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171.
172.
Hormones play a central role in the physiology and behaviour of animals. The recent development of noninvasive techniques
has increased information on physical and social states of individuals through hormone measurements. The relationships among
hormones, life history traits and behaviours are, however, still poorly known. For the first time, we evaluated natural winter
glucocorticoid and testosterone levels in young ungulates in relation to winter progression, diet quality and social rank.
Overwinter, levels of glucocorticoid and testosterone decreased, possibly due to the decline of fawns’ body mass. The relationships
between hormone levels and diet quality were surprising: Fawns fed the control diet presented higher glucocorticoid and lower
testosterone levels then fawns fed the poor diet, suggesting that control fawns faced a higher nutritional stress than those
on the poor diet. Similarly to other studies on social mammals, we found no relationship between faecal glucocorticoid levels
and social rank, suggesting that social stress was similar for dominant and subordinate fawns during winter. Testosterone
levels were not correlated to social rank as found previously in groups of individuals forming stable social hierarchies and
maintaining stable dominance relationships. The simultaneous suppression of glucocorticoid and testosterone levels suggests
for the first time that young ungulates present a hormonal strategy to prevent fast depletion of limited proteins and fat
resources during winter. 相似文献
173.
de Sousa Paloma Viana Ferreira de Oliveira André Fernando da Silva Antônio Alberto Lopes Renata Pereira 《Environmental science and pollution research international》2019,26(15):14883-14903
Environmental Science and Pollution Research - Recent studies have shown Cu(0) as a promising material for the removal of organic and inorganic pollutants. However, there is no review addressing... 相似文献
174.
Hagen Koch Ana Lígia Chaves Silva José Roberto Gonçalves de Azevedo Werônica Meira de Souza Johann Köppel Clecio Barbosa Souza Junior Alessandra Maciel de Lima Barros Fred F. Hattermann 《Regional Environmental Change》2018,18(7):1927-1942
Many renewable resources for the generation of electricity, such as hydropower and wind power, are dependent on climatic factors. Reservoirs have been created to overcome the stochastic nature of river flows and to make water supply more reliable. However, reservoirs are affecting the ecological status of river ecosystems, e.g., by modifying the flow regime, triggering discussions regarding the discharge of reservoirs. In Brazil’s northeast region, the installed capacity for wind power generation has increased substantially in recent years. Setting up a modeling system for simulating wind power and hydropower generation in this study, it is analyzed whether wind power generation, peaking in the dry season, can help to achieve a more environmentally oriented flow regime in the Sub-middle and Lower São Francisco River Basin. Simulated higher discharges from reservoirs during the rainy season and lower discharges during the dry season, representing a more natural flow regime, will reduce hydropower generation in the dry season. Under recent conditions, the resulting gap in electricity generation can only be partially covered by wind power. A large share needs to be generated by thermal power plants or be imported from other regions in Brazil. The planned future increase in installed wind power capacity can change this picture; the demand for electricity generated by thermal power plants and imported will decrease. Adopting an integrated approach for hydropower and wind power generation, the flow regime in the Sub-middle and Lower São Francisco River Basin can be modified to improve the ecological status of the river system. 相似文献
175.
Ait-Mouheb Nassim Bahri Akiça Thayer Bechir Ben Benyahia Boumediene Bourrié Guilhem Cherki Brahim Condom Nicolas Declercq Rémi Gunes Adem Héran Marc Kitir Nurgul Molle Bruno Patureau Dominique Pollice Alfieri Rapaport Alain Renault Pierre Riahi Khalifa Romagny Bruno Sari Tewfik Sinfort Carole Steyer Jean-Philippe Talozi Samer Topcuoglu Bulent Turan Metin Wéry Nathalie Yıldırım Ertan Harmand Jérôme 《Regional Environmental Change》2018,18(3):693-705
Regional Environmental Change - Climate change and a growing population around the Mediterranean Rim are increasing the need for water and, consequently, the pressure on resources in terms of both... 相似文献
176.
