21490
With the development of technology and improved understanding of nuclear spin - spin interactions and their behavior in static / oscillating magnetic fields , NMR spectroscopy has emerged as a powerful tool for characterizing molecular structure in a wide range of systems of chemical , physical and biological relevance .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
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