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Discrete Dynamics in Nature and Society
Volume 2009, Article ID 239209, 18 pages
Research Article

Multiple Positive Periodic Solutions for Delay Differential System

1Department of Mathematics, Qufu Normal University, Qufu, Shandong 273165, China
2Department of Mathematics, University of Science and Technology of China, Hefei 230026, China
3School of Mathematical Sciences, Fudan University, Shanghai 200433, China
4Department of Mathematics, Shanghai Jiao Tong University, Shanghai 200240, China

Received 11 September 2009; Accepted 6 December 2009

Academic Editor: Binggen Zhang

Copyright © 2009 Zhao-Cai Hao et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


We obtain some existence results for multiple positive periodic solutions of some delay differential systems. Examples are presented as applications. For a general positive integer , main results of this paper do not appear in former literatures as we know. Comparing with the existing results, our results are new also when .