How to completely copy a site if empty pages are displayed after simple/copying 1000 pages?

Question

Crawling

There is a site www.rlsnet.ru
and there is a need to copy it to disk.
the problem is that after copying 1000 pages (+/-) on the issue (we go to the drug page in the alphabetical index, or simply enter the name of the drug in the search), there are empty white pages. Their source code is empty. How to bypass this blocking?