PREFIX dcat: <http://www.w3.org/ns/dcat#> 
PREFIX dc: <http://purl.org/dc/elements/1.1/>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
{
  ?dataset rdf:type dcat:Dataset .
  ?dataset dc:modified ?modified_date .
}