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   360篇
  免费   10篇
  国内免费   2篇
安全科学   24篇
废物处理   20篇
环保管理   65篇
综合类   57篇
基础理论   67篇
环境理论   4篇
污染及防治   83篇
评价与监测   24篇
社会与环境   22篇
灾害及防治   6篇
  2023年   2篇
  2022年   8篇
  2021年   7篇
  2020年   5篇
  2019年   11篇
  2018年   7篇
  2017年   17篇
  2016年   15篇
  2015年   10篇
  2014年   12篇
  2013年   27篇
  2012年   16篇
  2011年   15篇
  2010年   16篇
  2009年   22篇
  2008年   15篇
  2007年   22篇
  2006年   13篇
  2005年   18篇
  2004年   12篇
  2003年   20篇
  2002年   13篇
  2001年   4篇
  1999年   6篇
  1998年   6篇
  1997年   3篇
  1996年   5篇
  1995年   3篇
  1994年   1篇
  1993年   3篇
  1992年   1篇
  1990年   2篇
  1989年   1篇
  1988年   2篇
  1987年   3篇
  1986年   2篇
  1985年   3篇
  1984年   1篇
  1983年   2篇
  1982年   3篇
  1981年   4篇
  1980年   2篇
  1979年   1篇
  1978年   3篇
  1975年   1篇
  1974年   1篇
  1973年   1篇
  1972年   2篇
  1971年   1篇
  1954年   1篇
排序方式: 共有372条查询结果,搜索用时 15 毫秒
341.

Problem

Safety belt use in the United States, as measured over daylight hours, has risen steadily over recent years reaching 80% in 2004. Yet, using the National Highway Traffic Safety Administration's (NHTSA) Fatality Analysis Reporting System (FARS), safety belt use among fatally injured front seat outboard occupants of passenger vehicles was only between 42% and 46% for the years 1999 to 2003. One possible contributing factor is that safety belt use at night, when crash rates are highest, is lower than during the day.

Method

A full statewide nighttime belt use observation survey was conducted in 2004. This survey was conducted simultaneously with Connecticut's annual full statewide daytime belt use survey. Night belt use observations of drivers and passengers are possible using newly available near military grade night vision goggles and handheld infrared spotlights. Both day and goggle-assisted night observations were conducted at 100 observation sites in Connecticut. Procedures for day and night observations were as nearly identical as possible.

