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281.
A geophysical seismic survey was conducted in the summer of 2001 off the northeastern coast of Sakhalin Island, Russia. The
area of seismic exploration was immediately adjacent to the Piltun feeding grounds of the endangered western gray whale (Eschrichtius robustus). This study investigates relative abundance, behavior, and movement patterns of gray whales in relation to occurrence and
proximity to the seismic survey by employing scan sampling, focal follow, and theodolite tracking methodologies. These data
were analyzed in relation to temporal, environmental, and seismic related variables to evaluate potential disturbance reactions
of gray whales to the seismic survey. The relative numbers of whales and pods recorded from five shore-based stations were
not significantly different during periods when seismic surveys were occurring compared to periods when no seismic surveys
were occurring and to the post-seismic period. Univariate analyses indicated no significant statistical correlation between
seismic survey variables and any of the eleven movement and behavior variables. Multiple regression analyses indicated that,
after accounting for temporal and environmental variables, 6 of 11 movement and behavior variables (linearity, acceleration,
mean direction, blows per surfacing, and surface-dive blow rate) were not significantly associated with seismic survey variables,
and 5 of 11 variables (leg speed, reorientation rate, distance-from-shore, blow interval, and dive time) were significantly
associated with seismic survey variables. In summary, after accounting for environmental variables, no correlation was found
between seismic survey variables and the linearity of whale movements, changes in whale swimming speed between theodolite
fixes, mean direction of whale movement, mean number of whale exhalations per minute at the surface, mean time at the surface,
and mean number of exhalations per minute during a whales surface-to-dive cycle. In contrast, at higher received sound energy
exposure levels, whales traveled faster, changed directions of movement less, were recorded further from shore, and stayed
under water longer between respirations. 相似文献
282.
Ryan J. K. Dunn Sasha Zigic Glenn R. Shiell 《Environmental monitoring and assessment》2014,186(10):6107-6125
Numerical models are useful for predicting the transport and fate of contaminants in dynamic marine environments, and are increasingly a practical solution to environmental impact assessments. In this study, a three-dimensional hydrodynamic model and field data were used to validate a far-field dispersion model that, in turn, was used to determine the fate of treated wastewater (TWW) discharged to the ocean via a submarine ocean outfall under hypothetical TWW flows. The models were validated with respect to bottom and surface water current speed and direction, and in situ measurements of total nitrogen and faecal coliforms. Variations in surface and bottom currents were accurately predicted by the model as were nutrient and coliform concentrations. Results indicated that the ocean circulation was predominately wind driven, evidenced by relatively small oscillations in the current speeds along the time-scale of the tide, and that dilution mixing zones were orientated in a predominantly north-eastern direction from the outfall and parallel to the coastline. Outputs of the model were used to determine the ‘footprint’ of the TWW plume under a differing discharge scenario and, particularly, whether the resultant changes in TWW contaminants, total nitrogen and faecal coliforms would meet local environmental quality objectives (EQO) for ecosystem integrity, shellfish harvesting and primary recreation. Modelling provided a practical solution for predicting the dilution of contaminants under a hypothetical discharge scenario and a means for determining the aerial extent of exclusion zones, where the EQOs for shellfish harvesting and primary recreation may not always be met. Results of this study add to the understanding of regional discharge conditions and provide a practical case study for managing impacts to marine environments under a differing TWW discharge scenario, in comparison to an existing scenario. 相似文献
283.
Sachs JD Remans R Smukler SM Winowiecki L Andelman SJ Cassman KG Castle D DeFries R Denning G Fanzo J Jackson LE Leemans R Lehmann J Milder JC Naeem S Nziguheba G Palm CA Pingali PL Reganold JP Richter DD Scherr SJ Sircely J Sullivan C Tomich TP Sanchez PA 《Journal of environmental monitoring : JEM》2012,14(3):738-742
The development of effective agricultural monitoring networks is essential to track, anticipate and manage changes in the social, economic and environmental aspects of agriculture. We welcome the perspective of Lindenmayer and Likens (J. Environ. Monit., 2011, 13, 1559) as published in the Journal of Environmental Monitoring on our earlier paper, "Monitoring the World's Agriculture" (Sachs et al., Nature, 2010, 466, 558-560). In this response, we address their three main critiques labeled as 'the passive approach', 'the problem with uniform metrics' and 'the problem with composite metrics'. We expand on specific research questions at the core of the network design, on the distinction between key universal and site-specific metrics to detect change over time and across scales, and on the need for composite metrics in decision-making. We believe that simultaneously measuring indicators of the three pillars of sustainability (environmentally sound, social responsible and economically viable) in an effectively integrated monitoring system will ultimately allow scientists and land managers alike to find solutions to the most pressing problems facing global food security. 相似文献
284.
Glenn EP Hucklebridge K Hinojosa-Huerta O Nagler PL Pitt J 《Environmental management》2008,41(3):322-335
Arid zone rivers have highly variable flow rates, and flood control projects are needed to protect adjacent property from
flood damage. On the other hand, riparian corridors provide important wildlife habitat, especially for birds, and riparian
vegetation is adapted to the natural variability in flows on these rivers. While environmental and flood control goals might
appear to be at odds, we show that both goals can be accommodated in the Limitrophe Region (the shared border between the
United States and Mexico) on the Lower Colorado River. In 1999, the International Boundary and Water Commission proposed a
routine maintenance project to clear vegetation and create a pilot channel within the Limitrophe Region to improve flow capacity
and delineate the border. In 2000, however, Minute 306 to the international water treaty was adopted, which calls for consideration
of environmental effects of IBWC actions. We conducted vegetation and bird surveys within the Limitrophe and found that this
river segment is unusually rich in native cottonwood and willow trees, marsh habitat, and resident and migratory birds compared
to flow-regulated segments of river. A flood-frequency analysis showed that the existing levee system can easily contain a
100 year flood even if vegetation is not removed, and the existing braided channel system has greater carrying capacity than
the proposed pilot channel. 相似文献
285.
A new framework for environmental assessment is needed because no existing framework explicitly includes all types of environmental
assessments. We propose a framework that focuses on resolving environmental problems by integrating different types of assessments.
Four general types of assessments are included: (1) condition assessments to detect chemical, physical, and biological impairments;
(2) causal pathway assessments to determine causes and identify their sources; (3) predictive assessments to estimate environmental,
economic, and societal risks, and benefits associated with different possible management actions; and (4) outcome assessments
to evaluate the results of the decisions of an integrative assessment. The four types of assessments can be neatly arrayed
in a two-by-two matrix based on the direction of analysis of causal relationships (rows) and whether the assessment identifies
problems or solves them (columns). We suggest that all assessments have a common structure of planning, analysis, and synthesis,
thus simplifying terminology and facilitating communication between types of assessments and environmental programs. The linkage
between assessments is based on intermediate decisions that initiate another assessment or a final decision signaling the
resolution of the problem. The framework is applied to three cases: management of a biologically impaired river, remediation
of a contaminated site, and reregistration of a pesticide. We believe that this framework clarifies the relationships among
the various types of assessment processes and their links to specific decisions. 相似文献