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171.
Giuseppe Castaldelli Elisa Soana Erica Racchetti Enrica Pierobon Micol Mastrocicco Enrico Tesini Elisa Anna Fano Marco Bartoli 《Environmental management》2013,52(3):567-580
Detailed studies on pollutants genesis, path and transformation are needed in agricultural catchments facing coastal areas. Here, loss of nutrients should be minimized in order to protect valuable aquatic ecosystems from eutrophication phenomena. A soil system N budget was calculated for a lowland coastal area, the Po di Volano basin (Po River Delta, Northern Italy), characterized by extremely flat topography and fine soil texture and bordering a network of lagoon ecosystems. Main features of this area are the scarce relevance of livestock farming, the intense agriculture, mainly sustained by chemical fertilizers, and the developed network of artificial canals with long water residence time. Average nitrogen input exceeds output terms by ~60 kg N ha?1 year?1, a relatively small amount if compared to sub-basins of the same hydrological system. Analysis of dissolved inorganic nitrogen in groundwater suggests limited vertical loss and no accumulation of this element, while a nitrogen mass balance in surface waters indicates a net and significant removal within the watershed. Our data provide multiple evidences of efficient control of the nitrogen excess in this geographical area and we speculate that denitrification in soil and in the secondary drainage system performs this ecosystemic function. Additionally, the significant difference between nitrogen input and nitrogen output loads associated to the irrigation system, which is fed by the N-rich Po River, suggests that this basin metabolizes part of the nitrogen excess produced upstream. The traditionally absent livestock farming practices and consequent low use of manure as fertilizer pose the risk of excess soil mineralization and progressive loss of denitrification capacity in this area. 相似文献
172.
Hydropower development in the lower Mekong basin: alternative approaches to deal with uncertainty 总被引:1,自引:0,他引:1
Ida Kubiszewski Robert Costanza Peter Paquet Shpresa Halimi 《Regional Environmental Change》2013,13(1):3-15
Governments in the Lower Mekong Basin (LMB) face decisions that involve trade-offs between the economic benefits from hydropower generation and potentially irreversible negative impacts on the ecosystems that provide livelihoods and food security to the rural poor. As a means of comparing these trade-offs, a sensitivity analysis of the benefit-cost analysis of certain Basin Development Plan (BDP) scenarios was undertaken. By changing some key assumptions in the BDP about discount rates, the value of lost capture fisheries, future aquaculture production in the LMB, and the value of lost ecosystem services from wetlands to reflect the full range of uncertainty, at the extremes, there could be a reversal of the Net Present Value (NPV) estimates of the scenarios from a positive $33 billion to negative $274 billion. This report recommends when dealing with large-scale, complex projects: a more comprehensive, integrated human and natural systems framework and adaptive management approach to LMB planning and development that deals with the entire watershed; a more comprehensive analysis and treatment of risk and uncertainty; a more thorough assessment of the value of direct and indirect ecosystem services; a broader set of scenarios that embody alternative models of development, broader stakeholder participation; and better treatment of the effects of infrastructure construction on local cultures and the poor. 相似文献
173.
Anna Bateman Dan van der Horst David Boardman Arun Kansal Cynthia Carliell-Marquet 《Resources, Conservation and Recycling》2011,55(12):1146-1153
Every year 90 million tonnes of housed livestock manures are produced in the UK. This is a valuable reservoir of global phosphorus (P) and a point in the cycle where it is vulnerable to being lost from the terrestrial system. Improved manure management for the effective reuse of phosphorus is vital to simultaneously tackle a major source of water pollution and reduce our dependence on imported fertilisers. This paper quantifies, for the first time, the spatial and temporal challenges of recycling the required amount of manure P from areas of livestock production to areas of crop production in eight regions of England. The analysis shows that England has a P deficit and therefore the capacity to fully utilise the manure P on arable land, but that uneven spatial distribution of livestock poses a significant challenge to closing the P loop in agriculture. Two of the eight regions were shown to have surplus manure P, with the remaining six regions having P deficits, indicating that an annual export of 4.7 thousand tonnes P (2.8 million tonnes manure) must take place from the west to the east of the country each year to balance P supply and demand. Moreover, housed manure production peaks between October and February, requiring an excess of 23.0 thousand tonnes P (15 million tonnes manure) to be stored until it can be used for crop fertilisation from March onwards. The results demonstrate the scale of the challenge in managing manure P in an agricultural system that has separated livestock production from crop production, a pattern that is echoed throughout the developed world. To overcome the spatial and temporal challenges, a logistical system is recommended that will balance the nutrient potential (nitrogen and P content and availability) and pollution potential (eutrophication, greenhouse gas emissions, particulates and nitrous oxide from transport) for cost-effective and environmentally compatible redistribution of manure P from areas of surplus to areas of deficit, when required. 相似文献
174.
