S-6 New Strategy and Technology to Improve Oral Drug Bioavailability: Manipulate Drug Properties and Utilize Biomembrane Functions   S6-1. Overview of the New Strategy to Improve Oral Drug Absorption   S6-2. Medicinal Chemistry on Bioavailability Improvement   S6-3. Improvement of Oral Bioavailability Based on Physicochemical Evaluation   S6-4. Improvement of Intestinal Absorption of Drugs by Utilizing Transporters   S6-5. Peptide-Mediated Delivery: Current Understanding and Prospect   S6-6. Experimental Proof of Oral BA Improvement of Biopharmaceuticals by Functional Peptides