全文获取类型
收费全文 | 11835篇 |
免费 | 1114篇 |
国内免费 | 2937篇 |
专业分类
安全科学 | 897篇 |
废物处理 | 252篇 |
环保管理 | 2004篇 |
综合类 | 8262篇 |
基础理论 | 1344篇 |
环境理论 | 6篇 |
污染及防治 | 985篇 |
评价与监测 | 1556篇 |
社会与环境 | 461篇 |
灾害及防治 | 119篇 |
出版年
2024年 | 50篇 |
2023年 | 264篇 |
2022年 | 397篇 |
2021年 | 490篇 |
2020年 | 503篇 |
2019年 | 438篇 |
2018年 | 386篇 |
2017年 | 485篇 |
2016年 | 524篇 |
2015年 | 628篇 |
2014年 | 654篇 |
2013年 | 826篇 |
2012年 | 837篇 |
2011年 | 919篇 |
2010年 | 702篇 |
2009年 | 704篇 |
2008年 | 598篇 |
2007年 | 812篇 |
2006年 | 834篇 |
2005年 | 625篇 |
2004年 | 556篇 |
2003年 | 609篇 |
2002年 | 493篇 |
2001年 | 460篇 |
2000年 | 431篇 |
1999年 | 315篇 |
1998年 | 226篇 |
1997年 | 200篇 |
1996年 | 184篇 |
1995年 | 130篇 |
1994年 | 118篇 |
1993年 | 81篇 |
1992年 | 80篇 |
1991年 | 63篇 |
1990年 | 48篇 |
1989年 | 19篇 |
1988年 | 14篇 |
1987年 | 29篇 |
1986年 | 15篇 |
1985年 | 11篇 |
1984年 | 6篇 |
1982年 | 16篇 |
1981年 | 17篇 |
1980年 | 13篇 |
1979年 | 10篇 |
1978年 | 16篇 |
1977年 | 5篇 |
1973年 | 8篇 |
1972年 | 10篇 |
1971年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 828 毫秒
971.
The size and isotopic behavior of sulfur pools in210Pb-dated peat cores were investigated to obtain aninsight into retention mechanisms of pollutant S in twomountain-top peatlands of the Northern Czech Republic, CentralEurope. The bogs were situated 40 km apart in an area whichbetween the years 1985 and 1995 received as much as 130 kg Sha-1 yr-1 from the atmosphere. Vertical peataccretion was faster at Pod Jelení horou (JH) than atVelký moál (VM). Organic carbon-bonded S was themost abundant sulfur pool, constituting 77 and 65 wt. % at JHand VM, respectively. At JH both the S concentration maximumand the highest annual S deposition rate were displaceddownward by more than 20 years (from 1987 to the 1960s)indicating that the buried S is vertically mobile. At VM the Sconcentration was the highest in the topmost 2-cm section eventhough atmospheric S deposition peaked in 1987. Differentmechanisms of S isotope redistribution prevailed in thetopmost peat layers at JH, where a negative 34Sshift occurred, and at VM, where a positive 34Sshift occurred. Bacterial sulfate reduction was responsiblefor the negative 34S shift at JH. One possibleexplanation of the positive 34S shift at VM isrelease of 32S-enriched products of mineralization duringpeat diagenesis. There was a strong positive correlationbetween the abundance of total and pyrite S along the profiles.The presence of pyrite S at VM (526 ± 60 ppm) suggestedthat even at VM bacterial sulfate reduction occurred. Ananaerobic incubation of JH peat indicated sulfate reductionrate of 600 nmol g-1 day-1. The turnover times forinorganic S pools were shorter than for the organic S pools.Cumulative S contents in the Czech peat bogs were found to besignificantly lower than in similar sites in the NortheasternU.S., even though the atmospheric S inputs were more thanthree times higher at the Czech sites. Possible causes of suchdiscrepancy are discussed. 相似文献
972.
