  With its relatively long observation time per pointing, the Parkes multibeam
survey was effective in detecting nulling pulsars. We have made 2-hour
observations of 23 pulsars which showed evidence for pulse nulling or mode
changing in the survey data. Because of the low flux density of these pulsars,
in most cases averaging times of between 10 s and 60 s were necessary and so
this analysis is insensitive to very short nulls. Seven of the pulsars had null
fractions of more than 40% with the largest having a lower limit of 95%. Mode
changes were observed in six pulsars with clear relationships between nulling
and mode changing in some cases. Combined with earlier results, the data
suggest that large null fractions are more related to large characteristic age
than to long pulse period. The observations suggest that nulling and mode
changing are different manifestations of the same phenomenon.
