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   1280篇
  免费   27篇
  国内免费   9篇
安全科学   51篇
废物处理   49篇
环保管理   331篇
综合类   133篇
基础理论   386篇
污染及防治   196篇
评价与监测   108篇
社会与环境   46篇
灾害及防治   16篇
  2023年   6篇
  2022年   12篇
  2021年   22篇
  2020年   14篇
  2019年   16篇
  2018年   25篇
  2017年   28篇
  2016年   44篇
  2015年   31篇
  2014年   32篇
  2013年   78篇
  2012年   72篇
  2011年   74篇
  2010年   53篇
  2009年   46篇
  2008年   58篇
  2007年   71篇
  2006年   77篇
  2005年   53篇
  2004年   48篇
  2003年   56篇
  2002年   38篇
  2001年   20篇
  2000年   27篇
  1999年   19篇
  1998年   24篇
  1997年   24篇
  1996年   23篇
  1995年   18篇
  1994年   12篇
  1993年   15篇
  1992年   16篇
  1991年   8篇
  1990年   13篇
  1989年   9篇
  1988年   11篇
  1987年   9篇
  1986年   11篇
  1985年   7篇
  1984年   14篇
  1983年   10篇
  1982年   11篇
  1981年   16篇
  1980年   7篇
  1979年   12篇
  1978年   7篇
  1977年   6篇
  1976年   4篇
  1975年   2篇
  1974年   2篇
排序方式: 共有1316条查询结果,搜索用时 31 毫秒
991.
Bushfire fighting is a hazardous occupation and control strategies are generally in place to minimize the hazards. However, little is known regarding firefighters' exposure to bushfire smoke, which is a complex mixture of toxic gases and particles. In Australia, during the prescribed burning season, firefighters are likely to be exposed on a regular basis to bushfire smoke, but whether these exposures affect health has yet to be determined. There are a number of factors that govern whether exposure to smoke will result in short-term and/or long-term health problems, including the concentrations of air pollutants within the breathing zone of the firefighter, the exposure duration, and health susceptibility of the individual, especially for pre-existing lung or heart disease. This paper presents measurements of firefighters' personal exposure to bushfire smoke, the first step within a risk management framework. It provides crucial information on the magnitude, extent and frequency of personal exposure to bushfire smoke for a range of typical scenarios. It is found that the primary air toxics of concern are carbon monoxide (CO), respirable particles and formaldehyde. Also, work activity is a major factor influencing exposure with exposure standards (both average and short-term limits) likely to be exceeded for activities such as suppression of spot fires, holding the fireline, and patrolling at the edge of a burn area in the urban-rural interface.  相似文献   
992.
We argue that the environment, broadly construed, has a profound effect on human cognition, action, and well-being. If this is true, then the field of environmental psychology has a far larger potential to aid humanity than is generally realized. We suggest that the field would be more likely to achieve this potential if it viewed environments from the perspective of human informational needs, and focused on environmental/informational patterns that have the potential to make it easier for people to help themselves. Further, achieving such benefits could be greatly enhanced by taking advantage of the many opportunities available for collaborating with researchers in other areas of psychology. The reasonable person model is offered as a perspective that could facilitate moving in these various new directions while taking advantage of the considerable existent knowledge about human–environment interactions that is currently underappreciated.  相似文献   
993.
The measurement of travel costs in recreational demand modeling has been a contentious issue for many decades. This article explores the use of a number of alternative methods of incorporating time costs in the travel cost modeling process. Travel cost values where the opportunity cost of time is excluded, where it is included as a percentage of the individual's reported wage rate and where it based on an estimated wage from a secondary data source (the European Community Household Panel) are compared and then used in a conditional logit model to estimate the demand for whitewater kayaking in Ireland. We then evaluate the effect of different treatments of the cost of travel time on the welfare impacts of a number of different management scenarios for kayaking rivers in Ireland, and find that statistically significant differences emerge.  相似文献   
994.
