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   597篇
  免费   11篇
  国内免费   8篇
安全科学   30篇
废物处理   28篇
环保管理   107篇
综合类   95篇
基础理论   142篇
污染及防治   138篇
评价与监测   53篇
社会与环境   16篇
灾害及防治   7篇
  2023年   5篇
  2022年   4篇
  2021年   12篇
  2020年   5篇
  2019年   9篇
  2018年   17篇
  2017年   18篇
  2016年   30篇
  2015年   18篇
  2014年   19篇
  2013年   45篇
  2012年   27篇
  2011年   38篇
  2010年   29篇
  2009年   28篇
  2008年   38篇
  2007年   35篇
  2006年   28篇
  2005年   32篇
  2004年   19篇
  2003年   23篇
  2002年   23篇
  2001年   12篇
  2000年   11篇
  1999年   10篇
  1998年   4篇
  1997年   6篇
  1996年   4篇
  1995年   8篇
  1994年   2篇
  1993年   4篇
  1992年   8篇
  1991年   3篇
  1990年   6篇
  1989年   7篇
  1988年   2篇
  1987年   2篇
  1985年   1篇
  1984年   3篇
  1983年   3篇
  1982年   2篇
  1981年   3篇
  1980年   2篇
  1979年   2篇
  1974年   2篇
  1973年   2篇
  1969年   1篇
  1964年   1篇
  1959年   1篇
  1955年   1篇
排序方式: 共有616条查询结果,搜索用时 15 毫秒
91.
Actions to slow atmospheric accumulation of greenhouse gases also would reduce conventional air pollutants yielding “ancillary” benefits that tend to accrue locally and in the near-term. Using a detailed electricity model linked to an integrated assessment framework to value changes in human health, we find a tax of $25 per metric ton of carbon emissions would yield NOx-related health benefits of about $8 per metric ton of carbon reduced in the year 2010 (1997 dollars). Additional savings of $4–$7 accrue from reduced investment in NOx and SO2 abatement in order to comply with emission caps. Total ancillary benefits of a $25 carbon tax are $12–$14, which appear to justify the costs of a $25 tax, although marginal benefits are less than marginal costs. At a tax of $75, greater total benefits are achieved but the value per ton of carbon reductions remains roughly constant at about $12.  相似文献   
92.
Prey require information if they are to respond to predation threat in a risk-sensitive manner. One way that individuals can obtain this information is through the predator-mediated, threat-induced behavior of conspecifics. We examined such a possibility in a refuge-seeking species, the sand fiddler crab (Uca pugilator). Crabs were either exposed directly to a simulated predation threat (a moving cylinder) or the threat-induced response of a near neighbor. We found that fiddler crabs responded to the flight of their neighbors even when they, themselves, were not privy to the stimulus that induced their neighbors response. However, the wider range of behaviors exhibited by these crabs—which included no reaction, freezing, running back to the burrow entrance, and burrow retreat—suggest that non-threatened crabs either (1) perceived the gravity of the predation threat differently from their directly threatened neighbors and/or (2) engaged in behaviors that allowed them to acquire further information in the face of uncertainty. Conspecific behaviors also had an effect on the hiding duration of crabs, with individuals hiding longer if they saw both the predation threat and the flight of their neighbor. Our results suggest that cues provided by conspecifics can play an important role in guiding the antipredator response of refuge-seeking prey.  相似文献   
93.
有机氯杀虫剂和多氯联苯(PCB)是环境中普遍而稳固的化合物。现已查明,由于它们从温暖的地区逐渐蒸发出来,并在较冷的地区凝聚下来,因而它们富集在寒冷的环境中。在本研究中,我们的结果是,消融的冰川供给阿尔伯达亚高山带湖泊中的有机氯输入量为50%~97%,而提供的水量为73%。对氚的分析结果表明,在夏季的中、晚期,至少10%的冰川消融物是在1950~1970年期间沉积下来的,这期间它受到有机氯更多的污染。这一发现表明,气候变暖可能会使消融的冰川成为日益增多的淡水污染物来源。由于有机物贫乏的冰川粘土对多氯联苯这样的疏水化合物的吸附能力有限,因此冰川水流带来的有机氯大多呈溶解状态。  相似文献   
94.
95.
