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   3046篇
  免费   21篇
  国内免费   39篇
安全科学   101篇
废物处理   140篇
环保管理   365篇
综合类   544篇
基础理论   599篇
环境理论   3篇
污染及防治   876篇
评价与监测   255篇
社会与环境   199篇
灾害及防治   24篇
  2023年   27篇
  2022年   85篇
  2021年   106篇
  2020年   52篇
  2019年   45篇
  2018年   104篇
  2017年   105篇
  2016年   128篇
  2015年   74篇
  2014年   121篇
  2013年   223篇
  2012年   136篇
  2011年   179篇
  2010年   128篇
  2009年   122篇
  2008年   130篇
  2007年   129篇
  2006年   90篇
  2005年   128篇
  2004年   166篇
  2003年   156篇
  2002年   103篇
  2001年   78篇
  2000年   35篇
  1999年   39篇
  1998年   17篇
  1997年   31篇
  1996年   20篇
  1995年   25篇
  1994年   22篇
  1993年   11篇
  1992年   12篇
  1991年   17篇
  1990年   12篇
  1989年   20篇
  1988年   6篇
  1987年   14篇
  1986年   19篇
  1985年   15篇
  1984年   14篇
  1983年   17篇
  1982年   6篇
  1981年   12篇
  1980年   6篇
  1979年   14篇
  1978年   14篇
  1977年   5篇
  1966年   5篇
  1964年   5篇
  1932年   5篇
排序方式: 共有3106条查询结果,搜索用时 15 毫秒
981.
Dead wood provides a huge terrestrial carbon stock and a habitat to wide-ranging organisms during its decay. Our brief review highlights that, in order to understand environmental change impacts on these functions, we need to quantify the contributions of different interacting biotic and abiotic drivers to wood decomposition. LOGLIFE is a new long-term 'common-garden' experiment to disentangle the effects of species' wood traits and site-related environmental drivers on wood decomposition dynamics and its associated diversity of microbial and invertebrate communities. This experiment is firmly rooted in pioneering experiments under the directorship of Terry Callaghan at Abisko Research Station, Sweden. LOGLIFE features two contrasting forest sites in the Netherlands, each hosting a similar set of coarse logs and branches of 10 tree species. LOGLIFE welcomes other researchers to test further questions concerning coarse wood decay that will also help to optimise forest management in view of carbon sequestration and biodiversity conservation.  相似文献   
982.
Ozone-sensitive and -tolerant individuals of cutleaf coneflower (Rudbeckia laciniata L.) were compared for their gas exchange characteristics and total non-structural carbohydrates at Purchase Knob, a high elevation site in Great Smoky Mountains National Park, USA. Photosynthesis and stomatal conductance decreased with increased foliar stipple. Sensitive plants had lower photosynthetic rates for all leaves, except the very youngest and oldest when compared to tolerant plants. Stomatal conductance decreased with increasing leaf age, but no ozone-sensitivity differences were found. Lower leaves had less starch than upper ones, while leaves on sensitive plants had less than those on tolerant plants. These results show that ambient levels of ozone in Great Smoky Mountains National Park can adversely affect gas exchange, water use efficiency and leaf starch content in sensitive coneflower plants. Persistence of sensitive genotypes in the Park may be due to physiological recovery in low ozone years.  相似文献   
983.
Dead wood provides a huge terrestrial carbon stock and a habitat to wide-ranging organisms during its decay. Our brief review highlights that, in order to understand environmental change impacts on these functions, we need to quantify the contributions of different interacting biotic and abiotic drivers to wood decomposition. LOGLIFE is a new long-term ‘common-garden’ experiment to disentangle the effects of species’ wood traits and site-related environmental drivers on wood decomposition dynamics and its associated diversity of microbial and invertebrate communities. This experiment is firmly rooted in pioneering experiments under the directorship of Terry Callaghan at Abisko Research Station, Sweden. LOGLIFE features two contrasting forest sites in the Netherlands, each hosting a similar set of coarse logs and branches of 10 tree species. LOGLIFE welcomes other researchers to test further questions concerning coarse wood decay that will also help to optimise forest management in view of carbon sequestration and biodiversity conservation.  相似文献   
984.
