全文获取类型
收费全文 | 513篇 |
免费 | 11篇 |
国内免费 | 9篇 |
专业分类
安全科学 | 21篇 |
废物处理 | 13篇 |
环保管理 | 137篇 |
综合类 | 50篇 |
基础理论 | 98篇 |
污染及防治 | 136篇 |
评价与监测 | 46篇 |
社会与环境 | 21篇 |
灾害及防治 | 11篇 |
出版年
2021年 | 6篇 |
2020年 | 1篇 |
2019年 | 5篇 |
2018年 | 4篇 |
2017年 | 6篇 |
2016年 | 8篇 |
2015年 | 14篇 |
2014年 | 20篇 |
2013年 | 65篇 |
2012年 | 20篇 |
2011年 | 22篇 |
2010年 | 20篇 |
2009年 | 18篇 |
2008年 | 21篇 |
2007年 | 28篇 |
2006年 | 24篇 |
2005年 | 20篇 |
2004年 | 13篇 |
2003年 | 19篇 |
2002年 | 13篇 |
2001年 | 9篇 |
2000年 | 11篇 |
1999年 | 9篇 |
1998年 | 6篇 |
1997年 | 5篇 |
1996年 | 4篇 |
1995年 | 9篇 |
1994年 | 13篇 |
1993年 | 9篇 |
1992年 | 7篇 |
1991年 | 8篇 |
1990年 | 7篇 |
1989年 | 4篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 4篇 |
1983年 | 9篇 |
1982年 | 9篇 |
1981年 | 8篇 |
1980年 | 11篇 |
1979年 | 9篇 |
1978年 | 5篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1973年 | 2篇 |
1971年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有533条查询结果,搜索用时 15 毫秒
411.
Ascorbic acid, β-carotene, sugars, phenols, and heavy metals in sweet potatoes grown in soil fertilized with municipal sewage sludge 总被引:1,自引:0,他引:1
Antonious GF Dennis SO Unrine JM Snyder JC 《Journal of environmental science and health. Part. B》2011,46(2):112-121
Municipal sewage sludge (MSS) used for land farming typically contains heavy metals that might impact crop quality and human health. A completely randomized experimental design with three treatments (six replicates each) was used to monitor the impact of mixing native soil with MSS or yard waste (YW) mixed with MSS (YW +MSS) on: i) sweet potato yield and quality; ii) concentration of seven heavy metals (Cd, Cr, Mo, Cu, Zn, Pb, and Ni) in sweet potato plant parts (edible roots, leaves, stem, and feeder roots); and iii) concentrations of ascorbic acid, total phenols, free sugars, and β-carotene in sweet potato edible roots at harvest. Soil samples were collected and analyzed for total and extractable metals using two extraction procedures, concentrated nitric acid (to extract total metals from soil) as well as CaCl? solution (to extract soluble metals in soil that are available to plants), respectively. Elemental analyses were performed using inductively coupled plasma mass spectrometry (ICP-MS). Overall, plant available metals were greater in soils amended with MSS compared to control plots. Concentration of Pb was greater in YW than MSS amendments. Total concentrations of Pb, Ni, and Cr were greater in plants grown in MSS+YW treatments compared to control plants. MSS+YW treatments increased sweet potato yield, ascorbic acid, soluble sugars, and phenols in edible roots by 53, 28, 27, and 48%, respectively compared to plants grown in native soil. B-carotene concentration (157.5 μg g?1 fresh weight) was greater in the roots of plants grown in MSS compared to roots of plants grown in MSS+YW treatments (99.9 μg g?1 fresh weight). Concentration of heavy metals in MSS-amended soil and in sweet potato roots were below their respective permissible limits. 相似文献
412.
