What research methods have made it possible to experimentally prove that DNA is replicated in a semi-conserved way?

Methods of tagged atoms and centrifugation were used. Semi-conserved DNA replication was proved using the N15 isotope and subsequent separation of the DNA mixture into two fractions with two nitrogen isotopes and N14.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.