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181.
In the terrestrial environment, standardized protocols are available for measuring the exposure and effects of contaminants to invertebrates, but none currently exist for vertebrates. In an effort to address this, we proposed that developing lizard embryos may be used as a terrestrial vertebrate model. Lizard eggs may be particularly susceptible to soil contamination and in ovo exposure may affect hatchling size, mortality, as well as thyroid function. Toxicant-induced perturbations of thyroid function resulting from in ovo chemical exposure may result in toxicity during the critical perinatal period in reptiles. Fertilized Eastern fence lizard (Sceloporus undulatus) eggs were placed in cadmium (Cd)-spiked expanded perlite (0, 1.48, 14.8, 148, 1480, 14 800 μg Cd/g, nominal concentrations), artificially incubated at 28 °C, and examined daily for mortality. Whole lizard hatchlings as well as failed hatches were homogenized in ethanol and the homogenate was divided for Cd body residue analysis and thyroid hormone (triiodothyronine (T3) and thyroxine (T4)) analyses. Acute mortality was observed in the two highest doses (1480 and 14 800 μg Cd/g). Cadmium body residues showed a higher internal concentration with increasing exposure concentration indicating uptake of Cd. There was a decrease in T3:T4 ratio at the highest surviving dose (148 μg Cd/g), however, there were no differences observed in hatchling size measured as weight and snout-vent length, or in whole body thyroid hormone levels. In summary, this study has shown Cd amended to a solid phase representing soil (perlite) can traverse the thin, parchment-like shell membrane of the fence lizard egg and bioaccumulate in lizard embryos. We believe this study is a good first step in investigating and evaluating this species for use as a model.  相似文献   
182.
Lead levels in wet and dry deposition were determined within this project. A network of 10 sampling stations was established. The stations were located in areas characterized by heavy traffic volumes, but away from industrial and/or municipal pollution sources. It was assumed, therefore, that lead in the samples collected was coming primarily from automobile emissions. Measurements were carried out over a period of one year. Both rain and snow samples were collected. Lead concentrations in the samples ranged from 0.6 to 141 microg dm(-3). They depended on street topography, traffic volume, average speed of the vehicles, frequency of traffic congestion and atmospheric conditions. The highest lead levels in deposition were observed during the cold season.  相似文献   
183.
In the present study, we investigated the contribution of methylsulfonyl metabolite derived from 1,2,4-trichlorobenzene (1,2,4-TCB) on the delta-aminolevulinic acid (ALA) synthetase induction by the parent compound in rats. The time courses of increasing of hepatic microsomal total cytochrome P450 content after a single i.p. administration of 1,2,4-TCB (1.36 mmol/kg), and 2,3,5- and 2,4,5-trichlorophenyl methyl sulfones (2,3,5- and 2,4,5-TCPSO2Mes) (50 micromol/kg each) were in parallel with those of increasing of the total heme content in liver microsomes. 1,2,4-TCB significantly increased the heme oxygenase activity, but 2,3,5- and 2,4,5-TCPSO2Mes did not. On the other hand, 1,2,4-TCB and 2,3,5-TCPSO2Me markedly enhanced the ALA synthetase activity. No change was observed in this enzyme activity after the administration of 2,4,5-TCPSO2Me. After the administration of 1,2,4-TCB to the rats treated with DL-buthionine-(S,R)-sulfoximine (BSO) and to the non-BSO-treated rats, the concentrations of both 2,3,5- and 2,4,5-TCPSO2Mes were significantly lower in liver of the BSO-treated rats than in liver of the non-BSO-treated rats. Additionally, the 1,2,4-TCB did not elevate the ALA synthetase activity in the BSO-treated rats. On the other hand, the administration of 2,3,5-TCPSO2Me to BSO-treated rats resulted in induction of ALA synthetase. The results strongly suggest that the methyl sulfone derived from 1,2,4-TCB, i.e., 2,3,5-TCPSO2Me, contributes highly to the induction of the ALA synthetase activity by the parent compound.  相似文献   
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Health benefits assessment is an analytic tool used extensively by the U.S. Environmental Protection Agency (EPA) in characterizing the costs and benefits of air quality regulations. In a 2002 review of EPA methods, the U.S. National Research Council (NRC) called on EPA to more fully account for and communicate uncertainties in estimates of the health benefits of air pollution regulations. In particular, the NRC recommended that EPA use expert judgment to quantify uncertainties in cases where empirical estimates are lacking. In response, EPA developed and carried out an expert elicitation (EE) study to quantify uncertainties in the effects of fine particulate matter (PM2.5) on mortality in the U.S. This work has yielded new estimates of the uncertainty distribution of a key relationship – the concentration–response (C–R) function – used around the world in benefits analyses for air quality regulations. This paper discusses the ways in which the EE results have informed and influenced recent regulatory impact analyses (RIAs) carried out by EPA to characterize and communicate the health benefits of regulations affecting ambient PM2.5 concentrations. Given the growing importance of PM benefits analysis across the globe, recent developments pioneered by EPA could have widespread relevance.  相似文献   
187.
