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211.
Prakash Karamchandani Kristen Lohman Christian Seigneur 《Environmental Fluid Mechanics》2009,9(1):59-71
Several air toxics are emitted from mobile sources on roadways and these emissions account for a significant fraction of the
health risks to the population. In addition, health effect studies are now becoming more comprehensive and some account for
the spatial heterogeneities of air pollutant concentration fields (as is the case near roadways). Standard models can simulate
either the near-source concentration fields or the urban background, but no model can handle both spatial scales in the vicinity
of roadways in a coherent and scientifically correct manner. Here, we present a model that provides such an integrated treatment
by combining a grid-based air quality model of the urban background with a plume-in-grid representation of roadway emissions.
The model is applied to simulate near-roadway concentrations due to emissions from a busy interstate highway in New York City.
Qualitative comparisons with typical measured concentration profiles show that the model captures the observed features of
toxic air pollutant concentrations near roadways. 相似文献
212.
Bárbara Marinho Carlos Coelho Magnus Larson Hans Hanson 《Journal of Coastal Conservation》2018,22(3):475-489
Dredged material resulting from deepening and maintenance activities of the Aveiro Harbor inlet channel, northwestern coast of Portugal, has been used to mitigate the erosion trend recorded on nearby beaches (from Barra to Costa Nova Beach) through direct placement of sand by using standard dredge equipment. The disposal activities of dredged material have been undertaken at two main sites: between the south breakwater and the 1st groin of Costa Nova (dumping area 1, DA1) and between the 3rd and the 5th groin of Costa Nova (dumping area 2, DA2).The sand was placed in the nearshore, between the ?2 and ?7 m Chart Datum, CD, contours.In this study, short- and long-term coastal morphologic changes in the sea bottom, in response to several nourishment operations and to the incoming waves, within the dumping area boundaries are investigated based on a data set of hydrographic surveys collected annually, just before and after the nourishments, between 2009 and 2015. Preliminary results describing the main morphologic changes, evolution trends, sediment budget variations, and nourishments performance are discussed using mainly Geographic Information System techniques. Overall, the analysis demonstrates that the short-term losses in the dumping areas (one month of interval) can reach 50% of the nourished volume, revealing a significant movement of the fill material towards offshore. Seasonal variations promoting cross-shore material exchange can also prevail and misrepresent the sediment balances, if the monitoring area is not comprehensive. Furthermore, some bathymetric analysis suggested that longshore transport gradients have moved the fill material from Barra beach to downdrift areas. All the obtained results contribute to the ongoing discussion about the effectiveness of nearshore sand placements especially in context of an energetic environment. 相似文献
213.
Su Sponaugle Kristen D. Walter Kelly L. Denit Joel K. Llopiz Robert K. Cowen 《Marine Biology》2010,157(4):839-849
Atlantic blue marlin (Makaira nigricans) and sailfish (Istiophorus platypterus) larvae were collected from 10 monthly cruises (June–October 2003 and 2004) across the Straits of Florida to test (1) whether
growth differed between the more productive western region near the Florida shelf, and the less productive eastern region
toward the Bahamas, and (2) whether growth was related to prey consumption. Examination of larval sagittal otoliths revealed
that instantaneous growth and daily growth during the first 2–3 weeks of life did not vary significantly between the two regions
for either species. However, recent growth during the last two full days prior to collection was greater in the west for blue
marlin larvae. Recent growth of blue marlin larvae <9 mm SL (primarily zooplanktivorous) was significantly related to prey
composition (faster growth when higher proportions of Farranula copepods were consumed). Western larvae grew faster and had higher proportions of Farranula in their guts. Trends for sailfish larvae were not significant. In both species, comparison of early growth between <9 and ≥9 mm
SL size groups indicated that growth trajectories diverged around 5–8 mm SL, the time when billfish larvae become capable
of piscivory. Significantly faster growth of larger (older) larvae suggests that mortality was selective for fast growers
and that the transition to piscivory may be a critical point in the early life of billfish. 相似文献
214.
Corporan E Reich R Monroig O DeWitt MJ Larson V Aulich T Mann M Seames W 《Journal of the Air & Waste Management Association (1995)》2005,55(7):940-949
The impacts of biodiesel on gaseous and particulate matter (PM) emissions of a JP-8-fueled T63 engine were investigated. Jet fuel was blended with the soybean oil-derived methyl ester biofuel at various concentrations and combusted in the turbine engine. The engine was operated at three power settings, namely ground idle, cruise, and takeoff power, to study the impact of the biodiesel at significantly different pressure and temperature conditions. Particulate emissions were characterized by measuring the particle number density (PND; particulate concentration), the particle size distribution, and the total particulate mass. PM samples were collected for offline analysis to obtain information about the effect of the biodiesel on the polycyclic aromatic hydrocarbon (PAH) content. In addition, temperature-programmed oxidation was performed on the collected soot samples to obtain information about the carbonaceous content (elemental or organic). Major and minor gaseous emissions were quantified using a total hydrocarbon analyzer, an oxygen analyzer, and a Fourier Transform IR analyzer. Test results showed the potential of biodiesel to reduce soot emissions in the jet-fueled turbine engine without negatively impacting the engine performance. These reductions, however, were observed only at the higher power settings with relatively high concentrations of biodiesel. Specifically, reductions of approximately 15% in the PND were observed at cruise and takeoff conditions with 20% biodiesel in the jet fuel. At the idle condition, slight increases in PND were observed; however, evidence shows this increase to be the result of condensed uncombusted biodiesel. Most of the gaseous emissions were unaffected under all of the conditions. The biodiesel was observed to have minimal effect on the formation of polycyclic aromatic hydrocarbons during this study. In addition to the combustion results, discussion of the physical and chemical characteristics of the blended fuels obtained using standard American Society for Testing and Materials (ASTM) fuel specifications methods are presented. 相似文献
215.
