Subharmonic solutions of first order Hamiltonian systems with   subquadratic condition
  Using a homologically link theorem in variational theory and iteration inequalities of Maslov-type index, we prove the existences of a sequence of subharmonic solutions for one type of sub-quadratic non-autonomous Hamiltonian systems. Moreover, we also study the minimal period problem of some autonomous Hamiltonian systems with sub-quadratic condition. 
Shanshan Tang
math.AP