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531.
532.
Emily Jane Davis Lauren Gwin Cassandra Moseley Hannah Gosnell Harmony Burright 《Journal of Environmental Planning and Management》2015,58(9):1562-1576
Payments for ecosystem or ecological services (PES) are voluntary, often market-based approaches to protecting environmental values. In the rural United States, some landowners receive PES through government led conservation programs, but little is known about their involvement in market based arrangements. We analyzed three examples of market based PES arrangements in northwestern Montana: watershed restoration and craft brewing, niche meat production, and certified timber supplies. We find that intermediaries were working between buyers and sellers in each case to set conditions for transactions and undertake the mechanics of implementation. These findings align with existing conceptualizations of intermediaries as crucial links in PES arrangements, but also suggest that intermediaries for market based PES arrangements are not always facilitators or neutral nongovernmental actors; they may actually be from the private sector and drive the process by serving as buyers. This research contributes to stronger understanding of the possibilities for local market based conservation in the rural West. 相似文献
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535.
The Influence of Two‐Stage Ditches with Constructed Floodplains on Water Column Nutrients and Sediments in Agricultural Streams
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Robert T. Davis Jennifer L. Tank Ursula H. Mahl Sarah G. Winikoff Sarah S. Roley 《Journal of the American Water Resources Association》2015,51(4):941-955
The two‐stage ditch is a novel management practice originally implemented to increase bank stability through floodplain restoration in channelized agricultural streams. To determine the effects of two‐stage construction on sediment and nutrient loads, we monitored turbidity, and also measured total suspended solids (TSS), dissolved inorganic nitrogen (N) species, and phosphorus (P) after two‐stage ditch construction in reference and manipulated reaches of four streams. Turbidity decreased during floodplain inundation at all sites, but TSS and P, soluble reactive phosphorus (SRP) and total phosphorus (TP) decreased only in the two‐stage ditches with longer duration of inundation. Both TSS and TP were positively correlated within individual streams, but neither were correlated with turbidity. Phosphorus was elevated in the stream to which manure was applied adjacent to the two‐stage reach, but not the reference reach, suggesting that landscape nutrient management plans could restrict nutrient transport to the stream, ultimately determining the efficacy of instream management practices. In addition, ammonium and nitrate decreased in two‐stage reaches with lower initial N concentrations. Overall, results suggest that turbidity, TSS, and TP were reduced during floodplain inundation, but the two‐stage alone may not be effective for managing high inorganic N loads. 相似文献
536.
This paper clarifies how polymers are dealt with under the Directive 67/548/EEC. Polymers are a particular group of substances under the Directive 67/548/EEC [1] and amendments [2,3] as they are not listed in the European INventory of Existing Commercial chemical Substances (EINECS [4]) which otherwise lists all substances which were on the European Community Market between 1 January 1971 and 18 September 1981, the ‘existing substances’. Instead, in EINECS polymers are registered under their ultimate building blocks. With the 6th amendment to the Directive [2] polymers became notifiable substances if containing 2% or more of new substance(s) (i.e. as a general rule substances not listed in EINECS), and the reporting criteria were used as definition. With the 7th amendment to the Directive [3] an exact definition was introduced and a special test package, given in Directive 93/105/EEC [5], was designed for polymers to take into account their particular properties. Changing the definition of polymers created a group of substances which under the 6th amendment had been defined as polymers, and could no longer be regarded as polymers under the 7th amendment, the No‐Longer‐Polymers. 相似文献
537.
D.W. Davis E.M. McDougall D.L. Hendrix T.L. Steele J.E. Adaskaveg E.E. Butler 《Journal of the Air & Waste Management Association (1995)》2013,63(8):1116-1121
Unusual air particulates are linked to recent heavy infestations of the ash whitefly in California using high-performance liquid chromatography, scanning electron microscopy, optical and infrared microscopy, ion chromatography and X-ray fluorescence spectrometry. The unusual particles apparently are microdroplets of ash whitefly honeydew. Most of the suspended honeydew is in microdroplets with diameters between about two and twenty microns. The microdroplets were found to contain substantial amounts of sugars, primarily the oligosaccharides stachyose and raffinose. They also contain about 1 percent potassium, mainly as K+ The unusual microdroplets have been found in samples of air particulates taken in many areas of California after 1988. Using a receptor model, the suspended honeydew was calculated to add as much as 40 microgm/M3 to PM10 mass. The highest levels of suspended honeydew occurred between late August and early November. 相似文献
538.
The mudsnail taxon Hydrobia s.l. plays a major role in numerous ecological and parasitological studies. Yet, its taxonomy is confusing and its biogeography
is poorly understood. A principal problem is that taxa of Hydrobia s.l. belong to morphostatic radiations – widely allopatric species radiations with little or no habitat diversification and
a low level of anatomical change. So far, three morphostatic radiations can be identified within Hydrobia s.l.: Hydrobia s.s., Peringia, and Ventrosia. These radiations are identical with the putative genera of Hydrobia s.l. The purpose of the paper is to infer phylogenetic relationships within one of these radiations, Hydrobia s.s. in the northern Atlantic and western Mediterranean. A total of 22 populations, including topotypical populations of
five commonly used taxa, were studied genetically using partial sequences of the mitochondrial cytochrome c oxidase subunit I gene. Based on molecular data and the species concept we define, the following species and subspecies were
identified: Hydrobia acuta acuta (Draparnaud, 1805) [=H. minoricensis (Paladilhe, 1875)], H. acuta neglecta Muus, 1963, and H. glyca (Servain, 1880) (=H. joossei van Aartsen, Menkhorst and Gittenberger, 1984). One population from Djerba, Tunisia (Hydrobia sp. A) and one population from Mallorca, Spain (Hydrobia sp. B) are genetically distinct from all other taxa studied here. Both populations potentially represent new species. Due
to the fact that only one population each has been studied, and so the degree of variation within these two taxa cannot be
assessed, a final decision regarding their species level cannot yet be made.
Received: 6 October 1999 / Accepted: 12 September 2000 相似文献
539.
Jeff Joireman Donelle C. Posey Heather Barnes Truelove Craig D. Parks 《Journal of environmental psychology》2009,29(2):181-192
Three studies examined the impact of warnings about depleting resources. In Study 1, participants played 16 trials of a 5-person resource dilemma game with complete resource uncertainty. After trial 12, participants were told they were close to depleting the resource, and thereafter received no additional warnings. Size of harvests dropped after the warning, but rebounded within 3 trials to pre-warning levels, a pattern stronger under low harvesting variability. In Study 2, participants received warnings after trials 12 and 16 of a 22-trial game. Again, harvesting dropped after the first warning, but rebounded to pre-warning levels within 3 trials, a pattern stronger under a short-term vs. a long-term warning. Harvesting was unaffected by the second warning. In Study 3, when participants received no feedback about others' harvests, harvesting dropped after both warnings, and was lower among those led to believe the resource would last a short number of trials. 相似文献
540.
Jeffrey Wielgus Leah R. Gerber Enric Sala Jeff Bennett 《Journal of environmental management》2009,90(11):3401-3409
Stated-preference surveys for the economic valuation of environmental resources typically assume no uncertainty in the hypothetical valuation scenarios. However, the outcomes of environmental policies are uncertain. We explored the effects of including information on probabilities of attribute improvement and provision in choice experiments. Our results suggest that stating explicitly a high probability for the occurrence of the valuation scenario can improve the goodness of fit of choice models and the consistency of choices. As the general public becomes more aware of the uncertainty of environmental outcomes under global change, omitting information on scenario risk may contribute to hypothetical bias and impair the validity of stated-preference valuations. 相似文献