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741.
David Bierbach Vanessa Sassmannshausen Bruno Streit Lenin Arias-Rodriguez Martin Plath 《Behavioral ecology and sociobiology》2013,67(4):675-683
Selection imposed by male competition (intrasexual selection) and female choice (intersexual selection) can be con- or discordant. Specifically, females may or may not prefer mating with dominant males, and direct costs of interacting with dominant (and possibly more harassing) males have been suggested to explain avoidance of dominant males. Here, we exemplify that inter- and intrasexual selection may normally act in the same direction, but can be temporarily conflicting when social information becomes available. Using video playback techniques, we presented females of the Mexican livebearing fish Poecilia mexicana with two size-matched males and established association preferences. Half of the females could then observe the same two males fight and establish dominance, while control females saw both males side by side, but physically separated, and female preferences were subsequently re-evaluated. Females in the control group showed a significant preference for future winners in the subsequent testing, confirming an innate or acquired preference for male traits that are indicative of physical superiority, even when body size as a choice criterion is excluded. When allowed to eavesdrop on male fights, however, females did not show a preference for observed winners and even decreased time spent with them relative to the control treatment in which no fight was shown. A subsequent experiment found contest winners to show elevated levels of sexual behavior, so we argue that the temporary offset of the intrinsic female preference for dominant males after having observed a fight is indeed driven by direct costs females expect from more harassing contest winners. 相似文献
742.
When juvenile mortality or juvenile growth is impacted by temperature and salinity, these factors have a substantial effect on recruitment success and population dynamics in benthic ecosystems. Using freshly settled cyprids of Amphibalanus improvisus, we investigated the combined effects of temperature (12, 20 and 28 °C) and salinity (5, 15 and 30 psu) on early juvenile stage performance. Mortality as well as size (basal diameter, dry weight, and ash-free dry weight) was monitored for a period of 40 days. Mortality was high (42–63 %) during the first week following attachment, regardless of the temperature and salinity treatments. Subsequently, mortality and size were interactively influenced by temperature and salinity. Highest mortality and lowest size of juveniles occurred at lowest temperature (12 °C) and salinity (5 psu). Apparently, low temperature (12 °C) narrowed the barnacles’ salinity tolerance. Juvenile barnacles constructed more shell material compared to body mass at high temperature and high salinity, while a reverse situation was observed at low temperature and low salinity. Our results demonstrate that environmental changes can directly and/or indirectly alter patterns of survivorship and size. Warming and desalination as predicted for the Baltic Sea in the course of climate change may, however, act antagonistically and compensate each other’s isolated effect on barnacles. 相似文献
743.
Hronn Egilsdottir Fanny Noisette Laure M.-L. J. Noël Jon Olafsson Sophie Martin 《Marine Biology》2013,160(8):2103-2112
Marine organisms inhabiting environments where pCO2/pH varies naturally are suggested to be relatively resilient to future ocean acidification. To test this hypothesis, the effect of elevated pCO2 was investigated in the articulated coralline red alga Corallina elongata from an intertidal rock pool on the north coast of Brittany (France), where pCO2 naturally varied daily between 70 and 1000 μatm. Metabolism was measured on algae in the laboratory after they had been grown for 3 weeks at pCO2 concentrations of 380, 550, 750 and 1000 μatm. Net and gross primary production, respiration and calcification rates were assessed by measurements of oxygen and total alkalinity fluxes using incubation chambers in the light and dark. Calcite mol % Mg/Ca (mMg/Ca) was analysed in the tips, branches and basal parts of the fronds, as well as in new skeletal structures produced by the algae in the different pCO2 treatments. Respiration, gross primary production and calcification in light and dark were not significantly affected by increased pCO2. Algae grown under elevated pCO2 (550, 750 and 1000 μatm) formed fewer new structures and produced calcite with a lower mMg/Ca ratio relative to those grown under 380 μatm. This study supports the assumption that C. elongata from a tidal pool, where pCO2 fluctuates over diel and seasonal cycles, is relatively robust to elevated pCO2 compared to other recently investigated coralline algae. 相似文献
744.
