  The aim of this article is to study Bloch-Kato's exponential map and
Perrin-Riou's "big" exponential map purely in terms of (\phi,\Gamma)-modules
over the Robba ring. We first generalize the definition of Bloch-Kato's
exponential map for all the (\phi,\Gamma)-modules without using Fontaine's
rings B_{cris}, B_{dR} of p-adic periods and then we generalize the
construction of Perrin-Riou's "big" exponential map for all the de Rham
(\phi,\Gamma)-modules and prove that this map interpolates our Bloch-Kato's
exponential map and the dual exponential map. Finally, we prove a theorem
concerning to the determinant of our "big" exponential map, which is a
generalization of Perrin-Riou's \delta(V)-conjecture. The key ingredients for
our study are Pottharst's theory of analytic Iwasawa cohomology and Berger's
construction of p-adic differential equations associated to de Rham
(\phi,\Gamma)-modules.
