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351.
Kristin Aunan Terje K. Berntsen Gunnar Myhre Kristin Rypdal David G. Streets Jung-Hun Woo Kirk R. Smith 《Atmospheric environment (Oxford, England : 1994)》2009,43(35):5674-5681
Household fuel use in developing countries, particularly as biomass and coal, is a major source of carbonaceous aerosols and other air pollutants affecting health and climate. Using state-of-the-art emission inventories, a global three-dimensional photochemical tracer/transport model of the troposphere, and a global radiative transfer model based on methods presented in the latest IPCC Assessment Report (2007-AR4), we estimate the radiative forcing (RF) attributable to household fuel combustion in Asia in terms of current global annual-mean RF and future global integrated RF for a one-year pulse of emissions (2000) over two time horizons (100 and 20 years). Despite the significant emissions of black carbon (BC) aerosols, these estimates indicate that shorter-lived (non-Kyoto) air pollutants from household fuel use in the region overall seem to exert a small net negative RF because of the strong influence of reflective aerosols. There are, however, major uncertainties in emission estimates for solid fuel burning, and about the sustainability of household fuel wood harvesting in Asia (the carbon neutrality of harvesting). In addition, there is still substantial uncertainty associated with the BC radiative forcing. As a result we find that the sign of the RF from household biomass burning in the region cannot be established. While recognizing the value of integrating climate change and air pollution policies, we are concerned that for a ‘Kyoto style’ post-Kyoto treaty (with global cap-and-trade and the Global Warming Potential as the metric) expanding the basket of components with a selection of short-lived species without also including the wider range of co-emitted species may lead to unintended consequences for global-scale climate. Additional measurement, modelling, and policy research is urgently needed to reduce the uncertainties so that the net impact on climate of emissions and mitigation measures in this sector can be accurately assessed. 相似文献
352.
秸秆禁烧禁抛与综合利用探讨 总被引:4,自引:0,他引:4
焚烧秸秆害人害已,综合利用利国利民。文中通过分析在实施秸秆禁烧禁抛与综合利用工作中存在的问题,提出了应对的举措。 相似文献
353.
Open burning of crop residues has been identified as an important emission source of PCDD/PCDF to the environment. This paper presents the first known data on the emission of PCDD/PCDF to the land considering the influence of pesticides applied in crops planting. Emission factor for PCDD/PCDF to the land from open burning of corn straw with pesticides contamination ranged from 0.07 to 0.57 ng WHO2005-TEQ/kg straw burned with a mean value of 0.24 ng WHO2005-TEQ/kg straw burned and median value of 0.20 ng WHO2005-TEQ/kg straw burned, respectively. The concentration was 35 to 270 times higher than that without additional pesticide contaminated. Initial observation was that emission factor for PCDD/PCDF from open burning of crop residues was overestimated in the former UNEP Dioxin Toolkit. Pesticides contamination should be considered in some hotpots where special and over dosed pesticides has been sprayed especially in developing countries. 相似文献
354.
Release of PCDD and PCDF from biomass combustion such as forest and agricultural crop fires has been nominated as an important source for these chemicals despite minimal characterisation. Available emission factors that have been experimentally determined in laboratory and field experiments vary by several orders of magnitude from <0.5 μg TEQ (t fuel consumed)−1 to >100 μg TEQ (t fuel consumed)−1. The aim of this study was to evaluate the effect of experimental methods on the emission factor.A portable field sampler was used to measure PCDD/PCDF emissions from forest fires and the same fuel when burnt over a brick hearth to eliminate potential soil effects. A laboratory burn facility was used to sample emissions from the same fuels. There was very good agreement in emission factors to air (EFAir) for forest fuel (Duke Forest, NC) of 0.52 (range: 0.40-0.79), 0.59 (range: 0.18-1.2) and 0.75 (range: 0.27-1.2) μg TEQWHO2005 (t fuel consumed)−1 for the in-field, over a brick hearth, and burn facility experiments, respectively. Similarly, experiments with sugarcane showed very good agreement with EFAir of 1.1 (range: 0.40-2.2), 1.5 (range: 0.84-2.2) and 1.7 (range: 0.34-4.4) μg TEQ (t fuel consumed)−1 for in-field, over a brick hearth, open field and burn facility experiments respectively. Field sampling and laboratory simulations were in good agreement, and no significant changes in emissions of PCDD/PCDF could be attributed to fuel storage and transport to laboratory test facilities. 相似文献
355.
