paper,we study a new class of quadratic systems and classify all its phase portraits.More precisely,we characterize the class of all quadratic polynomial differential systems