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   753篇
  免费   2篇
  国内免费   5篇
安全科学   24篇
废物处理   16篇
环保管理   235篇
综合类   51篇
基础理论   139篇
污染及防治   220篇
评价与监测   56篇
社会与环境   15篇
灾害及防治   4篇
  2022年   3篇
  2021年   4篇
  2020年   5篇
  2018年   3篇
  2017年   4篇
  2016年   14篇
  2015年   5篇
  2014年   4篇
  2013年   104篇
  2012年   17篇
  2011年   26篇
  2010年   26篇
  2009年   24篇
  2008年   36篇
  2007年   37篇
  2006年   42篇
  2005年   21篇
  2004年   31篇
  2003年   28篇
  2002年   31篇
  2001年   12篇
  2000年   16篇
  1999年   7篇
  1998年   14篇
  1997年   14篇
  1996年   12篇
  1995年   12篇
  1994年   9篇
  1993年   7篇
  1992年   10篇
  1991年   12篇
  1990年   5篇
  1989年   11篇
  1988年   8篇
  1987年   10篇
  1986年   8篇
  1985年   9篇
  1984年   17篇
  1983年   14篇
  1982年   9篇
  1981年   13篇
  1980年   3篇
  1979年   14篇
  1978年   8篇
  1976年   8篇
  1975年   5篇
  1974年   4篇
  1972年   5篇
  1971年   4篇
  1970年   4篇
排序方式: 共有760条查询结果,搜索用时 171 毫秒
241.
The influences of coal-mine hollow fills and associated settling ponds in three headwater streams were assessed in southern West Virginia, USA. Fill drainage waters had elevated conductivities and metal concentrations, compared to a regional reference. Benthic macroinvertebrate richness was not affected consistently by the hollow fill drainages, relative to a regional reference, although a more tolerant community, lacking in Ephemeroptera taxa at most locations, was evident. Collector-filterer populations were elevated at monitoring stations directly below the settling ponds, indicating that the ponds’ presence influenced macroinvertebrate community structure by means of organic enrichment. Corbicula fluminea growth was enhanced in monitoring locations directly below the settling ponds, also an apparent result of organic enrichment. Results of acute water column toxicity testing with Ceriodaphnia dubia, sediment chronic toxicity testing with Daphnia magna, and in-situ ecotoxicological assessments with C. fluminea demonstrated no mortality or toxic influence at most of the sites tested below the ponds. The settling ponds appear to serve as sinks in collecting some, but not all, trace metals.  相似文献   
242.
Gaseous and particulate pollutant concentrations associated with five samples per day collected during a July 2001 summer intensive study at the Pittsburgh Carnegie Mellon University (CMU) Supersite were used to apportion fine particulate matter (PM2.5) into primary and secondary contributions using PMF2. Input to the PMF2 analysis included the concentrations of PM2.5 nonvolatile and semivolatile organic material, elemental carbon (EC), ammonium sulfate, trace element components, gas-phase organic material, and NO(x), NO2, and O3 concentrations. A total of 10 factors were identified. These factors are associated with emissions from various sources and facilities including crustal material, gasoline combustion, diesel combustion, and three nearby sources high in trace metals. In addition, four secondary sources were identified, three of which were associated with secondary products of local emissions and were dominated by organic material and one of which was dominated by secondary ammonium sulfate transported to the CMU site from the west and southwest. The three largest contributors to PM2.5 were secondary transported material (dominated by ammonium sulfate) from the west and southwest (49%), secondary material formed during midday photochemical processes (24%), and gasoline combustion emissions (11%). The other seven sources accounted for the remaining 16% of the PM2.5. Results obtained at the CMU site were comparable to results previously reported at the National Energy Technology Laboratory (NETL), located approximately 18 km south of downtown Pittsburgh. The major contributor at both sites was material transported from the west and southwest. Some difference in nearby sources could be attributed to meteorology as evaluated by HYSPLIT model back-trajectory calculations. These findings are consistent with the majority of the secondary ammonium sulfate in the Pittsburgh area being the result of contributions from distant transport, and thus decoupled from local activity involving organic pollutants in the metropolitan area. In contrast, the major local secondary sources were dominated by organic material.  相似文献   
243.
