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921.
Long-term variability in the North Atlantic Oscillation (NAO) and the Atlantic thermohaline ocean circulation (THC) are both
shaping the European climate on time scales of decades and longer. Possible linear and non-linear changes in the characteristics
of these natural climate modes due to global warming are an important source of uncertainty in long-term regional projections
of future climate changes.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
922.
Christian Damgaard Vibeke Simonsen Juliet L. Osborne 《Environmental Modeling and Assessment》2008,13(4):483-490
Pollen-mediated gene flow between red clover fields by bumblebees is predicted by estimating or simulating the parameters
in a gene flow model for insect-pollinated crops. Generally, the predicted level of gene flow was found to depend on the visiting
bee species and the spatial arrangement of the red clover fields. When the fields are close to each other, the gene flow depends
mainly on the typical foraging distance of the visiting bee species, but when the fields are far apart, the gene flow between
red clover fields is more sensitive to the distances between red clover fields than to the actual bumblebee species that pollinates
the fields. Using the suggested methodology, the gene flow may be predicted in different agricultural scenarios. For example,
if the gene flow between red clover fields is mediated by Bombus terrestris and the red clover fields that were assumed to be quadrates with sides of 100 m are separated by 200 m, then the median gene
flow is predicted to be 0.17%. 相似文献
923.
Burger J Gochfeld M Jeitner C Burke S Volz CD Snigaroff R Snigaroff D Shukla T Shukla S 《Environmental monitoring and assessment》2009,152(1-4):179-194
Levels of mercury and other contaminants should be lower in birds nesting on isolated oceanic islands and at high latitudes without any local or regional sources of contamination, compared to more urban and industrialized temperate regions. We examined concentrations of arsenic, cadmium, chromium, lead, manganese, mercury and selenium in the eggs, and the feathers of fledgling and adult glaucous-winged gulls (Larus glaucescens) nesting in breeding colonies on Adak, Amchitka, and Kiska Islands in the Aleutian Chain of Alaska in the Bering Sea/North Pacific. We tested the following null hypotheses: 1) There were no differences in metal levels among eggs and feathers of adult and fledgling glaucous-winged gulls, 2) There were no differences in metal levels among gulls nesting near the three underground nuclear test sites (Long Shot 1965, Milrow 1969, Cannikin 1971) on Amchitka, 3) There were no differences in metal levels among the three islands, and 4) There were no gender-related differences in metal levels. All four null hypotheses were rejected at the 0.05 level, although there were few differences among the three test sites on Amchitka. Eggs had the lowest levels of cadmium, lead, and mercury, and the feathers of adults had the lowest levels of selenium. Comparing only adults and fledglings, adults had higher levels of cadmium, chromium, lead and mercury, and fledglings had higher levels of arsenic, manganese and selenium. There were few consistent interisland differences, although levels were generally lower for eggs and feathers from gulls on Amchitka compared to the other islands. Arsenic was higher in both adult feathers and eggs from Amchitka compared to Adak, and chromium and lead were higher in adult feathers and eggs from Adak compared to Amchitka. Mercury and arsenic, and chromium and manganese levels were significantly correlated in the feathers of both adult and fledgling gulls. The feathers of males had significantly higher levels of chromium and manganese than did females. The levels of most metals in feathers are below those known to be associated with adverse effects in the gulls or their predators. However, levels of mercury in some gull eggs are within a range suggesting that several eggs should not be eaten in one day by sensitive humans. 相似文献
924.
Isabelle J. Brisson Patrick Levallois Hélène Tremblay Jean Sérodes Christian Deblois Jeffrey Charrois Vincent Taguchi Jessica Boyd XingFang Li Manuel J. Rodriguez 《Environmental monitoring and assessment》2013,185(9):7693-7708
The spatiotemporal presence of eight N-nitrosamines in the water of seven supply systems in Quebec considered to be susceptible to these emerging disinfection by-products was evaluated. This is the first study on the presence of N-nitrosamines in drinking water utilities in Quebec. Seven sampling campaigns were carried out at several sampling points in each of the systems over a period of 1 year. The results show that N-nitrosamines, primarily N-nitrosodimethylamine (NDMA), were not commonly detected in the water of the facilities under study (10 % of samples). The concentrations measured were lower than those reported in recent North American studies. None of the 195 samples taken exceeded the Ontario standard of 9 ng/L for NDMA (maximum value observed of 3.3 ng/L). N-nitrosomethylethylamine and N-nitrosopiperidine were detected once, with concentrations of 3.7 and 6.0 ng/L, respectively. Chloramination was identified as being the main risk factor regarding the presence of N-nitrosamines, but water quality and some operating parameters, in particular disinfectant residual, also seem to be related to their presence. NDMA concentrations at the end of the distribution systems were generally higher than water leaving the plant. No seasonal trends were observed for the formation of N-nitrosamines in the investigated supply systems. Finally, an association between the presence of N-nitrosamines and the levels of trihalomethanes and haloacetic acids was observed in some facilities. 相似文献
925.
