全文获取类型
收费全文 | 9838篇 |
免费 | 113篇 |
国内免费 | 93篇 |
专业分类
安全科学 | 286篇 |
废物处理 | 459篇 |
环保管理 | 1243篇 |
综合类 | 1193篇 |
基础理论 | 2668篇 |
环境理论 | 2篇 |
污染及防治 | 2770篇 |
评价与监测 | 708篇 |
社会与环境 | 667篇 |
灾害及防治 | 48篇 |
出版年
2022年 | 100篇 |
2021年 | 76篇 |
2020年 | 65篇 |
2019年 | 73篇 |
2018年 | 146篇 |
2017年 | 139篇 |
2016年 | 229篇 |
2015年 | 164篇 |
2014年 | 237篇 |
2013年 | 742篇 |
2012年 | 296篇 |
2011年 | 440篇 |
2010年 | 362篇 |
2009年 | 396篇 |
2008年 | 470篇 |
2007年 | 476篇 |
2006年 | 422篇 |
2005年 | 366篇 |
2004年 | 323篇 |
2003年 | 375篇 |
2002年 | 324篇 |
2001年 | 503篇 |
2000年 | 331篇 |
1999年 | 192篇 |
1998年 | 137篇 |
1997年 | 133篇 |
1996年 | 138篇 |
1995年 | 162篇 |
1994年 | 125篇 |
1993年 | 102篇 |
1992年 | 123篇 |
1991年 | 118篇 |
1990年 | 130篇 |
1989年 | 130篇 |
1988年 | 94篇 |
1987年 | 87篇 |
1986年 | 65篇 |
1985年 | 90篇 |
1984年 | 89篇 |
1983年 | 86篇 |
1982年 | 82篇 |
1981年 | 73篇 |
1980年 | 61篇 |
1979年 | 68篇 |
1977年 | 53篇 |
1976年 | 48篇 |
1975年 | 53篇 |
1974年 | 51篇 |
1973年 | 53篇 |
1970年 | 45篇 |
排序方式: 共有10000条查询结果,搜索用时 359 毫秒
381.
To ensure science better informs the decision-making process, researchers and policy/program managers need to understand and respect each other's way of working, culture and operational timelines. However, there is little practical guidance on how this should be done and even less documented experience with specific mechanisms that better link these two groups. The published literature on information transfer has largely emphasized the dissemination of standard packages of information to ill-defined constituencies whose needs for scientific information are not well understood. Environment Canada's National Water Research Institute, on behalf of the Canadian Council of Ministers of the Environment, led a series of “Linking Water Science to Policy Workshops” as one such mechanism by which recent science could be delivered to practitioners, and practitioners could identify their research needs to scientists and research managers. There is a pressing need to explore and share experiences using creative mechanisms for sustained dialogue and networking between scientists and policy and program managers. The lessons learned from the workshop series and the need for science to continually inform the decision-making process has particular relevance for Canada's Ecosystem Initiatives given their integrated, place-based focus on long-term restoration and protection, and the challenge of continually changing ecosystems.The Canadian Crown reserves the right to retain a non-exclusive, royalty free licence in and to any copyright. 相似文献
382.
The Atlantic Coastal Action Program (ACAP) is a unique, community-based program initiated by Environment Canada in 1991 to help Atlantic Canadians restore and sustain watersheds and adjacent coastal areas. ACAP is the eastem-most Environment Canada Ecosystem Initiative. The ACAP family is currently made up of 14 ecosystem-based organizations in the four Atlantic provinces. Each one of these non-profit organizations operates independently, but is formally linked under the umbrella of ACAP to represent a force stronger than the individual parts. In Environment Canada's experience, the program consistently demonstrates the value of a community-based approach and produces results on an ecosystem basis. This paper will examine some of the impacts of ACAP in terms of economics, credible community science, and environmental results which most often align with Environment Canada's objectives. It will explore the influences of the community-based approach to environmental management on multiple scales (local, regional, etc.). Through examples, the paper will demonstrate the effectiveness of ACAP in influencing some of the policies, programs and attitudes of various levels of government and industry in the region, as well as describe how the community-based model has been exported internationally. The paper will conclude with a discussion on a planned path forward for ACAP. 相似文献
383.
