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科尔沁沙地旱作农田土壤退化的过程和特征 被引量:38
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作者 苏永中 赵哈林 +1 位作者 张铜会 李玉霖 《水土保持学报》 CSCD 北大核心 2002年第A01期25-28,115,共5页
在一个较小的时空尺度上对科尔沁沙地典型旱作农田土壤物理和化学特性在风蚀沙化过程中的演变特征及其退化过程进行了的探讨。结果表明 :旱作农田由于周边沙质草地的开垦而发生风蚀沙化 ,3~ 5年的时间就会使 5 %~ 15 %的细粒物质吹蚀 ... 在一个较小的时空尺度上对科尔沁沙地典型旱作农田土壤物理和化学特性在风蚀沙化过程中的演变特征及其退化过程进行了的探讨。结果表明 :旱作农田由于周边沙质草地的开垦而发生风蚀沙化 ,3~ 5年的时间就会使 5 %~ 15 %的细粒物质吹蚀 ,表土粗化 ,向风沙沉积特征发展 ,土体结构破坏 ,容重增加 0 .0 5~ 0 .15 g/ cm3,总孔隙度降低 3%~ 5 % ,持水性能变劣 ,养分也随之丧失 ;<0 .0 5 mm的粘粉粒吹蚀 1% ,土壤有机质和全氮含量下降 0 .2 5 9g/ kg和 0 .0 16 4 g/ kg;土壤退化的演变 ,既有系统本身的自然属性决定的内在原因 ,更重要的是人为的外部干扰体系的驱动 ;退化的过程既有渐变型 。 展开更多
关键词 土壤退化 过程和特征 科尔沁沙地
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典型喀斯特地区石漠化演变过程对土壤质量性状的影响 被引量:53
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作者 龙健 李娟 +1 位作者 汪境仁 李阳兵 《水土保持学报》 CSCD 北大核心 2006年第2期77-81,共5页
在一个较小的时空尺度上对典型喀斯特地区石漠化过程中的土壤质量演变特征及其退化过程进行了探讨。结果表明:由于植被破坏和耕地的开垦发生土壤颗粒粗化,向石漠化景观发展,土体结构破坏,容重增加0.12~0.60g/cm^3,总孔隙度降... 在一个较小的时空尺度上对典型喀斯特地区石漠化过程中的土壤质量演变特征及其退化过程进行了探讨。结果表明:由于植被破坏和耕地的开垦发生土壤颗粒粗化,向石漠化景观发展,土体结构破坏,容重增加0.12~0.60g/cm^3,总孔隙度降低12.0%~39.8%,持水性能变劣,养分也随之下降;〈0.05mm的粘粉粒流失,表层土壤有机质和全氮含量下降33.4%~84.6%和43.3%~85.2%。土壤质量的演变,既有系统本身的自然属性决定的内在原因,更重要的是人为的外部干扰体系的驱动;演变的过程既有渐变型,又有跃变型。 展开更多
关键词 喀斯特地区 土壤质量 石漠化 过程和特征
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Source-sink landscape spatial characteristics and effect on non-point source pollution in a small catchment of the Three Gorge Reservoir Region 被引量:9
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作者 WANG Jin-liang NI Jiu-pai +4 位作者 CHEN Cheng-long XIE De-ti SHAO Jing-an CHEN Fang-xin LEI Ping 《Journal of Mountain Science》 SCIE CSCD 2018年第2期327-339,共13页
The source and sink landscape patterns refer to landscape types or units that can either promote positive evolvement of non-point source(NPS) pollution process, or can prevent/defer the ecological process, respectivel... The source and sink landscape patterns refer to landscape types or units that can either promote positive evolvement of non-point source(NPS) pollution process, or can prevent/defer the ecological process, respectively. Therefore, the role of a catchment landscape pattern in nutrient losses can be identified based on the spatial arrangement of source and sink landscapes. To reveal the relations between landscape spatial characteristics and NPS pollution in small catchment, a case study was carried out in a Wangjiagou small catchment of the Three Gorges Reservoir Region(TGRR), China. Google earth imagery for 2015 were processed and used to differentiate source and sink landscape types, and six subcatchments were selected as sample regions for monitoring nitrogen and phosphorus nutrients.Relative elevation, slope gradient and relative flow length was used to construct the Lorenz curves of different source and sink landscape types in the catchment, in order to assess the source and sink landscape spatial characteristics. By calculating the location-weighted landscape indices of each subcatchment and total catchment, the landscape spatial load characteristics affecting the NPS pollution was identified, with a further Pearson correlation analysis for location-weighted landscape indices and nitrogen-phosphorus monitoring indicators. The analysis of Lorenz curve has revealed that the obtained distribution trend of Lorenz curve and curve area quantified well the spatial characteristics of source and sink landscape pattern related to the relative elevation, slope gradient and relative flow length in small catchment. Results of Pearson correction analysis indicated that location-weighted landscape index(LWLI) combining of terrain and landscape type factor did better in reflecting the status of nitrogen and phosphorus loss than the indices related to relative elevation, slope gradient and relative flow length. 展开更多
