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   10735篇
  免费   157篇
  国内免费   274篇
安全科学   303篇
废物处理   496篇
环保管理   1656篇
综合类   1593篇
基础理论   2607篇
环境理论   2篇
污染及防治   2619篇
评价与监测   770篇
社会与环境   1053篇
灾害及防治   67篇
  2023年   74篇
  2022年   151篇
  2021年   131篇
  2020年   96篇
  2019年   133篇
  2018年   198篇
  2017年   208篇
  2016年   307篇
  2015年   217篇
  2014年   321篇
  2013年   980篇
  2012年   379篇
  2011年   526篇
  2010年   425篇
  2009年   465篇
  2008年   531篇
  2007年   535篇
  2006年   423篇
  2005年   366篇
  2004年   392篇
  2003年   377篇
  2002年   346篇
  2001年   390篇
  2000年   254篇
  1999年   157篇
  1998年   124篇
  1997年   121篇
  1996年   151篇
  1995年   174篇
  1994年   133篇
  1993年   120篇
  1992年   112篇
  1991年   119篇
  1990年   114篇
  1989年   94篇
  1988年   96篇
  1987年   100篇
  1986年   87篇
  1985年   84篇
  1984年   93篇
  1983年   84篇
  1982年   87篇
  1981年   89篇
  1980年   65篇
  1979年   64篇
  1978年   46篇
  1977年   47篇
  1976年   45篇
  1973年   49篇
  1972年   60篇
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
311.
Global climate change will influence environmental conditions including temperature, surface radiation, soil moisture, and sea level, and it will also significantly impact regional-scale hydrologic processes such as evapotranspiration (ET), precipitation, runoff, and snowmelt. The quantity and quality of water available for drinking and other domestic usage is also likely to be affected by changes in these processes. Consequently, it is necessary to assess and reflect upon the challenges ahead for water infrastructure and the general public in metropolitan regions. One approach to the problem is to use index-based assessment, forecasting and planning. The drought indices previously developed were not developed for domestic water supplies, and thus are insufficient for the purpose of such an assessment. This paper aims to propose and develop a “Metropolitan Water Availability Index (MWAI)” to assess the status of both the quantity and quality of available potable water sources diverted from the hydrologic cycle in a metropolitan region. In this approach, the accessible water may be expressed as volume per month or week (i.e., m3/month or m3/week) relative to a prescribed historical record, and such a trend analysis may result in final MWAI values ranging from ?1 to +1 for regional water management decision making. The MWAI computation uses data and information from both historical point measurements and spatial remote-sensing based monitoring. Variables such as precipitation, river discharge, and water quality changes at drinking water plant intakes at specific locations are past “point” measurements in MWAI calculations. On the other hand, remote sensing provides information on both spatial and temporal distributions of key variables. Examples of remote-sensing images and sensor network technologies are in-situ sensor networks, ground-based radar, air-borne aircraft, and even space-borne satellites. A case study in Tampa Bay, Florida is described to demonstrate the short-term assessment of the MWAI concept at a practical level. It is anticipated that such a forecasting methodology may be extended for middle-term and long-term water supply assessment.  相似文献   
312.
The focus of the present study is on the implementation and some of the results of an evaluation of a safety culture campaign that partly was aimed at increasing workmate interventions (care). I focus on three groups either working on or with a Norwegian offshore platform: onshore managers, crane operators and process operators. The research questions are: “Has the safety culture campaign contributed to new safety cultures related to care in the three groups, why/why not and what can we learn from this?”. The study indicates that two of the groups have developed new safety cultures that sensitize them to new hazards, motivate and legitimize new preventive practices. In accordance with the interpretive approach to culture in organizations, these changes are discussed in light of members’ of each group’s negotiation over the meaning and relevance of campaign efforts on workmate interventions. Lessons that can be learned from the study are discussed.  相似文献   
313.
Rice straw can be used as a renewable fuel for heat and power generation. It is a viable mean of replacing fossil fuels and preventing pollution caused by open burning, especially in the areas where this residual biomass is generated. Nevertheless, the thermal conversion of rice straw can cause some operating problems such as slag formation, which negatively affects thermal conversion systems. So, the main objective of this research is studying the combustion behavior of rice straw samples collected from various regions by applying thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). In addition, the thermal behavior of ashes from rice straw was also analyzed in order to detect their melting points, and ash sintering was detected at different temperatures within the range between 550 and 1000 °C. Since washing rice straw with water could reduce the content of undesirable inorganic compounds related to the ash fusibility, samples of washed rice straw were analyzed under combustion conditions to investigate its differences regarding the thermal behavior of rice straw. The results showed that rice straw washing led to a significant improvement in its thermal behavior, since it reduced the ash contents and sintering formation.  相似文献   
314.
Adaptive maritime spatial planning (MSP) uses monitoring and evaluation of the effectiveness of spatial and temporal management measures to promote understanding and improve planning and decision-making. An adaptive approach to MSP involves exploring alternative ways to meet management objectives, predicting the outcomes of alternative management measures, implementing one or more of these alternative management measures, monitoring to learn about the effects of management measures, and then using the results to update knowledge and adjust management actions. A monitoring and evaluation plan should be designed to be both cost effective and comprehensive. The process of setting and assessing performance metrics requires that the ecological and socio-economic objectives of the spatial management plan must be clearly stated up front for management actions to reflect those objectives accurately. To evaluate the effectiveness of a MSP plan, a range of ecological, socio-economic and institutional indicators need to be developed and monitored.  相似文献   
315.
316.
Concerns over the loss of biodiversity and ecosystem services in farmland have prompted the development of agri-environment policy measures aimed at reducing farming pressure and maintaining semi-natural habitats in farmed landscapes. However, further knowledge is needed to guarantee successful agri-environment measures implementation. The current study assessed the quantity and the quality of semi-natural habitats in farms across a gradient of farming intensities in two contrasting regions in Ireland. Policy protection seemed fundamental for semi-natural habitats preservation. Habitats not protected by agricultural policy relied on extensive farming and are in danger of disappearing if they are intensified or abandoned. Due to the lack of policy incentives for habitat quality, no correlations were found between farming intensity and share of semi-natural habitats with habitat quality. Therefore, extensive farming and retention of habitats alone may not reverse the decline of farmland quality and biodiverisity and, thus, measures incentivising the environmental quality may be more successful.Electronic supplementary materialThe online version of this article (10.1007/s13280-020-01344-6) contains supplementary material, which is available to authorized users.  相似文献   
317.
Environmental Science and Pollution Research - Acrylamide (AA) is a hazardous chemical that is widely used in industrial practices. Spirulina platensis (SP) is a blue green alga that is rich in...  相似文献   
318.
Environmental Science and Pollution Research - Bio-waste materials from aquatic species are alternative sources of chitin and chitosan—high-value natural biodegradable and biocompatible...  相似文献   
319.
320.
Environmental Science and Pollution Research - The impact of uncontrolled municipal dumping sites on metal contamination in the surrounding waters, sediments, and soils are of great concern in many...  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