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231.
David Costantini Andrea Bonisoli-Alquati Diego Rubolini Manuela Caprioli Roberto Ambrosini Maria Romano Nicola Saino 《Die Naturwissenschaften》2014,101(7):541-548
Reproduction is a demanding activity, since organisms must produce and, in some cases, protect and provision their progeny. Hence, a central tenet of life-history theory predicts that parents have to trade parental care against body maintenance. One physiological cost thought to be particularly important as a modulator of such trade-offs is oxidative stress. However, evidence in favour of the hypothesis of an oxidative cost of reproduction is contradictory. In this study, we manipulated the brood size of wild barn swallows Hirundo rustica soon after hatching of their nestlings to test whether an increase in nestling rearing effort translates into an increased oxidative damage and a decreased antioxidant protection at the end of the nestling rearing period. We found that, while plasma oxidative damage was unaffected by brood size enlargement, females rearing enlarged broods showed a decrease in plasma non-enzymatic antioxidants during the nestling rearing period. This was not the case among females rearing reduced broods and among males assigned to either treatment. Moreover, individuals with higher plasma oxidative damage soon after the brood size manipulation had lower plasma non-enzymatic antioxidants at the end of the nestling rearing period, suggesting that non-enzymatic antioxidants were depleted to buffer the negative effects of high oxidative damage. Our findings point to antioxidant depletion as a potential mechanism mediating the cost of reproduction among female birds. 相似文献
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236.
Sergio Cinnirella Nicola Pirrone Alessia Allegrini Daniela Guglietta 《Environmental Fluid Mechanics》2008,8(2):129-145
Mercury emissions from forest fires in countries bordering the Mediterranean Sea have been estimated on the basis of satellite
observations for the year 2006. The assessment has been done by means of the Moderate Resolution Imaging Spectroradiometer
(MODIS) products (MOD12Q1, MOD14A2, MOD15A2, MOD44B). Estimates show that wild fires have burnt 310,268 ha in the Region,
affecting by 45% the Mixed Forest and by 37% the Evergreen Needleleaf Forest and the Evergreen Broadleaf Forest. The amount
of biomass burned was about 66,000 Mg for the Evergreen Needleleaf Forest, 72,000 Mg for the Evergreen Broadleaf Forest and
196,000 Mg for the Mixed Forest. The total amount of mercury released to the atmosphere in the Mediterranean countries accounted
for 4.3 Mg year−1 with Italy, France, Austria, Bulgaria, Algeria, Spain and Croatia being the most contributing countries with annual emission
ranging from 330 to 970 kg year−1. The maximum release of Gaseous Elemental Mercury (GEM) and particulate mercury (Hg(p)) in the region occurred in July with
1,218 kg. The uncertainty of our estimates is comparable with that associated to current assessments of mercury emissions
from major industrial sources. 相似文献
237.
Giuseppe Boncoraglio Roberta Martinelli Nicola Saino 《Behavioral ecology and sociobiology》2008,62(5):729-738
In diverse taxa, offspring solicit parental care using complex displays, which may evolve as reliable signals of condition
or as mechanisms to manipulate parental investment. Differential sex allocation may therefore result from adaptive parental
decisions or sex-related variation in competitive ability or because of sex-related asymmetries in kin selection. Under normal
food provisioning, female barn swallow (Hirundo rustica) nestlings begged more loudly but did not receive more food than male nestlings. After food deprivation, begging call loudness
of males but not females increased. Begging loudness positively predicted the number of feedings received by the nestlings,
and males gained more mass than females after food deprivation. Male nestlings are more severely affected by chronic food
reduction and may therefore accrue a larger benefit compared to females by increasing their food intake under short-term conditions
of food scarcity. These results suggest that either females do not increase begging intensity to favour male broodmates which
are more vulnerable to prolonged food stress, or that males prevail in scramble competition despite being similar in size
to females. 相似文献
238.
Spatial and temporal distribution of atmospheric mercury species over the Adriatic Sea 总被引:2,自引:0,他引:2
Field measurements of atmospheric mercury and related species were carried out during an intensive cruise campaign performed
over the Adriatic sea from October 26th to November 12th, 2004 on board the R/V Urania. Hg0 ranged between 0.8 and 3.3 ng/m3 with an average of 1.6 ± 0.4 ng/m3 over the entire period. Hg(II) concentrations ranged from 0.1 to 62.8 pg/m3 with an average of 6.7 ± 11.7 pg/m3 whereas Hg-p levels were in a range of 0.04 and 51 pg/m3 with an average of 4.5 ± 8 pg/m3. Higher Hg0 and Hg-p concentrations were observed in the Gulf of Venice and Gulf of Trieste due primarily to air masses transported from
the mainland reflecting the contribution from anthropogenic sources. In contrast, higher Hg(II) concentrations observed during
the first period of the cruise campaign were likely due to the occurrence of photo-oxidants production which are the main
players of the gas phase oxidation of to Hg(II)(g). These findings have been confirmed by the backward trajectories analysis of air masses crossing the studied area during
selected days. 相似文献
239.
We developed a method to predict the potential of non-native reptiles and amphibians (herpetofauna) to establish populations. This method may inform efforts to prevent the introduction of invasive non-native species. We used boosted regression trees to determine whether nine variables influence establishment success of introduced herpetofauna in California and Florida. We used an independent data set to assess model performance. Propagule pressure was the variable most strongly associated with establishment success. Species with short juvenile periods and species with phylogenetically more distant relatives in regional biotas were more likely to establish than species that start breeding later and those that have close relatives. Average climate match (the similarity of climate between native and non-native range) and life form were also important. Frogs and lizards were the taxonomic groups most likely to establish, whereas a much lower proportion of snakes and turtles established. We used results from our best model to compile a spreadsheet-based model for easy use and interpretation. Probability scores obtained from the spreadsheet model were strongly correlated with establishment success as were probabilities predicted for independent data by the boosted regression tree model. However, the error rate for predictions made with independent data was much higher than with cross validation using training data. This difference in predictive power does not preclude use of the model to assess the probability of establishment of herpetofauna because (1) the independent data had no information for two variables (meaning the full predictive capacity of the model could not be realized) and (2) the model structure is consistent with the recent literature on the primary determinants of establishment success for herpetofauna. It may still be difficult to predict the establishment probability of poorly studied taxa, but it is clear that non-native species (especially lizards and frogs) that mature early and come from environments similar to that of the introduction region have the highest probability of establishment. 相似文献
240.
A study of a small sample of construction fatal accidents was used to pilot a potential method of analysis for the UK Health and Safety Executive (HSE) Construction Division. The work was conducted in the context of a Governmental Inquiry into construction fatalities in 2009, but has been developed further since. The sample of 26 accidents (28 fatalities) was drawn from the 211 fatal accidents in the years ending 2006–2008, to be broadly illustrative of the range of accident characteristics. The accidents were analysed on the basis of available inspectorate reports and structured interviews with the investigating inspectors. A standard method of classification on four levels was developed, based on the Human Factors Analysis and Classification System (HFACS) classification of errors and task level factors, with additional categories covering the organisational and regulatory/market levels of the system. The results showed a concentration of underlying factors associated with inadequacies in planning and risk assessment, competence assurance, hardware design, purchase and installation, and contracting strategy. These findings were partially validated by comparing them with another sample of 50 accidents analysed earlier by the HSE. This paper describes the development and testing of the investigation and classification method and how it is being further developed since the initial study. It also provides a summary of the findings relating to underlying causes. 相似文献