关键词 Source-sink landscape Non-point sourcepollution Nutrient loss Lorenz curve Landscapeindex Small catchment
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Employment and Wage Effects of RMB Exchange Rate for Manufacturing Sectors in China and the US
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作者 Xu Weicheng 《China Economist》 2018年第2期54-68,共15页
By creating a labor market dynamic general equilibrium model, this paper derives the pass-through mechanism of exchange rate's employment and wage effects,carries out an empirical study on the employment and wage ... By creating a labor market dynamic general equilibrium model, this paper derives the pass-through mechanism of exchange rate's employment and wage effects,carries out an empirical study on the employment and wage effects of RMB exchange rate for manufacturing sectors in China and the United States based on ridge regression, and examines the role of industry characteristics in this process. Research findings suggest that: RMB depreciation will drive employment and wage growth for most of China's laborintensive manufacturing sectors, and RMB appreciation will increase employment for certain capital-and technology-intensive sectors; but RMB depreciation has insignificant employment and wage effects for most sectors in the US. Hence, in achieving the longterm stability of RMB exchange rate, China should take advantage of RMB appreciation's manufacturing upgrade effect and ensure the steady growth of manufacturing employment.The US should make breakthroughs in various links of its economic development in order to tackle unemployment, instead of blaming RMB exchange rate. In addition, the nature of business activities and trade union characteristic are both significant factors that lead to differences in inter-sector employment levels of Chinese and US manufacturing sectors.Technology characteristic and other monopolistic characteristics exert decisive effects on the difference of wage return for various sectors in China and the US. 展开更多
关键词 RMB exchange rate manufacturing sectors industrial upgrade industry characteristics
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重塑中国经济地理的方向与途径研究 被引量:10
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作者 孙久文 《南京社会科学》 CSSCI 北大核心 2016年第6期18-24,41,共8页
以"一带一路"为主的一系列区域经济发展新战略的实施,推动了中国经济地理的重塑。本文从新中国成立以来中国区域空间格局的演化分析入手,剖析了长期以来中国区域均衡协调发展的主要内涵,以及区域空间布局模式的变化,明确指出... 以"一带一路"为主的一系列区域经济发展新战略的实施,推动了中国经济地理的重塑。本文从新中国成立以来中国区域空间格局的演化分析入手,剖析了长期以来中国区域均衡协调发展的主要内涵,以及区域空间布局模式的变化,明确指出了中国经济进入新常态后区域空间格局所表现出的三个变化特征,同时从加快贸易自由化和国内一体化,平衡区域空间的人口与经济总量疏密度,依托"一带一路"、长江经济带和京津冀协同发展这三大支撑带,实现区域空间均衡协调发展等角度,提出了重塑中国经济地理的主要途径。 展开更多
关键词 中国经济地理 重塑 途径 演化过程和特征
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人工岛码头作业现场事故隐患简析及对策
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作者 鲁大成 刘宏伟 谢东 《中国石油和化工标准与质量》 2019年第6期108-109,共2页
人工岛码头属靠海作业,为保障油田建设需要,大量的人员、物资、车辆通过码头进行运输,生产活动的开展,势必会造成隐患,给安全生产带来诸多不确定因素,本文就此进行探讨。
关键词 事故隐患 发展过程和特征 表现及对策
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