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251.
Polycyclic aromatic hydrocarbons (PAHs) are possible contaminants in some former industrial sites, representing a potential risk to human health if these sites are converted to residential areas. This work was conducted to determine whether PAHs present in contaminated soils are transferred to edible parts of selected vegetables. Soils were sampled from a former gasworks and a private garden, exhibiting a range of PAH concentrations (4 to 53 to 172 to 1263 and 2526 mg PAHs kg-1 of dry soil), and pot experiments were conducted in a greenhouse with lettuce (Lactuca sativa L. var. Reine de Mai), potato (Solanum tuberosum L. var. Belle de Fontenay), and carrot (Daucus carota L. var. Nantaise). At harvest, above- and below ground biomass were determined and the PAH concentrations in soil were measured. In parallel, plates were placed in the greenhouse to estimate the average PAH-dust deposition. Results showed that the presence of PAHs in soils had no detrimental effect on plant growth. Polycyclic aromatic hydrocarbons were detected in all plants grown in contaminated soils. However, their concentration was low compared with the initial soil concentration, and the bioconcentration factors were low (i.e., ranging from 13.4 x 10(-4) in potato and carrot pulp to 2 x 10(-2) in potato and carrot leaves). Except in peeled potatoes, the PAH concentration in vegetables increased with the PAH concentration in soils. The PAH distribution profiles in plant tissues and in soils suggested that root uptake was the main pathway for high molecular weight PAHs. On the opposite, lower molecular weight PAHs were probably taken up from the atmosphere through the leaves as well as by roots.  相似文献   
252.
Shrimp aquaculture in Vietnam is in the process of being transformed into a major industry around the intensification of the production system. The experiences of other countries in the region, especially in Thailand where high input production systems dominate, suggests that now is a critical time for intervention to redirect industry into pathways that are more sustainable ecologically, socially, and economically. In Thailand, years of experience with intensified systems and a complex industrial organization has not led to sustainable solutions. The challenge here is for society to regain control and then to redirect the transformation along more efficient and benign pathways. Our analyses suggest that current pathways in both countries are unlikely to lead to a sustainable industry. A complete transformation of the way shrimp are grown, fed, processed, distributed, and regulated is needed.  相似文献   
253.
The establishment of a safe distance between sources of pollution and air intakes is based on a complex exercise that should take into account several wind, physical, and topographical factors. To estimate the maximum concentrations of the pollutants as a function of the distance from the emission source, some heating, ventilation, and air conditioning (HVAC) system designers use the atmospheric dispersion models suggested by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE). Two of these models, the Halitsky and Wilson-Chui-Lamb models, have been developed and evaluated mainly with laboratory data. There have been relatively few evaluations with full-scale field data. The objective of this study, carried out on a building in downtown Montreal, Quebec, Canada, was to compare the measured concentrations of a tracer gas emitted by an exhaust stack with those predicted by these models. The results indicate that the Halitsky model gives lower than actual dilution, while the Wilson-Chui-Lamb model generally gives acceptable estimates, with occasional over-estimations of the dilution.  相似文献   
254.
Gill U  Bigras L  Schwartz H 《Chemosphere》2004,56(11):1097-1103
A routine, automated analytical method for simultaneous determination of total and inorganic mercury by cold vapour atomic absorption spectrometry in multimedia is described. Excellent accuracy and precision results were obtained with human hair certified reference materials namely, BCR-397 and IAEA-086. The reproducibility relative standard deviation for total mercury was 4% and 22%, respectively. The limit of detection for total and inorganic mercury was 0.2 μg/g hair. The described method has been successfully applied in determination of total and inorganic mercury as well as organic mercury in human hair, urine and fish tissue samples.  相似文献   
255.
Concern about adverse health effects arising out of human exposure to polluted seawater through bathing and other forms of aquatic recreation has led to the development of various quality criteria and standards worldwide. Attempts at quantifying health hazards from polluted recreational waters have been made in several Mediterranean countries through the conduction of epidemiological studies aimed at establishing direct correlation between the microbiological quality of the water and health effects on exposed population groups. This article provides an overview on the development of the criteria and standards for coastal recreational waters in the Mediterranean by examining the evolution of the WHO guidelines, the WHO/UNEP interim criteria for bathing waters and the EU Directives. It also provides a brief account of the various quality criteria and standards for coastal recreational waters in current use in all the Mediterranean countries.  相似文献   
256.
A stream is set apart from all other aquatic ecosystems in that the water is continually entering and leaving the stream and is in almost constant motion. Thus, there is essentially a unidirectional flow, a constant mixing of the watery medium, a continuous erosion of the substrate with concomitant changes in the characteristics of the stream bed, and little or no opportunity for the accumulation and retention of the dissolved nutrients. The physical and chemical characteristics of the stream are largely reflections of the physical and chemical makeup of the watershed. Because of the constant replacement of the water as it flows away, new nutrients must be brought into the stream continually in order to support the biotic communities. The kinds and amounts of nutrients that enter the stream determine, to a large extent, the numbers and kinds of organisms in the different communities. The organisms that comprise those communities may be categorized as representative species indigenous to springs, riffles, and pools. Most plants in streams are sessile whereas most of the animals are vagile, at least during some phase of their life cycle. All sessile organisms must depend on the current bringing their foodstuffs to them, but the vagile forms may seek out their foods in different parts of the stream and may even move from one community to another. Each community is adapted to its particular environment. Spring communities, because of the constancy of the physical and chemical environment, may reach what is essentially a “climax” situation and remain stable over long periods of time. Communities that occupy riffle and pool habitats may change from season to season and from year to year depending on changes in temperature, volume of flow, and the character of the substrate. Between each of these kinds of communities there are transitional areas that may be occupied by wider varieties of organisms than any of the three principal kinds of communities. In any event, the continuity of these communities in time and space is determined by the speed of the current which in turn depends upon the volume of flow. On this basis it becomes evident that the characteristics of the biotic communities are different at the source of a stream than at any other location. Similarly, riffle communities are different than those living in pools. The most difficult evaluation to be made in studying a stream ecosystem is that of the interlocking relationships among the many kinds of organisms. The plants, whatever kind they may be, fix carbon and other elements into organic compounds that can be utilized as food by the animals. The multitude of organisms that make up the bottom fauna of any stream are largely supported by the food formed directly by the plants. Such animals as small crustaceans, insect larvae, worms, turbellarians, mollusks, and the like serve as food for the carnivorous species. To determine the role of each organism in maintaining such a complex structure is a tremendous challenge. Many tools and methods are at the disposal of the biologist who dares to undertake such a project. Still, the greatest of all these is the dedication to spending long hours of tedious and, frequently, very hard work.  相似文献   
257.