Martín-Díaz ML Tuberty SR McKenney CL Blasco J Sarasquete C Delvalls TA 《Environmental monitoring and assessment》2006,116(1-3):169-184
Individuals of the crayfish Procambarus clarkii (males and females) were exposed simultaneously to cadmium and zinc during 21 days. Exposure concentrations were those determined
at the Guadiamar river after the Aznalcóllar mining spill (SW, Spain): 10 and 30 μg L−1 of cadmium and 1000 and 3000 μg L−1 of zinc. Three biomarkers (MT: metallothioneins like proteins, VTG: vitellogenin/vitellin like proteins and histopathology)
together with heavy metal bioaccumulation were determined in soft tissues of male and female P. clarkii. At the concentrations tested, increasing cadmium exposure resulted in increasing cadmium bioaccumulation and increasing subletal
effects (induction of MT, VTG and histopathological damage in tissues). Nevertheless, although increasing zinc exposure showed
increasing VTG induction and histopathological damages, not a positive relationship was determined with MT induction. Concerning
to responses determined in male and female crayfishes only differences were found between sexes at the highest cadmium exposure
concentration related to bioaccumulation in hepatopancreas tissues. Biomarkers responses to heavy metal contamination in this
crayfish, even VTG induction not before tested in heavy metal contamination assessment in crustaceans resulted potential tools
for the monitoring of heavy metal environmental contamination. 相似文献
384.
Vaughan G Quinn PT Green AC Bean J Roscoe HK van Roozendael M Goutail F 《Journal of environmental monitoring : JEM》2006,8(3):353-361
We present in this paper fifteen years' measurements, from March 1991 to September 2005, of stratospheric NO2 vertical columns measured by a SAOZ zenith-sky visible spectrometer. The instrument spent most of its time at Aberystwyth, Wales, with occasional excursions to other locations. The data have been analysed with the WinDOAS analysis program with low-temperature high-resolution NO2 cross-sections and fitting a slit function to each spectrum. Because of a change in detector in May 1998 there is some uncertainty about the relative changes before and after this date, which are partially constrained by the results of an intercomparison exercise. However, the effect of the Mt Pinatubo aerosol cloud is very evident in the data from 1991-94, with a decrease of 10% in NO2 in the summer of 1992 (the SAOZ was located in Lerwick, Scotland during the winter of 1991-92 and observed very low NO2 values but these cannot be directly compared to the Aberystwyth data). To focus more on interannual and long-term variations in NO2, a seasonal variation comprising an annual and semi-annual component was fitted to the morning and evening twilight separately from 1995 to the present. This fit yielded average NO2 columns of 4.08 x 10(15) cm(-2) and 2.68 x 10(15) cm(-2) for the evening and morning twilight, respectively, with a corresponding annual amplitude of +/-2.08 x 10(15) cm(-2) and +/-1.50 x 10(15) cm(-2). Departures from the fitted curve show a trend of 6% per decade, consistent with that reported elsewhere, for the period 1998-2003, but in the past two years a distinct interannual variation of amplitude of approximately 8% has emerged. 相似文献
385.
Archambault DJ Li X Foster KR Jack TR 《Environmental monitoring and assessment》2006,115(1-3):509-530
Ethephon, which releases ethylene within plant tissues after application, was chosen to perform assessments of the relative sensitivity of crops to ethylene and to determine which stages of plant development were most sensitive. The species chosen were: barley, wheat, oats, canola and field pea, all of which are important crops in the province of Alberta, Canada. Plants were treated with ethephon at one of 7 different stages. Plants were assessed for their vegetative and reproductive growth, including height, biomass, yield and seed quality. Visual symptoms were photographed and documented to compare them with symptoms caused by ethylene applied as a gas. It was concluded that in barley, wheat and canola the late vegetative and early reproductive stages were most sensitive, at least when sensitivity was defined as reductions in yield and quality. As for field pea, ethephon had no effect on yield but did cause increased numbers of pods, which in certain conditions could lead to increased yields. Significant effects on vegetative growth were only observed in the early vegetative stages of development but with no effects on yield. The screening protocol successfully identified sensitive cultivars and growth stages for further investigation of the effects of ethylene exposure. 相似文献
386.
Rhea DT Harper DD Farag AM Brumbaugh WG 《Environmental monitoring and assessment》2006,115(1-3):381-393
Portions of the Boulder River watershed contain elevated concentrations of arsenic, cadmium, copper, lead, and zinc in water, sediment, and biota. We measured concentrations of As, Cd, Cu, Pb, and Zn in biofilm and macroinvertebrates, and assessed macroinvertebrate assemblage and aquatic habitat with the objective of monitoring planned remediation efforts. Concentrations of metals were generally higher in downstream sites compared with upstream or reference sites, and two sites contained metal concentrations in macroinvertebrates greater than values reported to reduce health and survival of resident trout. Macroinvertebrate assemblage was correlated with metal concentrations in biofilm and macroinvertebrates. However, macroinvertebrate metrics were significantly correlated with a greater number of biofilm metals (8) than metals in invertebrates (4). Lead concentrations in biofilm appeared to have the most significant impact on macroinvertebrate assemblage. Metal concentrations in macroinvertebrates were directly proportional to concentrations in biofilm, indicating biofilm as a potential surrogate for monitoring metal impacts in aquatic systems. 相似文献
387.
