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181.
The development of three pikeperch (Sander lucioperca (L.)) populations in the northern Baltic Sea was monitored using standardized multimesh gillnets in 1995–2009. Declining trends in the abundances of pikeperch over 40 cm total length, low numbers of individuals older than 6 years, and high mortality rates were observed in all three populations. In the site with the largest commercial catches per unit area and a rapidly increased colony of great cormorants (Phalacrocorax carbo sinensis Blumenbach 1798), also the abundance of pikeperch below 40 cm total length and year-class strength showed declining trends. The adverse population level changes did not correlate with changes in water quality or eutrophication status. Together, the results suggest that in all study sites fisheries are harvesting a large proportion of the pikeperch soon after or even before reaching the maturity, and that predation from great cormorants may increase mortality of juveniles. Pikeperch is important not only for fisheries but also for ecosystem functioning, and our results point at the need for further management measures to ensure viable populations in the areas studied.
Electronic supplementary material
The online version of this article (doi:10.1007/s13280-013-0429-z) contains supplementary material, which is available to authorized users. 相似文献182.
Climate change effects are expected to be more severe for some segments of society than others. In Mexico, climate variability associated with climate change has important socio-economic and environmental impacts. From the central mountainous region of eastern Veracruz, Mexico, we analyzed data of total annual precipitation and mean annual temperature from 26 meteorological stations (1922–2008) and from General Circulation Models. We developed climate change scenarios based on the observed trends with projections to 2025, 2050, 2075, and 2100, finding considerable local climate changes with reductions in precipitation of over 700 mm and increases in temperature of ~9°C for the year 2100. Deforested areas located at windward were considered more vulnerable, representing potential risk for natural environments, local communities, and the main crops cultivated (sugarcane, coffee, and corn). Socio-economic vulnerability is exacerbated in areas where temperature increases and precipitation decreases.
Electronic supplementary material
The online version of this article (doi:10.1007/s13280-015-0690-4) contains supplementary material, which is available to authorized users. 相似文献183.
Cox TP 《Disasters》2012,36(2):233-248
Prior to 1996 and the Congolese wars, exploitative land policies pushed farmers in the eastern highlands of the Democratic Republic of the Congo (DRC) into a vulnerable position, with cattle manure sustaining intensive cultivation. This exposed households to a complete breakdown in mixed farming as cattle became targets of war. This study of villages in South Kivu offers an inside understanding of continuity and change in farming practices in a region where there are no easy solutions, and it assesses how the province lost its present and where farmers look when they glance to the future. For farmers, who hold a broad view of soil fertility, the casualties of war were not only people and cattle but also the land itself, which has enduring scars. Perceiving a rupture in tradition, South Kivu farmers are searching desperately for new livelihoods that are built on education instead of livestock, setting aside old ethnic signifiers to seek a future beyond protracted conflict. 相似文献
184.
Monte L 《Journal of environmental radioactivity》2011,102(2):73-83
The present work illustrates the customisation and application of the decision support system MOIRA-PLUS (a MOdel-based computerised system for management support to Identify optimal remedial strategies for Restoring radionuclide contaminated Aquatic ecosystems and drainage areas) to the fresh water environment in Italy. MOIRA-PLUS is aimed at evaluating the behaviour of radiocaesium and radiostrontium in fresh water ecosystems and at assessing the appropriateness of suitable strategies for the management of contaminated water bodies by the application of multi-attribute analysis techniques. MOIRA-PLUS can be applied to complex networks of lakes, rivers and tributaries and can be straightforwardly customised utilising data and information from readily accessible sources such as official websites provided by scientific or government organisations. The present work shows an application of the decision system to 10 lakes and 18 rivers in Italy contaminated with 137Cs of Chernobyl origin. Site-specific values of some aggregated transfer parameters were estimated for the most important Italian lakes. Although high values of fish and water consumptions were hypothesised, very low doses to public from the fresh water pathway following the accident were calculated. 相似文献
185.
Ra isotopes are a powerful tool for quantifying the flux of submarine groundwater discharge (SGD) into the sea. Previous studies of 223Ra and 224Ra mass balances in coastal embayments have shown that the Ra balance is dominated by supply via SGD, exchange with the open ocean and radioactive decay. The current study shows that a single time series over a tidal cycle at the principal inlet to Great South Bay (NY, US) is sufficient to determine the net flux of Ra across the inlet, and also can be used to estimate the decay of short-lived Ra in the bay. Estimates of the net Ra flux obtained from a single tidal time-series by using three different approaches agree with those determined from a more time-consuming survey of Ra within the bay, and may represent a first step of estimating SGD in bays and coastal lagoons. 相似文献
186.
北方湖泊水化学特征与发展态势 总被引:1,自引:0,他引:1
通过对国家级自然保护区的核心区达里诺尔湖水环境4年的研究,得出:有着典型代表的达里诺尔北方湖泊水环境以含盐量高、碱度大为主要化学特征,而且随着生态环境的破坏、湖水蒸发量的逐年增加,湖泊水质有着明显的恶化趋势。 相似文献
187.