Results

The night belt use rate was 6.4 percentage points lower than the day rate (83.0 vs. 76.6). Consistent with belt use among Connecticut fatalities, day versus night differences were greatest in urban areas. There was evidence that day versus night differences were greater before as compared to after a May 2004 belt use enforcement program.  相似文献   
342.
Health Impact Assessment (HIA) is increasingly being acknowledged as an important tool for considering the health implications of projects and programmes of activity at local, national and international levels. However, standard HIA tools can be difficult to apply when the policy of programme under consideration is particularly complex and intertwined or where significant time, resource and skill constraints are involved. This paper describes a Health Impact Review (HIR) of the plans for a major redevelopment of Central Manchester Hospitals (England). This approach to HIA drew not only from HIR but also from Integrated Impact Assessment (IIA) in order to produce a summary of the most significant health impacts of a policy, programme or project in a more timely and cost-effective way. This example highlights the potential for involving Local Authority Overview and Scrutiny Committees in the HIA process as a way of ensuring that the recommendations of HIA are mainstreamed as part of the ongoing development of projects.  相似文献   
343.
344.
Leung KM  Grist EP  Morley NJ  Morritt D  Crane M 《Chemosphere》2007,66(7):1358-1366
Chronic toxicity, growth and reproduction were measured in the freshwater gastropod Lymnaea stagnalis exposed to waterborne bis(tri-n-butyltin) oxide (TBTO) over a range of four nominal concentrations (0-10microg TBTl(-1)). Egg development was completely inhibited at 10microg TBTl(-1), whilst abnormal embryonic development was observed at 1microg TBTl(-1). For the solvent control and the 0.01microg TBTl(-1)treatment group, normal development of L. stagnalis was observed. Survivorship of hatchlings was significantly reduced by TBT at 1microgl(-1) while inhibition of shell growth of L. stagnalis was also observed at this concentration. The data were used to determine intrinsic growth rates (r) using two theoretical approaches (the Euler-Lotka equation and a Leslie Matrix). Both approaches showed that survival, fecundity and population growth rate were reduced at 1microg TBTl(-1). Interestingly, at 0.01microg TBTl(-1) snails showed a higher fecundity and growth rate than in the solvent control. The TBT concentration at which the r would equal zero (ECr(0)) and the population NOEC (No Observed Effect Concentration) were estimated. The population NOEC was defined as either the lower 95% confidence or lower 95% pointwise percentile limit of the ECr(0). Values obtained using the two different approaches were similar and thus a geometric mean was calculated to obtain a final representative population NOEC value for L. stagnalis of 2745ng TBTl(-1). The present data together with chronic toxicity TBT data for freshwater organisms, obtained from peer-reviewed literature, were used to construct a species sensitivity distribution (SSD). A predicted no effect concentration was then derived from the SSD (hazardous concentration at 5%, i.e., HC5 or 95% protection level). This SSD was compared with the SSD derived from saltwater species datasets. The HC5 value for saltwater species (3.55ng TBTl(-1); lower confidence limit: 1.93ng TBTl(-1)) was significantly lower than that for freshwater species (30.13ng TBTl(-1); lower confidence limit: 9.23ng TBTl(-1)), indicating that saltwater species are probably more susceptible to TBT than their freshwater counterparts.  相似文献   
345.
Data are lacking on human exposure to air pollutants occurring in ground-level outdoor environments within a few meters of point sources. To better understand outdoor exposure to tobacco smoke from cigarettes or cigars, and exposure to other types of outdoor point sources, we performed more than 100 controlled outdoor monitoring experiments on a backyard residential patio in which we released pure carbon monoxide (CO) as a tracer gas for continuous time periods lasting 0.5–2 h. The CO was emitted from a single outlet at a fixed per-experiment rate of 120–400 cc min?1 (~140–450 mg min?1). We measured CO concentrations every 15 s at up to 36 points around the source along orthogonal axes. The CO sensors were positioned at standing or sitting breathing heights of 2–5 ft (up to 1.5 ft above and below the source) and at horizontal distances of 0.25–2 m. We simultaneously measured real-time air speed, wind direction, relative humidity, and temperature at single points on the patio. The ground-level air speeds on the patio were similar to those we measured during a survey of 26 outdoor patio locations in 5 nearby towns. The CO data exhibited a well-defined proximity effect similar to the indoor proximity effect reported in the literature. Average concentrations were approximately inversely proportional to distance. Average CO levels were approximately proportional to source strength, supporting generalization of our results to different source strengths. For example, we predict a cigarette smoker would cause average fine particle levels of approximately 70–110 μg m?3 at horizontal distances of 0.25–0.5 m. We also found that average CO concentrations rose significantly as average air speed decreased. We fit a multiplicative regression model to the empirical data that predicts outdoor concentrations as a function of source emission rate, source–receptor distance, air speed and wind direction. The model described the data reasonably well, accounting for ~50% of the log-CO variability in 5-min CO concentrations.  相似文献   
346.
We studied the effects of long-term exposure (nine years) of birch (Betula papyrifera) trees to elevated CO(2) and/or O(3) on reproduction and seedling development at the Aspen FACE (Free-Air Carbon Dioxide Enrichment) site in Rhinelander, WI. We found that elevated CO(2) increased both the number of trees that flowered and the quantity of flowers (260% increase in male flower production), increased seed weight, germination rate, and seedling vigor. Elevated O(3) also increased flowering but decreased seed weight and germination rate. In the combination treatment (elevated CO(2)+O(3)) seed weight is decreased (20% reduction) while germination rate was unaffected. The evidence from this study indicates that elevated CO(2) may have a largely positive impact on forest tree reproduction and regeneration while elevated O(3) will likely have a negative impact.  相似文献   
347.
Managed aquifer recharge (MAR) has potential for addressing deficits in water supplies worldwide. It is also widely used for preventing saltwater intrusion, maintaining the groundwater table, and augmenting ecological stream flows, among many other beneficial environmental applications. However, field MAR sites have experienced arsenic mobilization from aquifer formation minerals due to induced changes in groundwater chemistry. To address this environmental concern, it is crucial to understand the potential sources and sinks impacting arsenic mobilization. This paper outlines important mineral-water interactions that can occur at MAR sites. Detailed information on minerals of concern, physiochemical processes for arsenic mobilization or attenuation, and the potential impact of microbial activity and hydrology on these processes is provided. Based on these mineral-water interactions, guidelines for predicting arsenic mobility are presented, and recommendations are made concerning MAR site monitoring. The review emphasizes important aspects in correlating interfacial reactions to reactive transport modeling and elucidating future challenges, a first step toward developing safer and more sustainable MAR operations.  相似文献   
348.

