Multi-frequency Studies of Massive Cores with Complex Spatial and
  Kinematic Structures
  Five regions of massive star formation have been observed in various
molecular lines in the frequency range $\sim 85-89$ GHz. The studied regions
possess dense cores, which host young stellar objects. The physical parameters
of the cores are estimated, including kinetic temperatures ($\sim 20-40$ K),
sizes of the emitting regions ($\sim 0.1-0.6$ pc), and virial masses ($\sim
40-500 M_{\odot}$). Column densities and abundances of various molecules are
calculated in the local thermodynamical equilibrium approximation. The core in
99.982+4.17, associated with the weakest IRAS source, is characterized by
reduced molecular abundances. Molecular line widths decrease with increasing
distance from the core centers ($b$). For $b\ga 0.1$~pc, the dependences
$\Delta V(b)$ are close to power laws ($\propto b^{-p}$), where $p$ varies from
$\sim 0.2$ to $\sim 0.5$, depending on the object. In four cores, the
asymmetries of the optically thick HCN(1--0) and HCO$^+$(1--0) lines indicate
systematic motions along the line of sight: collapse in two cores and expansion
in two others. Approximate estimates of the accretion rates in the collapsing
cores indicate that the forming stars have masses exceeding the solar mass.
