Complex sentence: She spent four years at the University of Missouri-Columbia in pursuit of her doctorate in microbiology, which she received in December 1983, for a thesis on the toxicity of radiation, paraquat and adrimycin, a chemotherapy drug, to bacteria and mammals.
Split into simpler sentences: She spent four years at the University of Missouri-Columbia in pursuit of her doctorate in microbiology, which she received in December 1983. Her thesis focused on the toxicity of radiation, paraquat and adrimycin, a chemotherapy drug, to bacteria and mammals.