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   590篇
  免费   26篇
  国内免费   8篇
安全科学   18篇
废物处理   13篇
环保管理   129篇
综合类   116篇
基础理论   171篇
环境理论   3篇
污染及防治   110篇
评价与监测   33篇
社会与环境   24篇
灾害及防治   7篇
  2023年   10篇
  2022年   9篇
  2021年   20篇
  2020年   27篇
  2019年   25篇
  2018年   28篇
  2017年   29篇
  2016年   31篇
  2015年   35篇
  2014年   24篇
  2013年   48篇
  2012年   38篇
  2011年   56篇
  2010年   31篇
  2009年   21篇
  2008年   30篇
  2007年   32篇
  2006年   31篇
  2005年   20篇
  2004年   10篇
  2003年   17篇
  2002年   10篇
  2001年   3篇
  2000年   4篇
  1999年   8篇
  1998年   4篇
  1997年   4篇
  1996年   3篇
  1995年   3篇
  1994年   5篇
  1993年   2篇
  1992年   1篇
  1986年   1篇
  1984年   1篇
  1983年   1篇
  1982年   1篇
  1977年   1篇
排序方式: 共有624条查询结果,搜索用时 15 毫秒
561.
Objective: We compared the differences in the braking response to vehicle collision between an active human emergency braking (control condition) and cruise control (CC) or adaptive cruise control (ACC).

Methods: In 11 male subjects, age 22 to 67 years, we measured the active emergency braking response during manual driving using the accelerator pedal (control condition) or in condition mimicking CC or ACC. In both conditions, we measured the brake reaction time (BRT), delay to produce the peak braking force (PBD), total emergency braking response (BRT + PBD), and peak braking force (PBF). Electromyograms of leg and thigh muscles were recorded during braking. The tonic vibratory response (TVR), Hoffman reflex (HR), and M-waves were recorded in leg muscles to explore the change in sensorimotor control.

Results: No difference in PBF, TVR amplitude, HR latency, and Hmax/Mmax ratio were found between the control and CC/ACC conditions. On the other hand, BRT and PBD were significantly lengthened in the CC/ACC condition (240 ± 13 ms and 704 ± 70 ms, respectively) compared to control (183 ± 7 ms and 568 ± 36 ms, respectively). BRT increased with the age of participants and the driving experience shortened PBD and increased PBF.

Conclusions: In male subjects, driving in a CC/ACC condition significantly delays the active emergency braking response to vehicle collision. This could result from higher amplitude of leg motion in the CC/ACC condition and/or by the age-related changes in motor control. Car and truck drivers must take account of the significant increase in the braking distance in a CC/ACC condition.  相似文献   

562.
There has recently been a return in climate change risk management practice to bottom‐up, robustness‐based planning paradigms introduced 40 years ago. The World Bank's decision tree framework (DTF) for “confronting climate uncertainty” is one incarnation of those paradigms. In order to better represent the state of the art in climate change risk assessment and evaluation techniques, this paper proposes: (1) an update to the DTF, replacing its “climate change stress test” with a multidimensional stress test; and (2) the addition of a Bayesian network framework that represents joint probabilistic behavior of uncertain parameters as sensitivity factors to aid in the weighting of scenarios of concern (the combination of conditions under which a water system fails to meet its performance targets). Using the updated DTF, water system planners and project managers would be better able to understand the relative magnitudes of the varied risks they face, and target investments in adaptation measures to best reduce their vulnerabilities to change. Next steps for the DTF include enhancements in: modeling of extreme event risks; coupling of human‐hydrologic systems; integration of surface water and groundwater systems; the generation of tradeoffs between economic, social, and ecological factors; incorporation of water quality considerations; and interactive data visualization.  相似文献   
563.
564.
Human noroviruses (NoVs) are considered a worldwide leading cause of acute non-bacterial gastroenteritis. Due to a combination of prolonged shedding of high virus levels in feces, virus particle shedding during asymptomatic infections, and a high environmental persistence, NoVs are easily transmitted pathogens. Norovirus (NoV) outbreaks have often been reported and tend to affect a lot of people. NoV is spread via feces and vomit, but this NoV spread can occur through several transmission routes. While person-to-person transmission is without a doubt the dominant transmission route, human infective NoV outbreaks are often initiated by contaminated food or water. Zoonotic transmission of NoV has been investigated, but has thus far not been demonstrated. The presented review aims to give an overview of these NoV transmission routes. Regarding NoV person-to-person transmission, the NoV GII.4 genotype is discussed in the current review as it has been very successful for several decades but reasons for its success have only recently been suggested. Both pre-harvest and post-harvest contamination of food products can lead to NoV food borne illness. Pre-harvest contamination of food products mainly occurs via contact with polluted irrigation water in case of fresh produce or with contaminated harvesting water in case of bivalve molluscan shellfish. On the other hand, an infected food handler is considered as a major cause of post-harvest contamination of food products. Both transmission routes are reviewed by a summary of described NoV food borne outbreaks between 2000 and 2010. A third NoV transmission route occurs via water and the spread of NoV via river water, ground water, and surface water is reviewed. Finally, although zoonotic transmission remains hypothetical, a summary on the bovine and porcine NoV presence observed in animals is given and the presence of human infective NoV in animals is discussed.  相似文献   
565.
566.
Abstract

In this article I draw on recent anthropological literature on the senses to propose a novel approach to sustainable local development. I suggest that attention to how the senses are engaged in both discourses concerning and corporeal experiences of sustainable urban development, can produced insights into how these processes operate. In developing the discussion I draw from examples from ethnographic research in British member towns of the Cittàslow (Slow City) movement.  相似文献   
567.

