Online full-text content begins with the January 1999 issue, and will expand with each month's new issues. Abstracts are online beginning with the January 1975 issue.

Each issue will be placed online approximately on the date it is mailed to subscribers, so the online site may be days or even weeks ahead of your receipt of a paper copy.

The Web site also provides access to information about the journal (such as Instructions to Authors, the Editorial Board, and subscription information), as well as access to other services.

The site is free and available to all on the Internet through the end of the trial period (see above). Thereafter, access will be by institutional site license, which comes with all institutional subscriptions, or by personal subscription.

We encourage you, on your first visit to the site, to sign the guestbook. This will take only a minute or two, and will give us helpful information about who the online readers are, and how they are connecting to us. In addition, we would appreciate comments, critiques, questions, or suggestions from you; these can be sent via the Feedback button found on all pages of the site. Feedback from readers will help us decide what new features would be most valuable for the site, and how well it is working for its readers.

The site is being produced in conjunction with Stanford University's HighWire Press, which also works with other medical/research journals, such as Science, the Journal of Biological Chemistry, the Proceedings of the National Academy of Sciences, the journals of the American Heart Association and the journals of the American Psychiatric Association. A list of online journals and URLs is available at: http://highwire.stanford.edu