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351.
It is generally argued that leader visions motivate followers by focusing on reaching desirable end‐states. However, it has also been suggested that visions may motivate followers by focusing on avoiding undesirable situations. In this paper we investigate the effects of appeals that focus on preventing an undesirable situation (i.e., prevention‐appeals) as well as appeals that focus on promoting a desirable situation (i.e., promotion‐appeals). We argue that the effectiveness of promotion‐ and prevention‐appeals is contingent on follower regulatory focus. In two experiments we show that prevention‐appeals lead to better performance than promotion‐appeals for more prevention‐focused followers, while the reverse is true for more promotion‐focused followers. We find this pattern for a dispositional measure of follower regulatory focus (Study 1) as well as for a manipulation of follower regulatory focus (Study 2). Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
352.
BriAnne Addison Alexander S. Kitaysky J. Mark Hipfner 《Behavioral ecology and sociobiology》2008,63(1):135-141
Sex allocation theory posits that mothers should preferentially invest in sons when environmental conditions are favorable
for breeding, their mates are of high quality, or they are in good body condition. We tested these three hypotheses in rhinoceros
auklets (Cerorhinca monocerata), monomorphic seabirds that lay a single-egg clutch, in 2 years that differed in environmental conditions for breeding. Results
supported the environment and mate quality hypotheses, but these effects were interactive: offspring sex was independent of
paternal traits in the poor year for breeding, while females mated to larger and more ornamented males reared more sons in
the better year. Conversely, offspring sex was unrelated to female condition, as indexed by hatching date. We propose that
good rearing conditions enable females to rear sons possessing the desirable phenotypic attributes of their mates. Results
also supported two critical assumptions of sex allocation theory: (1) dimorphism in offspring condition at independence: daughters
fledged with higher baseline levels of corticosterone than sons and (2) differential costs of rearing sons versus daughters:
mothers rearing sons when environmental conditions were poor completed parental care in poorer condition than mothers rearing
daughters in the same year and mothers rearing either sex when conditions were better. These novel results may help to explain
the disparate results of previous studies of avian sex allocation. 相似文献
353.
Lindström ES Eiler A Langenheder S Bertilsson S Drakare S Ragnarsson H Tranvik LJ 《Ecology》2007,88(1):252-3; discussion 253-5
354.
Alexander H. Elliott Ton H. Snelder Richard W. Muirhead Ross M. Monaghan Amy L. Whitehead Santiago A. Bermeo-Alvear Carl J. Howarth 《Environmental management》2020,65(2):272-285
A common land and water management task is to determine where and by how much source loadings need to change to meet water quality limits in receiving environments. This paper addresses the problem of quantifying changes in loading when limits are specified in many locations in a large and spatially heterogeneous catchment, accounting for cumulative downstream impacts. Current approaches to this problem tend to use either scenario analysis or optimization, which suffer from difficulties of generating scenarios that meet the limits, or high complexity of optimization approaches. In contrast, we present a novel method in which simple catchment models, load limits, upstream/downstream spatial relationships and spatial allocation rules are combined to arrive at source load changes. The process iteratively establishes the critical location (river segment or lake) where the limits are most constraining, and then adjusts sources upstream of the critical location to meet the limit at that location. The method is demonstrated with application to New Zealand (268,000 km2) for nutrients and the microbial indicator E. coli, which was conducted to support policy development regarding water quality limits. The model provided useful insights, such as a source load excess (the need for source load reduction) even after mitigation measures are introduced in order to comply with E. coli limits. On the other hand, there was headroom (ability to increase source loading) for nutrients. The method enables assessment of the necessary source load reductions to achieve water quality limits over broad areas such as large catchments or whole regions. 相似文献
355.
Maximilian Berthold Ulf Karsten Mario von Weber Alexander Bachor Rhena Schumann 《Ambio》2018,47(1):146-158
The EU-water framework directive aims at nutrient reductions, since anthropogenically induced eutrophication is a major threat for coastal waters. However, phytoplankton biomass in southern Baltic Sea coastal water bodies (CWB) remains high and the underlying mechanisms are not well understood. Therefore, a CWB data set was analysed regarding changes in phytoplankton biomass and nutrient concentration of nitrogen (N) and phosphorus (P) from 2000 to 2014. It was expected to find imbalances between produced phytoplankton biomass and total nutrient concentrations. Inner CWB were cyanobacteria-dominated and showed up to five times higher chlorophyll a-concentrations compared to outer CWB with similar total phosphorus-concentrations. Phytoplankton tended to be P-limited during spring and N-limited during summer. Phytoplankton biomass and nutrient concentrations were even higher during very humid years, which indicated a close coupling of the CWB with their catchment areas. This study suggests that re-mesotrophication efforts need to consider the importance of changed phytoplankton composition and nutrient availabilities. 相似文献
356.