Sofia Thorsson Björn Holmer Andreas Andjelic Jenny Lindén Sandra Cimerman Lars Barregard 《Environmental monitoring and assessment》2014,186(7):4479-4492
A majority of households in developing countries rely on biomass fuel for cooking, typically burned in open fires or simple stoves. The incomplete combustion of these fuels causes adverse health effects such as respiratory diseases, especially among women and children. However, quantitative data on pollution levels and on associated diseases are limited. We examined cooking habits and self-reported health in 31 households with outdoor open wood fires in Ouagadougou, Burkina Faso, using structured interviews. In eight households, carbon monoxide (CO) was measured using passive sampling. In addition, meteorology and ambient CO concentrations were assessed. The average CO concentration during cooking was 4.3 ppm, with a maximum of 65.3 ppm and minimum of 0.3 ppm (1-min values). A clear daily pattern was observed, with relatively low concentrations during the day and high during the evening, occasionally exceeding the World Health Organization 1- and 8-h guidelines when the air stabilised. On average, CO concentrations were 43 % higher in kitchens located in closed yards than in those located in open yards, showing that fireplace location affected the levels. Eye irritation and coughing among women and children were reported by 30 % of the households. Based on previously reported relations between CO concentrations and fine particles (<2.5 μm), the exposure to biomass smoke appears to be high enough to pose a considerable health risk among women and children in households with outdoor open wood fires. The results suggest that burning should be limited between sunset and dawn and in areas with limited ventilation to reduce pollutions levels. 相似文献
926.
This study aimed to optimise the methodology for the use of Corophium insidiosum in a bioassay. Taking into account that it would be suitable to execute the bioassay with organisms having a good sensitivity
during the year and low mortality in control sediment, the influence of different temperatures (10–15–20 and 25°C) has been
examined. C. insidiosum was collected during August, November 2005 and January 2006, in Mar Piccolo basin (Ionian sea). The results obtained show
that this species mortality in the negative control sediment, ranged from 2.6 ± 0.6% at 10°C in August to 17 ± 2.2% at 20°C
in November, at different temperatures tested. At 20°C there were significant differences in mortality among different months
examined. Indeed no relationship among months was found at 15°C. Significant differences between August and November at 25°C,
between November and January were not found at 10°C. The 96-h LC50 values found for cadmium at all temperature experimental
conditions ranged from 2.11 mg/l (1.57–2.82) to 0.70 mg/l (0.54–0.93). The highest values were found at 10°C in November and
January. The results showed that the optimal temperature for the bioassay seems to be between 15°C and 20°C. Even if, at 20°C
the mortality differs significantly among organisms sampled. 相似文献
927.
Barbara A. Caspers Frank C. Schroeder Stephan Franke W. Jürgen Streich Christian C. Voigt 《Behavioral ecology and sociobiology》2009,63(5):741-749
Combining chemical analysis and odour preference tests, we asked whether two closely related sympatric species of sac-winged
bats use odour for species recognition. Males of the two sister species Saccopteryx bilineata and Saccopteryx leptura have pouches containing an odoriferous liquid in their antebrachial wing membrane, which is used in S. bilineata during courtship displays. Although both species occasionally share the same daytime roosts and are morphologically similar,
there is no evidence for interbreeding. We compared the production and composition of the wing sac odorant in male S. leptura and S. bilineata and performed odour preference tests with female S. bilineata. Similar to male S. bilineata, male S. leptura cleansed and refilled their wing sacs with secretions, but they spent more time each day in doing so than male S. bilineata. Chemical analysis by gas chromatography and mass spectrometry revealed that male Saccopteryx carried species-specific scents in their wing sacs. Binary choice tests confirmed that female S. bilineata preferred the wing sac scents of male S. bilineata to those of the sister species, suggesting that the species specificity of male wing sac scents maintain the pre-mating isolation
barrier between these closely related species. 相似文献
928.