Seasonal variations of hydroxylated and methoxylated brominated diphenyl ethers in blue mussels from the Baltic Sea 总被引:2,自引:0,他引:2
Hydroxylated polybrominated diphenyl ethers (OH-PBDEs) and methoxylated polybrominated diphenyl ethers (MeO-PBDEs) found at high levels in the Baltic biota are mainly natural products, but can also be formed through metabolism or abiotic oxidation of polybrominated diphenyl ethers (PBDEs). The formation of OH-PBDEs is of concern since there is growing evidence of phenolic toxicity. This study investigates seasonal variations in levels of OH-PBDEs and MeO-PBDEs, focusing on an exposed species, the blue mussel (Mytilus edulis), sampled in the Baltic Sea in May, June, August and October of 2008. Both the OH-PBDE and MeO-PBDE levels in the mussels showed seasonal variations from May to October, the highest concentration of each congener appearing in June. The seasonal variation was more marked for OH-PBDEs than in MeO-PBDEs, but all congeners showed the same trends, except 6-MeO-BDE47 and 2′-MeO-BDE68, which did not significantly decline in concentrations after June. Biotic or abiotic debromination is suggested as a possible reason for the rapid decrease in methoxylated penta- and hexa-BDE concentrations observed in blue mussels from June to August, while the tetraBDE concentrations were stable. In addition, 1,3,7/1,3,8-tribrominated dibenzo-p-dioxins showed the same seasonal variation. The seasonal variations indicates natural formation and are unlikely to be due to transformation of anthropogenic precursors. The levels of PBDEs were fairly constant over time and considerably lower than those of the OH-PBDEs and MeO-PBDEs. The timing of the peaks in concentrations suggests that filamentous macro-algae may be important sources of these compounds found in the blue mussels from this Baltic Sea location. 相似文献
413.
Samuel E. Cox Dennis L. Doncaster Peter E. Godfrey Michael D. Londe 《Environmental monitoring and assessment》2018,190(12):717
Headcuts are points of accelerated channel erosion that frequently have ecological consequences. A particularly large and dynamic headcut in southwest Wyoming has affected natural and anthropogenic resources for decades. To better understand and address this issue, we undertook a review of the headcut’s upstream retreat, followed by photogrammetric monitoring of the present condition for erosion monitoring. Aerial photography shows the Bitter Creek headcut retreated >?200 m upstream in 68 years (1948–2016) at ~?1.4 m year?1. Following installation of a concrete slab structure in the mid-1970s, headcut retreat slowed to ~?0.5 m year?1. Channel sinuosity downstream of the headcut is greater than upstream, which we attribute to the presence of the headcut, given that there are no major changes in valley geometry, geology, or soils through this reach. Both aerial and terrestrial-based image platforms were used to collect stereo imagery and create 3D photogrammetric models of the headcut in 2016. From these two models, we measured soil loss downstream of the headcut at ~?126 m3 m?1 valley length. Since 1954, soil loss within the channel has been ~?98 m3 year?1 or ~871 t ha?1 year?1since then. Models created from aerial- and terrestrial-based images differed in volumetric estimates by 2%, indicating that either method could be used for this type of monitoring. The ground-based imagery model showed more detail, especially on vertical and overhanging surfaces, while the aerial imagery model produced a more realistic orthomosaic and efficiently covered a larger area. Ground-based image acquisition took longer and was more costly per unit area, but is an efficient method for small project areas, or areas where aerial imagery cannot be safely or practically acquired. Historical imagery and photogrammetric modeling proved very useful in elucidating stream dynamics associated with this large, dynamic headcut. 相似文献
414.
Nitrogen Subsidies from Hillslope Alder Stands to Streamside Wetlands and Headwater Streams,Kenai Peninsula,Alaska
下载免费PDF全文
![点击此处可从《Journal of the American Water Resources Association》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Michael K. Callahan Dennis F. Whigham Mark C. Rains Kai C. Rains Ryan S. King Coowe M. Walker Jasmine R. Maurer Steven J. Baird 《Journal of the American Water Resources Association》2017,53(2):478-492
We examined nitrogen transport and wetland primary production along hydrologic flow paths that link nitrogen‐fixing alder (Alnus spp.) stands to downslope wetlands and streams in the Kenai Lowlands, Alaska. We expected that nitrate concentrations in surface water and groundwater would be higher on flow paths below alder. We further expected that nitrate concentrations would be higher in surface water and groundwater at the base of short flow paths with alder and that streamside wetlands at the base of alder‐near flow paths would be less nitrogen limited than wetlands at the base of long flow paths with alder. Our results showed that groundwater nitrate‐N concentrations were significantly higher at alder‐near sites than at no‐alder sites, but did not differ significantly between alder‐far sites and no‐alder sites or between alder‐far sites and alder‐near sites. A survey of 15N stable isotope signatures in soils and foliage in alder‐near and no‐alder flow paths indicated the alder‐derived nitrogen evident in soils below alder is quickly integrated downslope. Additionally, there was a significant difference in the relative increase in plant biomass after nitrogen fertilization, with the greatest increase occurring in the no‐alder sites. This study demonstrates that streamside wetlands and streams are connected to the surrounding landscapes through hydrologic flow paths, and flow paths with alder stands are potential “hot spots” for nitrogen subsidies at the hillslope scale. 相似文献
415.
