Based on review of international literatures about sex ratio at birth and its influence factors,author analyzed long-term dynamic tendency and race difference of sex ratio at birth in some developed countries,and probed into relationship between age of mother and sex ratio at birth using the relevant data of vital statistics,aimed at furthering the recognition about sex ratio at birth.

Related factors on natural spawning rate of Channel Catfish were been studied,including natural spawning in different parent fish ages,stocking densities,spawning tank type,feed type,local climatic and pond sediment type.

[Objective] To investigate the relationship between the birth weight and gender,maternal age,gestational age and birth method to provide the basic information for maternal and child health.

Through the variance analysis,we found both age of maternal plant and the substrate type had significant effects on rooting rate of cuttage and the mean rooting rate of cuttings from the 2-year-old maternal plant was 77.

The results indicated that the cutting propagation media,stock ages and planting time had obvious affection on rooting rate and root increment of Phoebe bournei,but different concentrations of rooting reagents had no obvious affection on rooting rate and root increment of Phoebe bournei.