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When prominence of security problems increasing,it is of importance to savethe sensitive electronic documents into database. The user-role mechanism is employed in the process of managing documents. However, it can't provide the flexibility of authorized access because of the dynamic generating particularity of the electronic documents which need maintaining continually. A tree model of entity authorization is introduced based on discretionary access control mechanism. The approach can grealty simplify the authorization, increase the flexibility and is more accordant with the practical requirement of enterprises. 相似文献
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顾德法 《上海交通大学学报(农业科学版)》1988,(4)
本实验使用 Mo 靶软 x 射线仪,35kV 的发射电压,10000R 的剂量,照射处理21个香稻品种(处在萌芽期的种子)。从武香203亲本品种辐射后代中选育出优异的新品系 SX0832,具有原品种的香味、优质,还具有矮秆,抗病、高产等特点。 相似文献
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