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   726篇
  免费   1篇
  国内免费   12篇
安全科学   17篇
废物处理   15篇
环保管理   64篇
综合类   163篇
基础理论   129篇
环境理论   3篇
污染及防治   260篇
评价与监测   51篇
社会与环境   35篇
灾害及防治   2篇
  2023年   6篇
  2022年   17篇
  2021年   10篇
  2020年   10篇
  2019年   8篇
  2018年   24篇
  2017年   15篇
  2016年   49篇
  2015年   29篇
  2014年   45篇
  2013年   55篇
  2012年   47篇
  2011年   52篇
  2010年   25篇
  2009年   26篇
  2008年   47篇
  2007年   43篇
  2006年   33篇
  2005年   25篇
  2004年   34篇
  2003年   25篇
  2002年   22篇
  2001年   12篇
  2000年   9篇
  1999年   1篇
  1998年   2篇
  1997年   8篇
  1996年   6篇
  1995年   8篇
  1994年   7篇
  1993年   2篇
  1992年   2篇
  1991年   4篇
  1990年   5篇
  1989年   2篇
  1988年   1篇
  1987年   3篇
  1986年   1篇
  1984年   1篇
  1983年   3篇
  1982年   3篇
  1981年   2篇
  1980年   2篇
  1977年   1篇
  1976年   1篇
  1975年   1篇
  1973年   1篇
  1968年   1篇
  1961年   1篇
  1952年   1篇
排序方式: 共有739条查询结果,搜索用时 15 毫秒
141.
乳状液膜法处理含氨基J酸工业废水的初步研究   总被引:7,自引:0,他引:7  
采用乳状液膜分离技术处理含氨基J酸工业废水,研究了表面活性剂种类和浓度、流动载体种类、内相NaOH的浓度和外相酸度等因素对分离效率的影响.结果表明,采用LMA-1(3g/100ml煤油)、TOA(2ml/100ml煤油)和10%NaOH的液膜时,分离效率可达60%以上;油相多次重复使用时,其分离效率基本不变.  相似文献   
142.
This paper seeks to investigate the effect of economic complexity on environmental degradation in 20 selected African countries over the period 1991–2014. The Feasible Generalized Least Square (FGLS), and Driscoll-Kraay estimators (DK) are used to capture the objectives of the study. The results suggest that economic complexity and economic growth enhance environmental degradation. Also, natural resources rents and globalization improve environmental quality. Furthermore, the findings reject the U-shaped relationship between economic complexity and environmental degradation. In addition, the Dumitrescu-Hurlin panel causality test shows a bidirectional causal relation between economic complexity and environmental degradation. Taking into account the ecological deficit or ecological reserve status of country, it is shown that while the natural resource rents reduce environmental degradation in ecological reserve countries, they increase environmental degradation in ecological deficit countries. The results are robust when an alternative measure of economic complexity is used. Based on these findings, the paper suggests that the governments of African countries should take into account economic complexity when designing their environmental protection policies.  相似文献   
143.
144.
145.
Gorgonians are widespread sub-littoral benthic suspension feeders in the world oceans. However, data on their trophic ecology and role in benthic–pelagic coupling and biogeochemical cycles remain limited. This study assesses the trophic ecology of Leptogorgia virgulata in the Skidaway River estuary, USA (31.9896N, 81.0242W) by analysing carbon and nitrogen isotopic signatures of its soft tissue and different-sized fractions of particulate organic matter (POM) in its environment. Samples were taken in 5 April, 2 August, and 15 October 2012 and 11 January 2013. Results support a distinct temporal shift in the diet of L. virgulata from the POM fraction <10 µm (i.e. pico- and nanoplankton) to the 10–63-µm fraction (i.e. microplankton). This trophic regime is likely associated with the natural abundance of prey items within these size classes, thus suggesting that L. virgulata may be an opportunistic feeder, and seasonal shifts in food availability in the water column affect its diet. As such small prey items affect the bioenergetics of L. virgulata, it is important to understand the implications of changes in food availability associated with environmental drivers on the physiology and population dynamics of this dominant species in the western Atlantic Ocean.  相似文献   
146.