Development and Adoption of a Simple Nonpoint Source Pollution Model for Port Phillip Bay,Australia 总被引:1,自引:0,他引:1
New computing tools and approaches allow tailored development of software to meet the needs of environmental managers. The processes required for such tailoring fit well with adaptive management concepts where, as knowledge and system understanding develop among managers, the software can be developed or replaced to match. This paper reports on development and adoption of a simple nonpoint source pollution modeling tool, including technical aspects of data support for modeling and social aspects of software design. The software, named FILTER, used a unit load model to generate expected pollutant loads from subcatchments of Port Phillip Bay, Australia. Monitoring data were used for calibration to modify the delivery of generated pollutants to receiving waters. Spatial, tabular, and charting software components were used to provide alternative forms of output visualization. FILTER was developed using a process that resulted in manager-stakeholders taking responsibility for setting of model parameter values and operation of the user interface, thereby encouraging uptake. The inclusive development process, tailoring of the software to manager needs and styles of usage, and matching of model complexity to data and knowledge, resulted in a successful application that has become the current agreed system representation among disparate stakeholder organizations. 相似文献
973.
本文通过番禺区东涌工业污水处理站污泥特性和污泥堆肥技术的研究,提出了污泥堆肥的可行性,并用之于实践,变废为宝,解决了污泥的处置问题. 相似文献
974.
Remobilisation of contaminant metals from sediments can occur by chemical, biological or physical changes. This in turn can lead to contaminant fluxes to the porewaters and ultimately the water column. The aim of the research presented here is to document post-depositional controls on metal mobility and fluxes in a heavily metal-contaminated estuary. This will allow for an improved understanding of the impact of contaminated sediments on water quality from both a short-term and long-term perspective. Dulas Bay is situated on the east coast of Anglesey, North Wales, and receives polluted waters from Parys Mountain. Metals within Dulas Bay sediments show surface enrichment and variations in mineralogical form. Diagenesis clearly plays a role in post-depositional behaviour of the metals, forming sulphides and potentially carbonates. The presence of a dominant exchangeable/carbonate fraction, and elevated porewater metals, in this sulphidic system is significant and could indicate the presence of freshwater diagenesis, or, reflect the high levels of metals in the sediment. 相似文献
975.
Wunsam Sybille Kamenik Christian Schmidt Roland 《Water, Air, & Soil Pollution: Focus》2002,2(4):93-108
Traunsee, a 191 m deep Alpine lake in Austria, is affected by industrial tailings from the soda and salt mining industries since 1883. In 1998 littoral water chloride concentrations ranged between 40 and 85 mg L-1 and the highest conductivity was 560 S cm-1, which is almost double as high as the values reported from the two nearby reference lakes. Chloride concentrations increased towards the location of the industrial salt and soda emission into the lake. Analogously to the chloride gradient, the epilithic littoral diatom flora changes towards the waste inlet. Shifts in the species percentages towards the emission source, a high percentage of taxa with large conductivity tolerances, the presence of a small Achnanthes minutissima Kützing morphotype, and occurrences of taxa focused at habitats of higher electrolyte content, indicate subtle impacts on the epilithic diatom flora. An analysis of the seasonal succession of the epilithic diatoms at the waste inlet compared to a lake intern reference site, reveals that only during the late summer period in 1998 the diatom assemblage at the waste inlet became significantly different, indicating seasonally restricted effects of the industrial emissions. 相似文献
976.
G. Theodoridis V. Karagiannis D. Valougeorgis 《Water, Air, & Soil Pollution: Focus》2002,2(5-6):525-539
A detailed simulation of the Goettinger Strasse pollutantdispersion problem is performed using the CFD code CFX-TASCflow for different wind directions. Two turbulencemodels, the k- and the RSM are adopted on three gridrefinement levels. Besides the typical reference gridimplemented by the TRAPOS group, two different gridresolutions are introduced. The first refinement is in thewhole street canyon region on the x-y level, while thesecond one is local in all three directions. Validation ofall involved computational schemes is performed based onrelative available experimental data. The computed velocityfields and concentration contours imply that the typicalreference grid is a suitable choice for the velocityfields, while local grid refinement in all three directionsin a small region containing the receptor is required toupgrade the pollutant concentration results with modestadditional computational effort. Finally the RSM modelresulted in smaller concentration levels. The k-model compared to the RSM seems a more appropriate choiceto solve this particular problem. 相似文献
977.
