I'm not trying to downplay their accomplishments, but how much of their scientific advances from the 40s-60s were due to capturing ex-Nazi tech (and scientists) or stealing from the US via their incredible intelligence efforts?

Depends on the sector.

They definitely supported a lot of their rocket science from found documentation in Peenemünde et. al. (The personnel OTOH did its best not to fall into Soviet hands, and most of them ended in America, even though some didn't make it and were captured by the Soviets.)

They had genuine excellency in mathematics and theoretical physics. First, those specializations didn't require much expensive or advanced equipment back then. Second, by their very nature, they were freer from ideological bullshit than other specializations, and that alone attracted many of the best and brightest there.

(I can confirm that even in late-stage Communist Czechoslovakia, very hard sciences were considered an intellectual haven for non-conformists. The ideologues didn't understand them and did not consider them subversive per se.)

On the other hand, biology was under full tyranny of Lysenko et. al. and "bourgeoise geneticists" would get imprisoned in concentration camps and even executed or starved to death. As a result, Soviet biology never recovered to a respectable science again, not even after Lysenko lost his power.

Until today, you will find ex-Soviet textbooks of maths and physics all over the net, and people actually download them and use them to study. That does not apply in most other domains.

> On the other hand, biology was under full tyranny of Lysenko et. al. and "bourgeoise geneticists" would get imprisoned in concentration camps and even executed or starved to death. As a result, Soviet biology never recovered to a respectable science again, not even after Lysenko lost his power.

This holds for "pure" biology. On the other hand, for medicine, in the East Block phage therapy was intensively developed (which in the West was barely done; instead in the Western countries there was an intense development of antibiotics).

> https://en.wikipedia.org/w/index.php?title=Phage_therapy&old...

"In the Soviet Union, extensive research and development soon began in this field. [...] Isolated from Western advances in antibiotic production in the 1940s, Soviet scientists continued to develop already successful phage therapy to treat the wounds of soldiers in field hospitals. During World War II, the Soviet Union used bacteriophages to treat soldiers infected with various bacterial diseases, such as dysentery and gangrene. Soviet researchers continued to develop and to refine their treatments and to publish their research and results. However, due to the scientific barriers of the Cold War, this knowledge was not translated and did not proliferate across the world."

I don't know why you are getting downvoted. As a simple example of practical biology in USSR, the Eastern Bloc basically invented modern doping programs.

I'd rather call this research medical science, and with some exceptions (the Doctor's Plot during the last year of Stalin's paranoid rule), medical science tended to be less policed than biology, because even the top dogs of the Party knew that they could fall ill and require top treatment.

Unlike with Lysenko, where shortages of food for the regular population never demonstrated themselves on the nomenklatura's own dinner tables, there was some feedback mechanism that could not be ignored.

But I agree that the exact border between biology and medical science is murky.

and or lend lease?