本文从生态学能量流的角度研究了简阳县不同时期农田系统能量投入量、投能结构，投能效率及能量投入产出关系。
The energy inputs and their structure, efficiencies, and the relationship between energy input and output in the farmland ecosystem of Jianyang County were studied in this paper.
农业生产经济学理论分析了农业生产函数中的投入产出关系；
The theory of the agricultural economy analysed the relationship of input and output in thd function of agricultural production;
第四部分是对教师资源投入与学生学业成绩产出关系的研究。
The fourth part analyzes the relations between the investment of teacher resources and the output of students'academic achievement.
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