Giacomo Bacci Anna Korre Sevket Durucan 《International Journal of Greenhouse Gas Control》2011,5(3):579-588
Carbon dioxide capture and storage (CCS) technology is gaining credibility as the best short to medium term solution for significantly reducing net carbon emissions into the atmosphere. From a capacity point of view, deep saline aquifers offer the greatest potential for CO2 storage. In this respect, well injectivity is considered a key technical and economical issue. Rock/fluid interactions – dissolution/precipitation of minerals, in particular carbonates – are currently considered as one of the principal reasons for wellbore injectivity changes in aquifers.This research investigated the mechanisms involved in injectivity losses through experimental and theoretical methods. The impact on injectivity of permeability changes occurring at various distances from the wellbore was studied using an idealised CO2 injection well flow model. A new experimental set-up was used to investigate the effect on dissolution/precipitation mechanisms of the pressure and temperature changes that the fluid is subjected to as it advances from the wellbore.Numerical modelling of the injection wellbore has shown that changes in the petrophysical properties of the reservoir several metres away from the wellbore can still have a significant impact on injectivity. As indicated by the experimental research carried out, pressure and temperature gradients that exist inside the reservoirs may lead to re-precipitation in the far field, however no significant permeability and porosity changes were detected to suggest major losses of injectivity due to these effects. 相似文献
175.
Serge Guillas Anna Bakare Jeremy Morley Richard Simons 《Journal of Coastal Conservation》2011,15(3):337-351
There is a need for decadal predictions of the seabed evolution, for example to inform resurvey strategies when maintaining
navigation channels. The understanding of the physical processes involved in morphological evolution, and the viability of
process models to accurately model evolution over these time scales, are currently limited. As a result, statistical approaches
are used to supply long-term forecasts. In this paper, we introduce a novel statistical approach for this problem: the autoregressive
Hilbertian model (ARH). This model naturally assesses the time evolution of spatially-distributed measurements. We apply the
technique to a coastal area in the East Anglian coast over the period 1846 to 2002, and compare with two other statistical
methods used recently for seabed prediction: the autoregressive model and the EOF model. We evaluate the performance of the
three methods by comparing observations and predictions for 2002. The ARH model enables a reduction of 10% of the root mean
squared errors. Finally, we compute the variability in the predictions related to time sampling using the jackknife, a method
that uses subsamples to quantify uncertainties. 相似文献
176.
Clow DW Peavler RS Roche J Panorska AK Thomas JM Smith S 《Environmental monitoring and assessment》2011,183(1-4):197-215
There is concern that visitor-use associated activities, such as bathing, dish washing, wastewater production, and stock animal use near lakes and streams, could cause degradation of water quality in Yosemite National Park. A study was conducted during 2004-2007 to assess patterns in nutrient and Escherichia coli (E. coli) concentrations in the Merced and Tuolumne Rivers and characterize natural background concentrations of nutrients in the park. Results indicated that nutrient and E. coli concentrations were low, even compared to other undeveloped sites in the United States. A multiple linear regression approach was used to model natural background concentrations of nutrients, with basin characteristics as explanatory variables. Modeled nitrogen concentrations increased with elevation, and modeled phosphorus concentrations increased with basin size. Observed concentrations (±uncertainty) were compared to modeled concentrations (±uncertainty) to identify sites that might be impacted by point sources of nutrients, as indicated by large model residuals. Statistically significant differences in observed and modeled concentrations were observed at only a few locations, indicating that most sites were representative of natural background conditions. The empirical modeling approach used in this study can be used to estimate natural background conditions at any point along a study reach in areas minimally impacted by development, and may be useful for setting water-quality standards in many national parks. 相似文献
177.
