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61.
This initial research examined the presence, distribution and bioavailability of Cu, Cr, Ni, Mn and Fe in a wetland area of southern
Guam. The research sites are within an area covered with saporite, a soil type derived from volcanic deposits on the island. Leaf tissue
of Pandanus tectorius was extracted and analysed to determine the bioaccumulation of the target metals. Metal accumulation at sites
considered aerobic and anaerobic was investigated together with an attempt to correlate actual accumulation of the target metals in the
plant tissue with a recognised bioavailability indicator, in this case, three step sequential extraction scheme. Manganese was found to be
accumulated in relatively high concentrations and to a lesser extent Cu was also accumulated. Chromium, Ni and Fe however exhibited
very low accumulation factors. Accumulation of Mn in particular was significantly a ected by aerobic conditions whereas the converse
e ect was experienced by Cu. Significant correlation between various steps of a Sequential Extraction Scheme and actual accumulation
was not achieved although the degree of aerobic conditions at each site and soil pH did a ect concentrations of metals extracted by
di ering steps of SES. Results obtained suggest that further research in the area should be undertaken using di erent plant species and
tissues. 相似文献
62.
Where clocks are redundant: weak circadian mechanisms in reindeer living under polar photic conditions 总被引:1,自引:0,他引:1
Biological rhythms are a result of interplay between endogenous clocks and the ambient light–dark (LD) cycle. Biological timing
in resident polar organisms presents a conundrum because these experience distinct daily LD cycles for only a few weeks each
year. We measured locomotor activity in reindeer, Rangifer tarandus platyrhynchus (SR, n = 5 and 6) and R. tarandus tarandus (NR, n = 6), ranging freely at 78 and 70°N, respectively, continuously throughout 1 year using data loggers. NR, but not SR, are
gregarious which enabled us to examine the integrated effects of differences in social organisation and the photic environment
at two different latitudes on the organisation of activity. In both sub-species, ultradian bouts of activity and inactivity
alternated across the 24-h day throughout the year. This pattern was modified by the LD cycle in NR but barely at all in SR.
Periodogram analysis revealed significant ultradian rhythmicity in both sub-species; the frequency of daily cycles of activity
increased from three per day in winter to nearly five in summer. We conclude that this increase, and a concomitant increase
in the level of daily activity, reflected the seasonal increase in the animals’ appetite and the quality of their forage.
Secondly, the combination, most evident in SR, of a weak photic response, weak circadian mechanisms and a weak social synchronization
reduces the constraints of biological timing in an environment which is effectively non-rhythmic most of the year and permits
expression of the basic ultradian pattern of ruminant activity. Third, the weaker 24-h rhythmicity in SR compared to NR indicates
a latitudinal decrease in circadian organization and photic responsiveness in Rangifer. 相似文献
63.
Forest to reclaimed mine land use change leads to altered ecosystem structure and function. 总被引:1,自引:0,他引:1
Jeffrey A Simmons William S Currie Keith N Eshleman Karen Kuers Susan Monteleone Tim L Negley Bob R Pohlad Carolyn L Thomas 《Ecological applications》2008,18(1):104-118
The United States' use of coal results in many environmental alterations. In the Appalachian coal belt region, one widespread alteration is conversion of forest to reclaimed mineland. The goal of this study was to quantify the changes to ecosystem structure and function associated with a conversion from forest to reclaimed mine grassland by comparing a small watershed containing a 15-year-old reclaimed mine with a forested, reference watershed in western Maryland. Major differences were apparent between the two watersheds in terms of biogeochemistry. Total C, N, and P pools were all substantially lower at the mined site, mainly due to the removal of woody biomass but also, in the case of P, to reductions in soil pools. Mineral soil C, N, and P pools were 96%, 79%, and 69% of native soils, respectively. Although annual runoff from the watersheds was similar, the mined watershed exhibited taller, narrower storm peaks as a result of a higher soil bulk density and decreased infiltration rates. Stream export of N was much lower in the mined watershed due to lower net nitrification rates and nitrate concentrations in soil. However, stream export of sediment and P and summer stream temperature were much higher. Stream leaf decomposition was reduced and macroinvertebrate community structure was altered as a result of these changes to the stream environment. This land use change leads to substantial, long-term changes in ecosystem capital and function. 相似文献
64.
