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   12851篇
  免费   100篇
  国内免费   98篇
安全科学   353篇
废物处理   603篇
环保管理   1729篇
综合类   2610篇
基础理论   2823篇
环境理论   6篇
污染及防治   3394篇
评价与监测   820篇
社会与环境   639篇
灾害及防治   72篇
  2022年   132篇
  2021年   145篇
  2020年   85篇
  2019年   100篇
  2018年   189篇
  2017年   163篇
  2016年   271篇
  2015年   204篇
  2014年   288篇
  2013年   975篇
  2012年   358篇
  2011年   513篇
  2010年   407篇
  2009年   461篇
  2008年   504篇
  2007年   569篇
  2006年   511篇
  2005年   405篇
  2004年   410篇
  2003年   427篇
  2002年   381篇
  2001年   446篇
  2000年   322篇
  1999年   222篇
  1998年   132篇
  1997年   133篇
  1996年   120篇
  1995年   175篇
  1994年   159篇
  1993年   134篇
  1992年   142篇
  1991年   161篇
  1990年   133篇
  1989年   139篇
  1988年   139篇
  1987年   120篇
  1986年   90篇
  1985年   112篇
  1984年   134篇
  1983年   139篇
  1982年   138篇
  1981年   119篇
  1980年   103篇
  1979年   119篇
  1978年   91篇
  1977年   86篇
  1976年   79篇
  1975年   94篇
  1974年   105篇
  1973年   76篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Biogenic volatile organic compounds (BVOCs) play an important role in atmospheric chemistry and the carbon cycle. Isoprene is quantitatively the most important of the non-methane BVOCs (NMBVOCs), with an annual emission of about 400–600 TgC; about 90% of this is emitted by terrestrial plants. Incorporating a mechanistic treatment of isoprene emissions within land-surface schemes has recently become a focus for the modelling community, the aim being to quantify the potential magnitude of associated climate feedbacks. However, these efforts are hampered by major uncertainties about why plants emit isoprene and the relative importance of different environmental controls on isoprene emission. The availability and reliability of observations of isoprene fluxes from different types of vegetation is limited, and this also imposes constraints on model development. Nevertheless, progress is being made towards the development of mechanistic models of isoprene emission which, in conjunction with atmospheric chemistry models, will ultimately allow improved quantification of the feedbacks between the terrestrial biosphere and climate under past and future climate states.  相似文献   
72.
Abstract:  The Society for Conservation Biology (SCB) can enhance conservation of biodiversity in North America by increasing its engagement in public policy. Toward this end, the North America Section of SCB is establishing partnerships with other professional organizations in order to speak more powerfully to decision makers and taking other actions—such as increasing interaction with chapters—geared to engage members more substantively in science-policy issues. Additionally, the section is developing a North American Biodiversity Blueprint, which spans the continental United States and Canada and is informed by natural and social science. This blueprint is intended to clarify the policy challenges for protecting continental biodiversity, to foster bilateral collaboration to resolve common problems, and to suggest rational alternative policies and practices that are more likely than current practices to sustain North America's natural heritage. Conservation scientists and practitioners can play a key role by drawing policy makers' attention to ultimate, as well as proximate, causes of biodiversity decline and to the ecological and economic consequences of not addressing these threats.  相似文献   
73.
Environmental Science and Pollution Research - The discovery of microRNAs (miRNAs) 20 years ago has advocated a new era of “small molecular genetics.” About 2000 miRNAs are present that...  相似文献   
74.
Environmental Science and Pollution Research - Global warming is considered as the main environmental stress affecting ecosystems as well as physiological and biochemical characteristics, and...  相似文献   
75.
Unprecedented and dramatic transformations are occurring in the Arctic in response to climate change, but academic, public, and political discourse has disproportionately focussed on the most visible and direct aspects of change, including sea ice melt, permafrost thaw, the fate of charismatic megafauna, and the expansion of fisheries. Such narratives disregard the importance of less visible and indirect processes and, in particular, miss the substantive contribution of the shelf seafloor in regulating nutrients and sequestering carbon. Here, we summarise the biogeochemical functioning of the Arctic shelf seafloor before considering how climate change and regional adjustments to human activities may alter its biogeochemical and ecological dynamics, including ecosystem function, carbon burial, or nutrient recycling. We highlight the importance of the Arctic benthic system in mitigating climatic and anthropogenic change and, with a focus on the Barents Sea, offer some observations and our perspectives on future management and policy.  相似文献   
76.
By mechanical-biological treatment (MBT) of residual municipal solid waste the behaviour of landfills can be significantly improved. After MBT the organic content (COD and BOD5), total organic carbon, and total nitrogen in the leachate, as well as the gas production rate, are reduced to values lower than 90% of the fresh untreated waste. The volume of the stabilized material to be disposed on landfills decreases enormously, by up to 70%. The monitoring effort for a landfill constructed under these conditions is reduced to a minimum and the stabilized material can be used in other ways, as material for reforestation, for cover material or for thermal utilization to produce energy. Environmental conditions are important in MBT, as well as waste characteristics. This paper describes the results of a pilot project of MBT performed in Rio de Janeiro, Brazil. The results have shown that this technology can be used successfully in developing countries, with economy for the society and important results for the environment.  相似文献   
77.
A laboratory-scale bioreactor was used to investigate the influence of dairy manure addition (as an inoculum and a carbon source) on the biological and thermal kinetics of the composting process of tomato plant residues-wood shavings mixture. Urea was added (as a nitrogen source) to correct the initial C:N ratio to 30:1 and the initial moisture content was also adjusted to 60%. The result of this study indicated that manure addition to the tomato residues-wood shavings mixture is a good source of macro and micronutrients required for supporting the composting microorganisms. Manure addition increased the rate of temperature increase and the duration of maximum temperature and reduced the lag and the peak time, all of which resulted in a significant reduction in the retention time. However, thermophilic temperature (> or = 40 degrees Celsius) was only achieved with 30%, 40% and 50% manure addition for 3, 7 and 9h. Total carbon reductions were in the range of 9.4-10.8% and TKN reductions were in the range of 3.4-6.0%. Neither the nitrogen nor the moisture content were limiting factors as the C:N ratio remained in the range of 26:1 to 28:1 and the moisture content remained within the optimum range of 58-61%. The maximum temperature of each mixture correlated with the reduction of total carbon, but carbon availability was a limiting factor in these experiments. In order to attain and sustain a thermophilic phase during the composting process, the addition of a readily available carbon source to the tomato should be investigated and carbon type (carbohydrates, proteins and fats) should be taken into account.  相似文献   
78.
79.
80.
Environmental Science and Pollution Research - Aedes aegypti and Culex quinquefasciatus are vectors of diseases that constitute public health problems. The discovery of products capable of...  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