Links below are for technical report citations and some online PDFs.
From the Department of Energy (DOE). For best results, sign up for a free account and use the Advanced Search. 1943 - present.
Also, try the DOE OpenNet System.
Contains PDFs of many reports. For better search capabilities, try NTIS.
Abstracts and full-text reports of NASA and NACA, 1915-present
Includes U.S. Atomic Energy Commissions (AEC), U.S. Bureau of Mines, U.S. Dept of Commerce, National Bureau of Standards. Most reports prior to 1975.
Some are available in Barton. Try a "Title Begins with" search for the series number. Example: NUREG/BR
Atomic and physical properties of the elements; atomic and molecular spectroscopy; nuclear physics data; condensed matter physics data; and more. A searchable element index combines the data from various sources.