Google tried to implement a version of the PageRank algorithm from their web search. In fact, the idea of PageRank came from the way researchers rank the papers and the authors. Instead of citations, web pages have backlinks.
"Google Scholar aims to sort articles the way researchers do, weighing the full text of each article, the author, the publication in which the article appears, and how often the piece has been cited in other scholarly literature. The most relevant results will always appear on the first page."