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71.
During R.R.S. Discovery Cruise 100 in the Southern Ocean (1979), 620 specimens of the Antarctic cranchiid squid Galiteuthis glacialis (Chun) were caught in the RMT8 opening-closing net, to the south of the Antarctic Polar Front (APF). The catch was dominated by individuals <20 mm dorsal mantle length (DML) and, apart from two specimens, the rest of the catch was <60 mm DML. Two larger squid (255 mm DML) were both immature and apparently female. The species is concentrated at a depth of 300 to 400 m; there is evidence of ontogenetic spreading and a shift in the modal depth of the population from the 300 to 400 m horizon in daylight to the 200 to 300 m horizon in darkness. The collection confirms the circumpolar distribution of the species and supports previous evidence that it rarely, if ever, occurs to the north of the APF. As in Mesonychoteuthis hamiltoni, the only other species of cranchiid squid known to occur south of the APF, the early-life phase of G. glacialis is concentrated in the upper zone of the warm deep water beneath the Antarctic surface layer where, putatively, there is a zone of enhanced biological activity. 相似文献
72.
Esther Clarke Ulrich H. Reichard Klaus Zuberbühler 《Behavioral ecology and sociobiology》2012,66(1):85-96
Predation on gibbons is rarely observed in the wild. However, the gibbons' moderate body size and relatively small social
groups suggest high vulnerability to predation. To assess the role of predation and to study their anti-predator behaviour,
we presented visual predator models to nine groups of wild white-handed gibbons at Khao Yai National Park, Thailand. We measured
subjects' immediate and delayed responses to four potential predators: tiger, clouded leopard, crested serpent eagle and reticulated
python. Subjects reliably approached all four predators. In response to tigers and leopards, they additionally produced predator-specific
songs and defecated copiously. In terms of delayed responses, distance between mated adults decreased, but only after exposure
to the tiger model. In response to eagles and pythons, gibbons consistently vocalised, but this did not always include predator
singing, and we found no long-term effects in overall activity or strata use. However, during 6 of 26 predator encounters,
the gibbons produced songs with a structure that was intermediate between a duet song and a predator song more than 20 min
after the predator encounter, indicating a long-term effect on their vocal behaviour. This study demonstrates that gibbons
discriminate between different potential predators and respond to them with adaptive anti-predator behaviour, which include
predator-specific vocal responses. We conclude that gibbons are not immune to predation and that terrestrial predators elicit
consistent immediate and delayed anti-predation responses. 相似文献
73.
The atomised nature of the humanitarian system has led to frequent and repeated attempts to coordinate humanitarian activity. Since 2005, some of the best resourced, and arguably most successful, coordination mechanisms have been the humanitarian Clusters, groups of UN (United Nations) and non‐UN actors that engage in sectoral coordination of humanitarian response (such as the provision of healthcare and water) at the global and country level. Nevertheless, it is not clear exactly what ‘coordination’ means in the context of a Cluster. Formal guidance suggests that they should be aiming to create a single, joint strategy to guide the activities of members. Actual experience of the Clusters, however, indicates that looser forms of coordination are more effective. This finding resonates with organisational theory, and with the experience of emergency management professionals beyond the international humanitarian sector. To capitalise fully on the success of the Clusters, policymakers may need to rethink their attitudes to, and expectations of, coordination. 相似文献
74.
Dune slack habitats are highly dependent on the availability of water to support flora and fauna. Typically this is provided
by shallow groundwater. This paper describes the seasonal and long term variation in groundwater levels in part of the Sefton
coastline between 1972 and 2007. The effects of climate change, vegetation management and coastline realignment on groundwater
levels are modelled. The observed annual water table levels rise and fall with an amplitude of 1.5 m, but longer term variations
and trends are apparent. A stochastic water balance model was used to describe the changes in water table levels in slack
floors in the open dunes and also in areas afforested with pine trees. It was found that the pine trees evaporated 214 mm/year
more than open dunes vegetation, resulting in the water table being 0.5–1.0 m lower under the trees than under the open dunes.
