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131.
Carbon-isotope ratio gradients in western arctic zooplankton 总被引:2,自引:0,他引:2
Zooplankton from 87 stations in the Bering, Chukchi and Beaufort Seas sampled in 1985, 1986 and 1987 showed a geographic gradient in stable carbon-isotope ratios (13C). The zooplankton most depleted in 13C were found in the central and eastern Beaufort Sea and those most enriched were from the Bering and Chukchi Seas. Average 13C values ranged from-20.9 to-26.7 for copepods and from-19.4 to-25.1 for euphausiids. Euphausiids show a minimum of 1.0 enrichment relative to copepods throughout the study area. Relative biomasses of the major zooplankton taxa varied significantly across the Alaskan Beaufort Sea in October 1986, with euphausiids dominating in the west and copepods in the east. These differences in taxonomic composition affected the weighted 13C values for total zooplankton and may produce an even more pronounced geographic gradient in zooplankton 13C than that found within a single taxon. The bowhead whale Balaena mysticetus migrates between wintering areas in the Bering Sea and summering areas in the Beaufort Sea and feeds over this geographic range. The zooplankton 13C gradient is the probable source of 13C oscillations found along the baleen plates of this planktivore. 相似文献
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133.
Acoustic Doppler Current Profilers (ADCPs) are now used routinely by physical oceanographers. A by-product of the signal processing for calculating the Doppler shift used to determine current velocity is the intensity of the acoustic backscatter, and this, in turn, is a measure of biomass. ADCPs can therefore potentially provide biological oceanographers with quantitative information, collected routinely and non-intrusively in near real time. If these acoustic measurements are obtained concurrently with hydrographic data, the possibility of collecting quantitative biological information on the same time and space scales as physicochemical data becomes a reality. ADCPs have been routinely operated on NERC ships for several years. Examples of the types of biological information which can be obtained are described here in the hope that this will stimulate other users to make use of a potentially valuable source of data. 相似文献
134.
135.
Education and public participation are recognized as important elements of coastal zone management. The current paper describes
the Uk’s largest public participation survey concerned with coastal issues. Coastwatch UK involves thousands of volunteers
in an annual survey of the coastline. The project has several aims—primarily to provide an insight into the major problems
and threats to the coastline and, through the involvement of volunteers, to raise public awareness and aid environmental education
at all levels. 相似文献
136.
This study examines the impact of flooding on land of high conservation value located along part of the southern shoreline
of the River Clyde Estuary in western Scotland. This paper hypothesizes that, over the next 50 years, the frequency and extent
of coastal flooding will increase due to the gradual effect of global warming and the consequent rise in sea-level and increase
in storminess. It is argued that because of the great cost of constructing new flood defence systems it will not be possible
to protect all land areas to an equal extent from flooding. A means of ranking different land use will be necessary so that
society can make a rational judgement concerning which sections of coastline will be worth protecting. This study provides
a methodology that combines an objective ranking of conservation areas using non-economic indicators with a GIS model of flood
potential, and permits accurate forecasts of flood losses to conservation areas of different ecological value. The conservation
case study used in this paper proposes the use of an ecological weighting value based on five ecological variables each of
10 categories. Tables and maps identify the sites that have been highlighted as consisting of the most ‘valuable’ conservation
sites. The methodology makes extensive use of geographical information systems (GIS) to model the predicted areas of flooding
and to calculate conservation weighting values of the land areas. 相似文献
137.
Tobias Kuemmerle Daniel Müller Patrick Griffiths Marioara Rusu 《Regional Environmental Change》2009,9(1):1-12
The drastic socio-economic and political changes that occurred after the breakdown of socialism in Eastern Europe triggered
widespread land use change, including cropland abandonment and forest cover changes. Yet the rates and spatial patterns of
post-socialist land use change remain largely unclear. We used Landsat TM/ETM+ images to classify land cover maps and assess
landscape pattern changes from 1990 to 2005 in Argeş County, Southern Romania. Cropland abandonment was the most widespread
change (21.1% abandonment rate), likely due to declining returns from farming, tenure insecurity, and demographic developments
during transition. Forest cover and forest fragmentation remained remarkably stable during transition, despite widespread
ownership transfers. Cropland abandonment provides opportunities for increased carbon sequestration, but threatens cultural
landscapes and biodiversity. Continued monitoring is important for assessing whether abandoned croplands will eventually reforest
or be put back into production and to better understand the consequences of post-socialist land use change for ecosystems
and biodiversity. 相似文献
138.
Karl Van Scyoc Gareth Hughes 《Journal of Loss Prevention in the Process Industries》2009,22(6):689-694
Process safety practices have undergone multiple refinements over the past few decades, but major accidents continue to occur. Most organizations strive to improve performance by strengthening existing methods or by adopting new and/or different approaches. Central to these continual improvement efforts is the practice of applying lessons learned as a means to drive out potential risk exposures. Often, lessons learned may be transferred from other industries; indeed, high-performing organizations regularly benchmark practices outside of their immediate industry.In pursuit of continual process safety improvement, this paper examines risk management practices in the Rail Industry, and explores how methods intended for managing passenger and public rail safety may be transferred to drive continual improvement of process safety. Rail safety has its roots in engineered safety solutions; modern practices have additionally embraced the human aspects of safety performance. A selection of approaches for rail safety assessment and risk management are described in three areas considered fundamental to safety management: management of systems, management of technology, and management of human elements. In light of these examples, the authors provide views regarding how the field of process safety management may leverage the rail experience. 相似文献
139.
Granger SJ Bol R Dixon L Naden PS Old GH Marsh JK Bilotta G Brazier R White SM Haygarth PM 《Journal of environmental monitoring : JEM》2010,12(5):1159-1169
A study was undertaken on drained and undrained 1 ha grassland lysimeters to assess the effectiveness of multiple novel tracing techniques in understanding how agricultural slurry waste moves from land to water. Artificial fluorescent particles designed to mimic the size and density of organic slurry particles were found to move off the grassland via inter-flow (surface + lateral through-flow) and drain-flow. Where both pathways were present the drains carried the greater number of particles. The results of the natural fluorescence and δ13C of water samples were inconclusive. Natural fluorescence was higher from slurry-amended lysimeters than from zero-slurry lysimeters, however, a fluorescence decay experiment suggested that no slurry signal should be present given the time between slurry application and the onset of drainage. The δ13C values of >0.7 microm and <0.7 microm material in drainage were varied and unrelated to discharge. The mean value of >0.7 microm δ13C in water from the drain-flow pathways was higher from the lysimeter which had received naturally enriched maize slurry compared to the lysimeter which received grass slurry indicating a contribution of slurry-derived material. Values of <0.7 microm δ13C from the same pathway, however, produced counter intuitive trends and may indicate that different fractions of the slurry have different δ13C values. 相似文献
140.
Lagerwall Gareth Kiker Gregory Muñoz-Carpena Rafael Wang Naiming 《Environmental management》2017,59(1):129-140
Environmental Management - The coupled regional simulation model, and the transport and reaction simulation engine were recently adapted to simulate ecology, specifically Typha domingensis... 相似文献