Depending on your chosen area of specialisation, you can use different portals to search for research data.
The TIB Portal contains research data that has been registered with a DOI name by TIB. You can search the TIB Portal, as usual, by author or keyword. Research data collected by this author or data that matches the keyword entered will be displayed in a hit list with the data source “DataCite”. With the filter display, you can also use the facet “type of medium” to restrict your search to “research data”.
In addition, the international organisation DataCite offers an extensive metadata search function for research data from all areas. The BASE search engine (Bielefeld Academic Search Engine) indexes the DataCite search and additionally offers access to numerous other sources such as e-journals and university servers. You can also use the system to search specifically for research data. Specific interdisciplinary repositories such as RADAR are also good search access points.
You can use re3data.org to search repositories, including specialist repositories containing data from a particular field.