In this paper, we investigate biharmonic maps from a complete Riemannian manifold into a Riemannian manifold with non-positive sectional curvature. We obtain some non-existence results for these maps.
In this paper,we introduce the notion of Hermitian pluriharmonic maps from Hermitian manifold into K¨ahler manifold.Assuming the domain manifolds possess some special exhaustion functions and the vecotor field V=JMδJM satisfies some decay conditions,we use stress-energy tensors to establish some monotonicity formulas of partial energies of Hermitian pluriharmonic maps.These monotonicity inequalities enable us to derive some holomorphicity for these Hermitian pluriharmonic maps.