1. The infant mortality rate is correlative with the average GDP, the total fertility rate and the crude birth rate. 人均GDP、总和生育率和出生率是少数民族婴儿死亡率的主要影响因素。
2. The infant mortality rate is correlative with the average GDP, the total fertility rate and the crude birth rate. 人均GDP、总和生育率和出生率是少数民族婴儿死亡率的主要影响因素。
3. Through field investigation and soil fertility index analysis, causes and mechanism of fertility degradation of black soil in the Songliao Plain were explored. 通过田间调查和土壤肥力指标分析,探讨了松辽平原玉米带黑土肥力退化的原因和机理。
4. Economic fertility of soil is a combined formation of artificial and natural fertility. 土地经济肥力是人工肥力和自然肥力的统一体;
5. Through field investigation and soil fertility index analysis, causes and mechanism of fertility degradation of black soil in the Songliao Plain were explored. 通过田间调查和土壤肥力指标分析,探讨了松辽平原玉米带黑土肥力退化的原因和机理。