Electronic transport properties through junctions in nanographite ribbons a
re investigated using the Landauer approach. In the low-energy regime ribbo
ns with zigzag boundary have a single conducting channel of edge states. Th
e conductance as a function of the chemical potential shows a rich structur
e with sharp dips of zero conductance. Each zero-conductance resonance is c
onnected with a resonant state which can be interpreted as the superpositio
n of two degenerate flux states with Kekule-like current patterns; These ze
ro-conductance dips are connected with a pronounced negative magnetoresista
nce.