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311.
Christine R. Dahlin Anna M. Young Breanne Cordier Roger Mundry Timothy F. Wright 《Behavioral ecology and sociobiology》2014,68(1):145-161
In many social species group, members share acoustically similar calls. Functional hypotheses have been proposed for call sharing, but previous studies have been limited by an inability to distinguish among these hypotheses. We examined the function of vocal sharing in female budgerigars with a two-part experimental design that allowed us to distinguish between two functional hypotheses. The social association hypothesis proposes that shared calls help animals mediate affiliative and aggressive interactions, while the password hypothesis proposes that shared calls allow animals to distinguish group identity and exclude nonmembers. We also tested the labeling hypothesis, a mechanistic explanation which proposes that shared calls are used to address specific individuals within the sender–receiver relationship. We tested the social association hypothesis by creating four–member flocks of unfamiliar female budgerigars (Melopsittacus undulatus) and then monitoring the birds’ calls, social behaviors, and stress levels via fecal glucocorticoid metabolites. We tested the password hypothesis by moving immigrants into established social groups. To test the labeling hypothesis, we conducted additional recording sessions in which individuals were paired with different group members. The social association hypothesis was supported by the development of multiple shared call types in each cage and a correlation between the number of shared call types and the number of aggressive interactions between pairs of birds. We also found support for calls serving as a labeling mechanism using discriminant function analysis with a permutation procedure. Our results did not support the password hypothesis, as there was no difference in stress or directed behaviors between immigrant and control birds. 相似文献
312.
Exposed limestone cliffs in central Europe harbor a highly divers flora with many rare and endangered species. During the
past few decades, there has been increasing recreational use of these cliffs, which has caused local environmental disturbances.
Successful restoration strategies hinge on identifying critical limitations. We examined the composition of aboveground forest
vegetation and density and species composition of seeds in the soil seed bank at the base of four limestone cliffs in mixed
deciduous forests that are intensively disturbed by human trampling and at four undisturbed cliffs in the Jura Mountains in
northwestern Switzerland. We found that long-term human trampling reduced total aboveground vegetation cover at the base of
cliffs and caused a significant shift in the plant-species composition. Compared with undisturbed cliffs, total seed density
was lower in disturbed cliffs. Human trampling also altered the species composition of seeds in the soil seed bank. Seeds
of unintentionally introduced, stress-tolerant, and ruderal species dominated the soil seed bank at the base of disturbed
cliffs. Our findings indicate that a restoration of degraded cliff bases from the existing soil seed bank would result in
a substantial change of the original unique plant composition. Active seed transfer, or seed flux from adjacent undisturbed
forest areas, is essential for restoration success. 相似文献
313.
314.
Poirier Larabie Sylvie Jutras Martin Leclair Grégoire St-Jean Isabelle Kleinert Christine Gagné François Gagnon Christian 《Environmental science and pollution research international》2022,29(30):45303-45313
Environmental Science and Pollution Research - Aquatic organisms are continuously exposed to emerging contaminants coming from urban effluents of wastewater treatment plants. The contamination of... 相似文献
315.
Christine S. Couturier Alice Rouault David McKenzie Robert Galois Serge Robert Lucette Joassard Guy Claireaux 《Marine Biology》2007,152(4):803-814
The French Atlantic coast contains large highly productive intertidal mudflats that are colonised by juveniles of numerous
flatfish species, including the common sole (Solea solea, L.). These ecosystems are also heavily exploited by the shellfish farming industry. Intensive bivalve culture is associated
with substantial biodeposition (1–6 t-dw ha−1 day−1), which directly or indirectly contributes to increase exopolysaccharide (EPS) concentrations at the interface between water
column and seabed. EPS are long-chain molecules organised into colloids, which influence rheological properties of water,
particularly viscosity. Increased water viscosity had consequences for ventilatory activity of juvenile flatfish, whereby
the minimal pressure required to ventilate the medium increases directly with EPS concentration. Moreover, the critical EPS
concentration ([EPS]crit) at which water was no longer able to flow through the branchial basket ranged from almost nil to over 30 mg l−1, depending on species and size. [EPS]crit was lower in small individuals and individuals from species with high metabolic rates (turbot and plaice). These differences
may depend upon gill and bucco-branchial cavity morphometrics. The ventilatory workload of sole increased with viscosity to
a maximum at 2 mg EPS l−1. Viscosity might, therefore, be a limiting factor for flatfish post larvae, which colonise the intertidal mudflats, depending
upon their size and species. EPS concentrations in the field can reach 15 mg l−1. A selective effect is conceivable but remains to be estimated in the field. 相似文献
316.
317.
318.
Christine Wallgren 《Local Environment》2006,11(2):233-251
This study compares energy use for food transport to a farmers' market in Sweden with energy use for transport in the conventional food system. The farmers' market was investigated through data sampling from on-site investigations. The conventional food system was studied with the aid of life cycle assessments reported in the literature. Overall, the study found no significant differences in levels of energy use for transport to the farmers' market compared with the conventional food system. For certain products, such as fresh fruits and vegetables, transport-related energy use was much lower in the local system although the season in Sweden for this kind of product is restricted to two or three months at the end of the summer. However, there is considerable potential to increase energy efficiency in local food systems by organizing the selling in new ways and by using more energy efficient vehicles. 相似文献
319.
Vincent Chatain Mostafa Benzaazoua Marie Loustau Cazalet Hassan Bouzahzah Cécile Delolme Mathieu Gautier Denise Blanc Christine de Brauer 《Environmental science and pollution research international》2013,20(1):51-59
The environmental assessment of potential effects of contaminated harbor sediments stabilized with hydraulic binders and the determination of remediation endpoints require the determination of pollutants leaching potentials. Moreover, little information about the speciation and mobility of inorganic contaminants in these specific solid matrices is available in the literature. The objective of this paper is to investigate the relationship between mineralogy and leachability of contaminants (copper, lead, and zinc) present in a French harbor sediment stabilized with quicklime and Portland cement. Batch equilibrium leaching tests at various pH, chemical analysis of leachates, and mineralogical studies (X-ray diffraction, scanning electron microscopy–energy dispersive spectroscopy, and diffuse reflectance infrared Fourier transform) have been combined in the present investigation. The acid neutralization capacity of the stabilized matrix studied is first controlled by the dissolution of portlandite (pH?~12), followed by the dissolution of C–S–H (pH?~11) and the dissolution of ettringite (pH?~10). Finally, a very high buffering capacity of this stabilized sediment is observed for pH values around 6. This equilibrium is mainly controlled by the dissolution of iron sulfides and carbonate minerals. Consequently, the mobilization of inorganic contaminants as a function of pH remains very low (<0.1 wt%) for pH values above 6 and significantly increases for pH below these values. This research confirms the importance of a combined methodology for the intrinsic characterization of potential mobilization of contaminants in a stabilized sediment and for a better understanding of geochemical processes that affect contaminant fate, transformation, and transport in the subsurface environment. 相似文献
320.