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311.
Environmental stratifications provide the framework for efficient surveillance and monitoring of biodiversity and ecological resources, as well as modelling exercises. An obstacle for agricultural landscape monitoring in Estonia has been the lack of a framework for the objective selection of monitoring sites. This paper describes the construction and testing of the Environmental Stratification of Estonia (ESE). Principal components analysis was used to select the variables that capture the most amount of variation. Seven climate variables and topography were selected and subsequently subjected to the ISODATA clustering routine in order to produce relatively homogeneous environmental strata. The ESE contains eight strata, which have been described in terms of soil, land cover and climatic parameters. In order to assess the reliability of the stratification procedure for the selection of monitoring sites, the ESE was compared with the previous map of Landscape Regions of Estonia and correlated with five environmental data sets. All correlations were significant. The stratification has therefore already been used to extend the current series of samples in agricultural landscapes into a more statistically robust series of monitoring sites. The potential for applying climate change scenarios to assess the shifts in the strata and associated ecological impacts is also examined.  相似文献   
312.
313.
The study deals with the problem of evaluating management strategies for pure stands of Norway spruce (Picea abies Karst) to balance adaptation to and mitigation of climate change, taking into account multiple objectives of a forest owner. A simulation and optimization approach was used to evaluate the management of a 1000 ha model Age-Class forest, representing the age-class distribution of an area of 66,000 ha of pure Norway spruce forests in the Black Forest region of Southwest Germany. Eight silvicultural scenarios comprising five forest conversion schemes which were interpreted as “adaptation” strategies which aims at increasing the proportion of Beech, that is expected to better cope with climate change than the existing Norway spruce, and three conventional strategies including a “Do-nothing” alternative classified as “mitigation”, trying to keep rather higher levels of growing stock of spruce, were simulated using the empirical growth simulator BWINPro-S. A linear programming approach was adapted to simultaneously maximize the net present values of carbon sequestration and timber production subject to the two constraints of wood even flow and partial protection of the oldest (nature protection). The optimized plan, with the global utility of 11,687 €/ha in forty years, allocated a combination of silvicultural scenarios to the entire forest area. Overall, strategies classified as “mitigation” were favored, while strategies falling into the “adaptation”-category were limited to the youngest age-classes in the optimal solution. Carbon sequestration of the “Do-nothing” alternative was between 1.72 and 1.85 million tons higher than the other alternatives for the entire forest area while the differences between the adaptation and mitigation approaches were approximately 133,000 tons. Sensitivity analysis showed that a carbon price of 21 €/t is the threshold at which carbon sequestration is promoted, while an interest rate of above 2% would decrease the amount of carbon.  相似文献   
314.
Potential exposures from ground-level pyrotechnics were assessed by air monitoring and developing emission factors. Total particulate matter, copper and SO2 exposures exceeded occupational health guidelines at two outdoor performances using consumer pyrotechnics. Al, Ba, B, Bi, Mg, Sr, Zn, and aldehyde levels were elevated, but did not pose a health hazard based on occupational standards. Emission factors for total particulate matter, metals, inorganic ions, aldehydes, and polyaromatic hydrocarbons (PAHs) were determined for seven ground-supported pyrotechnics through air sampling in an airtight room after combustion. Particle generation ranged from 5 to 13% of the combusted mass. Emission factors (g Kg?1) for metals common to pyrotechnics were also high: K, 23–45; Mg, 1–7; Cu, 0.05–7; and Ba, 0.03–6. Pb emission rates of 1.6 and 2.7% of the combusted mass for two devices were noteworthy. A high correlation (r2 ≥ 0.89) between metal concentrations in pyrotechnic compositions and emission factors were noted for Pb, Cr, Mg, Sb, and Bi, whereas low correlations (r2 ≤ 0.1) were observed for Ba, Sr, Fe, and Zn. This may be due to the inherent heterogeneity of multi-effect pyrotechnics. The generation of inorganic nitrogen in both the particulate (NO2?, NO3?) and gaseous (NO, NO2) forms varied widely (<0.1–1000 mg Kg?1). Aldehyde emission factors varied by two orders of magnitude even though the carbon source was carbohydrates and charcoal for all devices: formaldehyde (<7.0–82 mg Kg?1), acetaldehyde (43–210 mg Kg?1), and acrolein (1.9–12 mg Kg?1). Formation of lower molecular weight PAHs such as naphthalene and acenaphthylene were favored, with their emission factors being comparable to that from the combustion of household refuse and agricultural debris. Ba, Sr, Cu, and Pb had emission factors that could produce exposures exceeding occupational exposure guidelines. Sb and unalloyed Mg, which are banned from consumer fireworks in the US, were present in significant amounts.  相似文献   
315.
Ecological impacts of water-quality problems have developed in the western United States resulting from the disposal of seleniferous agricultural wastewater in wetland areas. Overt effects of selenium toxicosis occurred at five areas where deformities of wild aquatic birds were similar to those first observed at Kesterson National Wildlife Refuge in the west-central San Joaquin Valley of California. These areas are: Tulare Lake Bed Area, California, Middle Green River Basin, Utah, Kendrick Reclamation Project Area, Wyoming, Sun River Basin, Montana, and Stillwater Wildlife Management Area, Nevada. Potential for ecological damage is indicated at six more sites in Oregon, Colorado, the Colorado/Kansas border, and South Dakota out of 16 areas in 11 states where biological tissue data were collected. This conclusion is based on the fact that selenium bioaccumulated in bird livers to median levels that had exceeded or were in the range associated with adverse reproductive effects. Selenium concentrations in samples of fish and bird eggs support these conclusions at a majority of these areas. Reason for concern is also given for the lower Colorado River Valley, although this is not exclusively a conclusion from these reconnaissance data. Biogeochemical conditions and the extent of selenium contamination of water, bottom sediment, and biota from which this assessment was made are given here. In a companion paper, the biogeochemical pathway postulated for selenium contamination to take place from natural geologic sources to aquatic wildlife is defined.  相似文献   
316.
Dynamics of metal adaptation in riverine chironomids   总被引:3,自引:0,他引:3  
The ability of the non-biting midge Chironomus riparius to survive and reproduce in metal polluted lowland rivers facilitates the opportunity to study micro-evolutionary processes in situ. However, due to larval drift, adapted midge populations are subject to regular immigration of non-adapted specimens from clean upstream river reaches. To examine the influence of non-adapted genes in adapted midge populations on the level of metal adaptation, an upstream and downstream chironomid population were crossbred on eight separate occasions in the laboratory to mimic gene flow. Several life-history characteristics, indicating adaptation to metals, were followed seasonally in the parental strains as well as in the reciprocal crossings. Such crossings were done over a 14-month period and maternal effects were found to be absent, indicating a major genetic component for the increased metal tolerance in the exposed midge populations. Furthermore, results confirmed the presence of adaptation to metals in exposed chironomids. However, a rapid loss of metal adaptation in the first generation hybrid offspring was clearly demonstrated. Consequently, the large temporal variation in metal adaptation in midge populations from the river can be explained by the earlier reported seasonal variations in selection pressure and immigration rates from non-adapted sub-populations.  相似文献   
317.
Over the next century, society will increasingly be confronted with the impacts of global change (e.g. pollution, land use changes, and climate change). Multiple scenarios provide us with a range of possible changes in socio-economic trends, land uses and climate (i.e. exposure) and allow us to assess the response of ecosystems and changes in the services they provide (i.e. potential impacts). Since vulnerability to global change is less when society is able to adapt, it is important to provide decision makers with tools that will allow them to assess and compare the vulnerability of different sectors and regions to global change, taking into account exposure and sensitivity, as well as adaptive capacity. This paper presents a method that allows quantitative spatial analyses of the vulnerability of the human-environment system on a European scale. It is a first step towards providing stakeholders and policy makers with a spatially explicit portfolio of comparable projections of ecosystem services, providing a basis for discussion on the sustainable management of Europe’s natural resources.
Marc J. MetzgerEmail: Phone: +31-317-482983Fax: +31-317-484839
  相似文献   
318.
A residential area that was formerly part of a silver factory site severely contaminated with chlorinated solvents was remediated using an in situ electro‐bioreclamation technique. Electro‐bioreclamation is a method for heating soil and groundwater combined with soil vapor and low‐yield groundwater extraction and enhanced reductive dechlorination (ERD). During the first two years of remediation in the source area (the intensive phase), a total of 80 kg of volatile organic compounds (VOCs) was removed by heating combined with ERD. After another two years of ERD in the source and plume areas (the attenuation phase), the VOC concentrations were reduced to a level below 100 μg/L in groundwater. Given these satisfying results, electro‐reclamation in combination with ERD turned out to be a successful in situ remediation technique for removing VOCs. © 2006Wiley Periodicals, Inc.  相似文献   
319.

