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   645篇
  免费   8篇
  国内免费   15篇
安全科学   12篇
废物处理   5篇
环保管理   275篇
综合类   139篇
基础理论   90篇
污染及防治   44篇
评价与监测   45篇
社会与环境   39篇
灾害及防治   19篇
  2023年   2篇
  2022年   11篇
  2021年   10篇
  2020年   13篇
  2019年   7篇
  2018年   10篇
  2017年   19篇
  2016年   20篇
  2015年   16篇
  2014年   17篇
  2013年   19篇
  2012年   13篇
  2011年   45篇
  2010年   25篇
  2009年   52篇
  2008年   69篇
  2007年   68篇
  2006年   30篇
  2005年   25篇
  2004年   14篇
  2003年   25篇
  2002年   15篇
  2001年   13篇
  2000年   11篇
  1999年   10篇
  1998年   9篇
  1997年   11篇
  1996年   3篇
  1995年   8篇
  1994年   7篇
  1993年   10篇
  1992年   6篇
  1991年   6篇
  1990年   4篇
  1989年   4篇
  1988年   4篇
  1987年   7篇
  1986年   4篇
  1985年   5篇
  1984年   1篇
  1983年   2篇
  1982年   4篇
  1981年   2篇
  1980年   2篇
  1979年   5篇
  1978年   1篇
  1977年   3篇
  1974年   1篇
排序方式: 共有668条查询结果,搜索用时 727 毫秒
531.
城市化可能引起的地貌灾害及其防治   总被引:2,自引:0,他引:2  
陈宝冲 《灾害学》1990,(2):23-28
城市化可能导致流水地貌过程系统的变化,加剧水土流失和洪水威胁;还可能导致重力地貌过程系统的变化,造成土滑、滑坡和崩塌等灾害;城区地下水、地下其它液体和固体物质的开采,可能引起地面沉降或坍陷。这一切会影响自然环境与人类环境,故应采取相应的防治措施。  相似文献   
532.
面向生态监测与管理的国家级土地生态分类方案研究   总被引:2,自引:0,他引:2  
遥感能够为生态监测和管理提供有用的技术手段,能够实现生态的持续、快速、动态监测。土地生态分类体系是实现生态遥感的基础。目前世界上已有的土地分类系统基本是从土地利用/土地覆盖或资源调查的角度设计的,尚不能满足宏观生态和管理的需求。该研究提出的面向生态监测与管理的国家级土地生态分类方案就是为了满足这种需求而设计的。  相似文献   
533.
We compared the composition of diatom assemblages collected from New Jersey Pinelands blackwater streams draining four different land uses, including forest land, abandoned-cranberry bogs, active-cranberry bogs, and developed and upland-agricultural land. Over a 2-year period (2002-2003), we collected 132 diatom taxa at 14 stream sites. Between-year variability in the composition of stream samples was high. Most diatom species were rarely encountered and were found in low abundance. Specific conductance and pH were higher at developed/agricultural sites compared with all other site types. Neither species richness nor genus richness was significantly different between stream types. However, clear community patterns were evident, and a significant difference in species composition existed between the developed/agricultural sites and both cranberry and forest sites. The primary community gradient, represented by the first axis of a DCA ordination, was associated with variations in pH and specific conductance. Although community patterns revealed by ordinating the data collected in 2002 differed from those obtained using the 2003 data, both ordinations contrasted the developed/agricultural sites and the other sites. Acidobiontic and acidophilous diatoms characterized the dominant species at forest, abandoned-bog, and cranberry sites, whereas indifferent species dominated the developed/agricultural samples. Although our study demonstrated a relationship between the composition of diatom assemblages and watershed conditions, several factors, including taxonomic problems, the large number of diatom species, incomplete pH classifications, and year-to-year variability may limit the utility of diatom species as indicators of watershed conditions in the New Jersey Pinelands.  相似文献   
534.
We use an econometrically-based landscape simulation to investigate the effect of conservation on the net change in local development – the amount of land directly protected from development minus the amount of development that may occur on neighboring unprotected private land in response to conservation. First, we use spatial-panel data from Wisconsin to estimate parcel-level subdivision probabilities and density expectations, controlling for the endogenous location of open space. Second, we use these subdivision probabilities and density expectations in a landscape simulation model. Our simulation results indicate that 57% of conserved open space created between 1978 and 2009 generated close to zero net change in local development. This suggests that conserved open space mostly reallocated development in a small neighborhood (in a half-mile radius) rather than altering the total amount of development. We explore the landscape conditions that may lead to conservation having either a positive or negative effect on local development.  相似文献   
535.
以东莞市为例,运用环境经济学方法对“十一五”期间城市区域开发对生态系统服务功能的影响进行评价。2011年东莞市生态系统服务功能总价值约为25.44亿元,较2005年(31.20亿元)减少18.5%。气体调节、气候调节、水源涵养等9种生态系统服务功能价值均有不同程度的减少,其中水源涵养、废物处理和休闲娱乐3种生态系统服务功能的价值减少均超过20%。结果表明,东莞城市建设已经对区域生态系统服务功能造成了较大的影响,土地利用方式有待进一步优化。  相似文献   
536.
