  Flux densities are basic observation parameters to describe pulsars. In the
most updated pulsar catalog, 24% of the listed radio pulsars have no flux
density measurement at any frequency. Here, we report the first flux density
measurements, spectral indices, pulse profiles, and correlations of the
spectral index with pulsar parameters for 19 pulsars employing the
Ultra-Wideband Low (UWL) receiver system installed on the Parkes radio
telescope. The results for spectral indices of 17 pulsars are in the range
between -0.6 and -3.10. The polarization profiles of thirteen pulsars are
shown. There is a moderate correlation between the spectral index and spin
frequency. For most pulsars detected, the S/N ratio of pulse profile is not
high, so DM, Faraday rotation measure (RM), and polarization can not be
determined precisely. Twenty-nine pulsars were not detected in our
observations. We discuss the possible explanations for why these pulsars were
not detected.
