Use the National Science Foundation's National Center for Engineering Statistics (NCSES).

• Visit the Business and Industry R&D  page, as well as Federal R&D Funding by Budget Function.
• You can also search the Publication Index for  R&D-related reports.

Additionally, R&D expenditures are typically reported in 10-K filings, accessible via Mergent Online. Search by company and then select the Annual reports tab.

In the U.S. Census Bureau's Statistical Abstracts Series (historical data through 2012) R&D statistics appear in the Science & Technology section.