Kaishan Song Lin Li Lenore Tedesco Nicole Clercin Bob Hall Shuai Li Kun Shi Dawei Liu Ying Sun 《Environmental science and pollution research international》2013,20(8):5330-5340
Nuisance cyanobacterial blooms degrade water resources through accelerated eutrophication, odor generation, and production of toxins that cause adverse effects on human health. Quick and effective methods for detecting cyanobacterial abundance in drinking water supplies are urgently needed to compliment conventional laboratory methods, which are costly and time consuming. Hyperspectral remote sensing can be an effective approach for rapid assessment of cyanobacterial blooms. Samples (n?=?250) were collected from five drinking water sources in central Indiana (CIN), USA, and South Australia (SA), which experience nuisance cyanobacterial blooms. In situ hyperspectral data were used to develop models by relating spectral signal with handheld fluorescence probe (YSI 6600 XLM-SV) measured phycocyanin (PC in cell/ml), a proxy pigment unique for indicating the presence of cyanobacteria. Three-band model (TBM), which is effective for chlorophyll-a estimates, was tuned to quantify cyanobacteria coupled with the PC probe measured cyanobacteria. As a comparison, two band model proposed by Simis et al. (Limnol Oceanogr, 50(11): 237–245, 2005; denoted as SM05) was paralleled to evaluate TBM model performance. Our observation revealed a high correlation between measured and estimated PC for SA dataset (R 2?=?0.96; range: 534–20,200 cell/ml) and CIN dataset (R 2?=?0.88; range: 1,300–44,500 cell/ml). The potential of this modeling approach for imagery data were assessed by simulated ESA/Centinel3/OLCI spectra, which also resulted in satisfactory performance with the TBM for both SA dataset (RMSE %?=?26.12) and CIN dataset (RMSE %?=?34.49). Close relationship between probe-measured PC and laboratory measured cyanobacteria biovolume was observed (R 2?=?0.93, p?<?0.0001) for the CIN dataset, indicating a stable performance for PC probe. Based on our observation, field spectroscopic measurement coupled with PC probe measurements can provide quantitative cyanobacterial bloom information from both relatively static and flowing inland waters. Hence, it has promising implications for water resource managers to obtain information for early warning detection of cyanobacterial blooms through the close association between probe measured PC values and cyanobacterial biovolume via remote sensing modeling. 相似文献
65.
Massimo?TavoniEmail author Bob?van der?Zwaan 《Environmental Modeling and Assessment》2011,16(5):431-440
In this paper, we analyze the relative importance and mutual behavior of two competing base-load electricity generation options
that each are capable of contributing significantly to the abatement of global CO2 emissions: nuclear energy and coal-based power production complemented with CO2 capture and storage (CCS). We also investigate how, in scenarios developed with an integrated assessment model that simulates
the economics of a climate-constrained world, the prospects for nuclear energy would change if exogenous limitations on the
spread of nuclear technology were relaxed. Using the climate change economics model World Induced Technical Change Hybrid,
we find that until 2050 the growth rates of nuclear electricity generation capacity would become comparable to historical
rates observed during the 1980s. Given that nuclear energy continues to face serious challenges and contention, we inspect
how extensive the improvements of coal-based power equipped with CCS technology would need to be if our economic optimization
model is to significantly scale down the construction of new nuclear power plants. 相似文献
66.
Topi K. Lehtonen Bob B. M. Wong P. Andreas Svensson Axel Meyer 《Behavioral ecology and sociobiology》2011,65(4):613-619
In many taxa, parental strategies can vary among individuals. This is especially true in species with biparental care, with
males, more often than females, deserting their mates. While there is an abundance of theoretical predictions and empirical
data on factors inducing mate abandonment by males, much less is known about what consequences this may have on female behaviour,
particularly in the field and in non-avian systems. Here, we compared brood defence rate, behavioural defence types, and brood
success of solitary and paired females in two species of Neotropical cichlid fish in their natural habitat. In terms of the
rate of territorial aggression towards potential brood predators, solitary females were able to fully compensate in the absence
of a male but, in so doing, ended up maintaining smaller territories, which appeared to compromise offspring fitness in at
least one of the two species. Hence, our results suggest that even extensive quantitative compensation in parental effort
by solitary females may not be enough to ensure adequate qualitative compensation for the lack of male participation, highlighting
the importance of distinguishing between these two aspects of compensatory parental care. 相似文献
67.
Laura McCann Haluk Gedikoglu Bob Broz John Lory Ray Massey 《Journal of Environmental Planning and Management》2015,58(8):1346-1362
The ability of both regulators and farmers themselves to monitor the impact of environmental practices may be an issue with nonpoint source pollution. Effects that can be perceived via direct sensory evidence provide information at low cost. Results from a survey of livestock farmers suggest that a practice that has more obvious effects on water quality, manure application setbacks, is more likely to be adopted than a more complicated one with less visible effects, manure testing. Farmers’ perceptions of the profitability of the two practices were similar. The importance of observability and complexity has implications for educational programs. 相似文献
68.
69.
The last decade has seen considerable interest in the concept of social capital and there have been a number of publications focused around the concept. A wide range of claims have been made for the analytic potential of social capital leading some to question the concept's continued value. We think that the concept still has considerable value if used in a careful and rigorous way. We further think that the concept has particular value when considering policy for sustainable development. However, just as sustainable development is a multi‐faceted concept, this application requires a multi‐faceted reading of social capital. Having concluded that a clearer typology of social capital is needed, we propose a threefold typology, adding the new category of ‘bracing’ social capital to the more commonly used distinction between ‘bonding’ and ‘bridging’ social capital. We also address the issues of what social capital can do and how it actually works, specifically in the context of policy for sustainable development. 相似文献
70.
Kinnunen Paivo Yliniemi Juho Talling Bob Illikainen Mirja 《Journal of Material Cycles and Waste Management》2017,19(3):1220-1227
Journal of Material Cycles and Waste Management - Mineral wool waste is often considered unrecyclable, due to its difficult-to-process physical composition, and potential microbial contamination in... 相似文献