关键词: 银杏种仁, 银杏种仁, 总RNA提取

Abstract:

The security of cultivated land brings about a significant enfluence on both security of grain seccurity and the security of ecology and society. With the aim to provide observational constraints on the use of cultivated land in China, the author had set up a set of threshold indicator systems and derived a cultivated land risk evaluation model basing on the Probabilistic Neural Network (PNN) to distinguish the risk rank of cultivated land in China. The results showed that the highly risk area were located in the ecological vulnerable regions, it contained Sichuan, Yunnan, Neimenggu, Fujian, Chongqing, Shannxi, Guizhou, Gansu, Qinghai; The danger rank of cultivated land distributed in both the rapid economic areas and the relatively undeveloped areas, including to Shandong, Beijing, Shanghai, Tianjing, Guangxi; Ningxia, Jiangsu, Zhejiang, Xizang, Guangdong were listed in observed attention areas. By virtue of being given a special favorite policy, Chinese maple grain production areas, such as Liaoning, Shanxi, Henan, Hebei; Anhui, Hunan, Hubei, Xinjiang, Hainan, Jiangxi, Jilin, Helongjiang owned a relative safe situation. These implied that the environment and quality of cultivated land in China should be paid a special attention, the pressure imposed by improper economic growth on the cultivated land should be relieved, and Chinese maple food production area should be given a special protecting policy with a view to Chinese food safety.