Background

The analysis of the intrinsic effects of perfluorinated organic surfactants shows the group to have a characteristic overall picture:
  • -high polarity
  • -high thermal and chemical stability
  • -ubiquitous distribution
  • -non-biodegradability
  • -multiple toxicity
  • In addition, certain substances belonging to this group (e.g. PFOS) exhibit a very long retention time in the human body. Toxic properties vary and, like the mechanisms for global distribution, have not been fully clarified. In the meantime, individual members of this substance group have been (are being) removed from the market. This report shows that in future the planned EU chemicals law (REACH) can be used to prevent such substances being regulated after they have been distributed in the environment and thus after damage has already occurred. To this end, however, the requirements for registration for low tonnage substances (1–10 tonnes/a) must be supplemented with specific tests (in particular on biodegradability)

    Aim and Scope

    The aim of the work was to analyse the intrinsic properties and risks of a subgroup of fluorinated organic substances.

    Results

    A summarising article describes the toxic effects and properties of a group of substances selected from the approximately 30,000 existing substances. With regard to the ongoing debate on revising the European regulations of existing substances (REACH). it is apparent that standardised test requirements cannot be applied to impact and risk analyses which are at times highly complex. For governments, REACH only provides the starting points for this process in the form of prescribed standard tests. If a substance (or a substance group) draws attention, more detailed tests must be carried out by the industry itself in the framework of responsible care and in the framework of the evaluation step of REACH. It is therefore important that the standard requirements of REACH are selected appropriately. In this respect, the study reveals some serious deficiencies in the Commission proposal.

    Conclusion

    The standard information for low tonnage substances (1–10 tonnes/a) must be supplemented in particular with an obligatory test on biodegradability. The possibility provided by the REACH dossier to evaluate substances on the basis of group observarions (SAR, QSAR e.g.) is to be welcomed.  相似文献   
    320.
    Environmental Chemistry Letters - Groundwater is the main source of freshwater in the European Union, yet freshwaters are polluted by organic contaminants if contaminants are not efficiently...  相似文献   
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