What were some physics papers during the 1800-1950s?
That question is impossibly broad. That's a century and a half!
And in nuclear/atomic physics too! How about the entire development of modern atomic theory from Mendelev inventing the periodic table, to the plum pudding model, through to the development of modern atomic theory, the development of nuclear physics and the discovery of the various subatomic particles?
It's not too far off to say that atomic/nuclear physics didn't exist before 1800.
lonely_nucleus: This is a good place to start. http://atomictimeline.net/index.php
I understand that my question was broad, will anyone give me some websites where I can find original papers of nuclear science?
That's pretty broad, too.
If you are looking for the scientific papers of a particular scientist, look up his or her biography online and check the references and bibliography.
Depending on whom you are interested, be prepared to dig thru obscure journals published in foreign languages, like German, French, Italian, Russian, etc.
Some institutions, like the Prussian Academy of Science, which published some of Einstein's work, no longer exist.
The references in some pages (try Wikipedia in particular) should contain the titles of journal articles. When you've found the title of one that looks relevant, try a Google search for the exact title by putting the whole title in quotes. This will probably turn up an online copy.
Separate names with a comma.