Personal aerosol samplers are widely used to monitor human exposure to airborne materials. For bioaerosols, interest is growing in analyzing samples using molecular and immunological techniques. This paper presents a personal sampler that uses a two-stage cyclone to collect bioaerosols into disposable 1.5 ml Eppendorf-type microcentrifuge tubes. Samples can be processed in the tubes for polymerase chain reaction (PCR) or immunoassays, and the use of multiple stages fractionates aerosol particles by aerodynamic diameter. The sampler was tested using fluorescent microspheres and aerosolized fungal spores. The sampler had first and second stage cut-off diameters of 2.6 microm and 1.6 microm at 2 l min(-1)(geometric standard deviation, GSD = 1.45 and 1.75), and 1.8 microm and 1 microm at 3.5 l min(-1)(GSD = 1.42 and 1.55). The sampler aspiration efficiency was >or=98% at both flow rates for particles with aerodynamic diameters of 3.1 microm or less. For 6.2 microm particles, the aspiration efficiency was 89% at 2 l min(-1) and 96% at 3.5 l min(-1). At 3.5 l min(-1), the sampler collected 92% of aerosolized Aspergillus versicolor and Penicillium chrysogenum spores inside the two microcentrifuge tubes, with less than 0.4% of the spores collecting on the back-up filter. The design and techniques given here are suitable for personal bioaerosol sampling, and could also be adapted to design larger aerosol samplers for longer-term atmospheric and indoor air quality sampling. 相似文献
388.
T. I. Kazantseva B. V. Adamovich A. F. Alimov T. V. Zhukova V. N. Solntsev 《Russian Journal of Ecology》2018,49(1):1-13
Singular Spectrum Analysis (SSA) has been used to decompose continuous series of data on certain characteristics of Lake Naroch’ ecosystem during the vegetative seasons of years 1978–2015 into a long-time trend, a periodic component, and a residue not amenable to decomposition. The contribution of each component to changes in this variable has been assessed. The trends accounted for 78–97% of parameter variability, and the periodic components accounted for 2.5–15%. The fluctuations of phytoplankton and zooplankton biomass dynamics were the most diverse, and the contribution of these components was the greatest (15 and 8%, respectively). The periodic components in the changes of all parameters could be divided into four groups according to period duration (17–22, 7–15, 4–7, and less than 4 years). Multidimensional factor analysis of seven biotic parameters was performed in order to identify fluctuations in the ecosystem. Five major factors accounting for 93.6% of ecosystem changes together were identified, and each factor variable was subjected to SSA analysis. The period durations were similar for the oscillatory components identified. The first factor was interpreted as a trophic status of the water body, the second was taken to be the geographical location that defines the amount of solar radiation energy available, the third was taken to be the availability of biogenic elements (phosphorus in particular), and the fourth was interpreted as specific developmental cycles of live components of the ecosystem. 相似文献
389.
A. N. Mironovsky Yu. V. Slyn’ko A. N. Kasyanov T. V. Goroshkova 《Russian Journal of Ecology》2018,49(2):160-165
Analysis of variation in morphological characters of Potanin Altai osman, Oreoleuciscus potanini, from two freshwater and one brackish water lakes of Western Mongolia has shown that specimens of different ecological forms—herbivorous and piscivorous—form two integral and, at the level under consideration, internally indivisible units in the system of phenetic diversity of the species O. potanini. 相似文献
390.
Alexandra C. Halligan Amanda M. Becotte Ashley M. Crane Edward T. Dougherty 《Environmental Modeling and Assessment》2018,23(5):583-595
Nitrogen is commonly known as a food source for crops. However, the nitrogen compounds used in crop fertilizers, most commonly nitrate (NO3) and ammonium (NH4), are not widely understood. Blueberry plants do not take up these compounds as efficiently as organic nitrogen so varying amounts of leaching into the soil and groundwater will occur. A biogeochemical model consisting of ordinary and partial differential equations is implemented to computationally predict the concentrations of nitrate and ammonium in unsaturated soil of blueberry plants, specifically in the southern region of New Jersey. The model takes into account the type of soil of the region, the nitrate uptake of the plant, the water content in the roots region, the pressure heads in the soil pores, and the application rates of fertilizers containing nitrate, ammonium, and organic nitrogen. Computational simulations demonstrate that the model accounts for natural processes and, in addition, show that commonly used fertilizer application rates cause unnecessarily high concentrations of both nitrate and ammonium in the unsaturated soil level. Further, simulations show that decreasing nitrate fertilizer applications by 85.7% in annual and 91.8% in bi-annual schedules provides an optimal system for safe reapplication. 相似文献