985.
986.

Introduction  

Lists of compounds resulting from environmental monitoring may be conveniently represented in a very general way using Pareto distributions, after ranking them on descending order according to their concentration or hazard quotient expressed as percentages, depending on whether the objective of the monitoring is focussed on mass load occurrence or risk assessment respectively.  相似文献   
987.
The electrochemical transformation of the organophosphorous insecticide chlorpyrifos (CPF) was investigated in wastewater. The oxidation of CPF was carried out in a single-compartment electrochemical flow cell working under batch operation mode, using diamond-based material as anode and stainless steel as cathode. In order to evaluate its persistence and degradation pathway, two different concentration levels (1.0 mg L−1 and 0.1 mg L−1) were studied. Liquid chromatography/mass spectrometry was used for evaluation of the initial and electrolyzed solutions. The identification of CPF transformation products was performed by liquid chromatography-time of flight-mass spectrometry (LC-TOFMS). Results showed that CPF is completely removed at the end of treatment time. Analysis by LC-TOFMS allowed the identification of six degradation products (with Mw 154, 170, 197, 305 321 and 333). Three of the identified intermediates (Mw 170, 305 and 321) were completely removed at the end of electrolysis time. Interestingly, the formation of diethyl 3,5,6-trichloropyridin-2yl phosphate (chlorpyrifos oxon) and 3,5,6-trichloropyridin-2-ol was also found in previous reported degradation pathways using different degradation technologies.  相似文献   
988.
In early 2009, few would have expected that the Intergovernmental Panel on Climate Change (IPCC) would come under such massive attack. The IPCC had enjoyed a pristine reputation and had even advanced to become a role model for biodiversity and food security assessments (Loreau et al. 2006; Watson 2005). However, public trust and, with it, the organization’s credibility eroded dramatically after November 2009 with the events that became known as ‘climategate’. This article seeks to contribute to current debates about how to reform the IPCC. It argues that there are major flaws in the design of the IPCC which are rooted in the linear model of expertise and which are helping to stoke the backlash against the IPCC. The article analyzes the ways in which the IPCC’s activities conform to the linear model of expertise and considers the consequences of this for integrating adaptation into the IPCC assessments. It explains why adaptation played only a marginal role up until the IPCC Third Assessment Report. It then demonstrates why the use of the linear model of expertise constrains the scientific and political debate about adaptation and leads to proxy debates about scientific evidence, which result in depoliticizing the politics of adaptation and politicizing science. Finally, the article calls for the debate to be opened up to accommodate alternatives that are both politically more feasible and at the same time more appropriate to the specific needs of adaptation policies at different levels of decision-making.  相似文献   
989.
990.
The aim of this paper is to disclose livelihood strategy-poverty links and gain a better understanding by developing typologies of rural households. Based on qualitative and quantitative data, we group households into different typologies and explore interactions. We identified six main agronomic strategies, four dominant livelihood diversification strategies, and income quartiles (proxies for poverty) using cluster and principal component factor analysis. We found that nearly 82% of the surveyed farmers in the study area belong to the bottom income quartiles while about 18% are on the upper quartiles. Households in the bottom income quartiles engaged in casual off-farm work and cereal-dominated livelihood strategies that tend to pursue subsistence farming by growing cereals and oil crops. Contrarily, farmers in the upper income quartiles adapted intensive agronomic strategies by integrating root crops, legumes, and vegetables with livestock. This was largely attributed to access to key livelihood assets such as land, livestock, education, and institutional support in which the upper quartiles were more endowed. Improving availability of the key assets for the bottom income quartiles might be a way out of poverty and ensuring sustainable development. It is crucial to recognize local-level heterogeneities of rural households when targeting development interventions.  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