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   4017篇
  免费   277篇
  国内免费   290篇
安全科学   190篇
废物处理   21篇
环保管理   978篇
综合类   1408篇
基础理论   693篇
环境理论   76篇
污染及防治   192篇
评价与监测   214篇
社会与环境   593篇
灾害及防治   219篇
  2024年   15篇
  2023年   101篇
  2022年   98篇
  2021年   129篇
  2020年   133篇
  2019年   200篇
  2018年   182篇
  2017年   229篇
  2016年   245篇
  2015年   226篇
  2014年   150篇
  2013年   329篇
  2012年   244篇
  2011年   289篇
  2010年   206篇
  2009年   221篇
  2008年   186篇
  2007年   222篇
  2006年   178篇
  2005年   138篇
  2004年   130篇
  2003年   117篇
  2002年   95篇
  2001年   83篇
  2000年   103篇
  1999年   87篇
  1998年   38篇
  1997年   46篇
  1996年   23篇
  1995年   18篇
  1994年   16篇
  1993年   33篇
  1992年   11篇
  1991年   14篇
  1990年   15篇
  1989年   4篇
  1988年   3篇
  1987年   4篇
  1986年   2篇
  1985年   5篇
  1984年   2篇
  1983年   1篇
  1982年   3篇
  1981年   2篇
  1980年   3篇
  1977年   3篇
  1971年   2篇
排序方式: 共有4584条查询结果,搜索用时 15 毫秒
1.
Five new towns have been developed around the Seoul metropolitan area since 1996. However, these new towns generate lots of traffic and related problems in the areas including those new towns and Seoul as a result of increases in population and a lack of ecological-self-sufficiency. Currently, construction of another new town is under deliberation, and what should be a major consider is the notion that the new town be located within a wide, green zone. Many studies have revealed that green space can play an important role in improving urban eco-meteorological capability and air quality. In order to analyze the urban heat island which will be created by the new urban development, and to investigate the local thermal environment and its negative effects caused by a change of land use type and urbanization, Landsat TM images were used for extraction of urban surface temperature according to changes of land use over the last 15 years. These data are analyzed together with digital land use and topographic information. As a study result, it was found the urban heat island of the study area from 198.5 to 1999 rapidly developed which showed a difference of mean temperature above 2.0. Before the Bundang new town construction the temperature of the residential area was the same as a forest, but during the new town construction in 1991 analysis revealed the creation of an urban heat island. The temperature of a forest whose size is over 50% of the investigation area was lowest, and thus the presence of a forest is believed to have a direct cooling effect on the urban environment and its surroundings. The mean temperature of the residential and commercial areas in the study was found to be 4.5 higher than the forest, and therefore this part of land use is believed to be the main factor causing the temperature increase of the urban heat island.  相似文献   
2.
To study mitigation and adaptation to climate change, social scientists have drawn on different approaches, particularly sociological approaches to the future and comparative history of past societies. These two approaches frame the social and temporal boundaries of decision-making collectivities in different ways. A consideration of the responses to climate variability in three historical cases, the Classic Maya of Mexico and Central America, the Viking settlements in Greenland, and the US Dust Bowl, shows the value of integrating these two approaches.  相似文献   
3.
全球环境变化给发展中国家和南北关系带来深刻影响,理解环境问题的全球不平等需要以发展中国家80年代开始的经济结构调整和沉重债务为背景。南方的环境政策优先在很大程度上与其生活的可持续性相连,而不是通常与全球环境变化的长期性风险相关,然而,全球环境变化又与发展中国家贫困人口的日常生活紧密相关。从南方的立场看,当“问题”对他们不十分迫切时,就很难同意采取措施,仅此原因,北方对全球环境变化的关切要得到成功回应,真正的全球契约就需要解决基本“发展”问题,主要是贫困。  相似文献   
4.
This article does not focus on adaptation or mitigation policy directly but on an allied opportunity that exists for the Pacific Islands via the auspices of the Climate Convention, because the existing very costly energy systems used in the Pacific Island region are fossil-fuel dependent. It is argued here that efforts can be made towards the development of energy systems that are ecologically sustainable because Pacific Island nations are eligible to receive assistance to introduce renewable energy technology and pursue energy conservation via implementation mechanisms of the Climate Convention and, in particular, through transfer of technology and via joint implementation. It is contended that assistance in the form of finance, technology, and human resource development from developed countries and international organizations would provide sustainable benefits in improving the local Pacific Island environments. It is also emphasized that mitigation of greenhouse gas emissions is not the responsibility of the Pacific Islands as they contribute very little on a per capita global scale and a tiny proportion of total global greenhouse gas emissions.  相似文献   
5.
渭河径流特性研究   总被引:3,自引:0,他引:3  
田宏伟 《灾害学》2006,21(2):99-102
由于工农业的快速发展,渭河径流逐年减少,污染加重,河道淤积不断发展,洪涝灾害时有发生,对中下游人民生产生活造成严重影响.为了减少洪害,减轻污染,必须保证渭河常年径流稳定.  相似文献   
6.
