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中国同期作物空间格局变化分析──以小麦和油菜为例 被引量:7
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作者 徐慧 汪权方 +1 位作者 王新生 张景雄 《中国农学通报》 2016年第21期95-99,共5页
小麦和油菜是中国非常重要的两种大宗作物,它们的空间格局变化历来备受关注。利用1980—2014年间小麦、油菜的面积数据,以省级行政区为研究单元,采用Pearson相关系数和GIS空间几何重心分析技术,结合同期作物之间的竞争性用地关系,对油... 小麦和油菜是中国非常重要的两种大宗作物,它们的空间格局变化历来备受关注。利用1980—2014年间小麦、油菜的面积数据,以省级行政区为研究单元,采用Pearson相关系数和GIS空间几何重心分析技术,结合同期作物之间的竞争性用地关系,对油菜和小麦的空间分布格局及其变化特征进行分析。研究结果表明:中国小麦近30年空间格局的总体变化不明显,但是省际分布不均衡,其分布重心一直位于河南省境内;油菜种植的重心自1980年以来从湖北省境内不断地向南推移,目前分布在湖南省境内。受同期作物之间竞争性用地关系的影响,在陕西、青海、湖北、湖南、四川等地,油菜、小麦的面积变化表现出明显的"消-长"关系,彼此呈显著负相关。 展开更多
关键词 空间格局变化 空间几何重心 Pearson相关分析 同期作物 中国
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Nanoparticle mediated controlled delivery of dual growth factors 被引量:3
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作者 ZHANG LuZhong ZHOU YouLang +3 位作者 LI GuiCai ZHAO YaHong GU XiaoSong YANG YuMin 《Science China(Life Sciences)》 SCIE CAS 2014年第2期256-262,共7页
Peripheral nerve functional recovery after nerve injury generally requires multiple growth factors by synergistic effect.However,the optical combination of multiple synergistic growth factors for axonal regeneration h... Peripheral nerve functional recovery after nerve injury generally requires multiple growth factors by synergistic effect.However,the optical combination of multiple synergistic growth factors for axonal regeneration has been scarcely considered up to now.Meanwhile,the use of growth factors in promoting nerve regeneration was limited by its short biological half-life in vivo,its vulnerability to structure disruption or hydrolyzation,leading to loss of bioactivity.Herein,a novel polymeric nanoparticle delivery system composed of heparin andε-poly-L-lysine(PL)was prepared for control release of nerve growth factor(NGF)and basic fibroblast growth factor(bFGF).The nanoparticles were synthesized by polyelectrolyte complexation in aqueous solution at room temperature,followed by cross-linking with biological genipin.The obtained nanoparticles had a spherical shape,with a mean diameter of about 246 nm,and high growth factors encapsulation efficiency as well as good stability.NGF and bFGF were encapsulated in the nanoparticles and showed a continuous and slow release behavior in vitro.The bioactivities of the released growth factors were evaluated,and exhibited the synergistic effect.The controlled release of the dual synergistic growth factors would improve the treatment of peripheral nerve injury to mimic the natural cellular microenvironments. 展开更多
关键词 control release nerve growth factor basic fibroblast growth factor NANOPARTICLES
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