Ecological network analyses and their use for establishing reference domain in functional assessment of an estuary 总被引:1,自引:0,他引:1
Robert R. Christian Mark M. Brinson James K. Dame Galen Johnson Charles H. Peterson Daniel Baird 《Ecological modelling》2009,220(22):3113
We developed a framework to use ecological network analysis for functional assessment of large aquatic ecosystems in the context of ecosystem-based management. We established a reference domain for the Neuse River Estuary, North Carolina, USA, from changes over time. Four reference network models of the trophic structure of the estuary during early and late summers of 1997 and 1998 were constructed and analyzed. The estuary has experienced various symptoms of eutrophication during the past 20 years, including summer-time hypoxia and fish kills. The networks were used to quantify indices of nominal trophic dynamics and their variation. The ratio of biomass of nekton to that of macrobenthos, derived from network construction, was used to index severity of eutrophication and to promote accessibility of ecological network analysis to environmental management. The ratio increased from early to late summer, and network metrics demonstrated a variety of responses in association with that change. Some variables from network analysis, especially related to consumers, reflected some but not all of this change. Others reflected the most severe increase in the ratio in late summer 1997 when hypoxia was most extensive. We evaluated uncertainty and the modulating effects of hierarchy by comparing variation of input biomasses with integrative response variables. Relative variation in input variables was generally greater than that of the integrative response variables as predicted by hierarchy theory. Ecological network analysis has previously served as support for ecosystem-based management of large aquatic systems with some success. However, its use can be enhanced by making it more accessible to environmental managers and policy makers. Ways to do this include promoting simple metrics from network construction and explicitly associating network analysis to concepts familiar to the management community, such as functional assessment and reference. 相似文献
929.
Volker Huckstorf Wolf-Christian Lewin Thomas Mehner Christian Wolter 《Behavioral ecology and sociobiology》2009,63(12):1735-1742
Animal prey has developed a variety of behavioural strategies to avoid predation. Many fish species form shoals in the open
water or seek refuge in structurally complex habitats. Since anti-predator strategies bear costs and are energy-demanding,
we hypothesised that the nutritional state of prey should modify the performance level and efficiency of such strategies.
In aquaria either containing or lacking a structured refuge habitat, well-fed or food-deprived juvenile roach (Rutilus rutilus) were exposed to an open-water predator (pikeperch, Sander lucioperca). Controls were run without predators. In the presence of the predator, roach enhanced the performance of the anti-predator
strategy and increased the use of the refuge habitat whereby food-deprived roach were encountered more often in the structure
than well-fed roach. Nonetheless more starved than well-fed roach were fed upon by the predator. In the treatments offering
only open-water areas, roach always formed dense shoals in the presence of the predator. The shoal density, however, was lower
in starved roach. Starving fish in shoals experienced the highest predation mortality across all experimental treatments.
The experiment confirmed the plasticity of the anti-predator behaviour in roach and demonstrated that food deprivation diminished
the efficiency of shoaling more strongly than the efficiency of hiding. The findings may be relevant to spatial distribution
of prey and predator–prey interactions under natural conditions because when prey are confronted with phases of reduced resource
availability, flexible anti-predator strategies may lead to dynamic habitat use patterns. 相似文献
930.
Andreas M. Zipperle James A. Coyer Karsten Reise Eelo Gitz Wytze T. Stam Jeanine L. Olsen 《Marine Biology》2009,156(10):2139-2148
Genotypic structure and temporal dynamics of the dwarf seagrass, Zostera noltii, were studied in an intertidal meadow that has persisted since prior to 1936 near the Wadden Sea island of Sylt. Samples were
collected from two 10 × 10 m plots separated by 250 m from May 2002 to June 2005 and from four 1 × 1 m plots from June 2003
to September 2004. All the samples were genotyped with nine microsatellite loci. No genotypes were shared between the plots
separated by 250 m. Genetic diversity was higher in the Wadden Sea than in the other regions of its geographic range. The
average clone size (genets) (SD) in the two plots was 1.38 (0.26) and 1.46 (0.4) m2, respectively, with a range up to 9 m2
and <20% persisted for >4 years. A high genetic and genotypic diversity was maintained by annual recruitment of seedlings
despite a dramatic decrease in ramet density that coincided with the severe heat stress event of 2003. Fine-scale (1 m2) analysis
suggested that extensive loss of seagrass cover precluded space competition among the genets, while a persistent seed bank
prevented local extinction. Long-term persistence of Z. noltii meadows in the intertidal Wadden Sea was achieved by high genet turnover and frequent seedling recruitment from a seed bank,
in contrast to the low diversity observed in large and long-living clones of Z. noltii and other seagrasses in subtidal habitats. 相似文献