There is a virtual plethora of online journals and libraries devoted to scholarly research, analysis, and theory in the field of music, but I have cited some exceptional ones here.
\"Oxford Music Quarterly\":
The Musical Quarterly has long been cited as the premier scholarly musical journal in the United States. Over the years it has published the writings of many important composers and musicologists, including Aaron Copland, Arnold Schoenberg, Marc Blitzstein, Henry Cowell, and Camille Saint-Saens. The journal focuses on the merging areas in scholarship where much of the challenging new work in the study of music is being produced. Regular sections include \'American Musics\', \'Music and Culture\', \'The Twentieth Century\', and an \'Institutions, Industries, Technologies\' section which examines music and the ways it is created and consumed. In addition, a fifth section entitled \'Primary Sources\' features discussions on issues of biography, texts, and manuscripts; reflections on leading figures; personal statements by noted performers and composers; and essays on performances and recordings. Along with discussions of important new books, MQ publishes review essays on a wide variety of significant new music performances and recordings.
http://mq.oxfordjournals.org/
\"Music and Letters\":
Music and Letters is long established as the leading British journal of musical scholarship. Its coverage embraces all fields of musical enquiry, from the earliest times to the present day, and its authorship is international.
http://ml.oxfordjournals.org/
\"The Journal of Musicology\":
A fantastic site for music analysis. Everything from arias to symphonies is scrutinized. The Journal of Musicology offers an unparalleled journey into the world of musical scholarship. The journal furnishes comprehensive articles in music history, criticism, performance practice, and archival research. Each issue contains a selection of studies and occasional review essays representative of the full range of today\'s diverse approaches to the exploration of music. The Journal of Musicology is a sound forum for analysis in this still-expanding discipline, drawing a loyal readership from eminent scholars and musicians to performers and students.
http://www.journalofmusicology.org/
You can gain access to the journals that I have cited through the \"Scholarly Journal Archive\":
http://www.jstor.org/
You can learn more about participation information here:
http://www.jstor.org/about/participation.html