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141.
Luke Collins Brigitte Nerlich 《Environmental Communication: A Journal of Nature and Culture》2015,9(2):189-207
The public perception of climate change is characterized by heterogeneity, even polarization. Deliberative discussion is regarded by some as key to overcoming polarization and engaging various publics with the complex issue of climate change. In this context, online engagement with news stories is seen as a space for a new “deliberative democratic potential” to emerge. This article examines aspects of deliberation in user comment threads in response to articles on climate change taken from the Guardian. “Deliberation” is understood through the concepts “reciprocity”, “topicality”, and “argumentation”. We demonstrate how corpus analysis can be used to examine the ways in which online debates around climate change may create or deny opportunities for multiple voices and deliberation. Results show that whilst some aspects of online discourse discourage alternative viewpoints and demonstrate “incivility”, user comments also show potential for engaging in dialog, and for high levels of interaction. 相似文献
142.
Kerry L. Whitworth Janice L. Kerr Luke M. Mosley John Conallin Lorraine Hardwick Darren S. Baldwin 《Environmental management》2013,52(4):837-850
Hypoxic blackwater events occur when large amounts of organic material are leached into a water body (e.g., during floodplain inundation) and rapid metabolism of this carbon depletes oxygen from the water column, often with catastrophic effects on the aquatic environment. River regulation may have increased the frequency and severity of hypoxic blackwater events in lowland river systems, necessitating management intervention to mitigate the impacts of these events on aquatic biota. We examine the effectiveness of a range of mitigation interventions that have been used during large-scale hypoxic blackwater events in the Murray–Darling Basin, Australia and that may be applicable in other environments at risk from hypoxic blackwater. Strategies for hypoxia mitigation include: delivery of dilution flows; enhancement of physical re-aeration rates by increasing surface turbulence; and diversion of blackwater into shallow off-channel storages. We show that the impact of dilution water delivery is determined by relative volumes and water quality and can be predicted using simple models. At the dilution water inflow point, localized oxygenated plumes may also act as refuges. Physical re-aeration strategies generally result in only a small increase in dissolved oxygen but may be beneficial for local refuge protection. Dilution and natural re-aeration processes in large, shallow lake systems can be sufficient to compensate for hypoxic inflows and water processed in off-channel lakes may be able to be returned to the river channel as dilution flows. We provide a set of predictive models (as electronic supplementary material) for estimation of the re-aeration potential of intervention activities and a framework to guide the adaptive management of future hypoxic blackwater events. 相似文献
143.
In studies of commercial fishing, little attention has been paid to the use of bait. We examined lobster fishery bait-to-catch ratios in St. Margaret's Bay and Mahone Bay, Nova Scotia. Data were obtained from the Fishermen and Scientists Research Society's Lobster Recruitment Project. Local ecological knowledge of the resource users from within the study area was also gathered using semi-structured interviews. The estimated amount of bait required to catch each lobster, weighing about 480 g, ranged from 185 g (November) to 1455 g (April) for average months during the 2002/3, 2003/4 and 2004/5 fishing seasons. We estimated the overall ratio of bait-to-catch to be about 1.9 units of bait per unit of catch. The eco-efficiency and food-supply implications of consuming more bait than product in a fishery are outlined. 相似文献
144.
The plainfin midshipman Porichthys notatus Girard occurs in nearshore waters off the western coast of North America. We found that the ventrally directed photophores
of juvenile laboratory-grown P. notatus function in counterillumination. Their bioluminescence matched downwelling light to obscure the silhouette as viewed from
below. P. notatus did not obligatorily counterilluminate at all times in appropriate light. A hydrodynamic stimulus, in addition to appropriate
downwelling light, was required to induce counterillumination. This is perhaps an adaptation to conserve its Vargula-type luciferin, which is obtained from its diet. The angular distribution of light produced by P. notatus approximated that typical of downwelling light in the ocean. There was a direct relationship between downwelling irradiance
and the maximum intensity of P. notatus luminescence. Insufficient light was produced to replace the light blocked by the fish under lighting conditions typical
of the natural environment. The luminescence was, however, effective in eliminating the silhouette of P. notatus as observed with an image-intensifying camera and by dark-adapted human observers. Consequently, the effectiveness of counterillumination
probably originates in part from the disruptive pattern of the luminous photophores. P. notatus from the Puget Sound population, which lacks a luciferin source and is non-luminous, displayed counterillumination behavior
when its luminescent system was activated by force-feeding the fish with dried Vargula hilgendorfi. Experiments using adult P. notatus as predators on a mixed population of non-luminous (Puget Sound) and luminous (Santa Barbara Channel) juvenile P. notatus revealed that under conditions of dim overhead illumination non-luminous P. notatus were preyed upon at twice the rate of luminous individuals. This is the first experimental evidence suggesting that counterillumination
is effective as an anti-predatory strategy.