F. Galgani J. F. Chiffoleau P. LE Gall Y. Pichot B. Andral C. Martin 《Chemistry and Ecology》2013,29(2):133-141
We experimented with caging the Mediterranean mussel (Mytilus galloprovincialis) at various depths for 69 d to measure basic physiological parameters, histological response and bio-accumulation of contaminants in a deep-sea contaminated area. In preliminary experiments, we demonstrated, under artificial pressure conditions, the ability of mussels Mytilus galloprovincialis to tolerate rapid immersion (at a speed of up to 120 m min?1). In situ experiments were performed using submerged lines enabling mussels to be maintained at depths ranging of 40–1550 m with survival rates ranging from 80 to 38%, respectively. No significant differences in condition indexes were observed between treated and control specimens. However, histological observations demonstrated a clear reduction in thickness of the digestive epithelium with increasing depth exposure. By determining the contaminants in caged mussels, we found the following values for chromium accumulation: 27.4 μg g?1 dry weight at 580 m depth and 9.8 μg g?1 dry weight at 1550 m. Selected stations were located downstream of an industrial effluent at 420 m. The biological and environmental consequences of deep-sea contamination demonstrate the suitability of caged mussels for monitoring contaminant accumulation. 相似文献
745.
Poul Johansen Martin Munk Hansen Gert Asmund Palle Bo Nielsen 《Chemistry and Ecology》2013,29(1-2):35-55
In monitoring the impact of a lead-zinc mine in Greenland, species of fish, prawns, seaweed and mussels have been analysed for cadmium, copper, lead and zinc for several years. These metals have been released to the marine environment in significant amounts from the mining operation. 相似文献
746.
We report for the first time the use of beetroot fibers to eliminate heavy metals from polluted water. This biomass is used to remove lead, copper and zinc ions. The kinetics and beetroot fibers fixation capacities of lead, zinc and copper according to various physico‐chemical parameters such as pH, and the concentration of metal solutions were studied. The experiments were carried out in a laboratory column with fixed bed. For kinetic studies, samples of metal solutions were taken at regular intervals and measured by atomic absorption spectrometry. pH at 6.6 shows a maximum retention of the above cited metals by beetroot fibers (98%, 92%, 90% respectively). Quantity of cations retained by this biomass in simple and mixture solution is respectively estimated to be 23.6, 14.02 and 14.64 mg/g. Results indicate the usefulness of this biomass in the remediation of water contaminated by heavy metals by a rapid, practical and efficient method. 相似文献
747.
No-take reserves are sometimes implemented for sustainable population harvesting because they offer opportunities for animals to spatially avoid harvesters, whereas harvesters can benefit in return from the reserve spillover. Here, we used the framework of predator-prey spatial games to understand how protected areas shape spatial interactions between harvesters and target species and determine animal mortality. In these spatial games, the "predator" searches for "prey" and matches their habitat use, unless it meets spatial constraints offering the opportunity for prey to avoid the mortality source. However, such prey refuges could attract predators in the surroundings, which questions the potential benefits for prey. We located, in the Geneva Basin (France), hunting dogs and wild boar Sus scrofa L. during hunting seasons with global positioning systems and very-high-frequency collars. We quantified how the proximity of the reserve shaped the matching between both habitat uses using multivariate analyses and linked these patterns to animals' mortality with a Cox regression analysis. Results showed that habitat uses by both protagonists disassociated only when hunters were spatially constrained by the reserve. In response, hunters increased hunting efforts near the reserve boundary, which induced a higher risk exposure for animals settled over the reserve. The mortality of adult wild boar decreased near the reserve as the mismatch between both habitat uses increased. However the opposite pattern was determined for younger individuals that suffered from the high level of hunting close to the reserve. The predator-prey analogy was an accurate prediction of how the protected area modified spatial relationships between harvesters and target species. Prey-searching strategies adopted by hunters around reserves strongly impacted animal mortality and the efficiency of the protected area for this harvested species. Increasing reserve sizes and/or implementing buffer areas with harvesting limitations can dampen this edge effect and helps harvesters to benefit durably from source populations of reserves. Predator-prey spatial games therefore provide a powerful theoretical background for understanding wildlife-harvester spatial interactions and developing substantial application for sustainable harvesting. 相似文献
748.