This research used knowledge of the indigenous practice of timing nontimber forest product harvest with the full moon to demonstrate that chemicals controlling the decomposition rate of foliage fluctuate with the lunar cycle and may have developed as a result of plant-herbivore interactions. Indigenous knowledge suggests that leaves harvested during the full moon are more durable. Palm leaves harvested during the full moon had higher total C, hemicellulose, complex C and lower Ca concentrations. These chemical changes should make palm leaves less susceptible to herbivory and more durable when harvested during the full moon. This study proposes a mechanism by which plants in the tropics minimize foliage herbivory and influence the decomposition rates of senesced leaves and their durability, especially during the full moon. This research supports the need to use natural life cycles in managing forests and provides a scientific basis for an indigenous community's harvesting practice.  相似文献   
96.
97.
Novel applications of nanotechnology may lead to the release of engineered nanoparticles (ENPs), which result in concerns over their potential environmental hazardous impact. It is essential for the research workers to be able to quantitatively characterise ENPs in the environment and subsequently to assist the risk assessment of the ENPs. This study hence explored the application of nanoparticle tracking system (NTA) to quantitatively describe the behaviour of the ENPs in natural sediment-water systems. The NTA allows the measurement of both particle number concentration (PNC) and particle size distribution (PSD) of the ENPs. The developed NTA method was applied to a range of gold and magnetite ENPs with a selection of surface properties. The results showed that the positively-charged ENPs interacted more strongly with the sediment than neutral and negatively-charged ENPs. It was also found that the citrate coated Au ENPs had a higher distribution percentage (53%) than 11-mercaptoundecanoic acid coated Au ENPs (20%) and citrate coated magnetite ENPs (21%). The principles of the electrostatic interactions between hard (and soft) acids and bases (HSAB) are used to explain such behaviours; the hard base coating (i.e. citrate ions) will interact more strongly with hard acid (i.e. magnetite) than soft acid (i.e. gold). The results indicate that NTA is a complementary method to existing approaches to characterise the fate and behaviour of ENPs in natural sediment.  相似文献   
98.
Functional magnetic resonance imaging (fMRI) is likely to become the major tool for studying the neural underpinnings of organizational behavior. It is a technique for brain imaging that, according to advocates, provides information about which areas of the brain are activated during organizational processes (e.g., leadership and decision‐making). In this article, we take a critical look at this tool from a technical perspective. In particular, we take the reader through the assumptions that must be made at the three main steps of the research process (study design, data capture, and interpretation of results) in order to draw conclusions about organizational phenomena from fMRI research. Applying this analysis to three case studies demonstrates the gap between what fMRI can actually tell us and the claims often made about the contribution of fMRI to understanding and improving organizational behavior. Our discussion provides researchers with a series of recommendations oriented toward optimizing the use of fMRI to help it live up to its potential in the field of organizational behavior and consumers with a means of evaluating fMRI research in order to draw appropriate and warranted conclusions. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   
99.
Indicators for change: Taking a lead   总被引:1,自引:0,他引:1  
The authors argue that sustainable development is a political concept arising from interactions between socio-economic and physical systems. As such, political values are implicit in many qualitative aspects of sustainability and its communication through indicators. In Great Britain, local government has played the lead role in Local Agenda 21, involving interest groups and community organisations in varying degrees, through public participation. However, the need for local solutions to sustainability problems also exists in Northern Ireland, where governmental bodies are unwilling or unable to accept responsibility for Local Agenda 21. In the Northern Ireland context, the evolving role of Non-Governmental Organisations (NGOs) and the community sector in the indicators issue has been markedly different to that in the rest of the UK. There are potential problems concerning political values and mandates when the NGO/community sector assumes the lead in such tasks. The authors argue that, while criticisms of explicit and/or implied political values can be well grounded, addressing these must go beyond questions of objectivity in collection and presentation of indicators and projects must be understood by developing feedback and review mechanisms. The authors review the Northern Ireland sustainability indicators project and evaluate the feedback procedures in place. Lessons learnt from this exercise are explored with reference to (i) the current organisation of Local Agenda 21 within local government in Northern Ireland and (ii) national and international parallels.  相似文献   
100.
Environmental Geochemistry and Health - The contamination of soils by heavy metals from the mining industry nowadays is one of the greatest threats to environment and human health. The cleaning 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