The UML University Library has subscriptions for Nature through several publishers, and each link covers a slightly different date range.
For the most coverage, use the publisher link at "Nature (publisher)", which has the most up-to-date issues plus a deep backfile.
It includes abstracts but not full-text of articles from 1986-2007, so if you need full-text articles in that date range, next try the link with Nature hosted in "ProQuest's Biological Science Collection."
Links below: