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391.
Predation influences the ecology and behaviour of prey species and it is well known that the risk of predation affects prey’s decision making. We investigated whether predation risk through moon phase and exposure to the faecal odour of a natural predator, the red fox Vulpes vulpes, affect feeding behaviour and physiological response in wood mice (Apodemus sylvaticus). Antipredatory response was studied by live trapping under new and full moon in odourless control areas and areas experimentally manipulated with red fox fresh faeces. Food intake by individuals was determined as the amount of bait remaining in each trap and the physiological response was measured non-invasively analysing faecal corticosterone metabolites (FCM). Traps treated with faeces of red fox were the most avoided, and this avoidance was more significant during full moon. Food intake by wood mice varied according to the moon phase being significantly lower under full moon nights. We found sex, breeding condition and weight of individuals explaining the variation found in FCM concentrations, but no changes in FCM levels due to moon phase or exposure to red fox faeces were detected. These results indicate that wood mice avoid red fox faecal odour and this antipredatory response as well as feeding behaviour are significantly influenced by moon phase. However, no physiological response was found due to predation risk suggesting that wood mice do not take these predation cues enough reliable to experience physiological changes. 相似文献
392.
Niche complementarity, in which coexisting species use different forms of a resource, has been widely invoked to explain some of the most debated patterns in ecology, including maintenance of diversity and relationships between diversity and ecosystem function. However, classical models assume resource specialization in the form of distinct niches, which does not obviously apply to the broadly overlapping resource use in plant communities. Here we utilize an experimental framework based on competition theory to test whether plants partition resources via classical niche differentiation or via plasticity in resource use. We explore two alternatives: niche preemption, in which individuals respond to a superior competitor by switching to an alternative, less-used resource, and dominant plasticity, in which superior competitors exhibit high resource use plasticity and shift resource use depending on the competitive environment. We determined competitive ability by measuring growth responses with and without neighbors over a growing season and then used 15N tracer techniques to measure uptake of different nitrogen (N) forms in a field setting. We show that four alpine plant species of differing competitive abilities have statistically indistinguishable uptake patterns (nitrate > ammonium > glycine) in their fundamental niche (without competitors) but differ in whether they shift these uptake patterns in their realized niche (with competitors). Competitively superior species increased their uptake of the most available N form, ammonium, when in competition with the rarer, competitively inferior species. In contrast, the competitively inferior species did not alter its N uptake pattern in competition. The existence of plasticity in resource use among the dominant species provides a mechanism that helps to explain the manner by which plant species with broadly overlapping resource use might coexist. 相似文献
393.
A laboratory-based study was performed to assess the impact of climate warming on the recruitment of the endangered population
of the European lobster (Homarus gammarus) at Helgoland (North Sea, German Bight). Egg-bearing females collected in situ just after spawning in late summer were subjected
to various seasonal temperature regimes. Regimes with elevated temperatures (mild winters) resulted in a strong seasonal forward
shift of larval hatching. Hatching took place at significantly lower temperatures than under regimes with normal winters.
Experiments on larval development across a range of constant temperatures showed that no successful larval development occurred
at temperatures below 14°C. Larval survival increased from 9% at 14°C to 80% at 22°C, while duration of larval development
decreased correspondingly from 26 to 13 days. We hypothesize that an ongoing warming of the North Sea will strongly affect
the recruitment success of the Helgoland lobster, mainly resulting from a decoupling of the seasonal peak appearance of larvae
from optimal external conditions (temperature, food availability) for larval development. 相似文献
394.
Sofia Gamito Paula Chainho João Paulo Medeiros João Carlos Marques 《Ecological modelling》2010,221(3):459-466
The brackish water amphipod Corophium orientale is the dominant macroinvertebrate species in the upper Mira estuary, a small mesotidal system located in the southwest coast of Portugal. As climate changes will increase the frequency and intensity of extreme events such as floods and droughts, these will have a negative effect on benthic estuarine invertebrates, namely C. orientale. In order to understand the effects of these events on C. orientale, a dynamic model, based on published information and calibrated with field data, was developed and different scenarios were tested.For model construction, the annual development of three cohorts of C. orientale, their growth rates, and the establishment of the timing of each cohort rise and extinction are introduced. This structure can be repeated indefinitely, for years, and few parameters are required. The model simulations highlight the need for refuge areas that enable a fast recovery of the amphipod population after an extreme event and the recolozination of the affected areas. 相似文献
395.
Densely occupied drainage basins and coastal zones in developing countries that are facing economic growth are likely to suffer from moderate to severe environmental impacts regarding different issues. The catchment basins draining towards the Atlantic coast from northeastern to southern Brazil include a wide range of climatic zones and diverse ecosystems. Within its borders lies the Atlantic rain forest, significant extensions of semiarid thorn forests (caatinga), vast tree and scrub woodlands (cerrado) and most of the 6670 km of the Brazilian coast and its marine ecosystems. In recent decades, human activities have increasingly advanced over these natural resources. Littoralization has imposed a burden on coastal habitats and communities. Most of the native vegetation of the cerrado and caatinga was removed and only 7% of the original Atlantic rainforest still exists. Estuaries, bays and coastal lagoons have been irreversibly damaged. Land uses, damming and water diversion have become the major driving forces for habitat loss and aquatic ecosystem modification. Regardless of the contrast between the drought-affected northeastern Brazil and the much more prosperous and industrialized southeastern/southern Brazil, the impacts on habitat and communities were found equally severe in both cases. Attempts to halt environmental degradation have not been effective. Instead of focusing on natural resources separately, it is suggested that more integrated environmental policies that focus on aquatic ecosystems integrity are introduced. 相似文献
396.
