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Cultivation Influences on Soil Organic Carbon Associated with Texture in Seasonally Frozen Zones
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作者 Xiao PU Jing XIE +2 位作者 Hongguang CHENG Shengtian YANG Shuangbao WANG 《Agricultural Science & Technology》 CAS 2014年第7期1147-1151,共5页
[Objective] This study aimed to examine indicative roles of texture representing soil organic carbon presence and variability subsequent to cultivation under cold temperate climates with seasonal freeze-thaw events. [... [Objective] This study aimed to examine indicative roles of texture representing soil organic carbon presence and variability subsequent to cultivation under cold temperate climates with seasonal freeze-thaw events. [Method] Three chronosequences were selected for paired comparisons. Soil samples were collected at six depths with a 10 cm increment. Analysis of variance with general linear model and regression was performed for statistical analysis. [Result] In seasonally frozen soils where fragmentation of macroaggregates was stimulated, soil organic carbon level was positively associated with clay + silt proportion due to a wider textural range, better than sole clay content. Exponential function better fitted the experimental data to present progressively increased effectiveness of clay + silt content in maintaining carbon. Clay content explained 12%-41% and 14%-43% of variation via linear and exponential functions, respectively. Accordingly, clay + silt content explained 47%-65% and 46%-70%. [Conclusion] Texture reflected soil organic carbon occurrence as consequences of reclamation. For seasonally frozen soils with wider textural ranges, it is robust to adapt clay + silt content as dependent variable and exponential function. The generated algorithms provided an available pathway to estimate soil organic carbon losses following cultivation and to evaluate soil fertility. 展开更多
关键词 Soil organic carbon OCCURRENCE RECLAMATION Soil texture Seasonal freeze-thaw events
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我国海外专利技术的规模分布与结构特征分析 被引量:4
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作者 蔡虹 张洁 孙顺成 《情报杂志》 CSSCI 北大核心 2010年第4期1-4,30,共5页
依据美国国家经济研究局(NBER)专利数据库的数据,分析了我国海外专利授权的数量和化学、计算机与通信、医药、电气与电子、机械及其他共六大类的技术分布及时间序列分布,并采用Herfindahl指数量化分析了我国专利分布的集中程度。结果显... 依据美国国家经济研究局(NBER)专利数据库的数据,分析了我国海外专利授权的数量和化学、计算机与通信、医药、电气与电子、机械及其他共六大类的技术分布及时间序列分布,并采用Herfindahl指数量化分析了我国专利分布的集中程度。结果显示,1994年以前,我国专利构成基本稳定,1995和1996年出现了较大的波动,但1997年后技术构成逐渐均匀。根据反映专利之间技术创新关联性的专利被引次数,测度了我国专利的平均一般性指数。 展开更多
关键词 专利技术 集中度 一般性指数 NBER
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