Aerostat-lofted instrument and sampling method for determination of emissions from open area sources
An aerostat-borne instrument and sampling method was developed to characterize air samples from area sources, such as emissions from open burning. The 10 kg battery-powered instrument system, termed “the Flyer”, is lofted with a helium-filled aerostat of 4 m nominal diameter and maneuvered by means of one or two tethers. The Flyer can be configured variously for continuous CO2 monitoring, batch sampling of semi-volatile organic compounds (SVOCs), volatile organic compounds (VOCs), black carbon, metals, and PM by size. The samplers are controlled by a trigger circuit to avoid unnecessary dilution from background sampling when not within the source plume. The aerostat/Flyer method was demonstrated by sampling emissions from open burning (OB) and open detonation (OD) of military ordnance. A carbon balance approach was used to derive emission factors that showed excellent agreement with published values. 相似文献
356.
357.
Emission factors for PCDD/PCDF determined from open combustion are used to estimate national emission budgets; therefore, it is important to have confidence in their accuracy. It has been suspected that artefacts may form due to the presence of hot metal surfaces of sampling equipment, thus skewing emission factors. In this study, emissions of PCDD/PCDF from open burning of forest biomass over a brick hearth were sampled. Five experiments were carried out using a portable sampler. Experiments were designed where the key variable, sample hood and inlet temperatures were manipulated. Other variables such as fuel origin, type and density were consistent. The measured concentration of PCDD/PCDF in the smoke samples ranged from 0.01 μg TEQ (t fuel)−1 at the lowest maximum hood temperature (185 °C) to 15 μg TEQ (t fuel)−1 at the highest maximum hood temperature (598 °C). when hood inlet temperatures exceeded 400 °C emission factors were significantly elevated and this is attributed to the formation of artefacts that can cause the over estimation of emission factors. The increase in hood temperature also resulted in a change in the PCDD/PCDF congener and homologue profile of the emissions. For example at the lowest temperature (Fire 1) the PCDD/PCDF ratio measured was 50:1, whereas at the highest temperature (Fire 5) this ratio was about 0.53:1. When the sampler hood and inlet temperatures were kept in the normal operating range of <200 °C, emission factors were comparable to those observed in many previous studies in Australia with emissions dominated by PCDD. 相似文献
358.
359.
Determination of imazosulfuron persistence in rice crop and soil 总被引:1,自引:0,他引:1
Sondhia S 《Environmental monitoring and assessment》2008,137(1-3):205-211
Imazosulfuron is a new post-emergence sulfonylurea herbicide. It is highly active at low application rates to control annual
and perennial broad-leaf weeds and sedges in rice. There is increasing concerned about the persistence of pesticide residues
in soils, crop produce and subsequent contamination of groundwater. Thus persistence of imazosulfuron residues under field
condition was evaluated. Imazosulfuron was applied at 30, 40, 50 and 60 a. i. g ha −1 rates, 4 days after transplanting of rice as post-emergence herbicide. Soil and plant samples treated with imazosulfuron
were collected at 60, 90 and 120 days after herbicide application and analyzed for residues. Rice grains and straw samples
were sampled at harvest (120 days). Residues of imazosulfuron in soil were not found after 90 and 120 DAS (days after spraying).
Rice grains contained 0.006, 0.009 μg g−1 residues at 50 and 60 g ha −1 application rates. 0.009 and 0.039 μg g−1 residues of imazosulfuron were detected at 50 and 60 g/ha rates respectively in rice straw. Residues of imazosulfuron were
not detected applied at 30 and 40 g ha−1 in rice grains and straw, respectively and can be safely applied to the transplanted rice. 相似文献
360.