在河北塞罕坝樟子松林,设置对照样方、低氮(20 kg N/(hm^2·a))、中氮(50 kg N/(hm^2·a))和高氮(100kg N/(hm^2·a))添加4种处理,分0~10,10~20和20~30 cm共3个土层,系统地研究细根生产、周转、碳归还以及细根生产力(NPPfr...在河北塞罕坝樟子松林,设置对照样方、低氮(20 kg N/(hm^2·a))、中氮(50 kg N/(hm^2·a))和高氮(100kg N/(hm^2·a))添加4种处理,分0~10,10~20和20~30 cm共3个土层,系统地研究细根生产、周转、碳归还以及细根生产力(NPPfr)占生态系统净初级生产力(NPP)的比例对不同程度氮可获得性的响应,结论如下:1)细根生产力在低氮下增大,高氮下降低;细根生产力占NPP的比例则相反,在低氮下降低,中氮下升高;2)随氮浓度增大,细根生物量逐渐降低,细根周转率增大,细根碳归还先升(低、中氮)后降(高氮);3)施氮对细根生产力的影响随土壤深度的加深无显著变化,施氮对细根周转率的影响在不同深度间则差异显著;4)结构方程模型表明,氮添加通过对土壤碳氮含量、p H的影响而改变细根生产力,通过对细根碳氮含量的影响改变细根周转率。展开更多
We studied the impact of the thickness of GaN buffer layer on the properties of distributed Bragg reflector(DBR)grown by metalorganic chemical vapor deposition(MOCVD).The samples were characterized by using metallogra...We studied the impact of the thickness of GaN buffer layer on the properties of distributed Bragg reflector(DBR)grown by metalorganic chemical vapor deposition(MOCVD).The samples were characterized by using metallographic microscope,transmission electron microscope(TEM),atomic force microscopy(AFM),X-ray diffractometer(XRD)and spectrophotometer.The results show that the thickness of the GaN buffer layer can significantly affect the properties of the DBR structure and there is an optimal thickness of the GaN buffer layer.This work would be helpful for the growth of high quality DBR structures.展开更多
文摘在河北塞罕坝樟子松林,设置对照样方、低氮(20 kg N/(hm^2·a))、中氮(50 kg N/(hm^2·a))和高氮(100kg N/(hm^2·a))添加4种处理,分0~10,10~20和20~30 cm共3个土层,系统地研究细根生产、周转、碳归还以及细根生产力(NPPfr)占生态系统净初级生产力(NPP)的比例对不同程度氮可获得性的响应,结论如下:1)细根生产力在低氮下增大,高氮下降低;细根生产力占NPP的比例则相反,在低氮下降低,中氮下升高;2)随氮浓度增大,细根生物量逐渐降低,细根周转率增大,细根碳归还先升(低、中氮)后降(高氮);3)施氮对细根生产力的影响随土壤深度的加深无显著变化,施氮对细根周转率的影响在不同深度间则差异显著;4)结构方程模型表明,氮添加通过对土壤碳氮含量、p H的影响而改变细根生产力,通过对细根碳氮含量的影响改变细根周转率。
基金supported by the National Hi-Tech Research and Development Program of China("863"Project)(Grant No.2006AA03Z409)
文摘We studied the impact of the thickness of GaN buffer layer on the properties of distributed Bragg reflector(DBR)grown by metalorganic chemical vapor deposition(MOCVD).The samples were characterized by using metallographic microscope,transmission electron microscope(TEM),atomic force microscopy(AFM),X-ray diffractometer(XRD)and spectrophotometer.The results show that the thickness of the GaN buffer layer can significantly affect the properties of the DBR structure and there is an optimal thickness of the GaN buffer layer.This work would be helpful for the growth of high quality DBR structures.