According to the United States Environmental Protection Agency (US EPA), a significant percentage of residential onsite sewage
systems (OSSs) are failing at any given time. The US EPA has therefore issued a set of recommended guidelines for OSS regulatory
programs aimed at reducing overall failure rates. We conducted a survey of OSS regulatory program administrators with jurisdictions
bordering a Great Lake. Our goal was to determine their programs’ capacities to meet the US EPA’s recommendations. We found
that although some local programs meet the US EPA’s recommendations, most do not. In this article, we present our findings
and conclusions for one of the US EPA’s models, the baseline “Homeowner Awareness” model. Most areas do not have recommended
requirements that systems be inspected when properties transfer between owners. A majority do not track changes in ownership
within the computerized databases they use to record information about systems. Although most provide at least “one-time”
information to homeowners regarding proper OSS maintenance, most do not contact them periodically with reminders of needed
maintenance. We include recommendations for resolving some of the issues that our research identified. 相似文献
188.
What Drives Accelerated Land Cover Change in Central Argentina? Synergistic Consequences of Climatic,Socioeconomic, and Technological Factors 总被引:1,自引:0,他引:1
Synergistic combinations of climatic and land use changes have the potential to produce the most dramatic impacts on land
cover. Although this is widely accepted, empirical examples, particularly involving deforestation in Latin America, are still
very few. The geographic extent and causes of deforestation in subtropical seasonally dry forests of the world have received
very little attention. This is especially true for the Chaco forests in South America, which are being lost at an alarming
rate, sometimes higher than those reported for tropical forests. On this basis, the aims of this study were to analyze the
changes in land cover that have occurred during the last three decades of the 20th century in the Chaco forests of central
Argentina, and to explain the factors that have driven those changes. Results show major land cover changes. Approximately
80% of the area that was originally undisturbed forest is now occupied by crops, pastures, and secondary scrub. The main proximate
cause of deforestation has been agricultural expansion, soybean cultivation in particular. This appears as the result of the
synergistic convergence of climatic, technological, and socioeconomic factors, supporting the hypothesis of a multiple-factor
explanation for forest loss, while providing one of the very few existing analyses of changes in subtropical forests of the
world. 相似文献
189.
Morrice JA Danz NP Regal RR Kelly JR Niemi GJ Reavie ED Hollenhorst T Axler RP Trebitz AS Cotter AM Peterson GS 《Environmental management》2008,41(3):347-357
A better understanding of relationships between human activities and water chemistry is needed to identify and manage sources
of anthropogenic stress in Great Lakes coastal wetlands. The objective of the study described in this article was to characterize
relationships between water chemistry and multiple classes of human activity (agriculture, population and development, point
source pollution, and atmospheric deposition). We also evaluated the influence of geomorphology and biogeographic factors
on stressor-water quality relationships. We collected water chemistry data from 98 coastal wetlands distributed along the
United States shoreline of the Laurentian Great Lakes and GIS-based stressor data from the associated drainage basin to examine
stressor-water quality relationships. The sampling captured broad ranges (1.5–2 orders of magnitude) in total phosphorus (TP),
total nitrogen (TN), dissolved inorganic nitrogen (DIN), total suspended solids (TSS), chlorophyll a (Chl a), and chloride; concentrations were strongly correlated with stressor metrics. Hierarchical partitioning and all-subsets
regression analyses were used to evaluate the independent influence of different stressor classes on water quality and to
identify best predictive models. Results showed that all categories of stress influenced water quality and that the relative
influence of different classes of disturbance varied among water quality parameters. Chloride exhibited the strongest relationships
with stressors followed in order by TN, Chl a, TP, TSS, and DIN. In general, coarse scale classification of wetlands by morphology (three wetland classes: riverine, protected,
open coastal) and biogeography (two ecoprovinces: Eastern Broadleaf Forest [EBF] and Laurentian Mixed Forest [LMF]) did not
improve predictive models. This study provides strong evidence of the link between water chemistry and human stress in Great
Lakes coastal wetlands and can be used to inform management efforts to improve water quality in Great Lakes coastal ecosystems. 相似文献
190.
Steinman AD Biddanda B Chu X Thompson K Rediske R 《Environmental monitoring and assessment》2007,134(1-3):177-189
Groundwater withdrawal has major economic, social, and environmental implications. In Michigan, recent legislative activity
has begun to address the issue of groundwater sustainability. However, more hydrologic data are needed to help inform policy
and legislation. A study was conducted in Mecosta County, Michigan to: (1) determine if a relationship could be established
between land use/land cover and groundwater quality; and (2) develop a conceptual model for the shallow groundwater system
of the study region. In general, groundwater quality was good, with below detection levels of E. coli, low total bacterial counts, and relatively low nutrient concentrations. No statistically significant associations were found
between the bacterial numbers and either land use or the physical/chemical attributes measured, which may be because the scale
of our spatial analysis was too coarse to detect patterns. Finer-scale, localized processes may have a greater influence on
microorganism growth and abundance than coarser-scale, regional processes in this area. Our groundwater analysis suggested
that shallow groundwater flow paths are generally consistent with regional surface water flow networks, and that shallow groundwater
levels in most of the region have fluctuated within 1–2 m over the past 30 years, with no obvious increasing or decreasing
trend. 相似文献