  The behaviour of the pulsar spectrum at high radio frequencies can provide
decisive information about the nature of the radio emission mechanism. We
report recent observations of a selected sample of pulsars at lambda=9mm (32
GHz) with the 100-m Effelsberg radio telescope.Three pulsars, PSR B0144+59, PSR
B0823+26, and PSR B2022+50, were detected for the first time at this frequency.
We confirm the earlier flux density measurements for a sample of six pulsars,
and we are able to place upper flux density limits for another 12 pulsars. We
find that all pulsar spectra have a simple form that can be described using
only three parameters, one of which is the lifetime of short nano-pulses in the
emission region.The study of the transition region from coherent to incoherent
emission needs further and more sensitive observations at even higher radio
frequencies.