If you don't measure it, you can't manage it. Over the past decade, many companies have recognized this need to track environmental performance. Failure to plan metrics systems to fit organizational needs, work flows, and culture has left many companies with costly and ineffective environmental performance measurement systems. This article presents numerous practical steps for designing effective metrics systems which avoid common pitfalls. 相似文献
216.
Kristal A. Huggins Kristen J. Navara Mary T. Mendonça Geoffrey E. Hill 《Die Naturwissenschaften》2010,97(7):637-644
Carotenoid pigments produce yellow, orange, and red integumentary color displays that can serve as reliable signals of health
and condition. In many birds and fish, individuals gain competitive or mating advantages by ingesting and utilizing large
quantities of carotenoid pigments. Carotenoid pigments serve as antioxidants, performing important functions as free-radical
scavengers. The beneficial effects of carotenoid pigments are well documented, but rarely have researchers considered potential
detrimental effects of high-level accumulation of carotenoids. We maintained American goldfinches (Carduelis tristis) on high- or low-carotenoid diets through molt and tested for damage to the liver and skeletal muscle. High intake of carotenoids
had no measurable effect on liver enzymes but caused an increase in creatine kinase, an indicator of skeletal muscle breakdown,
and a reduction in vertical flight performance, a measure of skeletal muscle integrity. The detrimental effects of high-level
carotenoid accumulation were approximately equivalent to the negative effects of removing carotenoids from the diet. The adverse
effects observed in this study have important implications for theories of the function and evolution of colorful plumage. 相似文献
217.
This study used structural equation modelling to examine the effects of socio-demographic variables and outdoor recreation participation on pro-environmental behaviour (PEB) among an ethnically diverse population of adult state-park visitors near Atlanta, Georgia, USA (N?=?319). Data collected through intercept surveys at three state parks were used to examine interactions among potential predictors of PEB, including socio-demographics (ethnicity, gender, education, and income), outdoor recreation participation (during childhood and adulthood), and environmental value orientations (biocentric and anthropocentric). The best fitting model accounted for 40% of the variance in self-reported PEB and indicated the strongest positive relationship between adult outdoor recreation participation and PEB (β?=?0.54, t?=?5.70). Biocentric and anthropocentric value orientation scores were also significant antecedents of PEB (β?=?0.17, t?=?1.99, and β?=?0.19, t?=?2.56, respectively), and both were influenced by socio-demographic variables. Overall, results suggest that a diverse public's environmental ethos and propensity to engage in PEBs could be influenced by outdoor recreation opportunities. 相似文献
218.
Seigneur C Lohman K Vijayaraghavan K Jansen J Levin L 《Journal of the Air & Waste Management Association (1995)》2006,56(6):743-751
Two mathematical models of the atmospheric fate and transport of mercury (Hg), an Eulerian grid-based model and a Gaussian plume model, are used to calculate the atmospheric deposition of Hg in the vicinity (i.e., within 50 km) of five coal-fired power plants. The former is applied using two different horizontal resolutions: coarse (84 km) and fine (16.7 km). More than 96% of the power plant Hg emissions are calculated with the plume model to be transported beyond 50 km from the plants. The grid-based model predicts a lower fraction to be transported beyond 50 km: >91% with a coarse resolution and >95% with a fine resolution. The contribution of the power plant emissions to total Hg deposition within a radius of 50 km from the plants is calculated to be <8% with the plume model, <14% with the Eulerian model with a coarse resolution, and <10% with the Eulerian model with a fine resolution. The Eulerian grid-based model predicts greater local impacts than the plume model because of artificially enhanced vertical dispersion; the former predicts about twice as much Hg deposition as the latter when the area considered is commensurate with the resolution of the grid-based model. If one compares the local impacts for an area that is significantly less than the grid-based model resolution, then the grid-based model may predict lower local deposition than the plume model, because two compensating errors affect the results obtained with the grid-based model: initial dilution of the power plant emissions within one or more grid cells and enhanced vertical mixing to the ground. 相似文献
219.
Candis S. Claiborn Dennis Finn Timothy V. Larson Jane Q. Koenig 《Journal of the Air & Waste Management Association (1995)》2013,63(8):1440-1445
ABSTRACT The revised National Ambient Air Quality Standards for PM include fine particulate standards based upon mass measurements of PM25. It is possible in arid and semi-arid regions to observe significant coarse mode intrusion in the PM2.5 measurement. In this work, continuous PM10, PM2.5, and PM1.0 were measured during several windblown dust events in Spokane, WA. PM2 5 constituted ~30% of the PM10 during the dust event days, compared with ~48% on the non-dusty days preceding the dust events. Both PM10 and PM2.5 were enhanced during the dust events. However, PM1.0 was not enhanced during dust storms that originated within the state of Washington. During a dust storm that originated in Asia and impacted Spokane, PM1.0 was also enhanced, although the Asian dust reached Washington during a period of stagnation and poor dispersion, so that local sources were also contributing to high particulate levels. The “intermodal” region of PM, defined as particles ranging in aerodynamic size from 1.0 to 2.5 um, was found to represent a significant fraction of PM25 (~51%) during windblown dust events, compared with 28% during the non-dusty days before the dust events. 相似文献