期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1978
卷号：75
期号：8
页码：3540-3547
DOI：10.1073/pnas.75.8.3540
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Structure determination of single crystals by diffraction methods is reviewed in terms of the philosophical and mathematical aspects of the analytical techniques that are used. A key problem concerns the need to determine the relative phases of the scattered rays. A major advance in treating this problem resulted from recognition that useful consequences ensue from the fact that electron densities in crystals are non-negative functions. Advantage is also taken of the fact that the problem is usually greatly overdetermined by the number of experimental data. For biological macromolecules, the data available are more limited in range and accuracy and great use is made of the introduction of suitable heavy atom moieties. The developments in crystal structure analysis have had a considerable impact on progress in many scientific disciplines.
关键词：phase problem ; non-negativity ; ordinary structures ; biological macromolecules
