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61.
Passive sampler derived air concentrations of PBDEs along an urban-rural transect: spatial and temporal trends 总被引:1,自引:0,他引:1
Passive air samplers consisting of polyurethane foam (PUF) disks housed in chambers were deployed at several sites along a approximately 75 km urban-rural gradient in Toronto and analyzed for polybrominated diphenyl ethers (PBDEs). Samplers were allowed to integrate gas-phase PBDEs over three consecutive seasons starting in the summer of 2000. PBDEs were fairly uniform along the transect with air concentrations in Toronto (10-30 pgm(-3)) about a factor of two greater than at rural sites. Lowest concentrations were observed during the winter and probably associated with reduced inputs from indoor sources of PBDEs and to a preference for PBDEs to partition to the particle-phase at colder temperatures. The composition of PBDEs in the air samples did not differ across the transect or for the different seasons. 相似文献
62.
Ettler V Mihaljevic M Sebek O Molek M Grygar T Zeman J 《Environmental pollution (Barking, Essex : 1987)》2006,142(3):409-417
Stream sediments from the mining and smelting district of Príbram, Czech Republic, were studied to determine the degree, sources and dispersal of metal contamination using a combination of bulk metal and mineralogical determinations, sequential extractions and Pb isotopic analyses. The highest metal concentrations were found 3-4 km downstream from the main polymetallic mining site (9800 mg Pb kg(-1), 26 039 mg Zn kg(-1), 316.4 mg Cd kg(-1), 256.9 mg Cu kg(-1)). The calculated enrichment factors (EFs) confirmed the extreme degree of contamination by Pb, Zn and Cd (EF>40). Lead, Zn and Cd are bound mainly to Fe oxides and hydroxides. In the most contaminated samples Pb is also present as Pb carbonates and litharge (PbO). Lead isotopic analysis indicates that the predominant source of stream sediment contamination is historic Pb-Ag mining and primary Pb smelting (206Pb/207Pb=1.16), while the role of secondary smelting (car battery processing) is negligible. 相似文献
63.
Cupr P Klánová J Bartos T Flegrová Z Kohoutek J Holoubek I 《Environmental pollution (Barking, Essex : 1987)》2006,144(2):406-413
The capability of passive air sampling to be employed in the evaluation of direct genotoxicity of ambient air samples was assessed. Genotoxic effects of the total extracts from the polyurethane foam filters exposed for 28 days during a regional passive air sampling campaign were investigated. Twenty sampling sites were selected in Brno city on the area of approximately 20x20 km in October and November 2004. Brno is the second largest city of the Czech Republic, highly industrialized with approximately 370,000 of permanent inhabitants. The levels of PAHs, PCBs, and chlorinated pesticides were determined in all samples. Fraction of each extract was also assayed in the bacterial genotoxicity test using Escherichia coli sulA::lacZ. Complete dose-response relationships of the air extracts were determined. The statistical analysis showed significant correlation between observed biological effects and PAHs concentrations in samples. 相似文献
64.
65.
Rybová Kristýna Slavík Jan Burcin Boris Soukopová Jana Kučera Tomáš Černíková Alena 《Journal of Material Cycles and Waste Management》2018,20(3):1884-1891
Journal of Material Cycles and Waste Management - Increasing pressure of the European Union on diverting municipal waste from landfills requires an active role of households and commands a radical... 相似文献
66.
Tom Finch Simon Gillings Rhys E. Green Dario Massimino Will J. Peach Andrew Balmford 《Conservation biology》2019,33(5):1045-1055
Empirical evidence from many regions suggests that most species would be least negatively affected if human food demand were met through high-yield agricultural production and conservation of nonfarm ecosystems (land sparing), rather than through wildlife-friendly farming over a larger area (land sharing). However, repeated glaciation and a long history of agriculture may lead to different results in regions such as western Europe. We compared the consequences of land sparing and land sharing on breeding bird species in 2 lowland regions of England, The Fens, with 101 species, and Salisbury Plain, with 83. We derived density–yield responses for each species and then estimated regional population size under regional food production strategies, including land sharing and land sparing, a range of intermediate strategies, and a novel mixed strategy. In both regions, more species achieved maximum regional population size under land sparing than land sharing. In The Fens, the majority of birds were loser species (estimated to have smaller populations under all food production strategies than in the preagricultural baseline scenario), whereas in Salisbury Plain the majority were winners (smaller populations in the preagricultural baseline scenario). Loser species overwhelmingly achieved maximum regional population size under land sparing, whereas winner species achieved maximum regional population size under either land sharing or an intermediate strategy, highlighting the importance of defining which groups of species are the target of conservation. A novel 3-compartment strategy (combining high-yield farming, natural habitat, and low-yield farming) often performed better than either land sharing or land sparing. Our results support intermediate or 3-compartment land-sparing strategies to maximize bird populations across lowland agricultural landscapes. To deliver conservation outcomes, any shift toward land sparing must, however, ensure yield increases are sustainable in the long term, do not entail increased negative effects on surrounding areas, and are linked to allocation of land for nature. 相似文献
67.