Received: 25 August 1998 / Accepted: 25 March 1999 相似文献
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147.
Luke Beesley Eduardo Moreno-Jiménez Nicholas Lepp 《Environmental pollution (Barking, Essex : 1987)》2010,158(1):155-160
Three methods for predicting element mobility in soils have been applied to an iron-rich soil, contaminated with arsenic, cadmium and zinc. Soils were collected from 0 to 30 cm, 30 to 70 cm and 70 to 100 cm depths in the field and soil pore water was collected at different depths from an adjacent 100 cm deep trench. Sequential extraction and a column leaching test in the laboratory were compared to element concentrations in pore water sampled directly from the field. Arsenic showed low extractability, low leachability and occurred at low concentrations in pore water samples. Cadmium and zinc were more labile and present in higher concentrations in pore water, increasing with soil depth. Pore water sampling gave the best indication of short term element mobility when field conditions were taken into account, but further extraction and leaching procedures produced a fuller picture of element dynamics, revealing highly labile Cd deep in the soil profile. 相似文献
148.
Geographical variations in animal characters are one of the main subjects for study in macroecology. Variation with latitude
has received special interest. Articulated brachiopods are possibly the commonest macrofossil with large variations in size
of taxa through the fossil record. Here, we investigate trends in size of the 3 main orders of articulated brachiopod with
latitude and depth. Data were insufficient to identify patterns in Thecideida (a micromorph taxon only recorded from low latitudes).
Rhynchonellida had no clear trends in size with latitude or depth. Terebratulida exhibited hemispheric differences in size
relations, with increasing length of species towards the pole in the south and no significant trend in the north. Tropical
species were small (<20 mm length between 10°N and 10°S), and the largest species were found between 30° and 60° latitude
in both hemispheres. There were no articulated brachiopods recorded from the high arctic, and support for a continuous trend
in size with latitude was small or absent. In Terebratulida, there was a significant decrease in species length with depth
of 1.7 mm per 100 m depth increase. These trends could be explained by competition for space and reduced availability of habitat
with progressive depth beyond the continental shelf. 相似文献
149.
Deborah Keeley Shane TurnerPeter Harper 《Journal of Loss Prevention in the Process Industries》2011,24(3):237-241
The UK Health and Safety Executive (HSE) requires failure rate data for the assessment of COMAH safety reports and in the implementation of its statutory functions relating to land use planning in the vicinity of major hazard sites. Many of the existing failure rates used by HSE were derived over 20 years ago, but have been subject to periodic review to ensure that they remain appropriate for modern planning enquiries or quantified risk assessments. HSE needs to be assured that its sources of data and their application continue to be fit to support its statutory duties.HSE has implemented a programme of work to be carried out by the Health and Safety Laboratory (HSL). This includes the development and maintenance of a single source of quality assured failure rate data, ideally accessible from the Internet, bringing together and updating existing failure rate data sources and reviewing new sources not previously available to HSE.A review of HSE’s current failure rate values is being carried out and this will be used to generate a single source of publically available failure rate data for use by both HSE and the public. This would help industry and HSE move toward a common position or understanding on failure rates. It would also help ensure that HSE professional advice is defensible and transparent.This paper will detail the progress made to date on the programme of work. It will also discuss the issues that arise as a consequence of changing failure rates and how HSE deals with these issues. 相似文献
150.
Compared with groundwater pollution episodes of a point-source nature, nonpoint-source contamination makes for particularly
difficult policy design. This is especially true in the context of a mixed land-use aquifer, where the same pollutant may
derive from various human land-use activities and in different concentrations. To data, the emprirical literature attempting
to estimate the relative loadings of pollutants from alternative land uses is rather sparse. Yet this information is vital
to a variety of numerical computer models used to predict likelihood of groundwater contamination, and the statistical results
are useful in their own right for regional policy formation. Regression analysis is applied to estimate loadings of nitrate
and sodium from various land uses. The model is then used to illustrate how well-intended local groundwater protection policies
that fail to recognize land-use substitution and cross-pollutant effects may be misdirected. 相似文献