  The properties of isospin-asymmetric nuclear matter have been investigated in
the framework of the extended Brueckner-Hartree-Fock approximation at zero
temperature. Self-consistent calculations using the Argonne $V_{14}$
interaction are reported for several asymmetry parameters $\beta = \frac{N -
Z}{A}$ ranging from symmetric nuclear matter to pure neutron matter. The
binding energy per nucleon fulfills the $\beta^2$ law in the whole asymmetry
range. The symmetry energy is calculated for different densities and discussed
in comparison with other predictions. At the saturation point it is in fairly
good agreement with the empirical value. The present approximation, based on
the Landau definition of quasiparticle energy, is investigated in terms of the
Hugenholtz-Van Hove theorem, which is proved to be fulfilled with a good
accuracy at various asymmetries. The isospin dependence of the single-particle
properties is discussed, including mean field, effective mass, and mean free
path of neutrons and protons. The isospin effects in nuclear physics and
nuclear astrophysics are briefly discussed.
