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我国钢铁业行业集中度分析
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作者 韩文宾 潘新雨 《农村经济与科技》 2009年第3期39-40,共2页
本文以2008年11月份我国钢铁行业的生铁生产量为依据,分析我国钢铁行业的行业集中度,主要根据我国10大钢铁企业(宝钢、鞍钢、首钢、武钢、攀钢、太钢、马钢、包钢、唐钢、本钢)以及整个钢铁业的产量数据分析,进而得出行业集中度的结论,... 本文以2008年11月份我国钢铁行业的生铁生产量为依据,分析我国钢铁行业的行业集中度,主要根据我国10大钢铁企业(宝钢、鞍钢、首钢、武钢、攀钢、太钢、马钢、包钢、唐钢、本钢)以及整个钢铁业的产量数据分析,进而得出行业集中度的结论,分析造成该现象的原因,并提出解决方案。 展开更多
关键词 钢铁行业 集中度 产量数据分析 发展现状
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Spatial Variability of Soil Properties and Rice Yield Along Two Catenas in Southeast China 被引量:8
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作者 B. RTH B. LENNARTZ 《Pedosphere》 SCIE CAS CSCD 2008年第4期409-420,共12页
In the light of an increasing demand for staple food, especially rice, in southeast China, investigations on the specific site potential expressed as the relationship between soil and crop yield parameters gain increa... In the light of an increasing demand for staple food, especially rice, in southeast China, investigations on the specific site potential expressed as the relationship between soil and crop yield parameters gain increasing importance. Soil texture and several soil chemical parameters as well as plant properties such as crop height, biomass and grain yield were investigated along two terraced catenas with contrasting soil textures cropped with wet rice. We were aiming at identifying correlative relationships between soil and crop properties. Data were analyzed both statistically and geostatistically on the basis of semivariograms. Statistical analysis indicated a significant influence of the relief position on the spatial distribution of soil texture, total carbon and total nitrogen contents. Significant correlations were found for the catena located in a sandstone area (Catena A) between rice yield and silt as well as total nitrogen content. Corresponding relationships were not detectable for paddy fields that developed from Quaternary clays (Catena B). As suggested by the nugget to sill ratio, spatial variability of soil texture, total carbon and nitrogen was mainly controlled by intrinsic factors, which might be attributed to the erosional transport of fine soil constituents, indicating the importance of the relief position and slope in soil development even in landscapes that are terraced. The crop parameters exhibited short ranges of influence and about one third of their variability was unexplained. Comparable ranges of selected crop and soil parameters, found only for Catena A, are indicative of close spatial interactions between rice yield and soil features. Our findings show that especially in sandstone-dominated areas, a site-specific management can contribute to an environmentally safe rice production increase. 展开更多
关键词 rice productivity semivariogram analysis soil properties spatial data
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Comparative Analysis of Energy Efficiency in Wheat Production in Different Climate Conditions of Europe
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作者 Janusz Gotaszewski Marcel van der Voort +3 位作者 Andreas Meyer-Aurich Fatima Baptista Athanasios Balafoutis Hannu Juhani Mikkola 《Journal of Agricultural Science and Technology(B)》 2014年第8期632-640,共9页
This paper presents results concerning energy efficiency of wheat production considered in the context of specific energy input variation in different climatic conditions of Europe as well as case studies on implement... This paper presents results concerning energy efficiency of wheat production considered in the context of specific energy input variation in different climatic conditions of Europe as well as case studies on implementation of selected energy saving measures in practice. The source data collected from the six european union (EU) countries represent five agricultural regions of continental Europe and three climates: continental, temperate and Mediterranean. The life cycle assessment (LCA) methodology was applied to analyze the data excluding of pre-farm gate activities. The total primary energy consumption was decomposed into main energy input streams and it was regressed to yield. In order to compare energy efficiency of wheat production across the geographical areas, the data envelopment analysis (DEA) was applied. It was shown that the highest wheat yield (6.7 t/ha to 8.7 t/ha) at the lowest specific energy input (2.08 GJ/t to 2.56 G J/t) is unique for temperate climate conditions. The yield in continental and Mediterranean climatic conditions is on average lower by 1.3 t/ha and 2.7 t/ha and energy efficiency lower by 14% and 38%, respectively. The case studies have shown that the energy saving activities in wheat production may be universal for the climatic zones or specific for a given geographical location. It was stated that trade-offs between energy, economic, and environmental effects, which are associated with implementation of a given energy saving measure or a set of measures to a great extent depend on the current energy efficiency status of the farm and opportunity for investment, which varies substantially across Europe. 展开更多
关键词 WHEAT energy efficiency trade-off analysis
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使用生产数据和流压进行有效诊断
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作者 张国珍 马颖洁 《国外油田工程》 2005年第11期11-13,共3页
生产数据分析上的三个重要进步包括使用流压进行分析的方法;使用“边界优先”等效生产时间函数来生成恒定流量和恒定压力当量方法;使用拟时间修正随压力变化的气体特性方法。它们的价值取决于实际生产数据的质量,更重要的是,还取决于分... 生产数据分析上的三个重要进步包括使用流压进行分析的方法;使用“边界优先”等效生产时间函数来生成恒定流量和恒定压力当量方法;使用拟时间修正随压力变化的气体特性方法。它们的价值取决于实际生产数据的质量,更重要的是,还取决于分析家滤掉“无用”数据保留真实油藏信息的能力。不考虑数据质量而盲目使用递减分析方法会导致误释和错误的结果。几个有效的诊断方法,一些是通用的,而一些是比较特别的,可以应用于简单产量图表和先进样板曲线的生产数据上。 展开更多
关键词 产量数据分析 样板曲线 井底流压 实例研究
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Minimum Data Set for Assessing Soil Quality in Farmland of Northeast China 被引量:18
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作者 CHEN Yu-Dong WANG Huo-Yan +4 位作者 ZHOU Jian-Min XING Lu ZHU Bai-Shu ZHAO Yong-Cun CHEN Xiao-Qin 《Pedosphere》 SCIE CAS CSCD 2013年第5期564-576,共13页
Soil quality assessment provides a tool for agriculture managers and policy makers to gain a better understanding of how various agricultural systems affect soil resources. Soil quality of Hailun County, a typical soy... Soil quality assessment provides a tool for agriculture managers and policy makers to gain a better understanding of how various agricultural systems affect soil resources. Soil quality of Hailun County, a typical soybean (Glycine max L. Merill) growing area located in Northeast China, was evaluated using soil quality index (SQI) methods. Each SQI was computed using a minimum data set (MDS) selected using principal components analysis (PCA) as a data reduction technique. Eight MDS indicators were selected from 20 physical and chemical soil measurements. The MDS accounted for 74.9% of the total variance in the total data set (TDS). The SQI values for 88 soil samples were evaluated with linear scoring techniques and various weight methods. The results showed that SQI values correlated well with soybean yield (r = 0.658**) when indicators in MDS were weighted by the regression coefficient computed for each yield and index. Stepwise regression between yield and principal components (PCs) indicated that available boron (AvB), available phosphorus (AvP), available potassium (AvK), available iron (AvFe) and texture were the main factors limiting soybean yield. The method used to select an MDS could not only appropriately assess soil quality but also be used as a powerful tool for soil nutrient diagnosis at the regional level. 展开更多
关键词 norm value principal component analysis soil quality index stepwise regression
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