Solorzano-Ochoa G de la Rosa DA Maiz-Larralde P Gullett BK Tabor DG Touati A Wyrzykowska-Ceradini B Fiedler H Abel T Carroll WF 《Chemosphere》2012,87(9):1003-1008
Open burning for waste disposal is, in many countries, the dominant source of polychlorinated dibenzodioxins, dibenzofurans and biphenyls (PCDD/PCDF/PCB) release to the environment. To generate emission factors for open burning, experimental pile burns of about 100 kg of household waste were conducted with emissions sampling. From these experiments and others conducted by the same authors it is found that less compaction of waste or active mixing during the fire - “stirring” - promotes better combustion (as evidenced by lower CO/CO2 ratio) and reduces emissions of PCDD/PCDF/PCB; an intuitive but previously undemonstrated result. These experiments also support previous results suggesting PCDD/PCDF/PCB generation in open burning - while still highly variable - tends to be greater in the later (smoldering) phases of burning when the CO/CO2 ratio increases. 相似文献
416.
W.C. Cheng Chun-Ho Liu Dennis Y.C. Leung 《Atmospheric environment (Oxford, England : 1994)》2009,43(24):3682-3690
The ventilation and pollutant transport in a two-dimensional (2D) street canyon of building-height-to-street-width (aspect) ratio h/b = 1 under different unstable stratifications were examined. To characterize the combined wind-buoyancy-driven flow and pollutant transport at different Richardson number Ri, a computational fluid dynamics (CFD) model based on the Reynolds-averaged Navier–Stokes (RANS) equations with the Renormalization Group (RNG) k ? ε turbulence model was adopted. Unlike the isothermal condition, a secondary recirculation is initiated at the ground-level windward corner of the street canyon once the unstable stratification is switched on (Ri < 0). It traps the ground-level pollutant leading to elevated pollutant concentration there. As Ri further decreases, the enlarging secondary recirculation enables direct pollutant removal from its core to the shear layer that offsets the ground-level pollutant accumulation. The ventilation and pollutant removal performance under different unstable stratifications are compared by the air (ACH) and pollutant (PCH) exchange rates, and pollutant retention time (τ). Both the mean and turbulent components of ACH are found to increase with decreasing Ri, suggesting that unstable stratification promotes ventilation in street canyons. Moreover, the CFD results agree well with our theoretical model that ACH2 varies linearly with Ri. Turbulent transport originally dominates the pollutant removal under isothermal condition. However, progressive domination of pollutant removal by mean wind can be observed with decreasing stability (decreasing Ri from 0 to ?10.6). The critical value is estimated to be Ri = ?8, below which mean wind is the major pollutant removal carrier. Reduction in τ is also observed with decreasing Ri. Hence, in unstable stratification, pollutant resides shorter time in the street canyon compared with its isothermal counterpart, and the ventilation and pollutant removal are more favorable. 相似文献
417.
Donna B. Schwede Robin L. Dennis Mary Ann Bitz 《Journal of the American Water Resources Association》2009,45(4):973-985
Abstract: A tool for providing the linkage between air and water‐quality modeling needed for determining the Total Maximum Daily Load (TMDL) and for analyzing related nonpoint‐source impacts on watersheds has been developed. Using gridded output of atmospheric deposition from the Community Multiscale Air Quality (CMAQ) model, the Watershed Deposition Tool (WDT) calculates average per unit area and total deposition to selected watersheds and subwatersheds. CMAQ estimates the wet and dry deposition for all of its gaseous and particulate chemical species, including ozone, sulfur species, nitrogen species, secondary organic aerosols, and hazardous air pollutants at grid scale sizes ranging from 4 to 36 km. An overview of the CMAQ model is provided. The somewhat specialized format of the CMAQ files is not easily imported into standard spatial analysis tools. The WDT provides a graphical user interface that allows users to visualize CMAQ gridded data and perform further analyses on selected watersheds or simply convert CMAQ gridded data to a shapefile for use in other programs. Shapefiles for the 8‐digit (cataloging unit) hydrologic unit code polygons for the United States are provided with the WDT; however, other user‐supplied closed polygons may be used. An example application of the WDT for assessing the contributions of different source categories to deposition estimates, the contributions of wet and dry deposition to total deposition, and the potential reductions in total nitrogen deposition to the Albemarle‐Pamlico basin stemming from future air emissions reductions is used to illustrate the WDT capabilities. 相似文献
418.
