Perhaps you should try some spelling variations:
central science » cultural science, century science, dental sciences
research nejm » research new, research need, research needs
research firm » research from, research field, research final
2.1 research » 3.1 research, 2 research
central 2.1 » central 1, central 2008
firm series » film series, forum series, from series

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (( central 2.1 research nejm series. ) or ( central science research firm series. ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( central 2.1 research nejm series. ) OR ( central science research firm series. )).
• Adding a wildcard symbol may retrieve word variants: (( central 2.1 research nejm series. ) or ( central science research firm series. ))*.