The effects of climate change on the ground water was simulated using predictions of future climate conditions based on the
UKCIP02 medium high emissions scenario. The increase in temperature and change in rainfall patterns will result in a decrease
in mean ground water levels by 1.0–1.5 mm in the next 90 years. Typical patterns consist of sequences of 5–10 years of low
water table levels interspersed by infrequent sequences consisting of 2–5 years of relatively high or “normal” levels. These
results indicate that that flora and fauna that cannot survive a 5–10 year period of water table levels >2.5 m below ground
level are unlikely to survive or persist in many slack areas and a change in the ecology of these slack may become inevitable.
Other effects of climate change include sea level rise which will result in a gradual rise in water table levels. Coastal
erosion will increase the water table gradient to the sea and result in a slight lowering of the ground water levels. Conversely
coastal accretion will reverse this process. The spatial distribution of coastal erosion and accretion along the Sefton coastline
and its likely impacts on groundwater levels are discussed. The modelling work described in this paper has identified the
factors which have the largest effect on groundwater levels in temperate coastal dune systems. 相似文献
75.
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77.
The ability of near‐surface disposal facility cover designs to meet percolation performance criteria is influenced by degradation occurring over long periods of time. This study was conducted to determine the effect of degradation on percolation based on probabilistic distributions derived from historical climate data. Water‐balance predictions were evaluated using the HELP model, employing several variations of degradation in a traditional Resource Conservation and Recovery Act disposal facility cover design over a 100‐year simulation period. Analysis results were evaluated relative to two different selected thresholds for annual percolation (1 mm and 3 mm). Approximately 20 percent of the results did not exceed both the 1‐mm and 3‐mm thresholds, while 10 percent of the realizations exceeded the 1‐mm threshold but not the 3‐mm threshold, with remaining cases exceeding the 3‐mm threshold. These results demonstrate the importance of considering degradation in designing near‐surface disposal facilities, especially given the very long performance periods desired by different regulators. © 2013 Wiley Periodicals, Inc. 相似文献
78.
Charles L. Blanchard Shelley J. Tanenbaum 《Journal of the Air & Waste Management Association (1995)》2013,63(7):816-828
Abstract Ambient air quality data were analyzed to empirically evaluate the effects of reductions of volatile organic compounds (VOCs) and oxides of nitrogen (NOx) emissions on weekday and weekend levels of ozone (O3; 1991–1998) and particulate NO3 - (1980–1999) in southern California. Despite significantly lower O3 precursor levels on weekends, 20 of 28 South Coast Air Basin (SoCAB) sites (28 of all 78 southern California sites) showed statistically significant higher mean O3 levels on Sundays than on weekdays (p < 0.01); 49 of the remaining 50 sites showed no significant differences between mean weekday and Sunday peak O3 levels. We also observed no statistically significant differences between mean weekday and weekend concentrations of particulate NO3 - or nitric acid (HNO3, the precursor of particulate NO3 -). Averaged over sites, the mean Sunday NOx and nonmethane hydrocarbon concentrations were 25–41% and 16–30% lower, respectively, than on weekdays. Site-to-site differences between weekend and weekday mean peak hourly O3 levels were related to whether O3 formation was limited by the availability of NOx. A thermodynamic equilibrium model predicts that particulate NO3 - levels would decrease in response to a reduction of HNO3, and that particulate ammonium NO3 - formation was not limited by the availability of ammonia. The similarity of mean weekday and weekend levels of NO3 - therefore did not result from limitations on the formation of particulate NO3 - from its precursor, HNO3. 相似文献
79.
80.
Joseph H. Rustick David S. Kosson Steven L. Krahn Michael T. Ryan Craig H. Benson James H. Clarke 《补救:环境净化治理成本、技术与工艺杂志》2015,26(1):69-91
Near surface disposal facility design and management are examined and compared using a systems approach that defines facility performance as a function of three components (or subsystems): the disposal facility design (cover systems and bottom liners); the properties of the waste (waste composition, waste form and waste package); and the site‐specific environmental features (climate, geology, and hydrology). We report an evaluation of five DOE near surface disposal facility case studies, selected to provide a “representative” sample that included disposal sites with a range of waste and environmental characteristics across the DOE. The facilities selected were the Savannah River E‐Area Engineered Trenches, Hanford Integrated Disposal Facility, Idaho Radioactive Waste Management Complex, Oak Ridge Environmental Management Waste Management Facility, and Nevada National Security Site Area 5. ©2015 Wiley Periodicals, Inc. 相似文献