The planar delaydifferentialsystem (1) has significant biological and physical backgrounds. For example, some special cases of (1) have been proposed as models of neural networks.
平面系统（1）具有重要的生物和物理背景，大量的神经网络模型都是以这种形式被提出的。
2
So, it has a practical significance to study the character of solutions of either degenerate differentialsystem with delay or impulsive differential equations with delays.
因此研究退化、脉冲时滞微分方程解的性态具有重要的现实意义。
3
In the second chapter, we study an infinite delaydifferential equation, the system was widely applied in the biology, neural network and some other fields.