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Cortisol is thermally unstable. It is easily decomposed by loss of ketence and water. The spectrum of the resulting 11β-hydroxy-Δ4-androsten-3,17-dion can be superimposed upon the spectrum of the undecomposed cortisol, which only can be obtained free of the decomposition product under carefully controlled conditions. The thermal degradation product can be eaisly detected by its molecular peak at mass 302 and a key fragment at mass 163, which are nearly absent in the spectrum of cortisol. Cortisol is therefore an excellent testing material for the quality of inlet systems.  相似文献   

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Hunger is still a widespread problem. Due to population and income growth, as well as rising use of biofuels, global demand for agricultural products could double by 2050. Increasing production at the same rate without overusing natural resources and the environment will be a challenge. It necessitates harnessing science in all its facets, including the development and implementation of new technologies. Yet, sufficient production alone will not suffice. Food security also requires better economic access to food for all. Hence, poverty in developing countries will have to be reduced. A large proportion of people suffering from hunger depends on the small farm sector for their livelihoods, so promoting growth in this sector should have high priority.  相似文献   

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