Journal Article X-ray free-electron laser coherent X-ray diffraction imaging Research Support, Non-U.S. Gov't structure analysis of non-crystalline particles Proteins X-ray diffraction imaging ab initio molecular modeling biological cells cryogenic X-ray diffraction experiment cryogenic experiments frozen-hydrated non-crystalline specimens low-resolution structure multivariate analysis phase retrieval calculation protein structure small-angle X-ray scattering structural analysis of non-crystalline particles structure analysis of non-crystalline particles structures of cells and cellular organelles tomography