Goris Nazari Joy C. MacDermid Kathryn E. Sinden Tom J. Overend 《International journal of occupational safety and ergonomics》2019,25(1):1-7
Introduction. Few studies have addressed whether firefighters are fitter than the general population and possess sufficient levels of aerobic capacity and muscle strength to perform on-duty tasks in a safe and efficient manner, considering age and gender. We aimed to evaluate the fitness levels of Hamilton firefighters, and to determine the effects of age and gender. Methods. In total, 89 participants were recruited. The modified Canadian aerobic fitness test was used to determine participants’ estimated maximal oxygen consumption (VO2max) levels. For upper and lower body strength levels, a calibrated J-Tech hand-held dynamometer and a National Institute for Occupational Safety and Health (NIOSH) lifting device was used respectively. Results. Firefighters’ mean (SD) VO2max level was 40.30?±?6.25?ml·kg?1·min?1. Age proved to have a statistically significant impact on VO2max (p?<?0.001). Gender displayed statistically significant effects on strength levels. Firefighters’ age was the only statistically significant independent variable, and accounted for 61.00% of the variance in firefighters’ aerobic capacity levels. Conclusions. Firefighters possessed somewhat similar aerobic capacities but much higher levels of body strength when compared with the general population. With age, firefighters’ aerobic capacities decreased; however, their upper and lower body strength levels remained the same. 相似文献
68.
Opportunity and recognition isolation can lead directly to reproductive isolation, the former via divergence in the location
and timing of breeding, and the latter via differential mate preferences. We describe the potential significance of these
factors in the maintenance of reproductive isolation in a clade of triplefin fishes that occur sympatrically around coastal
New Zealand. Specifically, we investigate the roles of spawning time and nesting habitat in promoting opportunity isolation,
and of interspecific variation in male body length and breeding colouration in promoting recognition isolation. The triplefin
species investigated are reproductively active over several months and show high overlap in breeding times, thus rejecting
temporal isolation as a mechanism. Differences in nesting habitats resulted in a reduced probability of encounter between
some species, especially between sister-species pairs. Interspecific colour differences generally decreased during the reproductive
period, and males of sister-species pairs showed no interspecific colour differences in the ultraviolet light spectrum, thus
mate selection based on male colour patterns is unlikely to lead to premating isolation. Finally, males of closely related
triplefin species differed in body length, a secondary sexual trait often involved in assortative mating. Thus, spatial differences
in nesting habitats reduce the chances of encountering allospecific mates, which may facilitate opportunity isolation and
differences in male length, possibly related to species-specific female selection on male body size, may lead to recognition
isolation. The combination of limited spatial overlap in nesting habitat and differences in male body size may facilitate
species assortative mating in sympatry or parapatry. 相似文献
69.
Verônica da Fonsêca-Genevois Paul J. Somerfield Maria Helena Baeta Neves Ricardo Coutinho Tom Moens 《Marine Biology》2006,148(5):1039-1050
An experiment was undertaken at Farol Island, Brazil, to examine colonization of bare aluminium surfaces by microbes and meiofauna.
It was hypothesized that a primary source of meiofaunal colonists was sediment resuspended during upwelling events, two of
which occurred during the experiment. Microbial biofilms formed on the experimental substrata within 1 day, and continued
to develop throughout the experimental period. Among meiofaunal groups copepods also appeared on the first day, and nematodes
on the second. Meiofaunal community structure developed in three main phases: an initial phase of 2 days, characterized by
low abundances of copepods; a second phase during the first upwelling period characterized by higher abundances of copepods
and also by turbellarians; and a third phase from day 13 onwards characterized by relatively stable abundances of a range
of taxa including copepods, cirripedes, nematodes and ostracods. Nematode assemblages also developed in three phases, but
with different timings coinciding with upwelling events: an initial phase, from the beginning of the experiment to day 9,
characterized by few species and low (or no) abundances; a second phase following the first upwelling characterized by moderate
abundances of Chromadorina, Chromadorella, Daptonema and Euchromadora sp. 3; a third phase following the second upwelling period (from day 26 onwards) in which Daptonema disappeared and the assemblage was characterized by moderate to high abundances of Euchromadora (species 1 and 2) and Chromadorella. Although shifts in nematode assemblage structure coincided with upwelling events no evidence was found for sediments being
the primary source of colonizers on the aluminium substrata, in contrast to our hypothesis. 相似文献
70.
The regeneration rate of arms of the infaunal brittlestar Ophiophragmus filograneus was determined in natural and planted beds of the seagrass (Halodule wrighttii) in Tampa Bay, Florida, USA in 1990. Annually, brittlestar densities did not differ on average between the two beds, but they did show marked differences on individual dates. Rates of arm loss could not be determined for the two sites separately, but were estimated for the entire area. Between 52 and 94% of the brittlestars collected showed evidence of arm regeneration. Approximately one-third of those collected were regenerating one arm, with smaller proportions regenerating two or more arms. Regeneration rate was greater overall for individuals that had lost more tissue; however, the rate of soft-tissue regeneration per arm regenerated was significantly greater for those that had lost one arm compared to those that had lost three arms. The rate of soft-tissue regeneration did not differe between individuals from the two seagrass beds, and regeneration rate was lower than reported for other infaunal brittlestars. Skeletal regeneration per arm was similar in both arm-removal treatments. This result supports the hypothesis that echinoderm skeleton is energetically inexpensive and may help to lengthen arms during early regeneration. The rate of skeletal production was three-fold greater in individuals from the planted seagrass than in those from the natural. bed. As increased skeletal regeneration requires some additional energy, this indicates a greater energy expenditure and differential allocation by brittlestars regenerating in the planted seagrass areas. 相似文献