采用平板稀释法研究了微波处理对钙质土壤放线菌分离效果的影响。结果表明：①微波处理对提高放线菌出菌率有促进作用。在高氏1号培养基（GA）上,4种供试土壤经微波处理后放线菌总数较对照增加99.5%～234.1%,微波处理效应均达到极显著水平（P〈0.01）;链霉菌数较对照增加58.3%～377.7%,除3号土样外,微波处理效应均达到极显著水平（P〈0.01）;未鉴定放线菌较对照增加96.7%～304.8%,处理与对照的差异均达到显著水平（P〈0.05）;②不同培养基上的微波处理效应不同。GA培养基上的微波处理效应（Effect of Microwave Irradiation,EMI）最强,放线菌总数及未鉴定属放线菌的微波处理效应均表现为GA〉GA-Ca,GA培养基上放线菌总数的EMI较GA-Ca培养基提高26.4%～120.9%;③风干土样的微波处理效应大于湿土样。
Field investigations and laboratory analysis were conducted to study the characteristics of soil water-stable aggregates during vegetation rehabilitation in typical grassland soils of the hilly-gullied loess area. The relationship between water- stable aggregates and other soil properties was analyzed using canonical correlation analysis and principal component analysis. The results show that during the natural revegetation, the aggregates 〉 5 mm dominated and constituted between 50% and 80% of the total soil water-stable aggregates in most of the soil layers. The 2-5 mm aggregate class was the second main component. The mean value of water-stable aggregates 〉 5 mm within the 0-2 m soil profile under different plant communities decreased in the following order： Stipa grandis 〉 Stipa bungeana Trin. 〉 Artemisia sacrorum Ledeb. 〉 Thymus mongolicus Ronn. 〉 Hierochloe odorata （L.） Beauv. Clay, organic matter, and total N were the key factors that influenced the water stability of the aggregates. Total N and organic matter were the main factors that affected the water stability of the aggregates 〉 5 mm and 0.5-1 mm in size. The contents of Fe2O3, Al2O3, and physical clay （〈 0.01 mm） were the main factors which affected the water stability of the 1-2 and 0.25-0.5 mm aggregates.