Waha Katharina Krummenauer Linda Adams Sophie Aich Valentin Baarsch Florent Coumou Dim Fader Marianela Hoff Holger Jobbins Guy Marcus Rachel Mengel Matthias Otto Ilona M. Perrette Mahé Rocha Marcia Robinson Alexander Schleussner Carl-Friedrich 《Regional Environmental Change》2017,17(6):1623-1638
Regional Environmental Change - The Middle East and North Africa (MENA) region emerges as one of the hot spots for worsening extreme heat, drought and aridity conditions under climate change. A... 相似文献
357.
Alexander Golub Daiju Narita Matthias G. W. Schmidt 《Environmental Modeling and Assessment》2014,19(2):99-109
Uncertainty plays a key role in the economics of climate change, and research on this topic has led to a substantial body of literature. However, the discussion on the policy implications of uncertainty is still far from being settled, partly because the uncertainty of climate change comes from a variety of sources and takes diverse forms. To reflect the multifaceted nature of climate change uncertainty better, an increasing number of analytical approaches have been used in the studies of integrated assessment models of climate change. The employed approaches could be seen as complements rather than as substitutes, each of which possesses distinctive strength for addressing a particular type of problems. We review these approaches—specifically, the non-recursive stochastic programming, the real option analysis, and the stochastic dynamic programming—their corresponding literatures and their respective policy implications. We also identify the current research gaps associated with the need for further developments of new analytical approaches. 相似文献
358.
359.
Jose Alexander Elvir G. Bruce Wiersma Suzanne Bethers Peter Kenlan 《Environmental monitoring and assessment》2010,171(1-4):129-147
At the Bear Brook Watershed in Maine (BBWM), the forest tree composition was characterized and the effects of the chronic ammonium sulfate ((NH4)2SO4) treatment on basal area growth, foliar chemistry, and gas exchange were investigated on forest species. The BBWM is a paired watershed forest ecosystem study with one watershed, West Bear (WB), treated since 1989 with 26.6 kg N ha???1 year???1 and 30 kg S ha???1 year???1applied bimonthly as (NH4)2SO4, while the other watershed, East Bear (EB), serves as a reference. Tree species richness, density, and mortality were found to be similar between watersheds. Basal area increment was estimated from red spruce and sugar maple, showing that, for the first 7 years of treatment, it was significantly higher for sugar maple growing in WB compared to EB, but no differences were observed for red spruce between watersheds. However, the initial higher sugar maple basal area growth in WB subsequently decreased after 8 years of treatment. Foliar chemical analysis performed in trees, saplings, and ground flora showed higher N concentrations in the treated WB compared to the reference EB. But, foliar cation concentrations, especially Ca and Mg, were significantly lower for most of the species growing in WB compared with those growing in EB. For sugar maple, foliar N was higher on WB, but there were no differences in foliar Ca and Mg concentrations between treated and reference watersheds. In addition, only sugar maple trees in the treated WB showed significantly higher photosynthetic rates compared to reference EB trees. 相似文献
360.
Kevin S. Simon Michael A. Chadwick Alexander D. Huryn H. Maurice Valett 《Environmental monitoring and assessment》2010,171(1-4):83-92
The Bear Brook Watershed in Maine (BBWM) is a long-term, paired watershed experiment that addresses the effects of acid and nitrogen (N) deposition on whole watersheds. To examine stream response at BBWM, we synthesized data on organic matter dynamics, including leaf breakdown rates, organic matter inputs and standing stocks, macroinvertebrate secondary production, and nutrient uptake in treated and reference streams at the BBWM. While N concentrations in stream water and leaves have increased, the input, standing stocks, and breakdown rates of leaves, as well as macroinvertebrate production, were not responsive to acid and N deposition. Both chronic and acute increases of N availability have saturated uptake of nitrate in the streams. Recent experimental increases in phosphorus (P) availability enhanced stream capacity to take up nitrate and altered the character of N saturation. These results show how the interactive effects of multiple factors, including environmental flow regime, acidification, and P availability, may constrain stream response to chronic N deposition. 相似文献