Benthic communities on soft bottoms off Barcelona, at and around two main pollution sources, the mouth of the Besòs River and the outlet of the submarine pipeline draining wastewater and organic sludges from the wastewater treatment plant of Sant Adrià del Besòs, have been studied. Samples were obtained with a Van Veen grab from 36 stations covering a 100 km2 grid, between 10 and 70 m in depth. The effect of both pollution sources is clearly seen both at the species (the following macrofauna groups have been studied: Polychaeta, Mollusca, Echinodermata and Crustacea Decapoda) and community levels. The distribution of species and individuals numbers, species diversity and a pollution index, and of some selected (indicator) polychaeta species, all clearly define the degree of environmental degradation and the extent of the areas under the influence of the organic pollution.  相似文献   
147.
As a result of aquaculture activities, Pacific oysters Crassostrea gigas (Thunberg, 1793) have invaded European coasts. Using seven microsatellites, we found virtually no genetic differentiation between natural populations throughout the European range (from the south of the Wadden Sea (the Netherlands) to the south of France) and French cultivated oysters. The genetic homogeneity of Pacific oyster samples appears to be the result of repeated transfers from same seed stocks made for aquaculture and, to a lesser extent, widespread dispersal due to specific biological traits of this species. The only genetic differentiation of Sylt population in the north of the Wadden Sea (Germany) suggests a stronger, persistent impact of ongoing supply of new genetic material from hatchery production, corresponding to seeds selection made by breeders. All of our genetic data highlighted the importance of aquaculture practices on the genetic structure of the keystone invader C. gigas in Europe.  相似文献   
148.
For wearers of protective clothing in radiation environments there are no quantitative guidelines available for the effect of a radiative heat load on heat exchange. Under the European Union funded project ThermProtect an analytical effort was defined to address the issue of radiative heat load while wearing protective clothing. As within the ThermProtect project much information has become available from thermal manikin experiments in thermal radiation environments, these sets of experimental data are used to verify the analytical approach. The analytical approach provided a good prediction of the heat loss in the manikin experiments, 95% of the variance was explained by the model. The model has not yet been validated at high radiative heat loads and neglects some physical properties of the radiation emissivity. Still, the analytical approach provides a pragmatic approach and may be useful for practical implementation in protective clothing standards for moderate thermal radiation environments.  相似文献   
149.
This paper studies the emergence of one particular ‘new’ environmental policy instrument: disclosure of emission and pollution data. Disclosure is part of a relatively new sub‐set of regulatory measures, based on monitoring, transparency, citizen‐empowerment and accountability. It originated in the United States but has recently attracted international attention. The attractiveness of disclosure is obvious; it promises environmental improvement combined with strengthened environmental democracy and community empowerment. By analysing the experiences in the US, and the developments in the Netherlands, this paper seeks to assess the functioning and effectiveness of disclosure. The available empirical evidence suggests that disclosure has a positive impact on the environmental performance of industrial facilities as well as a democratising effect. It is argued that Dutch policy makers wrongfully assume that disclosure cannot work in the Netherlands. The consequence is that citizens are provided with little specific information that cannot be used to put pressure on polluters.  相似文献   
150.
A cover with capillary barrier effects (CCBE) was constructed in 1998 on the abandoned Lorraine mine tailings impoundment to limit the generation of acid mine drainage. The Ministry of Natural Resources and Fauna of Quebec (MRNF) is responsible for the site and for all restoration works on it, including CCBE construction. The CCBE is made up of three layers: a 0.3-m layer of sand used as a support and capillary break layer; a moisture-retaining layer with a thickness of 0.5 m (this layer is constructed of a nonplastic silt); and a 0.3-m sand and gravel layer on top. The main objective of the CCBE is to maintain one (or more) of the layers at a high degree of water saturation to impede oxygen migration and acid generation. Vegetation succession on the Lorraine CCBE results in an improvement in soil conditions, leading to the installation of deep-rooted species, which could represent a risk to CCBE long-term performance. Hence, the characterization of vegetation succession is an important aspect of the monitoring strategy for the Lorraine CCBE. Species occurrence was documented, and depth of tree roots was measured by excavation on a regular basis. Eight functional groups of plants were identified; herbaceous plants were the most abundant ecological plant groups. Tree ring counts confirmed that tree colonization started the year of CCBE construction (1999). Of the 11 tree species identified, the most abundant were poplar (Populus spp.), paper birch (Betula payrifera Marsh.), black spruce (Picea mariana Mill.), and willow (Salix spp.). Significant differences in occurrence related to environmental conditions were observed for most functional groups. Root excavation showed that tree roots exceeded the depth of the protective layer and started to reach the moisture-retaining layer; in 2008, root average depth was 0.4 m and the maximal root depth was 1.7 m.  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