Coupling a land use model and an ecosystem model for a crop-pasture zone   总被引:2,自引:0,他引:2  
This paper describes the development of a land use model coupling ecosystem processes. For a given land use pattern in a region, a built-in regional ecosystem model (TESim) simulates leaf physiology of plants, carbon and nitrogen dynamics, and hydrological processes including runoff generation and run-on re-absorption, as well as runoff-induced soil erosion and carbon and nitrogen loss from ecosystems. The simulation results for a certain period from 1976 to 1999 were then used to support land use decisions and to assess the impacts of land use changes on environment. In the coupling model, the land use type for a land unit was determined by optimization of a weighted suitability derived from expert knowledge about the ecosystem state and site conditions. The model was applied to the temperate crop-pasture band in northern China (CCPB) to analyze the interactions between land use and major ecosystem processes and functions and to indicate the added value of the feedbacks by comparing simulations with and without the coupling and feedbacks between land use module and ecosystem processes. The results indicated that the current land use in CCPB is neither economical nor ecologically judicious. The scenario with feedbacks increased NPP by 46.78 g C m−2 a−1, or 32.23% of the scenario without feedbacks, also decreased soil erosion by 0.65 kg m−2 a−1, or 23.13%. Without altering the regional land use structure (proportions of each land use type). The system developed in this study potentially benefits both land managers and researchers.  相似文献   
7.
Urban lakes are vulnerable to the accumulation of semivolatile organic compounds, such as PAHs from wet and dry atmospheric deposition. Little was reported on the seasonal patterns of atmospheric deposition of PAHs under Asian monsoon climate. Bulk (dry + wet) particle deposition, air-water diffusion exchange, and vapour wet deposition of PAHs in a small urban lake in Guangzhou were estimated based on a year-round monitoring. The total PAH particle deposition fluxes observed were 0.44-3.46 μg m−2 day−1. The mean air-water diffusive exchange flux was 20.7 μg m−2 day−1. The vapour deposition fluxes of PAHs ranged 0.15-8.26 μg m−2 day−1. Remarkable seasonal variations of particulate PAH deposition, air-water exchange fluxes and vapour wet deposition were influenced by seasonal changes in meteorological parameters. The deposition fluxes were predominantly controlled by the precipitation intensity in wet season whereas by atmospheric concentration in dry season.  相似文献   
8.
柚树间种短期经济作物在提高柚园经济效益的同时,还可提高土壤的有机质和N、P、K养分质量分数,改善柚园小区气候,增加有机肥来源。间种物残余体作为绿肥,可显著地提高柚果产量和质量。  相似文献   
9.
车载电子电器设备的温度变化试验   总被引:1,自引:0,他引:1  
卢兆明 《环境技术》2009,27(5):12-18,36
ISO16750《道路车辆电气及电子设备的环境条件和试验》系列国家标准转化已进入报批阶段。系列标准的第4部分《气候负荷》引用IEC 60068-2-14规定的试验N:温度变化(GB/T2423.22)中的试验Na:规定转换时间的温度快速变化和试验Nb:按规定温度变化速率的温度变化试验。2009年1月,IEC对60068-2-14进行了技术性改版。将IEC 60068-2-33《温度变化导则》(GB/T2424.13)的内容并入;对试验及温度变化容差的描述和要求、编辑和插图都做了修改和修订。等同采标的GB/T2423.22的改版修订工作已在进行,估计2010年稍晚就可以发布。这里就当前国际标准和将发布等同国标的试验方法对车载电子电器设备的温度变化试验进行描述,同时对试验要素和及其应用要素作一些介绍。ISO16750《道路车辆电气及电子设备的环境条件和试验》系列国家标准转化已进入报批阶段。系列标准的第4部分《气候负荷》引用IEC 60068-2-14规定的试验N:温度变化(GB/T2423.22)中的试验Na:规定转换时间的温度快速变化和试验Nb:按规定温度变化速率的温度变化试验。2009年1月,IEC对60068-2-14进行了技术性改版。将IEC 60068-2-33《温度变化导则》(GB/T2424.13)的内容并入;对试验及温度变化容差的描述和要求、编辑和插图都做了修改和修订。等同采标的GB/T2423.22的改版修订工作已在进行,估计2010年稍晚就可以发布。这里就当前国际标准和将发布等同国标的试验方法对车载电子电器设备的温度变化试验进行描述,同时对试验要素和及其应用要素作一些介绍。  相似文献   
10.
基于Markov模型的南京土地利用时空变化研究   总被引:1,自引:0,他引:1  
利用江苏2000年、2008年遥感数据,采用ArcGIS和Excel测算出南京市辖区8年土地利用的Matkov转移矩阵,从数量、空间和结构角度分析2000-2008年的土地利用变化状况,预测2016年的各类用地面积.结果表明,2000-2008年研究区的城镇和工矿交通用地扩张较快,农村居民点用地略有减少,呈集中态势;耕地、草地、林地、水域减少,未利用地减幅最大.在空间上,研究区的建设用地扩张由"同心圆状"变为"纺锤状",土地利用集中度和强度都增大.2016年预测显示,城镇用地比重达44.76%,耕地减少23.47%,其余用地基本保持前8年的变化趋势,但动态度有所减小,仅农村居民点用地减幅增大.  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