[IEEE 2007 4th IEEE International Symposium on Biomedical Imaging: From Nano to Macro - Arlington, VA, USA (2007.04.12-2007.04.15)] 2007 4th IEEE International Symposium on Biomedical Imaging: From Nano to Macro - DETERMINATION OF PROTEIN STRUCTURES IN SITU: ELECTRON TOMOGRAPHY OF INTACT VIRUSES AND CELLS