A review is given of attempts to describe nuclear properties in terms of
neutron--proton pairs that are subsequently replaced by bosons. Some of the
standard approaches with low-spin pairs are recalled but the emphasis is on a
recently proposed framework with pairs of neutrons and protons with aligned
angular momentum. The analysis is carried out for general j and applied to
N=Z nuclei in the 1f7/2 and 1g9/2 shells.Comment: 16 figures, 4 tables, accepted for publication in Int. J. of Modern
Physics
