  Context: Multiwavelength observations of supernova remnants can be explained
within the framework of the diffusive shock acceleration theory, which allows
effective conversion of the explosion energy into cosmic rays. Although the
models of nonlinear shocks describe reasonably well the nonthermal component of
emission, certain issues, including the heating of the thermal plasma and the
related X-ray emission, remain still open.
  Aims: To discuss how the evolution and structure of supernova remnants is
affected by strong particle acceleration at the forward shock.
  Methods: Analytical estimates combined with detailed discussion of the
physical processes.
  Results: The overall dynamics is shown to be relatively insensitive to the
amount of particle acceleration, but the post-shock gas temperature can be
reduced to a relatively small multiple, even as small as six times, the ambient
temperature with a very weak dependence on the shock speed. This is in marked
contrast to pure gas models where the temperature is insensitive to the ambient
temperature and is determined by the square of the shock speed. It thus appears
to be possible to suppress effectively thermal X-ray emission from remnants by
strong particle acceleration. This might provide a clue for understanding the
lack of thermal X-rays from the TeV bright supernova remnant RX J1713.7-3946.
