US Patent Full-Text Database Boolean Search
美国专利全文数据库
http://patft.uspto.gov/netahtml/PTO/search-bool.html
美国 uspto.gov
Patents from 1790 through 1975 are searchable only by Issue Date, Patent Number, and Current US Classification.
When searching for specific numbers in the Patent Number field, patent numbers must be seven characters in length, excluding commas, which are optional.