Antibiotics in soil environment are regarded as emerging pollutants and have introduced increasing risks to soil ecosystem and human health in rapid urbanization areas. Identifying the occurrence and spatial variability of antibiotics in soils is an urgent issue in sustaining soil security. In this study, antibiotics in soils were investigated and analyzed in Beijing-Tianjin-Hebei urban agglomeration. The occurrence, spatial distribution, and related affecting factors of antibiotics in soils were identified and ecological risks of antibiotics in soil environment were assessed. Results showed that (1) The mean concentration of soil antibiotics in Beijing-Tianjin-Hebei urban agglomeration was 21.79 µg/kg. Land use substantially affected the occurrence and concentration of antibiotics in soils. Concentrations of antibiotics in cropland and orchard soils were 2-3 times higher than the other land use types. (2) The concentrations of antibiotics in soils in Beijing-Tianjin-Hebei urban agglomeration presented a spatial pattern of high values in southeast, and low values in northwest. Spatial variability of antibiotics in soils was closely related to the application of organic fertilizer and wastewater irrigation as well as topographical features. Furthermore, soil properties and land management policy had substantial influences on soil antibiotics, and soil heavy metals may aggravate the accumulation of antibiotics in soils. (3) Ecological risks assessment of antibiotics in soils demonstrated that erythromycin (ERY), sulfamethoxazole (SMX), and doxycycline (DOX) may introduce high risks to soil ecosystem health, and more attention should be paid to the areas with intensive human activities that had potential high risk to soil ecosystem health. This study suggests that scientific land and soil management should be considered to prevent soil antibiotic pollution and sustain soil security in urban agglomeration.  相似文献   
537.
本章针对固体废物最终处置的两大途径,即陆地处置和海洋处置,着重介绍了卫生土地填埋、安全土地填埋、海洋倾倒、远洋焚烧、深井灌注处置等方法,以及它们的场地开发和利用、场地选择、设计、建造、操作等.  相似文献   
538.
The aim of the study was to delineate soil landscape constraints to various land uses for urban and regional planning in the coastal areas of New South Wales (NSW), Australia. Soil landscape units mapped at 1:100,000 or coarser were sub-divided into component facets using advanced terrain modelling techniques in a geographic information system (GIS). The output facet grids were further overlain and linked with relevant GIS layers and soil databases to derive soil landscape constraint ratings for various land use purposes such as residential development, cropping and grazing. The constraint ratings for a specific land use were calculated based on objective and rule-based assessments of soil and landscape features such as engineering hazards, intrinsic fertility, drainage and other parameters. A series of soil landscape constraint maps which portray specific land use capability have been produced for the NSW coast. The methodology developed in this study has been demonstrated to be efficient in delineating soil landscape constraints and there is over 90% agreement between the model outputs and the assessment by soil surveyors with local knowledge. The output maps show levels of unprecedented detail of soil and landscape constraint for the coast of NSW and can be readily interpreted by land use planners and land managers for sustainable land use decision making practices.  相似文献   
539.
Detailed analysis of the land cover of the Estonian coastal zone is presented based on Estonian laws on coastal zone management, the CORINE Land Cover (CLC) system, the status of protected areas, and administrative division data of Estonia. By law the coastal zone is defined as a 200-m wide zone landward from the mean sea level line. The length of the Estonian coastline (including the islands) is 3794 km. The 200-m zone of the Estonian coast is very diverse. Out of the 34 CORINE land cover types represented in Estonia 30 are found in the coastal zone. Three dominating land cover types in the coastal zone of Estonia are inland marshes, coniferous forest and semi-natural grassland. Their total share is 47%; the other 27 land cover types represented here cover 53% of the coastal zone. The Estonian coastal zone is generally in a good natural condition. The proportion of artificial surfaces throughout the zone is merely 4.7%, while agricultural landscapes cover only ca. 10%. Land cover data for the coastal zone are also presented by county. Of the 200-m coastal zone 24% is under protection, which is more than twice the value for Estonia as a whole (11%). Legislative protection of the coastal zone is presently satisfactory. The use of the CORINE Land Cover system enables comparisons with other European regions since CLC data have been compiled for most of Europe.  相似文献   
540.
土地资源是人类生存最基本的资源,对它的利用与开发必须保持协调的可持续的发展规划。本文以无公害农产品土地利用为例,从环境的角度,构建了产地环境条件子系统、自然条件子系统、经济效益分析子系统和环境影响分析子系统以及各自包含的评价指数集。产地环境条件指标集和自然条件指标集是基于现状的,采用结果指标表达;针对布局规划,环境影响分析和经济效益分析是一种预测评价,对其指标集的构建采用了过程指标的设计。  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