Are you looking for a specific journal title that was recommended to you or that you received from a source?
You can get a complete overview of all printed as well as electronic journals in Germany at the "German Union Catalogue od Serials" (in german called Zeitschriftendatenbank - ZDB).
For electronic journals, the eletronic journals library in german called Elektronische Zeitschriftenbibliothek (EZB) is available as a research tool.
Examplesearch in the "German Union Catalogue of Serials":
Examplesearch in the electronic Journals Library: