Answer:
C & D
Explanation:
C - The Sun has an 11 year solar cycle. When the solar cycle is at a <em>minimum</em>, active regions of the sun are rare and not many solar flares are detected. They dramatically increase as the Sun approaches the <em>maximum</em> part of its cycle.
D - It's the Sun. It's moody. Solar flares are pretty sporadic, they're sudden and often unpredictable.
The enlargement and situation of it
Answer:
The main difficulties of X-ray crystallography include:
1. It is very difficult to obtain crystals with high diffraction quality and proper size.
2. Phase analysis. In theory, X-ray crystallography technology has no requirement for the molecular weight of protein, and can obtain any high-resolution structure at the atomic level of protein. Because some proteins are very difficult to crystallize, or the quality of crystallization is very poor, there is no diffraction or only very low resolution diffraction data, which limits the X-ray crystallography analysis of protein structure.
Explanation:
http://www.creative-biostructure.com/protein-crystallization_26.htm
