  Using the Ogata-Shiba wave function, the spectral functions of the
one-dimensional infinite U Hubbard model are calculated for various
concentrations. It is shown that the ``shadow band'' feature due to 2k_F
fluctuations becomes more intense close to half-filling. Comparing these
results with exact diagonalization data obtained on finite clusters for the
finite U Hubbard model and for the t-J model, it is also shown that this
feature remains well-defined for physically reasonable values of the parameters
(U/t\simeq 10, J/t\simeq 0.4). The ``shadow'' structure in the spectral
functions should thus be observable in angle-resolved photoemission experiments
for a variety of quasi-one dimensional compounds.