Kudłak B Rogowska J Wolska L Kałas M Łęczyński L Namieśnik J 《Journal of environmental monitoring : JEM》2012,14(4):1231-1236
The paper presents the results of toxicity determinations carried out on sediment samples collected in the vicinity of the wreck of the German s/s Stuttgart (the southern part of the Gulf of Gdańsk, off the Polish coast) in relation to the determination of polycyclic aromatic hydrocarbons (PAHs). The toxicity of surface and core sediment samples was assessed using two biotest organisms-the bioluminescent bacteria Vibrio fischeri and the ostracod Heterocypris incongruens. PAH levels in these samples were determined by GC-MS. The surface sediments collected at W2 (ca. 34 m north of the shipwreck) and W4 (ca. 415 m north-east of the wreck) as well as the core sediments collected at WR3 (ca. 400 m north-east of the wreck) were the most heavily polluted with substances toxic to the biotest organisms. The chronic and acute toxicities in the case of most of the surface sediment samples studied are correlated. This may suggest that not only hydrophobic chemicals (like PAHs from fuel residues) but also more polar chemicals (resulting from the conversion of aromatic hydrocarbons) are responsible for the toxicity levels found. There is a clear dependence between the levels of chronic toxicity and PAH concentrations in the core sediment samples. In addition, a simultaneous decrease in the PAH content and chronic toxicity was noted in all the core sediment samples at depths below 80 cm. 相似文献
177.
Benoît Jobin Claudie Latendresse Alain Baril Charles Maisonneuve Céline Boutin Dominique Côté 《Environmental monitoring and assessment》2014,186(4):2215-2229
We studied landscape dynamics for three time periods (<1950, 1965, and 1997) along a gradient of agricultural intensity from highly intensive agriculture to forested areas in southern Québec. Air photos were analyzed to obtain long-term information on land cover (crop and habitat types) and linear habitats (hedgerows and riparian habitats) and landscape metrics were calculated to quantify changes in habitat configuration. Anthropogenic areas increased in all types of landscapes but mostly occurred in the highly disturbed cash crop dominated landscape. Perennial crops (pasture and hayfields) were largely converted into annual crops (corn and soybean) between 1965 and 1997. The coalescence of annual crop fields resulted in a more homogeneous agricultural landscape. Old fields and forest cover was consistently low and forest fragmentation remained stable through time in the intensive agriculture landscapes. However, forest cover increased and forest fragmentation receded in the forest-dominated landscapes following farm abandonment and the transition of old fields into forests. Tree-dominated hedgerows and riparian habitats increased in areas with intensive agriculture. Observed changes in land cover classes are related to proximate factors, such as surficial deposits and topography. Agriculture intensification occurred in areas highly suitable for agriculture whereas farm abandonment was observed in poor-quality agriculture terrains. Large-scale conversion of perennial crops into annual crops along with continued urbanization exerts strong pressures on residual natural habitats and their inhabiting wildlife. The afforestation process occurring in the more forested landscapes along with the addition of tree-dominated hedgerows and riparian habitats in the agriculture-dominated landscapes should improve landscape ecological value. 相似文献
178.
179.
180.
Sophie Beltran Frank Cézilly Jérôme Boissier 《Behavioral ecology and sociobiology》2009,63(9):1363-1368
“Divorce” (mate switching) rate is known to vary largely both between and within socially monogamous species. Although the
adult sex ratio can have an important influence on mating patterns, very few studies have investigated the influence of sex
ratio on divorce rate in monogamous species, and even less so from an experimental point of view. In addition, most studies
on the causes and consequences of divorce have been performed on vertebrate species, whereas data for invertebrate monogamous
species remain scarce. Schistosoma mansoni is a monogamous endoparasite with a complex life cycle characterized by asexual reproduction in the intermediate host and
sexual reproduction in the definitive host. In the wild, populations of S. mansoni inside their definitive hosts are characterized by a male-biased sex ratio. We studied the influence of experimentally varying
the adult sex ratio on divorce rate in S mansoni, using controlled infections of hosts with clonal populations. The more male-biased the sex ratio was, the more the divorce
rate increased, whereas no such effect was observed under a female-biased sex ratio. In this study and for the first time,
we showed, by handling the sex ratio, that the divorce rate increases in adult male-biased sex ratio conditions in a monogamous
species. 相似文献