  A good understanding of the electronic conduction processes through
nanocontacts is a crucial step for the implementation of functional
nanoelectronic devices. We have studied the current-voltage ($I$-$V$)
characteristics of nanocontacts between single metallic RuO$_2$ nanowires (NWs)
and contacting Au electrodes which were pre-patterned by simple
photolithography. Both the temperature behavior of contact resistance in the
low-bias voltage ohmic regime and the $I$-$V$ curves in the high-bias voltage
non-ohmic regime have been investigated. We found that the electronic
conduction processes in the wide temperature interval 1--300 K can be well
described by the fluctuation-induced tunneling (FIT) conduction theory. Taken
together with our previous work (Lin {\it et al.}, Nanotechnology {\bf 19},
365201 (2008)) where the nanocontacts were fabricated by delicate electron-beam
lithography, our study demonstrates the general validity of the FIT model in
characterizing electronic nanocontacts.
