全文获取类型
收费全文 | 917篇 |
免费 | 8篇 |
国内免费 | 15篇 |
专业分类
安全科学 | 27篇 |
废物处理 | 53篇 |
环保管理 | 93篇 |
综合类 | 142篇 |
基础理论 | 204篇 |
环境理论 | 2篇 |
污染及防治 | 304篇 |
评价与监测 | 55篇 |
社会与环境 | 58篇 |
灾害及防治 | 2篇 |
出版年
2023年 | 4篇 |
2022年 | 15篇 |
2021年 | 17篇 |
2020年 | 8篇 |
2019年 | 8篇 |
2018年 | 29篇 |
2017年 | 36篇 |
2016年 | 36篇 |
2015年 | 31篇 |
2014年 | 29篇 |
2013年 | 93篇 |
2012年 | 47篇 |
2011年 | 73篇 |
2010年 | 56篇 |
2009年 | 55篇 |
2008年 | 66篇 |
2007年 | 53篇 |
2006年 | 47篇 |
2005年 | 31篇 |
2004年 | 29篇 |
2003年 | 31篇 |
2002年 | 19篇 |
2001年 | 8篇 |
2000年 | 6篇 |
1999年 | 6篇 |
1998年 | 8篇 |
1997年 | 9篇 |
1996年 | 4篇 |
1995年 | 12篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1987年 | 2篇 |
1981年 | 3篇 |
1965年 | 7篇 |
1964年 | 3篇 |
1963年 | 4篇 |
1962年 | 9篇 |
1961年 | 11篇 |
1960年 | 1篇 |
1958年 | 2篇 |
1957年 | 1篇 |
1956年 | 1篇 |
1954年 | 1篇 |
1947年 | 1篇 |
1942年 | 1篇 |
1941年 | 2篇 |
1938年 | 1篇 |
1932年 | 1篇 |
排序方式: 共有940条查询结果,搜索用时 15 毫秒
41.
J. Christian Franson William L. Hohman Joseph L. Moore Milton R. Smith 《Environmental monitoring and assessment》1996,43(2):181-188
We used 363 blood samples collected from wild canvasback dueks (Aythya valisineria) at Catahoula Lake, Louisiana, U.S.A. to evaluate the effect of sample storage time on the efficacy of erythrocytic protoporphyrin as an indicator of lead exposure. The protoporphyrin concentration of each sample was determined by hematofluorometry within 5 min of blood collection and after refrigeration at 4 °C for 24 and 48 h. All samples were analyzed for lead by atomic absorption spectrophotometry. Based on a blood lead concentration of 0.2 ppm wet weight as positive evidence for lead exposure, the protoporphyrin technique resulted in overall error rates of 29%, 20%, and 19% and false negative error rates of 47%, 29% and 25% when hematofluorometric determinations were made on blood at 5 min, 24 h, and 48 h, respectively. False positive error rates were less than 10% for all three measurement times. The accuracy of the 24-h erythrocytic protoporphyrin classification of blood samples as positive or negative for lead exposure was significantly greater than the 5-min classification, but no improvement in accuracy was gained when samples were tested at 48 h. The false negative errors were probably due, at least in part, to the lag time between lead exposure and the increase of blood protoporphyrin concentrations. False negatives resulted in an underestimation of the true number of canvasbacks exposed to lead, indicating that hematofluorometry provides a conservative estimate of lead exposure.The U.S. Government's right to retain a non-exclusive, royalty-free licence in and to any copyright is acknowledgedDeceased 相似文献
42.
43.
Christian Damgaard Bodil K. Ehlers Johannes C. G. Ransijn Inger K. Schmidt Jens-Christian Svenning 《Environmental and Ecological Statistics》2018,25(2):221-235
It has been suggested that in order to infer ecological processes from observed patterns of species abundance we need to investigate the covariance in species abundance. Consequently, an expression for the expected covariance of pin-point cover measurements of two species is developed. By comparing the observed covariance with the expected covariance we get a new type of information on the spatial arrangement of two species. Here the discrepancy between the observed and expected covariance may be thought of as a measure of the spatial configuration of the two species that may indicate underling ecological processes. The method is applied in a case study of Calluna vulgaris and Deschampsia flexuosa on dry heathland sites. The observed covariance of Calluna and Deschampsia at the level of the sites was positively and significantly correlated with the expected covariance. Negative covariance was observed on sites where both Calluna and Deschampsia had a high cover, which is in agreement with the notion that both species form distinct patches. Oppositely, at sites where both species have a low cover, we found that both the expected and observed covariance were positive. The proposed measure for the expected covariance of two species does capture information on the combined spatial configuration of the two species if the species are common. We show how this may be relevant for understanding the underlying ecological processes leading to the observed covariance. 相似文献
44.
