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   45141篇
  免费   612篇
  国内免费   767篇
安全科学   1554篇
废物处理   1999篇
环保管理   6197篇
综合类   7565篇
基础理论   11749篇
环境理论   34篇
污染及防治   11643篇
评价与监测   2868篇
社会与环境   2580篇
灾害及防治   331篇
  2023年   200篇
  2022年   414篇
  2021年   465篇
  2020年   391篇
  2019年   406篇
  2018年   741篇
  2017年   722篇
  2016年   1071篇
  2015年   851篇
  2014年   1239篇
  2013年   3629篇
  2012年   1606篇
  2011年   2198篇
  2010年   1749篇
  2009年   1866篇
  2008年   2146篇
  2007年   2207篇
  2006年   1915篇
  2005年   1614篇
  2004年   1488篇
  2003年   1531篇
  2002年   1398篇
  2001年   1669篇
  2000年   1255篇
  1999年   779篇
  1998年   544篇
  1997年   574篇
  1996年   548篇
  1995年   645篇
  1994年   625篇
  1993年   527篇
  1992年   523篇
  1991年   506篇
  1990年   527篇
  1989年   474篇
  1988年   413篇
  1987年   393篇
  1986年   360篇
  1985年   370篇
  1984年   432篇
  1983年   389篇
  1982年   388篇
  1981年   353篇
  1980年   293篇
  1979年   322篇
  1978年   258篇
  1977年   212篇
  1975年   210篇
  1974年   203篇
  1972年   217篇
排序方式: 共有10000条查询结果,搜索用时 265 毫秒
1.
Environment, Development and Sustainability - The current study explores the role of green trust, green perceived risk and green perceived quality in changing green purchase intention....  相似文献   
2.
Russian Journal of Ecology - A study of the anthropogenic impacts on the on-shore aggregation of true seals was carried out at a haul-out located at the mouth of Piltun Bay (the northeastern part...  相似文献   
3.
Environmental Science and Pollution Research - Heavy metals are well known for their toxicity and become significant environmental pollution with a continually rising technology and public outcry...  相似文献   
4.
Environmental Science and Pollution Research - A current environmental problem is the uncontrolled use of various pesticides that are harmful to the environment and public health. The herbicide...  相似文献   
5.
Russian Journal of Ecology - Climate change entails shifts in the ranges of woody plants along both latitudinal and altitudinal gradients in the boreal forest biome. In this study,...  相似文献   
6.
Journal of Material Cycles and Waste Management - Power generation from municipal solid waste plays significant role to mitigate the environmental pollution. The power generation potential of...  相似文献   
7.
The current study is interested in evaluating the decay of cotton, Whatman and chemical pulp caused by Trichoderma harzianum and Paecilomyces variotii. The structural changes of the paper were evaluated by Infrared Spectroscopy (FTIR) and Scanning Electron Microscope (SEM). The SEM results show differences in hyphae colonization and paper decay patterns between studied species under the current study; P. variotii caused an eroded structure in the cotton (cavity forming), whereas the initial T. harzianum colonization produced rupture and erosion (soft-rot decay type II) for the three types of paper ,the gaps were elongated with sharp pointed ends, which consisted either of individual cavities or in chains. Moreover, FTIR results confirmed that there a relationship could be observed between fungal decay and crystalline cellulose content because the intensity of peaks at 1335 and 1111 cm?1 significantly decreased due to the fungal decay. Furthermore, the intensity of O–H stretching absorption slightly decreased, and this may be attributed to hydrolysis of cellulose molecules.  相似文献   
8.
Reservoirs have a wide variety of uses that have led to frequent conflicts over ecological conservation and contamination, especially as land management has intensified. Oligotrophication must be implemented in numerous tropical reservoirs that experience advanced eutrophication to maintain aquatic ecosystem functions. To quantify impacts on ecosystem functions and to develop an adaptive management policy, multiple studies have been conducted on the Itaparica Reservoir, São Francisco River, in the semi-arid north-eastern region of Brazil. Here, we add to that existing body of knowledge through investigating how nutrient accumulation is affected by water exchange between the main river flow and Icó-Mandantes Bay. Operational water-level fluctuations in the reservoir create large desiccated littoral areas that release high amounts of nutrients when they are rewetted. In particular, water-level variation promotes proliferation of Egeria densa, a noxious weed, thus elevating trophic levels of the Itaparica Reservoir and Icó-Mandantes Bay. Analysis with a P efficiency model determined 25 μg P L?1 to be the critical concentration and further indicated that the critical load in both bodies of water have been exceeded. Moreover, intensive fish aquaculture using net cages has led to further overtaxing of the reservoir. We conclude that an effective ecological reservoir management policy must involve oligotrophication, harvesting of noxious water weeds for use as soil amendment in agriculture or biogas production, “blue” aquaculture, and limiting hydroelectric power production based on current water availability.  相似文献   
9.
Objective: There have been substantial reductions in motor vehicle crash–related child fatalities due to advances in legislation, public safety campaigns, and engineering. Less is known about non-traffic injuries and fatalities to children in and around motor vehicles. The objective of this study was to describe the frequency of various non-traffic incidents, injuries, and fatalities to children using a unique surveillance system and database.

Methods: Instances of non-traffic injuries and fatalities in the United States to children 0–14 years were tracked from January 1990 to December 2014 using a compilation of sources including media reports, individual accounts from families of affected children, medical examiner reports, police reports, child death review teams, coroner reports, medical professionals, legal professionals, and other various modes of publication.

Results: Over the 25-year period, there were at least 11,759 events resulting in 3,396 deaths. The median age of the affected child was 3.7 years. The incident types included 3,115 children unattended in hot vehicles resulting in 729 deaths, 2,251 backovers resulting in 1,232 deaths, 1,439 frontovers resulting in 692 deaths, 777 vehicles knocked into motion resulting in 227 deaths, 415 underage drivers resulting in 203 deaths, 172 power window incidents resulting in 61 deaths, 134 falls resulting in 54 deaths, 79 fires resulting in 41 deaths, and 3,377 other incidents resulting in 157 deaths.

Conclusions: Non-traffic injuries and fatalities present an important threat to the safety and lives of very young children. Future efforts should consider complementary surveillance mechanisms to systematically and comprehensively capture all non-traffic incidents. Continued education, engineering modifications, advocacy, and legislation can help continue to prevent these incidents and must be incorporated in overall child vehicle safety initiatives.  相似文献   

10.
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