Evernote is a great way to push your notes to the cloud. And the content you create is indexed for later searching. LaTeX is the standard document markup language used in scientific research papers, or any other document that requires some math. However taking notes in LaTeX is not really feasible since it is not very easy to type documents on the fly. Even editors that provide buttons to insert symbols are hard to use and slow down note taking speed. The ideal solution is to simply be able to write notes like with a tablet. However the notes you take should use some sort of recognition to convert the notes into LaTex. From there, the documents should be uploaded to evernote and indexed.