Developing a translational discourse to communicate uncertainty in flood risk between science and the practitioner 总被引:7,自引:0,他引:7
The language and tools of risk and uncertainty estimation in flood risk management (FRM) are rarely optimized for the extant communication challenge. This paper develops the rationale for a pragmatic semiotics of risk communication between scientists developing flood models and forecasts and those professional groups who are the receptors for flood risk estimates and warnings in the UK. The current barriers to effective communication and the constraints involved in the formation of a communication language are explored, focusing on the role of the professional's agenda or "mission" in creating or reducing those constraints. The tools available for the development of this discourse, for both flood warnings in real time and generalized FRM communications, are outlined. It is argued that the contested ownership of the articulation of uncertainties embedded in flood risk communications could be reduced by the development of a formally structured translational discourse between science and professionals in FRM, through which process "codes of practice" for uncertainty estimation in different application areas can be developed. Ways in which this might take place in an institutional context are considered. 相似文献
419.
A. Dennis Lemly 《Environmental monitoring and assessment》2000,63(3):431-446
A combination field and laboratorystudy was conducted to evaluate the ability of arecently developed bioindicator to detect detrimentalnutrient conditions in streams. The method utilizesbacterial growth on aquatic insects to determinenutrient impacts. Field investigations indicated thatelevated concentrations of nitrate and phosphate wereassociated with growth of filamentous bacteria oninsect body surfaces, and that there was a significantreduction in the density of major insect taxa in thenutrient-enriched stream reaches. Laboratoryinvestigations confirmed a strong linkage betweenbacterial growth and reduced survival of insects. Survival was examined for insects with bacterialinfestation ranging from 0% to greater than 50%coverage of the body surface. A threshold forcatastrophic mortality occurred at about 25% bodycoverage; there were few survivors above that amount. Based on these findings, the diagnostic endpoint forthe bioindicator is 25% body coverage by bacterialgrowth, a level that signifies major impacts and isalso easy to detect visually. This study providesadditional evidence that the insect-bacteriabioindicator is a reliable tool for assessing nutrientimpacts on stream macroinvertebrate communities. Thebioindicator should prove useful for identifyingnutrient-impacted sites as well as monitoring thesuccess of management actions to improve water quality. 相似文献
420.
Cumulative impact assessment (CIA) is the process of systematically assessing a proposed action's cumulative environmental effects in the context of past, present, and future actions, regardless of who undertakes such actions. Previous studies have examined CIA efforts at the federal level but little is known about how states assess the cumulative impacts of nonfederal projects. By examining state environmental review statutes, administrative rules, agency-prepared materials, and a national survey of the administrators of state environmental review programs, this study identifies the legal and administrative frameworks for CIA. It examines current CIA practice, discusses the relationship between CIA policy and its implementation, and explores the opportunities for improvement. The results of the study show that twenty-nine state environmental review programs across twenty-six states required the assessment of cumulative environmental impacts. More than half of these programs have adopted specific procedures for implementing their policies. Some programs assessed cumulative impacts using a standard review document, and others have created their own documentations incorporated into applications for state permits or funding. The majority of programs have adopted various scales, baselines, significance criteria, and coordination practices in their CIA processes. Mixed methods were generally used for data collection and analysis; qualitative methods were more prevalent than quantitative methods. The results also suggest that a program with comprehensive and consistent environmental review policies and procedures does not always imply extensive CIA requirements and practices. Finally, this study discusses the potential for improving existing CIA processes and promoting CIA efforts in states without established environmental review programs. 相似文献