The REDD-ALERT (Reducing Emissions from Deforestation and Degradation from Alternative Land Uses in the Rainforests of the Tropics) project started in 2009 and finished in 2012, and had the aim of evaluating mechanisms that translate international-level agreements into instruments that would help change the behaviour of land users while minimising adverse repercussions on their livelihoods. Findings showed that some developing tropical countries have recently been through a forest transition, thus shifting from declining to expanding forests at a national scale. However, in most of these (e.g. Vietnam), a significant part of the recent increase in national forest cover is associated with an increase in importation of food and timber products from abroad, representing leakage of carbon stocks across international borders. Avoiding deforestation and restoring forests will require a mixture of regulatory approaches, emerging market-based instruments, suasive options, and hybrid management measures. Policy analysis and modelling work showed the high degree of complexity at local levels and highlighted the need to take this heterogeneity into account—it is unlikely that there will be a one size fits all approach to make Reducing Emissions from Deforestation and Degradation (REDD+) work. Significant progress was made in the quantification of carbon and greenhouse gas (GHG) fluxes following land-use change in the tropics, contributing to narrower confidence intervals on peat-based emissions and their reporting standards. There are indications that there is only a short and relatively small window of opportunity of making REDD+ work—these included the fact that forest-related emissions as a fraction of total global GHG emissions have been decreasing over time due to the increase in fossil fuel emissions, and that the cost efficiency of REDD+ may be much less than originally thought due to the need to factor in safeguard costs, transaction costs and monitoring costs. Nevertheless, REDD+ has raised global awareness of the world’s forests and the factors affecting them, and future developments should contribute to the emergence of new landscape-based approaches to protecting a wider range of ecosystem services.  相似文献   
258.
The phylogeny of Collembola, originally discussed from a morphological point of view, has more recently benefited from novel insights brought by molecular analyses. Both morphological and molecular characters produced a well-resolved phylogenetic hypothesis including all orders, most families, and a large number of genera. However, several conflicting points exist between molecular and morphological data, and new characters are clearly needed to resolve these inconsistencies. In this study the usefulness of a new character type not previously used in the phylogenetic study of Collembola was tested: the epicuticular chemical compounds. Our phylogenetic analysis was based on 380 compounds from 26 Collembola species. The results show good resolution for terminal branches but not for internal nodes. This is probably due to the partial involvement of epicuticular lipids in ecological functions such as water conservation and sexual attraction. Thus, this character type is appropriate for reconstructing phylogenetic relationships among recently diversified groups. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   
259.
Global sustainability is increasingly influenced by processes of industrialisation and urbanization in non-OECD countries, especially in Asia. Growth models suggest that developing economies and regions will become first relatively more resource- and pollution-intensive, before converging on more resource-efficient and low-pollution production and consumption patterns expressed in developed countries. Alternative less resource- and pollution-intensive growth models for latecomer countries promise social and economic benefits in the short- and long-term. Drawing on insights from system innovation research on long-run change in socio-technical systems, we discuss the potential role of ‘sustainability experiments’ to generate innovations that will constitute new ‘greener’ growth models. We observe a great number of technology-based initiatives that we characterize as sustainability experiments in East and South Asian countries. These experiments emerge in the context of the growth of new socio-technical regimes in key sectors, including energy, transport, manufacturing, food and the built environment. We set out a conceptual framework for assessing the role of experiments, and for evaluating how they link with and become anchored into alternative more sustainable regimes. In this paper we argue that sustainability experiments represent a significant new source of innovation and capability-formation, linked to global knowledge and technology flows, which could reshape emergent socio-technical regimes and so contribute to alternative development pathways in latecomer countries. We conclude by summarizing the six papers published in this Special Issue.  相似文献   
260.
Social capacity building for natural hazards is a topic increasingly gaining relevance not only for so-called developing countries but also for European welfare states which are continuously challenged by the social, economic and ecological impacts of natural hazards. Following an outline of recent governance changes with regard to natural hazards, we develop a heuristic model of social capacity building by taking into account a wide range of existing expertise from different fields of research. Particular attention is paid to social vulnerability and its assessment, as well as to risk communication and risk education as specific strategies of social capacity building. We propose to distinguish between interventionist and participatory approaches, thus enabling for a better understanding of existing practices of social capacity building as well as their particular strengths and weaknesses. By way of conclusion, we encourage more research on social capacity building for natural hazards in the European context which at present is highly diverse and, at least in parts, only poorly investigated.  相似文献   
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