The doubly uniparental system of mitochondrial inheritance (DUI) is best known in marine mussels Mytilus. Under DUI there are two types of mitochondrial DNA (mtDNA). The female type (F) is transmitted to offspring of both genders and the male type (M) exclusively to sons; consequently two distinct mtDNA lineages exist. The M lineage evolves under more relaxed selection than the F lineage resulting in higher polymorphism within the M lineage. Though this polymorphism is expected to make inferences on fine population structure easier using M instead of F data, no comprehensive comparative data exist to support this claim. We sequenced a 1,205 bp fragment of M and F mtDNA comprising parts of the COIII and ND2 genes, and analysed 204 individuals representing three Mytilus species: M. edulis, M. galloprovincialis and M. trossulus from 13 European sampling sites. A clear distinction between Mediterranean and Atlantic populations was found with both M and F data, but much better geographic differentiation was found within the Atlantic using F rather than M data. In particular, Atlantic M. galloprovincialis can be differentiated from Atlantic M. edulis, and further subdivision of Atlantic M. edulis is possible using the F data but not the M data. Multiple tests of selection were carried out to attempt to explain this paradox. We concluded that the overall pattern of polymorphism is consistent with strong purifying selection; not only is this selection relaxed in the M lineage in comparison with the F lineage, but it is also more frequently interrupted by periodic selective sweeps within the M lineage.  相似文献   
188.
The article presents the results of screening research on acute toxicity of groundwater contaminated by leachates to the bacterium Vibrio fischeri (ToxAlert 100® test) and crustacean Daphnia magna (Daphtoxkit F? magna test according to PN-EN ISO 6341), as well as on chronic toxicity to D. magna (test according to ISO 10706). The groundwater samples were taken from seven large city landfills in the Pomeranian province (Poland), which were open before 1990 and designed without proper attention to being leak-tight. Due to the lack of either European or Polish classification of ecotoxicological qualities of surface and underground waters, an attempt was made to evaluate the ecotoxicological quality of the examined waters on the basis of the Helsinki Committee's recommendations for industrial effluents, the classification of sediment according to Krebs (Krebs F. The pT-value as a classification index in aquatic toxicology. GIT Edition Umweltanalytik-Umweltschutz 1988;1:57–63) and the classification system of toxicity levels for natural waters and sewers, recently proposed by Persoone et al. (Persoone G, Marsalek B, Blinova, I, Törökne A, Zarina D, Manusadzianas L, Nalecz-Jawecki G, Tofan L, Stepanova N, Tothova L, Kolar B. A practical and user-friendly toxicity classification system with microbiotests for natural waters and wastewaters. Environ. Toxicol. 2003;18 (6):395-402).  相似文献   
189.
Environmental Chemistry Letters - Pollution by toxic metals is a worldwide health issue, yet analytical methods to monitor selectively metal ions in complex media are limited. Fluorescence sensing...  相似文献   
190.
Environmental Science and Pollution Research - The paper presents an assessment of vegetation (composition and cover-abundance), nutrient supply, and especially sulfur accumulation in the trees...  相似文献   
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