全文获取类型
收费全文 | 248篇 |
免费 | 1篇 |
国内免费 | 5篇 |
专业分类
安全科学 | 6篇 |
废物处理 | 16篇 |
环保管理 | 27篇 |
综合类 | 32篇 |
基础理论 | 75篇 |
环境理论 | 2篇 |
污染及防治 | 64篇 |
评价与监测 | 12篇 |
社会与环境 | 18篇 |
灾害及防治 | 2篇 |
出版年
2022年 | 2篇 |
2021年 | 3篇 |
2020年 | 2篇 |
2019年 | 2篇 |
2018年 | 8篇 |
2017年 | 6篇 |
2016年 | 10篇 |
2015年 | 3篇 |
2014年 | 13篇 |
2013年 | 15篇 |
2012年 | 14篇 |
2011年 | 13篇 |
2010年 | 11篇 |
2009年 | 22篇 |
2008年 | 16篇 |
2007年 | 21篇 |
2006年 | 13篇 |
2005年 | 14篇 |
2004年 | 5篇 |
2003年 | 13篇 |
2002年 | 12篇 |
2001年 | 6篇 |
1999年 | 5篇 |
1998年 | 8篇 |
1997年 | 1篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1992年 | 3篇 |
1987年 | 1篇 |
1985年 | 2篇 |
1983年 | 2篇 |
1981年 | 1篇 |
1979年 | 2篇 |
1975年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有254条查询结果,搜索用时 0 毫秒
101.
Thiel V Blumenberg M Hefter J Pape T Pomponi S Reed J Reitner J Wörheide G Michaelis W 《Die Naturwissenschaften》2002,89(2):60-66
Hexactinellid sponges are often considered to be the most ancient metazoans. Lipid biomarkers from 23 species were studied for information on their phylogenetic properties, particularly their disputed relation to the two other sponge classes (Demospongiae, Calcarea). The most prominent lipid compounds in the Hexactinellida comprise C28 to C32 polyenoic fatty acids. Their structures parallel the unique patterns found in demosponge membrane fatty acids ('demospongic acids') and strongly support a close phylogenetic association of the Demospongiae and the Hexactinellida. Both taxa also show unusual mid-chain methylated fatty acids (C15-C25) and irregular C25- and C40-isoprenoid hydrocarbons, tracers for specific eubacteria and Archaea, respectively. These biomarkers indicate a similar, highly conservative symbiont community, although some shift in the abundance of the associated microbiota was observed. The lack of these features in calcareous sponges further contradicts the still common view that Calcarea and Demospongiae are more closely related to each other than either is to the Hexactinellida. 相似文献
102.
Sulphur deposition in Sweden has decreased to less than half of the levels recorded in 1970 and now signs of recovery from acidification of surface waters are beginning to appear. We investigated time trends of water chemistry between 1985 and 1998 in 13 streams draining small forested catchments with generally shallow acid sensitive soils. At nine of the catchments, bulk deposition was monitored as well. Sulphate concentrations decreased in both stream water and deposition, although with somewhat smaller trends in stream water compared with deposition. The magnitude of the trends in sulphate increased from north to south, following a gradient of increasing industrial influence. Five sites in the southern half of the country showed weak signs of recovery from acidification in terms of increasing concentrations of acid neutralising capacity and decreasing concentrations of hydrogen ions, corresponding to annual increases of 0.01 pH units. Changes in stream discharge and concentrations of marine salts and organic acids could not explain the observed decrease in acidity and the results were interpreted as recovery from anthropogenic acidification. For the northern half of Sweden, any changes in water chemistry could be attributed to natural variation in climate and marine influence, and the effect of anthropogenic acidification was negligible. 相似文献
103.
Hybholt TK Aamand J Johnsen AR 《Environmental pollution (Barking, Essex : 1987)》2011,159(5):1085-1091
The aim of the study was to determine centimeter-scale spatial variation in mineralization potential in diffusely polluted soil. To this end we employed a 96-well microplate method to measure the mineralization of 14C-labeled organic compounds in deep-well microplates and thereby compile mineralization curves for 348 soil samples of 0.2-cm3. Centimeter-scale spatial variation in organic matter and the mineralization of glucose, benzoic acid, and PAHs (phenanthrene and pyrene) was determined for urban road-side soil sampled as arrays (7 × 11 cm) of 96 subsamples. The spatial variation in mineralization was visualized by means of 2-D contour maps and quantified by means of semivariograms. The geostatistical analysis showed that the easily degradable compounds (glucose and benzoic acid) exhibited little spatial variation in mineralization potential, whereas the mineralization was highly heterogeneous for the PAH compounds that require specialized degraders. The spatial heterogeneity should be taken into account when estimating natural attenuation rates. 相似文献
104.
Ole Rüdiger Sjøholm Jens Aamand Ole Nybroe 《Environmental pollution (Barking, Essex : 1987)》2010,158(1):292-298
The metabolite 2,6-dichlorobenzamide (BAM) is a frequent groundwater pollutant produced during degradation of the herbicide 2,6-dichlorobenzonitrile (dichlobenile). Spatial variability of BAM mineralisation is uncharacterized in surface soil, however, and factors controlling the heterogeneity remain unknown. We addressed these issues by sample-to-sample comparisons of BAM mineralisation rates and a range of soil characteristics at spatial scales ranging from meters to centimetres. For mineralisation assays nano-molar concentrations of labelled BAM were added to determine mineralisation rates under realistic conditions. We found a significant variability of BAM mineralisation which increased with decreasing spatial scale. BAM mineralisation rates were correlated to the density of BAM-degrading bacteria but not to water content, TOC, NH4+, NO3−, or pH. The genus Aminobacter, which contains the only BAM degraders known, was detected in MPN samples of BAM degraders by a specific PCR assay targeting the 16S rRNA gene, confirming a role of Aminobacter in BAM mineralisation. 相似文献
105.