The first annual Sustainable Community competition, co-sponsored by the Federation of Canadian Municipalities (FCM) and CH2M Hill in 2000, received 52 submissions from municipalities across Canada. These submissions were systematically analysed to identify common characteristics shared by competition entrants, including what differentiates competition participants from other Canadian municipalities, what kinds of sustainability projecs municipalities have been most likely to undertake and what motivating and success factors are most commonly cited. Urban municipalities were more likely than rural municipalities to undertake sustainability projects. Stakeholder involvement was found to be the most important factor in determining the success of a project. Many projects in the competition had not identified clear holistic visions and benchmarks, and these were noted as areas where improvement could be made. The impact of higher levels of government in setting benchmarks and providing support was also noteworthy.  相似文献   
568.
This paper uses a randomized controlled trial to test whether doorstep canvassing can raise participation in kerbside recycling. Existing research shows that canvassing can confront negative attitudes, increase understanding and resolve structural obstacles, but there is less known about the longitudinal effects of such interventions, which may fall away over time. 194 streets in Trafford, in the North West of England, UK were randomly assigned into a treatment and a control group. All households in the treatment group were visited by canvassers who were trained to promote and encourage recycling. Recycling participation rates for all households were measured by observing bin set out rates over a three-week period. Measurement was done before and after the canvassing campaign and then again three months later to see if the intervention had been effective in raising participation rates. Random-effects multilevel regression models, controlling for baseline recycling, street size, deprivation and size of ethnic minority population, show that the canvassing raised recycling participation rates for the treatment group compared to the control group, but there was a decline in the impact of the intervention over time. The intervention was more effective on streets with low levels of recycling at baseline.  相似文献   
569.
While US climate change mitigation policy has stalled at the national level, local and regional actors are increasingly taking progressive steps to reduce their greenhouse gas emissions. Universities are poised to play a key role in this grassroots effort by targeting their own emissions and by working with other local actors to develop climate change mitigation programmes. Researchers at the Pennsylvania State University have collaborated with university administrators and personnel to inventory campus emissions and develop mitigation strategies. In addition, they have facilitated a stakeholder-driven climate change mitigation project in one Pennsylvania county and started an ongoing service-learning project aimed at reducing emissions in another county. These campus and community outreach initiatives demonstrate that university-based mitigation action may simultaneously achieve tangible local benefits and develop solutions to broader challenges facing local climate change mitigation efforts. Outcomes include improved tools and protocols for measuring and reducing local emissions, lessons learned about service-learning approaches to climate change mitigation, and methods for creating climate change governance networks involving universities, local governments and community stakeholders.  相似文献   
570.
We studied the effects of tree species on leaf litter decomposition and forest floor dynamics in a common garden experiment of 14 tree species (Abies alba, Acer platanoides, Acer pseudoplatanus, Betula pendula, Carpinus betulus, Fagus sylvatica, Larix decidua, Picea abies, Pinus nigra, Pinus sylvestris, Pseudotsuga menziesii, Quercus robur, Quercus rubra, and Tilia cordata) in southwestern Poland. We used three simultaneous litter bag experiments to tease apart species effects on decomposition via leaf litter chemistry vs. effects on the decomposition environment. Decomposition rates of litter in its plot of origin were negatively correlated with litter lignin and positively correlated with mean annual soil temperature (MAT(soil)) across species. Likewise, decomposition of a common litter type across all plots was positively associated with MAT(soil), and decomposition of litter from all plots in a common plot was negatively related to litter lignin but positively related to litter Ca. Taken together, these results indicate that tree species influenced microbial decomposition primarily via differences in litter lignin (and secondarily, via differences in litter Ca), with high-lignin (and low-Ca) species decomposing most slowly, and by affecting MAT(soil), with warmer plots exhibiting more rapid decomposition. In addition to litter bag experiments, we examined forest floor dynamics in each plot by mass balance, since earthworms were a known component of these forest stands and their access to litter in litter bags was limited. Forest floor removal rates estimated from mass balance were positively related to leaf litter Ca (and unrelated to decay rates obtained using litter bags). Litter Ca, in turn, was positively related to the abundance of earthworms, particularly Lumbricus terrestris. Thus, while species influence microbially mediated decomposition primarily through differences in litter lignin, differences among species in litter Ca are most important in determining species effects on forest floor leaf litter dynamics among these 14 tree species, apparently because of the influence of litter Ca on earthworm activity. The overall influence of these tree species on leaf litter decomposition via effects on both microbial and faunal processing will only become clear when we can quantify the decay dynamics of litter that is translocated belowground by earthworms.  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