Experiments and descriptions in human cells

Statement: 

Get all the experiments on human cells and its descriptions. Limit the number of results to $number$

Query: 
PREFIX dcterms: <http://purl.org/dc/terms/> PREFIX obo: <http://purl.obolibrary.org/obo/> PREFIX atlasterms: <http://rdf.ebi.ac.uk/terms/atlas/> SELECT ?id_experiment ?description { ?experiment a atlasterms:Experiment . ?experiment dcterms:identifier ?id_experiment . ?experiment atlasterms:isAbout obo:NCBITaxon_9606 . ?experiment dcterms:description ?description } LIMIT ??number