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971.
A variety of species was observed as either visitors, permanent, or summer residents on surface mines with different ecological adaptations. Passerine species were the most prevalent of the 25 families represented. Bird communities as well as individual species were correlated with the structure and species of vegetation on the mines. The composition of the bird communities changed in response to successional vegetation stages from grassland to forest communities. 相似文献
972.
地下水取水构筑物早期报废的原因错综复杂,而含铁地下水取水构筑物的早期报废问题常常比一般情况更为突出,本文对含铁地下水取水构筑的进水面上的腐蚀与沉积问题进行了初步探讨,供分析研究。 相似文献
973.
Sustainable Development of Water Resources in India 总被引:4,自引:0,他引:4
974.
Fred J. Brenner Elaine K. Brenner Patricia E. Brenner Richard P. Steiner 《Environmental management》1994,18(2):307-315
Current surface mine regulations as ascribed under the Surface Mining Control and Reclamation Act of 1977 require that mine
lands be returned to the approximate original contours (AOC) with an area coverage of at least 70% and to biological productivity
equal to or greater than that which existed prior to mining. Six different procedures were evaluated on nine mine sites in
northwestern Pennsylvania as to their suitability to estimate aboveground biomass on mines reclaimed as hayland and pastures.
Biomass estimates determined by different procedures were compared to those obtained by random clip plots and with landowner
estimates of the annual yield from each site. Biomass estimates determined from a disk meter and landowner interviews varied
approximately ±10% from those obtained from random clip plots compared to a variation of ±8%–37% for the other procedures.
The number of samples required to obtain reliable estimates within ±10% of the mean at 95% confidence intervals varied among
the different sampling procedures according to the variance in biomass on the site. Although all procedures may be used either
singly or in combination to estimate above ground biomass on reclaimed mine lands, the combination of the disk meter, profile
board, and vegetation height is recommended because of their ease of measurement compared to the other procedures. 相似文献
975.
Syed R. Qasim Andrew T. Armstrong John Corn Betty L. Jordan 《Journal of the American Water Resources Association》1980,16(3):522-531
ABSTRACT: Data were developed to determine the quality of water and bottom sediments in the Trinity River, and the mobility of various contaminants when bottom sediments were mixed with the river water under simulated dredging conditions. Thirteen sampling sites were selected. A number of chemical tests including heavy metals and pesticides were conducted on river water, elutriates, and bottom sediments. Statis bioassays using Daphnia magna were conducted on river water and elutriates. Results indicated that the river in the upper reach is grossly polluted due to discharge of waste water effluents from several large treatment plants. High concentrations of nitrogen, phosphorus, organic carbon, COD, heavy metals, and pesticides were found in water and bottom sediments. The concentrations of most of these pollutants exceeded the EPA recommended limits. Elutriation gave no consistent results, perhaps because of release or uptake of contaminants from the sediments. High mortality of D. magna were also recorded in the upper reach of the river. The quality of water and bottom sediments gradually improved in lower reaches. 相似文献
976.
The impact of surface mining for coal on the nature and extent of freshwater wetlands was assessed on 73,200 ha in western Pennsylvania. The influence of mining on wetlands was not uniform across physiographic regions, varying with regional differences in hydrology and soils. Overall, mined lands supported 18% more palustrine wetlands than unmined lands, primarily because of a 270% gain in permanent, open-water wetlands on mined lands in the glaciated region. Open-water wetlands declined on mined lands in unglaciated regions owing to unfavorable hydrologic conditions. The number and size of emergent wetlands declined as a result of mining. Mined lands supported 81% fewer riverine wetlands than unmined lands. This was caused primarily by avoidance of lands containing streams, and secondarily by a 10% reduction in replacement of riverine wetlands during reclamation. Land managers need to develop land use policies that maximize the ecological and social benefits that can be derived from developing diverse wetland communities on mined lands. 相似文献
977.