Selecting the most appropriate test species for sediment and water column assays has been a primary goal for ecotoxicologists. Standard test organisms and established test guidelines exist, but the USEPA-recommended species may not be the most sensitive organisms to anthropogenic inputs. This paper describes preliminary results of toxicity tests with the mayfly, Isonychia bicolor (Ephemeroptera). Results suggested that Isonychia were moderately sensitive to NaCl after 96 h with an average LC50 value of 3.10 g NaCl per liter. This value decreased after 7 days of exposure, resulting in a mean LC50 value of 1.73 g NaCl per liter. When exposed to a coal-mine-processed effluent, Isonychia generated LC50 values that ranged from 13% to 39% effluent. I. bicolor were more sensitive to the coal processing effluent than Ceriodaphnia dubia with conductivity lowest observable effects concentration (LOEC) values for mayfly survivorship that ranged from 1,508 to 4,101 μS/cm, while LOEC values for C. dubia reproduction ranged from 2,132 to 4,240 μS/cm.  相似文献   
244.
This paper examines the attitudes and perceptions of local people about ecological resources, environmental hazards, and future land use of the Idaho National Engineering and Environmental Laboratory (INEEL). Such monitoring of attitudes is an important aspect of environmental assessment. We interviewed 262 people who attended the 42nd Annual Free Fishermen's Breakfast at St. Anthony, Idaho, on 23 March 1997. We tested the null hypotheses that there were no differences in perceptions about ecological resources, hazards and future land use of INEEL as a function of gender, age, education, and place of residence. Dumping trash in the ocean and cutting rainforests rated as the environmental problems of highest concern, and ozone, radon and high voltage lines rated the lowest; cleaning up Department of Energy sites rated intermediate. Respondents were most willing to expend government funds to make drinking water clean. Three significant differences were found: 1) women rated environmental problems as more severe than did men, and women were more willing to expend federal funds to solve these problems, 2) respondents under 30 years of age rated environmental problems as more severe than older people, and they were more willing to spend money to solve them, and, 3) respondents who had not finished high school were more concerned with environmental problems and were more willing to spend money to solve them than respondents with a high school education. Maintaining INEEL as a National Environmental Research Park (NERP) rated as the most preferred future land use, followed by continued reprocessing of nuclear materials and hunting. Using INEEL for housing and additional nuclear waste storage rated the lowest. Men rated grazing livestock and additional nuclear waste storage higher than did women. In general, respondents from 30 – 49 rated several economic uses (hunting, grazing livestock, growing crops) higher than did people in other age groups. Respondents with some college rated these economic uses higher than did respondents who had not graduated from high school. These results indicate that respondents living around INEEL believe that INEEL should continue with a reprocessing and NERP mission, but that other peripheral uses, such as hunting, hiking and grazing, should be allowed on some of the land. These views should aid in environmental assessment of the site, and in developing further management plans for INEEL.  相似文献   
245.
Canada responded to the Global Biodiversity Convention by completing the Canadian Biodiversity Strategy in 1995. At the same time, Environment Canada also completed a national Science Assessment on Biodiversity. During this period, the Smithsonian Institution, in partnership with Parks and Environment Canada, initiated the implementation of a global biodiversity monitoring program in Canada. Under the auspices of the United Nations Man and the Biosphere Program, the SI/MAB monitoring protocols and plots have spread across Canada at an unprecedented rate. National champions in the science and educational sectors, working within an inter-disciplinary ecological framework, have guided the development, education, quality control and sharing of atmosphere-biodiversity observations electronically.Atmospheric-Biodiversity Networks and Networking have traditionally operated within separate mandates with little degree of integration. Air-Bio Networks were designed within an integrated framework to better understand the atmospheric stress on biodiversity and the adaptation actions, nationally and regionally. Detailed examples of the cumulative effects of climate change, stratospheric ozone depletion, acid deposition, ground-level ozone, suspended particulate matter and hazardous air pollutants on biodiversity will be discussed using a Southern Ontario case study. In addition, recommendations will be presented for future paired SI/MAB plots, linked networks and networking for adaptation within the context of climate, chemical and ecological gradients.  相似文献   
246.
