• Require a term with +term; prohibit with -term
• Put quote marks around multi-word phrases such as "animal welfare"
• Build complex searches using (, ), AND, OR, and NOT
• Fuzzy terms allow spelling variants: sample~ also matches “sampling”, “samples”
• Title search: title:term; similarly, authors:name
• Restrict by date: prrs AND vaccine AND date:[NOW-1YEAR TO *] finds only results in past year

If you want more, look at the documentation for the Solr standard query parser.