首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   171篇
  免费   3篇
  国内免费   68篇
安全科学   12篇
废物处理   6篇
环保管理   21篇
综合类   97篇
基础理论   26篇
污染及防治   53篇
评价与监测   13篇
社会与环境   8篇
灾害及防治   6篇
  2023年   2篇
  2022年   6篇
  2021年   5篇
  2020年   6篇
  2019年   5篇
  2018年   3篇
  2017年   5篇
  2016年   2篇
  2015年   12篇
  2014年   11篇
  2013年   30篇
  2012年   21篇
  2011年   19篇
  2010年   11篇
  2009年   10篇
  2008年   15篇
  2007年   12篇
  2006年   5篇
  2005年   9篇
  2004年   4篇
  2003年   8篇
  2002年   8篇
  2001年   8篇
  2000年   2篇
  1999年   7篇
  1998年   3篇
  1997年   2篇
  1996年   2篇
  1995年   5篇
  1994年   2篇
  1993年   1篇
  1990年   1篇
排序方式: 共有242条查询结果,搜索用时 15 毫秒
81.
Intensive agricultural development can change land use, which can further affect regional ecosystem services and functions. With the rapid growth of the population and the national demand for food, the northeast of China, which is located in the high latitudes, has experienced four agricultural developments since the 1950s. The original wetlands of this area were developed for farmland. The evaluation of ecosystem services is conducted to reveal the ecosystem status and variable trends caused by land reclamation. The aim of this study is to provide scientific basis for environmental management and for the sustainable development of agriculture in Northeast China. With GIS-RS technology, a typical farm was chosen to analyze variations in the ecosystem service value in response to land use changes during the study period. The total ecosystem service value of the farm decreased from 7523.10 million Yuan in 1979 to 4023.59 million Yuan in 2009 with an annual rate of ?1.6?% due to the decreasing areas of woodland and wetland. The increased areas of cropland, water area and grassland partly offset the loss of the total value, but the loss was still greater than the compensation. Waste treatment and climate regulation were the top two service functions with high service values, contributing to approximately 50?% of the total service value. The spatial difference of the ecosystem service value also was analyzed. The wetlands located in the central and northeastern sections of the farm changed significantly. From the aspect of ecosystem service value, the wetland and water area should be conserved, as they have the highest value coefficients. The accuracy of the value coefficient, however, needs to be studied further in future research.  相似文献   
82.
83.
In order to comprehensively evaluate the environmental impact of multi-media mercury pollution under differentiated emission control strategies in China, a literature review and case studies were carried out. Increased human exposure to methylmercury was assessed through the dietary intake of residents in areas surrounding a typical coal-fired power plant and a zinc(Zn) smelter, located either on acid soil with paddy growth in southern China, or on alkaline soil with wheat growth in northern Chi...  相似文献   
84.
建立了便携式GC-MS快速测定固定污染源废气中挥发性卤代烃方法,26种卤代烃内标定量工作曲线的相关系数r≥0.985,线性关系良好;精密度好,相对标准偏差2.33%~18.1%;准确度高,加标回收率为101%~134%;方法检出限为0.002 ppm~0.016 ppm.在实际现场监测固定污染源中挥发性卤代烃时,使用便携式GC-MS的速查(Survey)功能初步判断样品浓度,确定稀释倍数,并验证了气袋和玻璃注射器采样对挥发性卤代烃测定结果无显著性差异.  相似文献   
85.
To evaluate the long-term effects of reforestation types on soil erosion on degraded land, vegetation and soil properties under conventional sloping farmland (CSF) and three different reforestation types including a Pinus massoniana secondary forest (PSF), an Eucommia ulmoides artificial economic forest (EEF) and a natural succession type forest (NST), were investigated at runoff plot scale over a six-year period in a red soil region of southern China. One hundred and thirty erosive rainfall events generating runoff in plots were grouped into four rainfall types by means of K-mean clustering method. Erosive rainfall type I is the dominant rainfall type. The amount of runoff and the soil loss under erosive rainfall type III were the most, followed by rain-fall type II, IV and I. Compared with CSF treatment, reforestation treatments decreased the average annual runoff depth and the soil loss by 25.5%–61.8% and 93.9%– 96.2% during the study period respectively. Meanwhile, runoff depth at PSF and EEF treatments was significantly lower than that in NST treatment, but no significant difference existed in soil erosion modulus among the three reforestation treatments. This is mainly due to the improved vegetation properties (i.e., vegetation coverage, biomass of above- and below-ground and litter-fall mass) and soil properties (i.e., bulk density, total porosity, infiltration rate and organic carbon content) in the three reforestation treatments compared to CSF treatment. The PSF and EEF are recommended as the preferred reforestation types to control runoff and soil erosion in the red soil region of southern China, with the NST potentially being used as an important supplement.  相似文献   
86.
节能分析篇(章)在工业固定资产投资项目节能评估和审查中占有重要的地位,节能分析篇(章)是否全面、是否规范不仅决定了项目节能评估和审查的最终结论,也对项目投运后的能源管理产生着决定的作用。文章针对某重型机械有限公司大型高效水、火、核电及轧辊等大型轴类锻件加工基地建设项目节能分析情况进行了探讨。  相似文献   
87.
根据表土孢粉分析和植被样方调查,重庆南平养兔场内外5个不同方位的表土孢粉组合较好地揭示了该区孢粉组合特点及其与植被的关系。通过对该区表土孢粉组合差异性的研究,探讨了影响表土孢粉与现代植被对应关系的主要因素,即外来孢粉、孢粉产量、孢粉保存和孢粉鉴定等。运用LuoPacias孢粉鉴定系统将孢粉鉴定到种,共132种,为在这一地区开展第四纪古植被、古气候和古环境等研究提供参考性依据。  相似文献   
88.
Ozone sensitivity analysis with the MM5-CMAQ modeling system for Shanghai   总被引:3,自引:0,他引:3  
Ozone has become one of the most important air pollution issues around the world. This article applied both O3/(NOy-NOx) and H2O2/HNO3 indicators to analyze the ozone sensitivity in urban and rural areas of Shanghai, with implementation of the MM5-CMAQ modeling system in July, 2007. The meteorological parameters were obtained by using the MM5 model. A regional emission inventory with spatial and temporal allocation based on the statistical data has been developed to provide input emission data to the MM5-CMAQ modeling system. Results showed that the ozone concentrations in Shanghai show clear regional differences. The ozone concentration in rural areas was much higher than that in the urban area. Two indicators showed that ozone was more sensitive to VOCs in urban areas, while it tended to be NOx sensitive in rural areas of Shanghai.  相似文献   
89.
The interaction between pollution sources change and implementation of air pollution control measures was the main driving factor that caused the variation in air quality.  相似文献   
90.
The rapid development in Beijing, the capital of China, has resulted in serious air pollution problems. Meanwhile great efforts have been made to improve the air quality, especially since 1998. The variation in air quality under the interaction of pollution and control in this mega city has attracted much attention. We analyzed the changes in ambient air quality in Beijing since the 1980’s using the Daniel trend test based on data from long-term monitoring stations. The results showed that different polluta...  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号