(Z)-Dodec-3-en-1-ol has been identified as the major component of the trail-following pheromone of nine species of Kalotermitidae
belonging to six different genera, suggesting that this compound represents a common signal in this family of termites. The
homogeneous nature of trail-following pheromones of Kalotermitidae well agrees with the monophyly of this family. It also
supports the postulated position of this family as a sister group of the Rhinotermitidae and Termitidae, which also secrete
C12-alcohols as trail-following pheromones. The significance of a trail pheromone in termites of the ‘one-piece’ life type,
which spend their whole life within the same piece of wood, is discussed. 相似文献
45.
Comparative study of the fate and mobility of metals discharged in mining and urban effluents using sequential extractions on suspended solids 总被引:1,自引:0,他引:1
Christian Gagnon Patrice Turcotte Bernard Vigneault 《Environmental geochemistry and health》2009,31(6):657-671
The fate, bioavailability and environmental impacts of metals discharged in municipal and mining wastewater discharge will
depend to a large extent on chemical speciation and distribution. Previous studies on metal bioaccumulation have shown that
total metal concentrations are not a good predictor of bioavailability in the dispersion plumes of municipal effluents. The
objective of this study was to determine the solid phase speciation of metals in surface waters receiving urban and mining
effluents in order to assess their fate and relative mobility in the receiving environment. Suspended particulate matter was
sampled using sediment traps at several sites downstream of effluent outfall plumes as well as at reference upstream sites.
Particulate metal in operationally defined fractions—exchangeable/carbonates, reducible, oxidisable and residual—were determined
in suspended particulate matter with a series of selective chemical extractions. Metal enrichment in suspended particles was
generally observed in both mining and urban effluent discharges. When compared to its receiving environment, the mining effluent
appeared to release more particulate metals (Cu, Fe, Zn) in the most reactive fractions (i.e. exchangeable/carbonates + reducible
forms, 23–43%), while other released metals, such as Cd and Mn, were predominantly in the least reactive forms (i.e., oxidisable + residual,
73–97%). In contrast, the reactivity of all particulate metals, with the exception of Mn, from the urban effluent was much
higher, with up to 65, 42, 30 and 43% for Cd, Cu, Fe and Zn, respectively, in the two most reactive fractions. As expected
in effluent dispersion plumes, parameters such as the organic carbon, Fe oxide and carbonate contents have specific effects
on the partitioning of several trace metals, particularly Cd, Cu and Zn. Our results indicated that the relative distributions
of metals among geochemical fractions varied in the effluent receiving waters where organic carbon and Fe oxides appeared
as the most important parameters. This could therefore decrease the exposure for aquatic organisms that are exposed to those
contaminated sediments as well as the risk to human health. 相似文献
46.
The main principle of the economic approach to a trophic system we propose here lies in assuming that there is a transfer of food along a path between a prey and a predator if, for the predator, the benefits are greater than costs of predation on this path. Conversely, if the costs exceed the benefits, there are no flows. This trade-off, considered all along the food chains of an ecosystem, together with ecological processes (assimilation, somatic maintenance) results in a model coupling mass balance equations (biological constraints) and complementarity principles (Walras’ law). Here is the core of the Network Economics Approach to Trophic Systems (NEATS). 相似文献
47.
48.