Mercury (Hg) concentrations were measured in 26 Scottish single malt whiskies, and all found to be very low (<10 ng L−1), posing no threat to human health through reasonable levels of consumption. However, a significant south-to-north declining gradient in Hg concentrations was observed reflecting that reported for atmospheric deposition. We speculate that this gradient could be due to a combination of contemporary deposition and the legacy of industrial mercury emissions and deposition over the last 200 years affecting concentrations in local waters used in whisky production. As UK atmospheric emissions of mercury have declined by 90 % since the 1970s, we suggest that whisky being produced today should have even lower Hg concentrations when consumed in 10- to 15-years time. This reduction may be compromised by the remobilisation of contaminants stored in catchment soils being transferred to source waters, but is very unlikely to raise the negligible health risk due to Hg from Scottish single malt whisky consumption.

  相似文献   
349.
Habitat valuation methods are most often developed and used to prioritize candidate lands for conservation. In this study the intent of habitat valuation was to inform the decision-making process for remediation of chemical contaminants on specific lands or surface water bodies. Methods were developed to summarize dimensions of habitat value for six representative aquatic and terrestrial contaminated sites at the East Tennessee Technology Park (ETTP) on the US Department of Energy Oak Ridge Reservation in Oak Ridge, TN, USA. Several general valuation metrics were developed for three broad categories: site use by groups of organisms, site rarity, and use value added from spatial context. Examples of use value metrics are taxa richness, a direct measure of number of species that inhabit an area, complexity of habitat structure, an indirect measure of potential number of species that may use the area, and land use designation, a measure of the length of time that the area will be available for use. Measures of rarity included presence of rare species or communities. Examples of metrics for habitat use value added from spatial context included similarity or complementarity of neighboring habitat patches and presence of habitat corridors. More specific metrics were developed for groups of organisms in contaminated streams, ponds, and terrestrial ecosystems. For each of these metrics, cutoff values for high, medium, and low habitat value were suggested, based on available information on distributions of organisms and landscape features, as well as habitat use information. A companion paper describes the implementation of these habitat valuation metrics and scoring criteria in the remedial investigation for ETTP.  相似文献   
350.
This 6-year experimental study measured the response of bird populations and abundance to combinations of mixed cropping and low pesticide regimes associated with a commercial crop rotation. The results show a rapid and sustained population increase among a wide range of bird species, in contrast to local regional trends for the same species. Seventy percent of the increase occurred within the first 3 years of the experiment, with species of high conservation concern, and those monitored as environmental indicators on lowland farmland in the UK, increasing on average, by 30% and 20% respectively (reaching respective peaks of 44% and 33% after 4 years). For some individual species, the increase was higher still, i.e., 300% (1–4 pairs) for grey partridge (Perdix perdix) and 46% (13–19 pairs) for skylarks (Alauda arvensis) in peak years. The results demonstrate that bird species typical of lowland arable farmland in the UK are responsive to suitable farm-scale changes in habitat and food provision (roughly, manipulation within less than 1-km2). They show that the carrying capacity of modern, commercially viable, arable farmland can be increased significantly for birds, in this case, mainly by using crops mosaics to create habitats alongside the appropriate use of herbicides on non-cropped habitats.  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