Two dissipative structures of a nematic liquid crystal, the coherent oscillation of domains in a DC electric field (SO) and the grid pattern in an AC field (GP AC ), are investigated experimentally from the viewpoint of the temporally ordered structure. For SO, a discrete change of slope of the current-voltage characteristic of the cell at threshold voltages, the estimation of coherency, the frequency pulling effect and the suppression of oscillation by an additional AC electric field and some occuring conditions are shown. For GP AC , the voltage and frequency dependences of regularity and the conditions for the most regular GP AC are determined. It is shown that the SO is more coherent than the fluctuation of GP AC .