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41.
42.
Sas-Nowosielska A Galimska-Stypa R Kucharski R Zielonka U Małkowski E Gray L 《Environmental monitoring and assessment》2008,137(1-3):101-109
Phytoremediation, an approach that uses plants to remediate contaminated soil through degradation, stabilization or accumulation,
may provide an efficient solution to some mercury contamination problems. This paper presents growth chamber experiments that
tested the ability of plant species to stabilize mercury in soil. Several indigenous herbaceous species and Salix viminalis were grown in soil collected from a mercury-contaminated site in southern Poland. The uptake and distribution of mercury
by these plants were investigated, and the growth and vitality of the plants through a part of one vegetative cycle were assessed.
The highest concentrations of mercury were found at the roots, but translocation to the aerial part also occurred. Most of
the plant species tested displayed good growth on mercury contaminated soil and sustained a rich microbial population in the
rhizosphere. The microbial populations of root-free soil and rhizosphere soil from all species were also examined. An inverse
correlation between the number of sulfur amino acid decomposing bacteria and root mercury content was observed. These results
indicate the potential for using some species of plants to treat mercury contaminated soil through stabilization rather than
extraction. The present investigation proposes a practical cost-effective temporary solution for phytostabilization of soil
with moderate mercury contamination as well as the basis for plant selection. 相似文献
43.
Burger J Gochfeld M Jeitner C Gray M Shukla T Shukla S Burke S 《Environmental monitoring and assessment》2007,128(1-3):311-321
Kelp may be useful as a bioindicator because they are primary producers that are eaten by higher trophic level organisms,
including people and livestock. Often when kelp or other algae species are used as bioindicators, the whole organism is homogenized.
However, some kelp can be over 25 m long from their holdfast to the tip of the blade, making it important to understand how
contaminant levels vary throughout the plant. We compared the levels of arsenic, cadmium, chromium, lead, manganese, mercury
and selenium in five different parts of the kelp Alaria nana to examine the variability of metal distribution. To be useful as a bioindicator, it is critical to know whether levels are
constant throughout the kelp, or which part is the highest accumulator. Kelp were collected on Adak Island in the Aleutian
Chain of Alaska from the Adak Harbor and Clam Cove, which opens onto the Bering Sea. In addition to determining if the levels
differ in different parts of the kelp, we wanted to determine whether there were locational or size-related differences. Regression
models indicated that between 14% and 43% of the variation in the levels of arsenic, cadmium, chromium, manganese, mercury,
and selenium was explained by total length, part of the plant, and location (but not for lead). The main contributors to variability
were length (for arsenic and selenium), location (mercury), and part of the plant (for arsenic, cadmium, chromium and manganese).
The higher levels of selenium occurred at Clam Cove, while mercury was higher at the harbor. Where there was a significant
difference among parts, the holdfast had the highest levels, although the differences were not great. These data indicate
that consistency should be applied in selecting the part of kelp (and the length) to be used as a bioindicator. While any
part of Alaria could be collected for some metals, for arsenic, cadmium, chromium, and manganese a conversion should be made among parts.
In the Aleutians the holdfast can be perennial while the blade, whipped to pieces by winter wave action, is regrown each year.
Thus the holdfast may be used for longer-term exposure for arsenic, cadmium, chromium and manganese, while the blade can be
used for short-term exposure for all metals. Cadmium, lead and selenium were at levels that suggest that predators, including
people, may be at risk from consuming Alaria. More attention should be devoted to heavy metal levels in kelp and other algae from Adak, particularly where they may play
a role in a subsistence diets. 相似文献
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45.