Katharina Maria Jörger Martin Heß Timea Pamela Neusser Michael Schrödl 《Marine Biology》2009,156(6):1159-1170
Sperm transfer via spermatophores is common among organisms living in mesopsammic environments, and is generally considered
to be an evolutionary adaptation to reproductive constraints in this habitat. However, conclusions about adaptations and trends
in insemination across all interstitial taxa cannot be certain as differences in mode of insemination via spermatophores do
exist, details of insemination are lacking for many species, and evolutionary relationships in many cases are poorly known.
Opisthobranch gastropods typically transfer sperm via reciprocal copulation, but many mesopsammic Acochlidia are aphallic
and transfer sperm via spermatophores, supposedly combined with dermal fertilisation. The present study investigates structural
and functional aspects of sperm transfer in the Mediterranean microhedylacean acochlid Pontohedyle milaschewitchii. We show that spermatophore attachment is imprecise. We describe the histology and ultrastructure of the two-layered spermatophore
and discuss possible functions. Using DAPI staining of the (sperm-) nuclei, we document true dermal insemination in situ under
the fluorescence microscope. Ultrastructural investigation and computer-based 3D reconstruction from TEM sections visualise
the entire spermatozoon including the exceptionally elongate, screw-like keeled sperm nucleus. An acrosomal complex was not
detected. From their special structure and behaviour we conclude that sperm penetrate epithelia, tissues and cells mechanically
by drilling rather than lysis. Among opisthobranchs, dermal insemination is limited to mesopsammic acochlidian species. In
this spatially limited environment, a rapid though imprecise and potentially harmful dermal insemination is discussed as a
key evolutionary innovation that could have enabled the species diversification of microhedylacean acochlidians. 相似文献
749.
Mid-ocean ridges are common features of the world’s oceans but there is a lack of understanding as to how their presence affects
overlying pelagic biota. The Mid-Atlantic Ridge (MAR) is a dominant feature of the Atlantic Ocean. Here, we examined data
on euphausiid distribution and abundance arising from several international research programmes and from the continuous plankton
recorder. We used a generalized additive model (GAM) framework to explore spatial patterns of variability in euphausiid distribution
on, and at either side of, the MAR from 60°N to 55°S in conjunction with variability in a suite of biological, physical and
environmental parameters. Euphausiid species abundance peaked in mid-latitudes and was significantly higher on the ridge than
in adjacent waters, but the ridge did not influence numerical abundance significantly. Sea surface temperature (SST) was the
most important single factor influencing both euphausiid numerical abundance and species abundance. Increases in sea surface
height variance, a proxy for mixing, increased the numerical abundance of euphausiids. GAM predictions of variability in species
abundance as a function of SST and depth of the mixed layer were consistent with present theories, which suggest that pelagic
niche availability is related to the thermal structure of the near surface water: more deeply-mixed water contained higher
euphausiid biodiversity. In addition to exposing present distributional patterns, the GAM framework enables responses to potential
future and past environmental variability including temperature change to be explored. 相似文献
750.
The spring zooplankton community in the Strait of Georgia (British Columbia, Canada) is characterized by the presence of several
calanoid copepod species which collectively make up ~90% of the mezozooplankton biomass. Here, we investigate interspecific,
interannual, and geographic variability in the diets and trophic positions of these copepods using a combination of fatty
acids and stable isotopes. To characterize geographic variability in diet, we compare our findings from the Strait of Georgia
with similar data from Ocean Station P in the subarctic northeast Pacific. Both fatty acid and stable isotope signatures indicate
the existence of three trophic levels, even within the limited size range of these copepods: Neocalanus plumchrus and Calanus marshallae are primarily omnivorous, while Euchaeta elongata is carnivorous and Eucalanus bungii is herbivorous. Fatty acid markers of trophic position (e.g., DHA/EPA, 18:1n-9/18:1n-7) correlate significantly with δ15N, while markers indicating the proportion of diatoms to flagellates in the diet (e.g., 16PUFA/18PUFA and DHA/EPA) correlate
significantly with δ13C, after the effect of lipid concentration on δ13C is accounted for. Despite the general correlation between stable isotopes and fatty acids, the former are not sensitive
enough to capture the range of interannual variability observed in the latter, and can only capture substantial shifts in
the diet over geographic scales. However, regardless of variability in food quality, the relative trophic positions of these
copepods do not change significantly either spatially or temporally. 相似文献