TY - JFULL AU - Changjin Xu and Qianhong Zhang PY - 2011/3/ TI - Periodic Solutions in a Delayed Competitive System with the Effect of Toxic Substances on Time Scales T2 - International Journal of Mathematical and Computational Sciences SP - 169 EP - 173 VL - 5 SN - 1307-6892 UR - https://publications.waset.org/pdf/15291 PU - World Academy of Science, Engineering and Technology NX - Open Science Index 50, 2011 N2 - In this paper, the existence of periodic solutions of a delayed competitive system with the effect of toxic substances is investigated by using the Gaines and Mawhin,s continuation theorem of coincidence degree theory on time scales. New sufficient conditions are obtained for the existence of periodic solutions. The approach is unified to provide the existence of the desired solutions for the continuous differential equations and discrete difference equations. Moreover, The approach has been widely applied to study existence of periodic solutions in differential equations and difference equations. ER -