Advancing the understanding of spatiotemporal aspects of air pollution in the urban environment is an area where improved methods can be of great benefit to exposure assessment and policy support. This paper explores the potential of a technique known as kriging with external drift (KED) to provide high resolution maps of fine particulate matter for a downtown region of Cusco, Peru. There were three stages in this research. The first was to conduct a pilot level monitoring campaign to investigate ambient, regional, and street-level air pollutant concentrations for particulate matter (PM2.5, PM10) and carbon monoxide (CO) in the Province of Cusco. The second was to compile observations within a geographic information system (GIS) in order to characterize the proximal effect of the local transportation network, elevation, and land use classifications on PM2.5. Third, regression, ordinary kriging and kriging with external drift were used to model PM2.5 for three select time periods during a 24-h day. Statistical evaluations indicate kriging with external drift resulted in the strongest models explaining 64% of variability seen with morning particle concentrations, 25% for afternoon particles, and 53% in evening particles. These models capture spatial and temporal variability for air pollution in Cusco. These variations seem to be influenced, to varying degrees, by elevation, meteorological conditions, spatial location, and transportation characteristics. In conclusion, combining GIS, meteorological data and geostatistics proved to be a complementary suite of tools for incorporating spatiotemporal analysis into the air quality assessment.  相似文献   
995.
Global climate change, along with continued habitat loss and fragmentation, is now recognized as being a major threat to future biodiversity. There is a very real threat to species, arising from the need to shift their ranges in the future to track regions of suitable climate. The Important Bird Area (IBA) network is a series of sites designed to conserve avian diversity in the face of current threats from factors such as habitat loss and fragmentation. However, in common with other networks, the IBA network is based on the assumption that the climate will remain unchanged in the future. In this article, we provide a method to simulate the occurrence of species of conservation concern in protected areas, which could be used as a first-step approach to assess the potential impacts of climate change upon such species in protected areas. We use species-climate response surface models to relate the occurrence of 12 biome-restricted African species to climate data at a coarse (quarter degree-degree latitude-longitude) resolution and then intersect the grid model output with IBA outlines to simulate the occurrence of the species in South African IBAs. Our results demonstrate that this relatively simple technique provides good simulations of current species' occurrence in protected areas. We then use basic habitat data for IBAs along with habitat preference data for the species to reduce over-prediction and further improve predictive ability. This approach can be used with future climate change scenarios to highlight vulnerable species in IBAs in the future and allow practical recommendations to be made to enhance the IBA network and minimize the predicted impacts of climate change.  相似文献   
996.
A method was developed to score the ecological condition of first- to third-order stream reaches in the Auckland region of New Zealand based on the performance of their key ecological functions. Such a method is required by consultants and resource managers to quantify the reduction in ecological condition of a modified stream reach relative to its unmodified state. This is a fundamental precursor for the determination of fair environmental compensation for achieving no-net-loss in overall stream ecological value. Field testing and subsequent use of the method indicated that it provides a useful measure of ecological condition related to the performance of stream ecological functions. It is relatively simple to apply compared to a full ecological study, is quick to use, and allows identification of the degree of impairment of each of the key ecological functions. The scoring system was designed so that future improvements in the measurement of stream functions can be incorporated into it. Although the methodology was specifically designed for Auckland streams, the principles can be readily adapted to other regions and stream types.  相似文献   
997.
ABSTRACT Many of the resources generating aesthetic and visual benefits are publically owned and their optimum use and development depends upon public investment. Traditionally, public investment decisions have been couched in economic terms requiring quantitative measurement of benefits and costs. Since many of the benefits these resources provide are not consumed when they are enjoyed, the total contribution of the resource is imperfectly measured in the usual market sense. Thus, if the provision of these public goods is left to the conventional market mechanism, less than socially optimal investment may occur. This study was designed to investigate whether aesthetic preferences related to water projects could be determined, and whether they differ among different groups of people. A Q sort of 44 photographs of a wide variety of water development projects was conducted with two groups, i.e., photographers (aesthetic man) and town assessors (economic man). The resultant analysis identified two significant factors. Factor 1 provided insight into a hypothesis of nature dominant or man dominant scenes. Factor 2 indicated that the respondents had a negative preference for projects which were in varying stages of completion or appeared to be polluted. Preferences were consistent between the two groups tested. The test revealed that people do not necessarily equate only naturalness with aesthetic appeal, but will accept development as aesthetic, provided that it is designed to complement the natural landscape.  相似文献   
998.