Svendsen TC Vorkamp K Rønsholdt B Frier JO 《Journal of environmental monitoring : JEM》2007,9(11):1213-1219
Atlantic salmon (Salmon salar) populations from four locations, two from isolated Swedish lake systems, one of the Baltic Sea and one of the North Atlantic, were analyzed to determine the concentrations and spatial variations of polybrominated diphenyl ethers (PBDEs) and organochlorines (DDT, PCB and HCH). Levels in both liver and muscle were in the same range as previously reported in Atlantic salmon, except for elevated concentrations found per lipid weight (lw) in the muscle samples of salmon from the North Atlantic ( summation PBDE 263 ng g(-1) lw, summation PCB 3262 ng g(-1) lw, summation DDT 4063 ng g(-1) lw summation HCH 131 ng g(-1)). In general, elevated concentrations in the muscles compared to the liver were observed, especially in lipid depleted migrating salmon, possibly caused by a faster lipid depletion compared with the redistribution of PBDEs, PCBs and DDTs. These findings indicated that the life stage and thereby the lipid dynamics of the fish must be considered prior to comparison based on lipid weight, especially as Atlantic salmon experience large variations in lipid content during periods of migration. The dominating PBDE congener was BDE-47, representing more than 25% in all fish. The PBDE pattern changed between locations, with a significant separation of the fish from the freshwater and marine environment when analyzed using principal component analysis. 相似文献
49.
Rodriguez MJ Vinette Y Sérodes JB Bouchard C 《Environmental monitoring and assessment》2003,89(1):69-93
The levels of trihalomethanes (THMs) – the main species of by-product from water chlorination – were monitored in thedistribution systems of the five major drinking water utilitiesof the greater area of Québec City in order to investigate andmodel their occurrence on a spatial and seasonal basis. Data forTHMs and other water quality and operational parametersassociated with their formation were generated through a 16 monthsampling program involving several sites representing variablewater residence times, from the plant to the system extremity.The results demonstrate that the differences in measured THMlevels between the five utilities are mainly due to the variablequality of raw waters, the type of water treatment process beingused and the type and levels of applied disinfectant. Dependingon the utility, average THM levels were from 1.3 to 2.5 timeshigher in the system extremities than in the water leaving thetreatment plant. Also, average levels of THMs measured in summerat the distribution system extremities were, depending on theutility, from 2.5 to 5 times higher than the average levelsmeasured in winter. The seasonal differences were found to besignificantly greater than those observed by others in waterutilities in the United States and Europe and are explained inlarge part by the considerable changes, over the year, in thequality and temperature of surface waters in Southern Québec. Forthe five utilities under study, multivariate regression modelswere developed in order to predict spatial and seasonalvariations of THMs. Both residual chlorine demand and temperaturewere found to be better, statistically, as predictors for THMoccurrence. The usefulness of the developed models for routineand long term water quality management, as well as for assessmentof human exposure to THMs, are also discussed. 相似文献
50.
Kriech AJ Osborn LV Wissel HL Kurek JT Sweeney BJ Peregrine CJ 《Journal of environmental monitoring : JEM》2004,6(10):827-833
Exposure to asphalt fumes has a threshold limit value (TLV of 0.5 mg m(-3) (benzene extractable inhalable particulate) as recommended by the American Conference of Governmental Industrial Hygienists (ACGIH). This reflects a recent change (2000) whereby two variables are different from the previous recommendation. First is a 10-fold reduction in quantity from 5 mg m(-3) to 0.5 mg m(-3). Secondly, the new TLV specifies the "inhalable" fraction as compared to what is presumed to be total particulate. To assess the impact of these changes, this study compares the differences between measurements of paving asphalt fume exposure in the field using an "inhalable" instrument versus the historically used 'total' sampler. Particle size is also examined to assist in the understanding of the aerodynamic collection differences as related to asphalt fumes and confounders. Results show that when exposures are limited to asphalt fumes, a 1:1 relationship exists between samplers, showing no statistically significant differences in benzene soluble matter (BSM). This means that for the asphalt fume ACGIH TLV, the 'total' 37-mm sampler is an equivalent method to the "inhalable" method, referred to as IOM (Institute of Occupational Medicine), and should be acceptable for use against the TLV. However, the study found that when confounders (dust or old asphalt millings) are present in the workplace, there can be significant differences between the two samplers' reported exposure. The ratio of IOM/Total was 1.37 for milling asphalt sites, 1.41 for asphalt paving over granular base, and 1.02 for asphalt over asphalt pavements. 相似文献