  Short timescale flux variations are closely related to the energy release
process of magnetic reconnection during solar flares. Radio light curves at 1,
2, 3.75, 9.4, and 17 GHz of 209 flares observed by the Nobeyama Radio
Polarimeter from 2000 to 2010 are analyzed with a running smooth technique. We
find that the impulsive component (with a variation timescale shorter than 1
second) of 1 GHz emission of most flares peaks at a few tens of solar flux unit
and lasts for about 1 minute and the impulsive component of 2 GHz emission
lasts a shorter period and peaks at a lower flux level, while at the three high
frequency channels the occurrence frequency of flares increases with the
decrease of the flux density up to the noise level of the corresponding
background. The gradual components of these emissions, however, have similar
duration and peak flux density distributions. We also derive the power spectrum
on different timescales and a normalized wavelet analysis is used to confirm
features on short timescales. At a time resolution of 0.1 second, more than
$\sim$ 60$\%$ of these radio light curves show significant flux variation on 1
second or shorter time scales. This fraction increases with the decrease of
frequency and reaches $\sim$ 100$\%$ at 1 GHz, implying that short timescale
processes are universal in solar flares. We also study the correlation between
the impulsive radio flux densities and soft X-ray fluxes obtained with the GOES
satellites and find that more than 65$\%$ of the flares with an impulsive
component have their impulsive radio emission reach a peak value ahead of the
soft X-ray fluxes and this fraction increases with the radio frequency.
