Actually you generally get more functionality reading an e-book from ProQuest Ebook Library or EBSCO eBooks in your browser versus downloading it to your desk/laptop or reading it on tablet or, (even more so) a smartphone.

Reminder: e-books available from other providers (i.e. publishers such as Springer, Wiley, Science Direct/Elsevier) will generally allow you to easily read your e-books online and also download individual chapters as PDFs for you to keep without the need to read them only on Adobe Digital Editions-compatible e-reading applications.