The emissions from a Garrett-AiResearch (now Honeywell) Model GTCP85-98CK auxiliary power unit (APU) were determined as part of the National Aeronautics and Space Administration's (NASA's) Alternative Aviation Fuel Experiment (AAFEX) using both JP-8 and a coal-derived Fischer Tropsch fuel (FT-2). Measurements were conducted by multiple research organizations for sulfur dioxide (SO2, total hydrocarbons (THC), carbon monoxide (CO), carbon dioxide (CO2), nitrogen oxides (NOx), speciated gas-phase emissions, particulate matter (PM) mass and number, black carbon, and speciated PM. In addition, particle size distribution (PSD), number-based geometric mean particle diameter (GMD), and smoke number were also determined from the data collected. The results of the research showed PM mass emission indices (EIs) in the range of 20 to 700 mg/kg fuel and PM number EIs ranging from 0.5 x 10(15) to 5 x 10(15) particles/kg fuel depending on engine load and fuel type. In addition, significant reductions in both the SO2 and PM EIs were observed for the use of the FT fuel. These reductions were on the order of approximately 90% for SO2 and particle mass EIs and approximately 60% for the particle number EI, with similar decreases observed for black carbon. Also, the size of the particles generated by JP-8 combustion are noticeably larger than those emitted by the APU burning the FT fuel with the geometric mean diameters ranging from 20 to 50 nm depending on engine load and fuel type. Finally, both particle-bound sulfate and organics were reduced during FT-2 combustion. The PM sulfate was reduced by nearly 100% due to lack of sulfur in the fuel, with the PM organics reduced by a factor of approximately 5 as compared with JP-8.  相似文献   
247.
The problem of contamination to land and groundwater from improper handling of hazardous materials/ waste is faced by all countries. Also, the need for reliable, cost-effective technologies to address this problem at contaminated sites exists throughout the world. Many countries have only started to develop new innovative/ alternative technologies while others have already started to apply these technologies to the cleanup of contaminated sites. The purpose of this NATO/ CCMS (North Atlantic Treaty Organization/Committee for the Challenges to Modern Society) Pilot Study is to discuss and evaluate new innovative/alternative technologies and/or existing systems that may be applicable to the cleanup of contaminated sites. Through this pilot study, the exchange of information on new and existing technologies for dealing with problem hazardous waste sites is promoted. The pilot study is made up of an international group of experts drawn from the participating countries. The study, which was initiated in 1986, is planned to last five years. It is piloted by the United States and copiloted by the Federal Republic of Germany (FRG) and The Netherlands.

This report includes an overview and history of the NATO/CCMS Pilot Study, but it primarily presents a documentation of the NATO/CCMS Second International Conference on the Demonstration of Remedial Action Technologies for Contaminated Land and Groundwater held in Bilthoven, The Netherlands on November 7-11,1988.  相似文献   
248.
A cryogenic procedure for concentrating trace gases in the atmosphere has been developed and applied to the ambient air at Research Triangle Park, NC, Atlantic Beach, NC, and New York City. The concentrated gases have been analyzed by long path infrared absorption spectroscopy, with a detectability down to partial pressures of 10?11 atmospheres. Carbonyl sulfide has been detected at partial pressures in the range 1 × 10?10 atm. to 3 × 10?10 atm. Carbon tetrachloride was always detected with a rather narrow partial pressure range of 0.7 × 10?10 atm. to 1.1 × 10?10 atm. Fluorocarbon-11 values ranged from about 1.3 × 10?10 atm. at Research Triangle Park to 8 × 10?10 atm. at New York City. Fluo-rocarbon-12 covered the range 1.8 × 10?10 atm. to 1.0 × 10?9 atm. Hydrocarbon pollutants varied widely in concentration, but were always detected, even in the clean rural air.  相似文献   
249.
250.
A charging/collecting device for high-resistivity fly ash has been developed which controls back ionization by cooling the collector electrode internally with water. The device consists of parallel 6.0 cm pipes with corona wires suspended between the pipes. The pipes provide a simple means of interfacing with a cooling water system and also minimizing the collector area needing to be cooled. By cooling the pipes with 38°C (100°F) water, back ionization is eliminated and average field strengths of 7 kV/cm can be achieved with fly ash having a resistivity > 1012 ω-cm. Results of tests on an actual flue gas stream and plans for future testing are described. Initial tests using heated instead of cooled electrodes are described as well as other tests that lead to the present design. The results of tests with the heated electrode show the kind of improvements in performance that can be obtained when resistivity is controlled in only a small collection area.  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