86de5828_User_Tips__SERP_URL_Parameters__Description
[URL Parameter] as_qdr [Format Example] http://google.com/search?q=cheese&as_qdr=d [Description] 
Search within a date range to present. Use y for year, m for month, w for week, d for day, h for hour, n for minute, and s for second. Follow the letter with a number if you want more than one. For example, “m3″ is for three months, “h5″ is for 5 hours. Want to see only the freshest of results, like within the last 5 minutes? Specify “n5″. If you want to search for a date range that ends prior to the present day, use the daterange operator or use the “Custom range” under the “More search options” link in the left sidebar of the Google SERP.
Google Power User Tips: SERP URL Parameters
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