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   1093篇
  免费   29篇
  国内免费   9篇
安全科学   72篇
废物处理   37篇
环保管理   294篇
综合类   86篇
基础理论   310篇
环境理论   3篇
污染及防治   197篇
评价与监测   84篇
社会与环境   43篇
灾害及防治   5篇
  2023年   10篇
  2022年   13篇
  2021年   15篇
  2020年   16篇
  2019年   12篇
  2018年   25篇
  2017年   31篇
  2016年   41篇
  2015年   27篇
  2014年   33篇
  2013年   79篇
  2012年   53篇
  2011年   73篇
  2010年   49篇
  2009年   42篇
  2008年   63篇
  2007年   67篇
  2006年   60篇
  2005年   41篇
  2004年   44篇
  2003年   46篇
  2002年   35篇
  2001年   21篇
  2000年   13篇
  1999年   20篇
  1998年   17篇
  1997年   15篇
  1996年   20篇
  1995年   22篇
  1994年   15篇
  1993年   13篇
  1992年   11篇
  1991年   10篇
  1990年   7篇
  1989年   8篇
  1988年   9篇
  1987年   6篇
  1986年   2篇
  1985年   4篇
  1984年   9篇
  1983年   4篇
  1982年   6篇
  1981年   4篇
  1979年   3篇
  1978年   5篇
  1977年   2篇
  1974年   2篇
  1967年   1篇
  1963年   1篇
  1938年   1篇
排序方式: 共有1131条查询结果,搜索用时 484 毫秒
131.
This study examined the effects of mentor success, relationship duration, and the amount of mentoring received on protégés' performance after the supervisory mentoring relationship had ended. Data collected from former protégés paired with objective measures of performance indicated that a mentor's success moderated the impact of mentoring functions received on subsequent protégé success. Additionally, the strength of these relationships depended on the length of the mentoring relationship. The present study suggests more emphasis should be placed on the capabilities of the mentor. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   
132.
The acute toxicity of two organophosphorus (OP) insecticides, azinphosmethyl and acephate, was evaluated in the mummichog, Fundulus heteroclitus. In addition, the effects of certain intrinsic (sex) and extrinsic (salinity and multiple toxicant interraction) variables on the toxic response were also investigated. Azinphosmethyl was by far the most toxic of the two OP insecticides with a 96h LC50 approximately 100,000 x lower than that for acephate. Slight sex differences were observed in the sensitivity of mummichogs to each of the OP insecticides with male fish being marginally more sensitive. Significant effects of low salinity stress were observed only with acephate exposure and, in this case, low salinity appeared to be slightly protective. In general, all of the insecticide mixtures (azinphosmethyl/endosulfan, azinphosmethyl/fenvalerate and acephate/fenvalerate) tested exhibited simple additive toxicity.  相似文献   
133.
Differences in Evaporation Between a Floating Pan and Class A Pan on Land1   总被引:1,自引:0,他引:1  
Abstract: Research was conducted to develop a method for obtaining floating pan evaporation rates in a small (less than 10,000 m2) wetland, lagoon, or pond. Floating pan and land pan evaporation data were collected from March 1 to August 31, 2005, at a small natural wetland located in the alluvium of the Canadian River near Norman, Oklahoma, at the U.S. Geological Survey Norman Landfill Toxic Substances Hydrology Research Site. Floating pan evaporation rates were compared with evaporation rates from a nearby standard Class A evaporation pan on land. Floating pan evaporation rates were significantly less than land pan evaporation rates for the entire period and on a monthly basis. Results indicated that the use of a floating evaporation pan in a small free‐water surface better simulates actual physical conditions on the water surface that control evaporation. Floating pan to land pan ratios were 0.82 for March, 0.87 for April, 0.85 for May, 0.85 for June, 0.79 for July, and 0.69 for August.  相似文献   
134.
Are shrubland birds edge specialists?   总被引:1,自引:0,他引:1  
In studies of forest fragmentation, birds of scrubby, early-successional habitats are considered edge specialists. Because these birds are assumed to thrive in fragmented, edge-dominated areas, their landscape ecology has received little attention from ecologists. With populations of shrubland birds declining throughout the eastern United States, the question of whether or not these birds really prefer edge habitats has important conservation implications. We used a meta-analysis to test how edges affect the abundance of shrubland birds in early-successional habitats. We analyzed data for 17 species from seven studies that compared the abundances of birds in the interiors and edges of regenerating clearcuts surrounded by mature forest. The meta-analysis clearly showed that shrubland birds avoid edges. All 17 species tested had higher abundances in patch centers than along edges, and edge effects were significant for 8 of 17 species. The key implication of this result is that small or irregular patches, dominated by edge, are unlikely to provide suitable habitat for shrubland birds. Thus, management for these declining species should involve providing large patches and minimizing edges. These findings demonstrate the importance of testing widely accepted ecological classifications and the need to view landscape ecology from the perspective of non-forest wildlife.  相似文献   
135.
136.
This study presents a reconstruction of the fire activity of the last ~14,200 cal. years BP (before AD 1950) from Gooches Crater Right, located on the Newnes Plateau, approximately 150 km to the west of Sydney (~33°27′S, 150°16′E) within the Blue Mountains National Park. Charcoal analysis and palynology were undertaken with the aim of untangling any inter-relationship between climate, humans and fire. A chronology of the site was provided by radiocarbon dating. The dominant control on fire in this environment during the Holocene appears to be climate. Periods of climate change, identified in previous studies, are associated with higher levels of fire activity. Fire was less ubiquitous between ~9,000 and 6,000 years BP, a period normally described as having a higher effective moisture in south-eastern Australia. The mid-Holocene fluctuations in charcoal may reflect anthropogenic fire, climate forcing or alternatively human responses to any climate change. Coeval changes in palaeoclimatic sequences elsewhere and palynology at the site support a climatic explanation or that Aboriginal people used fire within a climatic framework.  相似文献   
137.
138.
The field of engineering is changing rapidly as the growing global population puts added demands on the earth's resources: engineering decisions must now account for limitations in materials and energy as well as the need to reduce discharges of wastes. This means educators must revise courses and curricula so engineering graduates are prepared for the new challenges as practicing engineers. The Center for Sustainable Engineering has been established to help faculty members accommodate such changes through workshops and new educational materials, including a free access website with peer-reviewed materials.  相似文献   
139.
The Office of Radiation and Indoor Air of the U.S. Environmental Protection Agency has demonstrated a soil washing plant for the treatment of radioactively contaminated soils from two Superfund sites in New Jersey. The plant employs unit operations that are widely used in the processing of minerals and coal. These operations were examined and tested to determine how they would apply to volume reduction of these contaminated soils. In this context, they are considered to be innovative candidates for remediation of other sites with large volumes of soil contaminated with low-level radioactivity. Laboratory testing of soil characteristics and behavior in unit processes is used to assess the applicability of volume reduction/chemical extraction (VORCE) technology to specific sites.  相似文献   
140.
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