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The oxidation and acidification of sulfidic soil materials results in the re-partitioning of metals, generally to more mobile forms. In this study, we examine the partitioning of Fe, Cr, Cu, Mn, Ni and Zn in the acidified surface soil (0-0.1 m) and the unoxidised sub-soil materials (1.3-1.5 m) of an acid sulfate soil landscape. Metal partitioning at this acidic site was then compared to an adjacent site that was previously acidified, but has since been remediated by tidal re-inundation. Differences in metal partitioning were determined using an optimised six-step sequential extraction procedure which targets the “labile”, “acid-soluble”, “organic”, “crystalline oxide”, “pyritic” and “residual” fractions. The surficial soil materials of the acidic site had experienced considerable losses of Cr, Cu, Mn and Ni compared to the underlying parent material due to oxidation and acidification, yet only minor losses of Fe and Zn. In general, the metals most depleted from the acidified surface soil materials exhibited the greatest sequestration in the surface soil materials of the tidally remediated site. An exception to this was iron, which accumulated to highly elevated concentrations in the surficial soil materials of the tidally remediated site. The “acid-soluble”, “organic” and “pyritic” fractions displayed the greatest increase in metals following tidal remediation. This study demonstrates that prolonged tidal re-inundation of severely acidified acid sulfate soil landscapes leads to the immobilisation of trace metals through the surficial accumulation of iron oxides, organic material and pyrite. 相似文献
124.
Park SS Kozawa K Fruin S Mara S Hsu YK Jakober C Winer A Herner J 《Journal of the Air & Waste Management Association (1995)》2011,61(10):1046-1056
Fuel-based emission factors for 143 light-duty gasoline vehicles (LDGVs) and 93 heavy-duty diesel trucks (HDDTs) were measured in Wilmington, CA using a zero-emission mobile measurement platform (MMP). The frequency distributions of emission factors of carbon monoxide (CO), nitrogen oxides (NO(x)), and particle mass with aerodynamic diameter below 2.5 microm (PM2.5) varied widely, whereas the average of the individual vehicle emission factors were comparable to those reported in previous tunnel and remote sensing studies as well as the predictions by Emission Factors (EMFAC) 2007 mobile source emission model for Los Angeles County. Variation in emissions due to different driving modes (idle, low- and high-speed acceleration, low- and high-speed cruise) was found to be relatively small in comparison to intervehicle variability and did not appear to interfere with the identification of high emitters, defined as the vehicles whose emissions were more than 5 times the fleet-average values. Using this definition, approximately 5% of the LDGVs and HDDTs measured were high emitters. Among the 143 LDGVs, the average emission factors of NO(x), black carbon (BC), PM2.5, and ultrafine particle (UFP) would be reduced by 34%, 39%, 44%, and 31%, respectively, by removing the highest 5% of emitting vehicles, whereas CO emission factor would be reduced by 50%. The emission distributions of the 93 HDDTs measured were even more skewed: approximately half of the NO(x) and CO fleet-average emission factors and more than 60% of PM2.5, UFP, and BC fleet-average emission factors would be reduced by eliminating the highest-emitting 5% HDDTs. Furthermore, high emissions of BC, PM2.5, and NO(x) tended to cluster among the same vehicles. 相似文献
125.
de Nazelle A Nieuwenhuijsen MJ Antó JM Brauer M Briggs D Braun-Fahrlander C Cavill N Cooper AR Desqueyroux H Fruin S Hoek G Panis LI Janssen N Jerrett M Joffe M Andersen ZJ van Kempen E Kingham S Kubesch N Leyden KM Marshall JD Matamala J Mellios G Mendez M Nassif H Ogilvie D Peiró R Pérez K Rabl A Ragettli M Rodríguez D Rojas D Ruiz P Sallis JF Terwoert J Toussaint JF Tuomisto J Zuurbier M Lebret E 《Environment international》2011,37(4):766-777
126.
Colin Scott Steve E. Lewis Rob Milla Matthew C. Taylor Andrew J.W. Rodgers Geoff Dumsday Jon E. Brodie John G. Oakeshott Robyn J. Russell 《Journal of environmental management》2010,91(10):2075-2078
Herbicide contamination from agriculture is a major issue worldwide, and has been identified as a threat to freshwater and marine environments in the Great Barrier Reef World Heritage Area in Australia. The triazine herbicides are of particular concern because of potential adverse effects, both on photosynthetic organisms and upon vertebrate development. To date a number of bioremediation strategies have been proposed for triazine herbicides, but are unlikely to be implemented due to their reliance upon the release of genetically modified organisms. We propose an alternative strategy using a free-enzyme bioremediant, which is unconstrained by the issues surrounding the use of live organisms. Here we report an initial field trial with an enzyme-based product, demonstrating that the technology is technically capable of remediating water bodies contaminated with the most common triazine herbicide, atrazine. 相似文献
127.
