  The rotational bands in nuclei with $Z \approx 100$ are investigated
systematically by using a cranked shell model (CSM) with the pairing
correlations treated by a particle-number conserving (PNC) method, in which the
blocking effects are taken into account exactly. By fitting the experimental
single-particle spectra in these nuclei, a new set of Nilsson parameters
($\kappa$ and $\mu$) and deformation parameters ($\varepsilon_2$ and
$\varepsilon_4$) are proposed. The experimental kinematic moments of inertia
for the rotational bands in even-even, odd-$A$ and odd-odd nuclei, and the
bandhead energies of the 1-quasiparticle bands in odd-$A$ nuclei, are
reproduced quite well by the PNC-CSM calculations. By analyzing the
$\omega$-dependence of the occupation probability of each cranked Nilsson
orbital near the Fermi surface and the contributions of valence orbitals in
each major shell to the angular momentum alignment, the upbending mechanism in
this region is understood clearly.