Ecologists commonly use grouped or clustered count data to estimate temporal trends in counts, abundance indices, or abundance. For example, the U.S. Breeding Bird Survey data represent multiple counts of birds from within each of multiple, spatially defined routes. Despite a reliance on grouped counts, analytical methods for prospectively estimating precision of trend estimates or statistical power to detect trends that explicitly acknowledge the characteristics of grouped count data are undescribed. These characteristics include the fact that the sampling variance is an increasing function of the mean, and that sampling and group-level variance estimates are generally estimated on different scales (the sampling and log scales, respectively). We address these issues for repeated sampling of a single population using an analytical approach that has the flavor of a generalized linear mixed model, specifically that of a negative binomial-distributed count variable with random group effects. The count mean, including grand intercept, trend, and random group effects, is modeled linearly on the log scale, while sampling variance of the mean is estimated on the log scale via the delta method. Results compared favorably with those derived using Monte Carlo simulations. For example, at trend = 5% per temporal unit, differences in standard errors and in power were modest relative to those estimated by simulation (< or = /11/% and < or = /16/%, respectively), with relative differences among power estimates decreasing to < or = /7/% when power estimated by simulations was > or = 0.50. Similar findings were obtained using data from nine surveys of fingernail clams in the Mississippi River. The proposed method is suggested (1) where simulations are not practical and relative precision or power is desired, or (2) when multiple precision or power calculations are required and where the accuracy of a fraction of those calculations will be confirmed using simulations. 相似文献
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48.
The behaviour of intertidal consumers is often tightly constrained to tidal movements, although activity patterns can vary
within these constraints. Spatio-temporal variability in behaviour of a limpet, Cellana grata, was analysed over different tidal conditions (spring and neap tides) and during different times of the year (one summer
and one winter) at sites in Hong Kong. Activity was generally dictated by tidal movements, being concentrated when animals
were awash. Plasticity in behaviour was observed, with some limpets anticipating activity during the summer period and delaying
activity during winter time. Limpets were active for a time equal, or slightly less, than time awash. As the time awash exceeded
~14–16 h, however, activity duration decreased. Within this general pattern, tidal variation as well as variation among times
of the year was noted, with the lowest dependence on time awash being recorded during winter neap tides. Limpets showed a
slight preference for being active during nighttime, which was particularly evident when animals were emersed during the summer
period. Although the basic activity in C. grata is constrained to a specific temporal window, this limpet is able to modulate its foraging strategies and resting height,
according to local, daily changes in environmental conditions. 相似文献
49.
Understanding variation in physiological adaptations to thermal stress is vital when investigating intertidal species?? distribution patterns. The thermal sensitivities of two limpets, Cellana grata and C. toreuma, differed in accordance with their vertical distributions. Cardiac performance was maintained at higher temperatures (~47°C) for the high-zone C. grata than the mid-zone C. toreuma (~42°C). At 40°C, C. grata maintained regular heart function for ~4?h, while heart function of C. toreuma decreased rapidly. Heat shock protein expression revealed that C. toreuma had two constitutive isoforms, Hsp77 and Hsp72, and C. grata one inducible form, Hsp75, which was upregulated at 40°C, suggesting C. grata has a more effective heat shock response than C. toreuma. The temperature-adaptive differences in cardiac thermal tolerance and Hsp expression match observed differences in thermally induced mortalities with the onset of summer and may help predict differential effects of climate change on the two congeners. 相似文献
50.
Dr. M. J. Bennett F. Allison G. W. Lowther R. G. F. Gray D. I. Johnston J. S. Fitzsimmons N. J. Manning R. J. Pollitt 《黑龙江环境通报》1987,7(2):135-141
A fatal case of medium-chain acyl-coenzyme A dehydrogenase deficiency is described in a patient who presented with hypoglycaemia and a gross non-ketotic dicarboxylic aciduria. Cultured skin fibroblasts released 14CO2 from [1–14C] octanoic acid at half the normal rate. Prenatal diagnosis was undertaken in a subsequent pregnancy in which cultured amniotic fluid cells revealed a marked reduction in octanoate oxidation indicative of an affected fetus. The pregnancy was terminated and the diagnosis was confirmed by enzyme analysis of skin fibroblasts taken from the fetus. The high residual octanoate oxidation by affected fibroblasts together with the absence of any characteristic abnormality of amniotic fluid organic acids are a potential limitation to the reliability of this type of prenatal diagnosis. 相似文献