K. R. Reddy E. Flaig L. J. Scinto O. Diaz T. A. DeBusk 《Journal of the American Water Resources Association》1996,32(5):901-915
ABSTRACT: The ability to predict how streams and wetlands retain phosphorus (P) is critical to the management of watersheds that contribute nutrients to adjacent aquatic systems such as lakes. Field and laboratory experiments were conducted to determine the P assimilatory capacity of a stream (Otter Creek) in the Taylor Creek/Nubbin Slough Basin located north of Lake Okeechobee, Florida. Dominant soils in this basin are sandy Spodosols; landuse is primarily dairy farms and beef cattle pastures. Estimates of P assimilation show that sediments assimilate approximately 5 percent of the P load. Phosphorus assimilation rates in the stream were estimated using first-order relationships based on the total P concentration of the water column as a function of distance from the primary source. This method assumes minimal lateral inputs. Stream lengths required for one turnover in P assimilation were estimated to be in the range of 3–16 km. Laboratory studies using intact sediment cores indicated a P assimilation rate of 0.025 m day?1, and equilibrium P concentration of 0.16 ± 0.03 mg L?1 in the water column. Dissolved P concentration gradients in the sediments showed upward flux of P at water column P concentration of <0.16 mg L?1. Approximately 56–77 percent of the P assimilated in the above-ground vegetation during active growth was released or translocated within six months of senesence, suggesting short-term storage in above-ground vegetation. Bottom sediments and recalcitrant detrital plant tissue provide for long-term P assimilation in the creek. Although stream sediments have the potential to adsorb P, high flow rate and low contact period between water and sediment limits this process. 相似文献
978.
979.
Xiaojia He Sabrieon Sanders Winfred G.Aker Yunfeng Lin Jessica Douglas Huey-min Hwang 《环境科学学报(英文版)》2016,28(4):50-60
In this study,the cytotoxicity of two different crystal phases of TiO2 nanoparticles,with surface modification by humic acid(HA),to Escherichia coli,was assessed.The physicochemical properties of TiO2 nanoparticles were thoroughly characterized.Three different initial concentrations,namely 50,100,and 200 ppm,of HA were used for synthesis of HA coated TiO2 nanoparticles(denoted as A/RHA50,A/RHA100,and A/RHA200,respectively).Results indicate that rutile(LC50(concentration that causes 50%mortality compared the control group)=6.5)was more toxic than anatase(LC50=278.8)under simulated sunlight(SSL)irradiation,possibly due to an extremely narrow band gap.It is noted that HA coating increased the toxicity of anatase,but decreased that of rutile.Additionally,AHA50 and RHA50had the biggest differences compared to uncoated anatase and rutile with LC50of 201.9 and21.6,respectively.We then investigated the formation of reactive oxygen species(ROS)by TiO2 nanoparticles in terms of hydroxyl radicals(OH)and superoxide anions(O2-).Data suggested that O2- was the main ROS that accounted for the higher toxicity of rutile upon SSL irradiation.We also observed that HA coating decreased the generation of OH and O2- on rutile,but increased O2- formation on anatase.Results from TEM analysis also indicated that HA coated rutile tended to be attached to the surface of E.coli more than anatase. 相似文献
980.
Field scale interaction and nutrient exchange between surface water and shallow groundwater in the Baiyang Lake region, North China Plain 总被引:1,自引:0,他引:1
Fertilizer input for agricultural food production, as well as domestic and industrial surface water pollutants in the North China Plain, increases pressures on locally scarce and vulnerable water resources. In order to: (a) understand pollutant exchange between surface water and groundwater, (b) quantify nutrient loadings, and (c) identify major nutrient removal pathways by using qualitative and quantitative methods, including the geochemical model PHREEQC, a one-year study at a wheat (Triticum aestivum L.) and maize (Zea mays L.) double cropping system in the Baiyang Lake area in Hebei Province, China, was undertaken. The study showed a high influence of low-quality surface water on the shallow aquifer. Major inflowing pollutants into the aquifer were ammonium and nitrate via inflow from the adjacent Fu River (up to 29.8 mg/L NH4-N and 6.8 mg/L NO3-N), as well as nitrate via vertical transport from the field surface (up to 134.8 mg/L NO3-N in soil water). Results from a conceptual model show an excess nitrogen input of about 320 kg/ha/a. Nevertheless, both nitrogen species were only detected at low concentrations in shallow groundwater, averaging at 3.6 mg/L NH4-N and 1.8 mg/L NO3-N. Measurement results supported by PHREEQC-modeling indicated cation exchange, denitrification, and anaerobic ammonium oxidation coupled with partial denitrification as major nitrogen removal pathways. Despite this current removal capacity, the excessive nitrogen fertilization may pose a future threat to groundwater quality. Surface water quality improvements are therefore recommended in conjunction with simultaneous monitoring of nitrate in the aquifer, and reduced agricultural N-inputs should be considered. 相似文献