Differential equations 6 Nonlinear nonautonomous delay differential equations 6 Angiogenesis 4 Mathematical models 4 Nonautonomous 4 Nonlinear equations 4 Positive periodic solution 4 Problem solving 4 A priori estimates 2 A-priori estimates 2 Blood 2 Chronic myelogenous leukemia 2 Degree theory 2 Differentiation (calculus) 2 Dynamics 2 Equilibria 2 Existence of positive periodic solutions 2 Global and local stability 2 Global attractor 2 Hematopoiesis 2 Leray-Schauder degree 2 LeraySchauder degree methods 2 Lienard equations 2 Local stability 2 M-matrix 2 Model with pharmacokinetics 2 Multiplicity 2 Non-Lipschitz nonlinearities 2 Nonlinear nonautonomous delay differential equation 2 Positive periodic solutions 2