The editor of Nature wrote a piece on the Huffington post recently about how to read a scientific abstract.

A well-written abstract typically provides several basic types of information about a research project in concise arrangement, facilitating the reader’s ability to quickly ascertain the context, questions asked or purpose, results & methodology, interpretation and conclusions of one particular line of experimentation. The presentation style can vary widely from publisher to publisher, but each important element can often be identified by language cues or even more simply, by the order of the sentences.

He then walks through an abstract, explaining each part. It’s a great read, check it out here.