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981.
Marty D. Matlock Monty E. Matlock Daniel E. Storm Michael D. Smolen William J. Henley 《Journal of the American Water Resources Association》1998,34(5):1141-1147
ABSTRACT: The decline of water quality in United States’ lotic ecosystems (streams and rivers) has been linked to nonpoint source nutrient loading (U.S. EPA, 1990). Determining limiting nutrients in streams is difficult due to the variable nature of lotic ecosystems. We developed a quantitative passive diffusion periphyton nutrient enrichment system, called the Matlock Periphytometer, to measure the response of attached algae (periphyton) to nutrient enrichment. The system is simple to build and provides quantitative nutrient enrichment of a surface for periphytic growth. The periphyton grow on a glass fiber filter, which allows complete recovery of periphyton for chlorophyll a analysis. A 14-kilodalton dialysis membrane was used as a biofilter to prevent bacterial and algal contamination of the nutrient solution. We determined the rates of diffusion of nitrogen and phosphorus ions across the Matlock Periphytometer's dialysis membrane and glass fiber filter over a 21-day period (42 and 22 μg/cm2/hr, respectively). We used the Matlock Periphytometer to determine the limiting nutrient in a woodland stream. Six replicates each of a control, nitrogen, and phosphorus treatment were placed in the stream for 14 days. The results indicated that phosphorus was the limiting nutrient in the stream for the period and location sampled. 相似文献
982.
983.
Changing places, changing emissions: The cross-scale reliability of greenhouse gas emission inventories in the US 总被引:1,自引:0,他引:1
William E. Easterling Colin Polsky Doug Goodin Michael W. Mayfield William A. Muraco Brent Yarnal 《Local Environment》1998,3(3):247-262
Greenhouse gas (GHG) emission inventories, which currently inform abatement policy discussions, are developed mostly from national scale data. Nevertheless, although the policy debate tends to take place in global and national arenas, action to abate GHG emissions is inherently within the provenance of local institutions and communities. The purpose of this paper is to examine how much information is lost by not estimating GHG emissions data at scales finer than the whole US. Such information may be critical in bridging global and local policy. Differences in the composition of GHG emission sources based on GHG emission inventories at three nested spatial scales (national, state, local) for four study sites (in Kansas, North Carolina, Ohio and Pennsylvania) are analysed, drawing upon initial results of a large collaborative study known as the 'Association of American Geographers-Global Change in Local Places (GCLP)' project. The concept of spatial sovereignty of emissions is developed to test the cross-scale reliability of emission inventories. For the test year 1990, close agreement is found in the by-gas composition of GHG emissions among national, state and local inventories. Spatial sovereignty in this case is maintained. However close agreement is not found in the by-source composition of GHG emissions among national, state and local inventories. Spatial sovereignty in this case is not maintained. Regular compilation of state and local emissions source inventories may be necessary to track important spatial and temporal deviations from national trends. 相似文献
984.
985.
A system to turn a potentially harmful stream of solid waste into a set of substreams with either commercial value or highly concentrated residual streams is presented. The waste which is considered is metal impregnated (in particular Chromated Copper Arsenate (CCA) treated) wood waste and timber, such as telephone poles, railway sleepers, timber from landscape and cooling towers, wooden silos, hop-poles, cable drums and wooden playground equipment. These waste streams sum up to several 100,000 tons of material per year currently to be dumped in every major country of the European Community (EC). Technologies need to be developed to reduce this CCA treated wood waste, such that all of the metals are contained in a marketable product stream, and the pyrolysis gases and/or pyrolysis liquid are used to their maximum potential with respect to energy recuperation. Pyrolysing the CCA treated wood waste may be a good solution to the growing disposal problem since low temperatures and no oxidising agents are used, which result in lower loss of metals compared to combustion. An experimental labscale pyrolysis system has been developed to study the influence of the pyrolysis temperature and the duration of the pyrolysis process on the release of metals and the mass reduction. The macrodistribution and microdistribution of the metals in the solid pyrolysis residue is studied using Inductively Coupled Plasma Mass Spectrometry (ICP–MS) and Scanning Electron Microscopy coupled with Energy Dispersive X-ray Analysis (SEM–EDXA). Furthermore, a complete mass balance is calculated over the pyrolysis system. Based on these results a semi-industrial pyrolysis system (pilot plant scale) has been developed consisting of three stages: grinding, packed bed pyrolysis and metal separation. Special types of equipment have been developed to carry out the three stages. A new grinding system has been developed, based on a crushing mechanism rather than a cutting mechanism. The crushed wood is introduced by means of a screw feeding system into a reaction column. In this pyrolysis reactor the wood is heated by subjecting it to a flow of hot gases. This causes an adiabatic pyrolysis, which results in volatilisation of the volatile compounds whereas the mineral compounds (containing the metals) remain entrapped in a coal-type residue which is very rich in carbon. The condensable compounds in the pyrolysis gas condense while leaving the reaction zone due to the inverse temperature gradient. The pyrolysis gas leaving the reactor is used as fuel for the hot gas generator. The charcoal which is extracted at the bottom of the reactor, is cooled, compressed, removed and stored, ready to feed the subsequent stage. A specially developed grinder is used to remove the metal particles from the charcoal and the separation between metal and charcoal particles is accomplished in a pneumatic centrifuge as a result of the difference in density. Using this system the ultimate waste is less than 3% of the initial wood mass. Results obtained with a semi-industrial scale prototype confirm the effectiveness of the process. 相似文献
986.