Jens Søndergaard Gert Asmund Bo Elberling 《Environmental pollution (Barking, Essex : 1987)》2010,158(5):1319-4071
Identification of mining-related contaminants is important in order to assess the spreading of contaminants from mining as well as for site remediation purposes. This study focuses on lead (Pb) contamination in biota near the abandoned ‘Black Angel Mine’ in West Greenland in the period 1988-2008. Stable Pb isotope ratios and total Pb concentrations were determined in lichens, seaweed and mussels as well as in marine sediments. The results show that natural background Pb (207Pb/206Pb: 0.704-0.767) and Pb originating from the mine ore (207Pb/206Pb: 0.955) have distinct isotopic fingerprints. Total Pb in lichens, seaweed, and mussels was measured at values up to 633, 19 and 1536 mg kg−1 dry weight, respectively, and is shown to be a mixture of natural Pb and ore-Pb. This enables quantification of mining-related Pb and shows that application of Pb isotope data is a valuable tool for monitoring mining pollution. 相似文献
106.
Pär Byström Ulf Bergström Alexander Hjälten Sofie Ståhl David Jonsson Jens Olsson 《Ambio》2015,44(3):462-471
Intraguild predation interactions make fish communities prone to exhibit alternative stable states with either piscivore or prey fish dominance. In the Baltic Sea, local declines of coastal piscivores like perch (Perca fluviatilis) have been observed to coincide with high densities of sticklebacks (Gasterosteus aculeatus). Mechanisms behind this shift between piscivore and stickleback dominance were studied both experimentally and in field. Results showed that predation by sticklebacks has a strong negative effect on perch larvae survival, but this effect rapidly decreases with increasing perch size, likely due to gape limitations and digestion constraints in sticklebacks. Large spatial and temporal variations in patterns of stickleback migration into perch spawning sites were observed. Whether or not high density of sticklebacks will cause declines in coastal piscivore populations is suggested to depend on the availability of spawning sites in which sticklebacks do not migrate into or arrive late in the reproduction season of coastal piscivores. 相似文献
107.
108.
We report three cases of Turner's syndrome with cystic hygromata, which were diagnosed by routine ultrasound scanning before amniocentesis in the second trimester of pregnancy. Maternal and amniotic level of alpha-fetoprotein were normal. Karyotyping carried out afterwards showed a 45,X karyotype. Our data indicate, that cystic hygromata in Turner's syndrome may coexist with a normal amniotic fluid AFP, thus questioning the theory of leakage from the hygroma. It remains to be investigated if all cases of Turner's syndrome present a cystic hygroma in utero. 相似文献
109.
Ashley?J.?W.?WardEmail author Philip?Thomas Paul?J.?B.?Hart Jens?Krause 《Behavioral ecology and sociobiology》2004,55(6):561-568
Behavioural variation is known to occur between individuals of the same population competing for resources. Individuals also vary with respect to their boldness or shyness. An individuals position along the shy-bold axis may be defined as the extent to which it is willing to trade off potentially increased predation risks for possible gains in resources. Similarly, group living may be interpreted as a trade-off between anti-predatory tactics and foraging efficiency. The responses of three-spined sticklebacks (Gasterosteus aculeatus) were tested across four social contexts to assess relative boldness or shyness and to further examine whether their behaviour would be consistent within and between contexts. Individuals displayed consistent responses within and between the first two contexts: those individuals which resumed foraging rapidly after a simulated aerial predator attack also displayed low shoaling tendencies. Such fish were deemed to be bold, whilst those which displayed the converse behaviour, slow resumption of foraging and a high shoaling tendency, were deemed to be shy. In a third context, bold individuals out-competed shy conspecifics for food. Boldness was also positively correlated with growth over a 6-week period. The position adopted by an individual within a group is usually interpreted as a trade-off between predation risk and foraging efficiency—both are greater at the front of a mobile group. Bold individuals showed significantly stronger tendencies towards front positions than shy conspecifics. The results suggest that, contrary to some previous studies on other animals, bold or shy behaviour in sticklebacks is consistent between contexts.Communicated by T. Czeschlik 相似文献
110.
Bernd R. Sch?ne David L. Rodland Achim Wehrmann Bj?rn Heidel Wolfgang Oschmann Zengjie Zhang Jens Fiebig Lothar Beck 《Marine Biology》2007,150(6):1237-1252
The grey top-shell, Gibbula cineraria is a common member of temperate to cold water kelp forest communities, but its longevity and the age structure of its populations
remains unresolved. Combined measurements of shell growth rates (sclerochronology) and oxygen isotope composition allow analysis
of rate and timing of shell growth. Eight specimens were analyzed from the southern North Sea (near Helgoland, German Bight).
Three age groups were identified but external measurements (width, height, ornamentation patterns and number of whorls) and
shell weight are not adequate for ontogenetic age discrimination. Stable oxygen isotope data is consistent with shell growth
during the interval from April to December in isotopic equilibrium with seawater, and growth increments exhibit strong tidal
controls with fortnightly bundles well preserved. Reliable environmental proxy data (water temperature) can be extracted from
the shell aragonite using conventional stable oxygen isotope analyses, with a temporal resolution of days attainable during
intervals of maximum growth, but annual extremes are not always recorded in the shell. While demonstrating the utility of
G. cineraria as a environmental and potential paleoenvironmental proxy for kelp forest habitats, its longevity has been significantly
overestimated. 相似文献