  We consider neutrino oscillations as non stationary phenomenon based on
Schrodinger evolution equation and mixed neutrino states with definite flavor.
  We demonstrate that for such states invariance under translations in time
does not take place. We show that time-energy uncertainty relation plays a
crucial role in neutrino oscillations. We compare neutrino oscillations with
$K^{0}\leftrightarrows\bar K^{0}$, $B_{d}^{0}\leftrightarrows\bar B_{d}^{0}$
etc oscillations.
