PORTUGALIAE MATHEMATICA Vol. 61, No. 2, pp. 177191 (2004) 

Positive periodic solutions of impulsive delay differential equations with signchanging coefficientYuji Liu, Zhanbing Bai, Zhanjie Gui and Weigao GeDepartment of Applied Mathematics, Beijing Institute of Technology,Beijing 100081  P.R.\ CHINA and Department of Mathematics, Yueyang Teacher's University, Yueyang 414000  P.R.\ CHINA Department of Applied Mathematics, Beijing Institute of Technology, Beijing 100081  P.R.\ CHINA Zhanjie Gui, Department of Mathematics, Hainan Teacher's University, Haikou, 570000  P.R.\ CHINA} {Weigao Ge, Department of Applied Mathematics, Beijing Institute of Technology, Beijing 100081  P.R.\ CHINA Abstract: Consider the existence and nonexistence of positive periodic solutions of the nonautonomous delay differential equation Keywords: impulses; functional differential equation; positive periodic solution; cone; fixed point theorem. Full text of the article:
Electronic version published on: 7 Mar 2008.
© 2004 Sociedade Portuguesa de Matemática