Chloramines,in practice,are formed onsite by adding ammonia to chlorinated drinking water to achieve the required disinfection.While regulated disinfection byproducts(DBPs)are reduced during chloramine disinfection,other DBPs such as iodinated(iodo-)DBPs,that elicit greater toxicity are formed.The objective of this study was to investigate the impact of prechlorination time on the formation of both halogen-specific total organic halogen(TOX)and iodo/chlorinated(chloro-)DBPs during prechlorination/chloramination in source waters(SWs)containing iopamidol,an X-ray contrast medium.Barberton SW(BSW)and Cleveland SW(CSW)containing iopamidol were prechlorinated for 5–60 min and afterwards chloraminated for 72 hr with ammonium chloride.Chlorine contact time(CCT)did not significantly impact total organic iodine(TOI)concentrations after prechlorination or chloramination.Concentrations of total organic chlorine(TOCl)formed during prechlorination did not significantly change regardless of pH and prechlorination time,whileTOClappearedtodecreaseafter 72 hrchloraminationperiod.Dichloroiodomethane(CHCl_2I)formation during prechlorination did not exhibit any significant trends as a function of p H or CCT,but after chloramination,significant increases were observed at pHs 6.5 and 7.5 with respect to CCT.Iodo-HAAs were not formed during prechlorination but were detected after chloramination.Significant quantities of chloroform(CHCl_3)and trichloroacetic acid(TCAA)were formed during prechlorination but formation ceased upon ammonia addition.Therefore,prechlorination studies should measure TOX and DBP concentrations prior to ammonia addition to obtain data regarding the initial conditions.  相似文献   
999.
The Reedy River in South Carolina is affected by the urban area of Greenville, the third most populous city in the state, and by the effluents from two large-scale municipal wastewater treatment plants (WWTPs) located on the river. Riverine water chemistry was characterized using grab samples collected annually under spring season baseflow conditions. During the 4-year time period associated with this study, climatic variations included two severe drought spring seasons (2001 and 2002), one above-normal precipitation spring season (2003), and one below-normal precipitation spring season (2004). The influence of drought and human activities on the baseflow chemistry of the river was evaluated by comparing concentrations of dissolved anions, total metals, and other important water chemistry parameters for these different years. Concentrations of copper and zinc, common non-point source contaminants related to urban activities, were not substantially elevated in the river within the urban area under baseflow conditions when compared with headwater and tributary samples. In contrast, nitrate concentrations increased from 1.2–1.6 mg/l up to 2.6–2.9 mg/l through the urban stream reach. Concentrations of other major anions (e.g., sulfate, nitrate) also increased along the reach, suggesting that the river receives continuous inputs of these species from within the urban area. The highest concentrations of major cations and anions typically were observed immediately downstream from the two WWTP effluent discharge locations. Attenuation of nitrate downstream from the WWTPs did not always track chloride changes, suggesting that nitrate concentrations were being controlled by biochemical processes in addition to physical processes. The relative trends in decreasing nitrate concentrations with downstream distance appeared to depend on drought versus non-drought conditions, with biological processes presumably serving as a more important control during non-drought spring seasons.  相似文献   
1000.
A new method of determining the composition of sediment/soil gases and their volatile organic compound (VOC) content is described. VOCs were collected in situ from intertidal sediments in the Menai Strait and surrounding areas. The sampling was performed using a portable sampler comprising a funnel coupled to a SPME fibre. Gases were extracted from the sediments using a small vacuum pump pulling 100 mL min(-1) at atmospheric pressure. Sixty one different compounds were detected in the samples, and their fluxes and concentrations were determined. The compounds were classified into groups: halogenated, sulfur containing compounds, aldehydes, BTEXs (benzene, toluene, ethyl benzene and xylene) and aliphatic hydrocarbons. Results of principal component analysis (PCA) showed that the chemical composition of extracted gas was influenced primarily by sediment type. Muddy anoxic sediments were dominated by halogenated and sulfur containing compounds and sandy sediments had more aldehydes and BTEXs.  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