Tom Van Remmen 《Waste management (New York, N.Y.)》1998,18(6-8)
After many years of research and debate, in August of 1997 the United States Environmental Protection Agency (EPA) issued New Source Performance Standards (NSPS) and Emission Guidelines (EG) for medical/infectious waste incinerators in the United States. These new emissions and operational standards establish considerably more restrictive limitations on air emissions for medical/infectious waste incinerators and will undoubtedly have a significant impact on the over 2300 hospitals presently operating an incinerator on-site. This paper will explore the options available to these facilities, and those facilities which may be considering installation of an incinerator, relative to achieving compliance with the NSPS and EG for medical/infectious waste incinerators. 相似文献
987.
Spermophilus townsendii ) prey. These changes could occur directly or as a result of changes in the vegetation available as food and cover for the
ground squirrels. We assessed the effects of long-term tracking by armored vehicles by comparing 9-ha areas in sagebrush (Artemisia tridentata) -dominated shrubsteppe and bluegrass (Poa secunda) -dominated grasslands subjected to low-intensity tracking for ∼50 years with others that had not been tracked. We did not
detect any effect on ground squirrel population dynamics associated with long-term tracking. Although densities of adults
and juveniles tended to be higher in the areas exposed to such tracking, we attribute this difference to other factors that
varied spatially. To determine short-term (two-year) effects, we experimentally tracked two sagebrush and two grassland sites
with an M-1 tank after animals had begun their inactive season. In the following two active seasons we monitored squirrel
demography and behavior and vegetative characteristics on the experimentally tracked sites and compared the results with control
sites. Although we experimentally tracked ∼33% of the surface of each of four sites where ground squirrel densities were assessed,
the tracking had a detectable effect only on some herbaceous perennials and did not influence ground squirrel densities or
behavior significantly during the subsequent two active seasons. We conclude that tracking after the start of the inactive
season is likely to influence ground squirrel demography or behavior only if vegetation cover is substantially changed by
decreasing coverage of preferred food plants or increasing the coverage of annual grasses and forbs that are succulent for
only a short time each year. 相似文献
988.
Shunli Zhang Eric Forssberg Bo Arvidson William Moss 《Resources, Conservation and Recycling》1998,23(4):225-241
The amount of electronic scrap which contains a substantial portion of non-ferrous metals, primarily copper and aluminum, has been growing. The present study is directed toward aluminum recovery by a newly developed eddy current separator. The investigation on shredded personal computer and printed circuit board scrap demonstrates that the High-Force® eddy-current separator will be applicable for this purpose. It has been shown that, by a single pass of the materials on the High-Force® eddy-current separator, an aluminum concentrate out of personal computer scrap can be obtained with a purity of 85%, while maintaining a recovery in excess of 90%, with the feed rate being up to 0.3 kg/min. 相似文献
989.
J. Van Sickle P J. Wigington M. K. Church 《Journal of the American Water Resources Association》1997,33(2):359-366
ABSTRACT: Programs of monthly or annual stream water sampling will rarely observe the episodic extremes of acidification chemistry that occur during brief, unpredictable runoff events. When viewed in the context of data from several streams, however, baseflow measurements of variables such as acid neutralizing capacity, pH and NO3· are likely to be highly correlated with the episodic extremes of those variables from the same stream and runoff season. We illustrate these correlations for a water chemistry record, nearly two years in length, obtained from intensive sampling of 13 small Northeastern U.S. streams studied during USEPA's Episodic Response Project. For these streams, simple regression models estimate episodic extremes of acid neutralizing capacity, pH, NO3·, Ca2+, SO42?, and total dissolved Al with good relative accuracy from statistics of monthly or annual index samples. Model performances remain generally stable when episodic extremes in the second year of sampling are predicted from first-year models. Monthly or annual sampling designs, in conjunction with simple empirical models calibrated and maintained through intensive sampling every few years, may estimate episodic extremes of acidification chemistry with economy and reasonable accuracy. Such designs would facilitate sampling a large number of streams, thereby yielding estimates of the prevalence of episodic acidification at regional scales. 相似文献
990.
Project RENEWAL is an innovative new environmental business project taking place in New Jersey. Project RENEWAL stands for Resource Efficiency Network to Eliminate Waste and Liability. The purpose of this project is to investigate and promote the linkages between ecology, technology, and business economics for the benefit of the economy and the environment. This is a collaborative effort, initially focused on equipment and inventory assets, between the business and environmental communities in order to explore new ways to increase business efficiency and profitability and also benefit the environment. Participants in the project include representatives from industry, consulting, local and state government, environmental agencies, trade groups and academia. This article will outline the background and initial framework of Project RENEWAL's initiatives. (The authors are open to comments, suggestions, criticism, and most importantly input from others who share their vision and are willing to cooperatively accelerate the change process). 相似文献