Limit cycles coming from some uniform isochronous centers

摘要

Agraïments: The first author is supported by the NSF of China (No. 11201086), the Foundation for Distinguished Young Talents in Higher Education of Guangdong, China (No.2012LYM0087) and the Excellent Young Teachers Training Program for colleges and uni- versities of Guangdong Province, China (No. Yq2013107).