Jinxia Wang Jikun Huang Lijuan Zhang Qiuqiong Huang Scott Rozelle 《Journal of the American Water Resources Association》2010,46(4):665-685
Wang, Jinxia, Jikun Huang, Lijuan Zhang, Qiuqiong Huang, and Scott Rozelle, 2010. Water Governance and Water Use Efficiency: The Five Principles of WUA Management and Performance in China. Journal of the American Water Resources Association (JAWRA) 46(4): 665-685. DOI: 10.1111/j.1752-1688.2010.00439.x Abstract: In recent years China has attempted to reform water management by decentralizing water management responsibilities. The overall goal of our paper is to better understand the emergence of water user associations (WUAs) in China and assess if they are adhering to the practices spelled out by the Five Principles, a set of recommended practices that are supposed to lead to successful WUA operation. Using four sets of different types of villages to examine implementation and performance, we find that World Bank-supported WUA villages (“Bank villages”) can be thought of as operating mostly according to the Five Principles. For example, the Bank villages were endowed with a more reliable water supply; were set up and were operating with a relatively high degree of farmer participation; and leaders were more consultative and the process more formal. When WUAs are run according to the Five Principals, we show that WUAs increase water use efficiency. The study also provides evidence that there is a perception in the Bank villages that water management is improving in general and that there is less conflict both within the village and among villages. Perhaps more importantly, we find that the Bank’s effort to promote WUAs extended beyond their own project villages. The openness, consultative nature, and transparency found in the Bank WUAs are also found (albeit at a somewhat lower level) in the non-Bank WUA villages. 相似文献
128.
Justin M. Langridge R. Joel Gustafsson Paul T. Griffiths R. Anthony Cox Richard M. Lambert Roderic L. Jones 《Atmospheric environment (Oxford, England : 1994)》2009,43(32):5128-5131
The photoenhanced uptake of nitrogen dioxide (NO2) to the surface of commercially available self-cleaning window glass has been studied under controlled laboratory conditions. This material is one of an array of modern building products which incorporate titanium dioxide (TiO2) nanoparticles and are finding increasing use in populated urban areas. Amongst the principal drivers for the use of these materials is that they are thought to facilitate the irreversible removal of pollutants such as NO2 and organic molecules from the atmosphere and thus act to remediate air quality. While it appears that TiO2 materials do indeed remove organic molecules from built environments, in this study we show that the photoenhanced uptake of NO2 to one example material, self-cleaning window glass, is in fact accompanied by the substantial formation (50–70%) of gaseous nitrous acid (HONO). This finding has direct and serious implications for the use of these materials in urban areas. Not only is HONO a harmful respiratory irritant, it is also readily photolysed by solar radiation leading to the formation of hydroxyl radicals (OH) together with the re-release of NOx as NO. The net effect of subsequent OH initiated chemistry can then be the further degradation of air quality through the formation of secondary pollutants such as ozone and VOC oxidation products. In summary, we suggest that a scientifically conceived technical strategy for air quality remediation based on this technology, while widely perceived as universally beneficial, could in fact have effects precisely opposite to those intended. 相似文献
129.
Long-term depletion of calcium and other nutrients in eastern US forests 总被引:10,自引:0,他引:10
C. Anthony Federer James W. Hornbeck Louise M. Tritton C. Wayne Martin Robert S. Pierce C. Tattersall Smith 《Environmental management》1989,13(5):593-601
Both harvest removal and leaching losses can deplete nutrient capital in forests, but their combined long-term effects have not been assessed previously. We estimated changes in total soil and biomass N, Ca, K, Mg, and P over 120 years from published data for a spruce-fir site in Maine, two northern hardwood sites in New Hampshire, central hardwood sites in Connecticut and Tennessee, and a loblolly pine site in Tennessee. For N, atmospheric inputs counterbalance the outputs, and there is little long-term change on most sites. For K, Mg, and P, the total pool may decrease by 2%–10% in 120 years depending on site and harvest intensity. For Ca, net leaching loss is 4–16 kg/ha/yr in mature forests, and whole-tree harvest removes 200–1100 kg/ha. Such leaching loss and harvest removal could reduce total soil and biomass Ca by 20%–60% in only 120 years. We estimated unmeasured Ca inputs from rock breakdown, root-zone deepening, and dry deposition; these should not be expected to make up the Ca deficit. Acid precipitation may be the cause of current high leaching of Ca. Although Ca deficiency does not generally occur now in acid forest soils, it seems likely if anthropogenic leaching and intensive harvest removal continue. 相似文献
130.
Scott N. Ralston William M Park 《Journal of the American Water Resources Association》1989,25(6):1259-1265
ABSTRACT: A travel cost model is developed to estimate the potential reductions in recreational benefits from sedimentation in Reelfoot Lake in northwestern Tennessee. In addition to the consumer surplus estimates generated by the model, three other aspects of the study were significant. First, the study applied a relatively untested methodology for deriving the opportunity cost of travel time. The study resulted in a value that is less than one-half of the Water Resource Council's “one-third of the wage rate” rule-of-thumb. Second, water quality perceptions were unsuccessfully incorporated into the model as a demand shifter. This raised questions as to the appropriate manner in which perceptions could be included in a travel cost model. Finally, a simple methodology was outlined by which estimates of the recreational value of Reelfoot Lake could be used to suggest how much cost could be justified for soil erosion control on agricultural land surrounding the lake. 相似文献