A non-ionic surfactant (Genapol OX-80) was proposed as a means of reducing destructive crayfish activity in rice. In order to study the toxicity of this product on algae, a test in accordance to the ISO 8692 protocol (1989) was performed. The growth inhibiting effect of the pure formulation of Genapol OX-80 was studied on Selenastrum capricornutum in the concentration range of 0.01-1.0 mg/l. The result indicated a 72 h EC50-value of 0.5 mg/l. The suggested field concentration of approximately 50 mg/l is therefore two orders of magnitude above the algal EC50-value. From our findings it is expected that the impact on the rice field algae will not be negligible. 相似文献
397.
Rosa M. Pintó M. Isabel Costafreda Francisco J. Pérez-Rodriguez Lucía D’Andrea Albert Bosch 《Food and environmental virology》2010,2(3):127-135
Hepatitis A is the most common among all hepatitis worldwide in spite of an efficient vaccine and improved hygiene. Shellfish-borne
outbreaks are still of major concern causing hundreds of cases and huge economical losses in the present context of global
food trade. Hepatitis A virus (HAV) is a unique picornavirus with many differences in its molecular biology including both
its incapacity to induce the inhibition of the cellular protein synthesis and a highly biased and deoptimized codon usage
with respect the cell. The final goal of this intriguing strategy seems to be the need for a fine-tuning control of the translation
kinetics, particularly at the capsid coding region, and the underlying mechanism is the use of a right combination of common
and rare codons to allow a regulated ribosome traffic rate thus ensuring the proper protein folding. Capsid folding is critical
to warrant a high environmental stability for a virus transmitted through the fecal–oral route with long extracorporeal periods. 相似文献
398.
<正>两个五年规划的过渡期是中国的关键时刻,受到中外分析家的密切关注。但30年的极速增长之后,这种发展模式的所有困境和后果也随之而来,而第十二个五年规划(以下简称"十二五"规划)展现了中国政府承诺将继续胸怀壮志地走向更可持续发展的道路模式。若"十二五"规划取得成功,"十二五"或将成为中国发展的关键时期,甚至将成为具有国 相似文献
399.
Contaminant input into the environment can affect the biochemical responses of exposed organisms. Activity of conjugation enzymes, such as glutathione S-transferase (GST) has been proposed as a biomarker of susceptibility to the presence of potentially damaging xenobiotics. The aim of the present study was to evaluate the activity of total and Pi-class GST in the hepatopancreas of pink-shrimp Farfantepenaeus brasiliensis. The shrimp were caught at a single site at Concei??o Lagoon and transplanted to another site (Canto da Lagoa - CA) in the same lagoon, and to the laboratory (LAB), where they were kept for 15 days. This experiment was carried out in winter 2003 and in summer 2004. Shrimp were sampled before the exposure, at a zero time (t0), and after 15-days at CA site and LAB. The activity of total GST and Pi-isoform were analyzed using CDNB and ethacrynic acid (EA) as substrates, respectively. Shrimp caught in winter showed higher levels of Pi-class GST than those caught in summer, for both t0 and CA groups. Moreover, differences in the activity of this GST isoform between groups were observed only in winter, where the animals from t0 and CA groups presented higher activity when compared to those kept in the laboratory. This difference could be associated either to changes in the contaminant input or to other water quality parameters in this ecosystem. The elevated GST Pi activity observed in the shrimp of both t0 and CA groups sampled in winter could be related to salinity, since it was higher in winter than in summer. We could also suggest a possible association of this finding to a seasonal metabolic variation in this penaeid. If that is the case, one should take into account these alterations when considering the use of this GST isoform as biomarker in F. brasiliensis in environmental monitoring programs. 相似文献
400.
Smallegange IM 《Die Naturwissenschaften》2011,98(4):339-346
Investigating how the environment affects age and size at maturity of individuals is crucial to understanding how changes
in the environment affect population dynamics through the biology of a species. Paternal phenotype, maternal, and offspring
environment may crucially influence these traits, but to my knowledge, their combined effects have not yet been tested. Here,
I found that in bulb mites (Rhizoglyphus robini), maternal nutrition, offspring nutrition, and paternal phenotype (males are fighters, able to kill other mites, or benign
scramblers) interactively affected offspring age and size at maturity. The largest effect occurred when both maternal and
offspring nutrition was poor: in that case offspring from fighter sires required a significantly longer development time than
offspring from scrambler sires. Investigating parental effects on the relationship between age and size at maturity revealed
no paternal effects, and only for females was its shape influenced by maternal nutrition. Overall, this reaction norm was
nonlinear. These non-genetic intergenerational effects may play a complex, yet unexplored role in influencing population fluctuations—possibly
explaining why results from field studies often do not match theoretical predictions on maternal effects on population dynamics. 相似文献