"Nucleic acid structure" . . "DNA portion" . "structure of nucleic acids" . "Nucleic acid structure" . . "nucleic acid structure" . . "DNA structures" . "structure" . "DNA topology" . . "structural and mechanical properties of DNA" . "structure of DNA" . "secondary structures" . "2\u2019 sugar modifications" . . "Secondary structure" . "DNA structure" . "structures" . "conformation" . "structurally" . . .