Eleni Costa Christopher Thrasivoulou David L. Becker Jan A. Deprest Anna L. David Tina T. Chowdhury 《黑龙江环境通报》2023,43(10):1284-1295
Objective
The effects of mechanical stimulation in preterm amniotic membrane (AM) defects were explored.Methods
Preterm AM was collected from women undergoing planned preterm caesarean section (CS) due to fetal growth restriction or emergency CS after spontaneous preterm prelabour rupture of the membranes (sPPROM). AM explants near the cervix or placenta were subjected to trauma and/or mechanical stimulation with the Cx43 antisense. Markers for nuclear morphology (DAPI), myofibroblasts (αSMA), migration (Cx43), inflammation (PGE2) and repair (collagen, elastin and transforming growth factor β [TGFβ1]) were examined by confocal microscopy, second harmonic generation, qPCR and biochemical assays.Results
In preterm AM defects, myofibroblast nuclei were highly deformed and contractile and expressed αSMA and Cx43. Mechanical stimulation increased collagen fibre polarisation and the effects on matrix markers were dependent on tissue region, disease state, gestational age and the number of fetuses. PGE2 levels were broadly similar but reduced after co-treatment with Cx43 antisense in late sPPROM AM defects. TGFβ1 and Cx43 gene expression were significantly increased after trauma and mechanical stimulation but this response dependent on gestational age.Conclusion
Mechanical stimulation affects Cx43 signalling and cell/collagen mechanics in preterm AM defects. Establishing how Cx43 regulates mechanosignalling could be an approach to repair tissue integrity after trauma. 相似文献178.
Ellen Hollands Steffensen Lars Henning Pedersen Stina Lou Ida Vogel the Danish Fetal Medicine Study Group the Danish Cytogenetic Central Registry Study Group 《黑龙江环境通报》2023,43(1):51-61
Objective
To investigate if the Down syndrome phenotype differs according to the result of first-trimester combined screening (FTS).Method
We included all Down syndrome cases diagnosed by karyotype in pregnancy or after birth in Denmark during 2005–2018. We compared screen positive (odds ≥1:300) and screen negative (odds <1:300) cases as well as screen result subgroups with respect to anthropometrics, congenital malformations, childhood diseases, and hospitalization.Results
Absolute measures of fetal and birth anthropometrics were comparable between groups. A prenatal malformation diagnosis was more prevalent among screen positive than screen negative cases. Analyses suggested that this could reflect a detection bias. Cases with a screen result of 1:2–1:10 had a higher probability of being diagnosed with a malformation prenatally and with severe congenital heart disease (CHD) postnatally compared with a result of 1:11–1:300. Screen positive cases more often had non-severe CHD but less often a non-heart malformation compared with screen negative cases, while proportions of severe CHD were similar in these groups. Data on hospitalizations showed inconsistent results.Conclusion
The 1:300 screening threshold had limited or no value in predicting Down syndrome phenotype severity. In contrast, cases with a screen result between 1:2 and 1:10 may represent a more severe phenotype. 相似文献179.
Fillimonova Elena Kharitonova Natalia Baranovskaya Ekaterina Maslov Alexey Aseeva Anna 《Environmental geochemistry and health》2022,44(7):2281-2299
Environmental Geochemistry and Health - The Caucasian mineral water (CMW) region is a unique area where mineral waters differ by their chemical composition and balneological properties. The... 相似文献
180.
F. Badalamenti C. J. Sweeting N. V. C. Polunin J. Pinnegar G. D’Anna C. Pipitone 《Marine Biology》2008,154(5):765-773
Trawling has a significant effect on the structure of marine communities, yet the ubiquity of trawling impacts makes testing
such effects difficult. This study examines trawling impacts on trophodynamics of three fishes among the Gulfs of Castellammare
and Termini Imerese (northern Sicily), the first of which has been subject to a trawling ban since 1990 that initially resulted
in an eightfold increase in total fish biomass. The Gulf of Termini Imerese remains heavily fished and was treated as a control
site. Nitrogen and carbon stable isotope data were used to assess fishing induced changes in trophic levels or source of production
supporting three demersal fish species; Mullus barbatus,
Merluccius merluccius and Lophius budegassa following a control-impact approach. The exclusion of trawling resulted in only small alteration of δ15N in two of the three-three species. There were no systematic changes in the δ13C of any species sampled. Thus, a large influence of trawling on the trophodynamics of the studied species at sampled size
was discounted. Although stable isotopes do not have spatial or temporal resolution to identify detailed shifts in diet composition,
their integrative nature highlights that the trophic role these species play is robust to fishing impacts at scales over which
the fishery operates. This is despite a significant increase in the abundance of these species and of total fish biomass within
the protected area.
相似文献
C. J. SweetingEmail: |