I guess you have already tried this, but just in case, you can search the publishers' websites. For example, here's all research and review papers under the "Mathematics and Computing" category in Nature Publishing Group's journals:

http://www.nature.com/subjects/mathematics-and-computing#research-and-reviews

For Science, go to http://www.sciencemag.org/cgi/collection/comp_math and then choose "Original Research" from the "Refine By Section" menu.

If computing doesn't count as mathematical research by your definition, I don't know how to narrow down the search results from here.

I guess you have already tried this, but just in case, you can search the publishers' websites. For example, here's all research and review papers under the "Mathematics and Computing" category in Nature Publishing Group's journals:

http://www.nature.com/subjects/mathematics-and-computing#research-and-reviews

You can refine the search by choosing narrower subjects such as Applied Mathematics.

For Science, go to http://www.sciencemag.org/cgi/collection/comp_math and then choose "Original Research" from the "Refine By Section" menu.

If computing doesn't count as mathematical research by your definition, I don't know how to narrow down the search results from here. But there seem to be only 50 or so articles in Science. So, it shouldn't be too difficult to locate the paper(s) you had in mind.