TY - Acta Geographica Sinica A1 - DONG Xiaobin, GAO Wangsheng, YAN Maochao T1 - Emergy Analysis of Agroecosystem Productivity of Typical Valley in Loess Hilly-gully Region of the Loess Plateau: A Case Study in Zhifanggou Valley of Ansai County Y1 - 2004-03-25 00:00:00.0 JF - Acta Geographica Sinica JO - Acta Geographica Sinica SP - 223 EP - 229 VL - 59 IS - 2 UR - {https://www.geog.com.cn/EN/10.11821/xb200402008} N1 - 10.11821/xb200402008 ER -