P. D. Kalabokas J. G. Bartzis P. Papagiannakopoulos 《Water, Air, & Soil Pollution: Focus》2002,2(5-6):703-716
Oil refining is among the industrial activities that emit considerable amounts of air pollutants into the atmosphere. Nitrogen oxides are important air pollutants that are emitted by oil refineries as products of combustion processes. The ambient air concentrations of nitrogen oxide (NO) and nitrogen dioxide (NO2) were monitored continuously at a site close to an oil refinery, near the city of Corinth in Greece, during autumn 1997 together with the main meteorological parameters. The contribution of the oil refinery to the measured atmospheric levels of nitrogen oxides was estimated. The ambient air concentration of nitrogen oxides in the area surrounding the oil refinery were generally lower than the ambient air concentrations in the urban area of Athens in Greece, and the NO2 levels were always below the existing air quality standards. The influence of the refinery emitted NOx in the photochemical production of ozone seems to be more important in terms of human and vegetation exposure given the high ozone backgrounds measured in the area. 相似文献
978.
Water, even in its natural environment, contains some level of impurities. Water is nearly a universal solvent. It contains dissolved solids and gases, and hosts a number of micro-organisms. The exploitation of groundwater by means of boreholes for supplying small user groups and rural communities with water has been widely applied in certain parts of the world for several decades. In recent years this practice has spread all over the globe, and hundred of thousands of boreholes have beendrilled to tap low-yield aquifers. It is evident that such boreholes require pumps for lifting thewater. In developing countries these are usually handpumps, butsolar as well as other systems with submersible pumps are also used, depending upon the energy sources available and the financial means of the beneficiaries. This article gives a general overview of groundwater quality with regard to itsphysico-chemical composition. The results presented originatefrom the experience gained from handpump equipped boreholes within the UNICEF through German Centre for Technical EducationTransfer executed inter-regional UNDP-Handpumps Project inWest African Regions. Particular attention is paid to presenting corrosion onthe water quality of wells in terms of iron concentrationand other parameters. Furthermore, the corrosion attack ongalvanised iron, the effect of biofilms on the corrosionrate, and the difference between internal and externalcorrosion of rising mains are shown. 相似文献
979.
980.
Human impacts on the stream-groundwater exchange zone 总被引:13,自引:0,他引:13
Hancock PJ 《Environmental management》2002,29(6):763-781
Active exchanges of water and dissolved material between the stream and groundwater in many porous sand- and gravel-bed rivers
create a dynamic ecotone called the hyporheic zone. Because it lies between two heavily exploited freshwater resources—rivers
and groundwater—the hyporheic zone is vulnerable to impacts coming to it through both of these habitats. This review focuses
on the direct and indirect effects of human activity on ecosystem functions of the hyporheic zone. River regulation, mining,
agriculture, urban, and industrial activities all have the potential to impair interstitial bacterial and invertebrate biota
and disrupt the hydrological connections between the hyporheic zone and stream, groundwater, riparian, and floodplain ecosystems.
Until recently, our scientific ignorance of hyporheic processes has perhaps excused the inclusion of this ecotone in river
management policy. However, this no longer is the case as we become increasingly aware of the central role that the hyporheic
zone plays in the maintenance of water quality and as a habitat and refuge for fauna. To fully understand the impacts of human
activity on the hyporheic zone, river managers need to work with scientists to conduct long-term studies over large stretches
of river. River rehabilitation and protection strategies need to prevent the degradation of linkages between the hyporheic
zone and surrounding habitats while ensuring that it remains isolated from toxicants. Strategies that prevent anthropogenic
restriction of exchanges may include the periodic release of environmental flows to flush silt and reoxygenate sediments,
maintenance of riparian buffers, effective land use practices, and suitable groundwater and surface water extraction policies. 相似文献