Electronic Journal of Qualitative Theory of Differential Equations《微分方程定性理论电子期刊》(不定期). The Electronic Journal of Qualitative Theory of Differential Equations (EJQTDE) is a completely open access journal dedicated to bringing you high quality papers on the qualitative theory of differential equations. All topics related to the qualitative theory (stability, periodicity, boundedness, etc.) of differential equations (ODEs, PDEs, integral equations, functional differential equations, etc.) and their applications will be considered for publication.