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771.
Designatable Units for Status Assessment of Endangered Species 总被引:8,自引:1,他引:8
DAVID M. GREEN 《Conservation biology》2005,19(6):1813-1820
Abstract: Species status assessment and the conservation of biological diversity may require defining units below the species level to portray probabilities of extinction accurately and to help set priorities for conservation efforts. What those units should be has been debated in the scientific literature largely in terms of evolutionarily significant units (ESUs), but this discourse has had little impact on government policy with regard to status assessment. As with species concepts, the variously proposed ESU concepts have not been resolvable into a single approach. The need for a practicable procedure to identify infraspecific entities for status assignment is the motivation behind employing designatable units (DUs). In aid of a policy to prevent elements of biodiversity from becoming extinct or extirpated, DUs are determined during the process of resolving a species' conservation status according to broadly applicable guidelines. The procedure asks whether putative DUs are distinguishable based on a reliably established taxonomy or a well-corroborated phylogeny, compelling evidence of genetic distinction, range disjunction, and/or biogeographic distinction as long as extinction probabilities also differ. The language of the DU approach avoids wording that implies value judgments concerning evolutionary importance or significance. Because species conservation status assessment is not science but, rather, the use of science to further policy, DUs contribute to a precautionary approach to listing whereby status may be assessed even though knowledge of systematic relationships below the species level may be lacking or unresolved. The pragmatic approach of using DUs has been adopted by the Committee on the Status of Endangered Wildlife in Canada for status assessment of species under the Canadian Species at Risk Act. 相似文献
772.
Market responses to hurricanes 总被引:7,自引:0,他引:7
Daniel G. Hallstrom V. Kerry Smith 《Journal of Environmental Economics and Management》2005,50(3):541-561
This paper uses one of the strongest hurricanes to hit the US, Andrew in 1992, to define a quasi-random experiment that permits estimation of the responses of housing values to information about new hurricanes. Lee County, Florida did not experience damage from Andrew. The storm was a “near-miss.” We hypothesize that Andrew conveyed risk information to homeowners in the county. A difference-in-differences (DND) framework identifies the effect of this information on property values in areas likely to experience significant storm damage. The DND findings indicate at least a 19 percent decline in property values. 相似文献
773.
Xyleborini are a species-rich tribe of ambrosia beetles, which are haplodiploid and typically mate among siblings within their
natal brood chamber. Several characteristics of this tribe would predict the evolution of higher levels of sociality: high
genetic relatedness within galleries due to inbreeding, high costs of dispersal and the potential benefit of cooperation in
brood care within the natal gallery (e.g. by fungus gardening, gallery extension, offspring feeding and cleaning). However,
information on the social system of these beetles is very limited. We examined the potential for cooperative breeding in Xyleborinus saxeseni by monitoring dispersal in relation to brood size and composition. Results show that adult female offspring delay dispersal
despite dispersal opportunities, and apparently some females never disperse. The females’ decision to stay seems to depend
on the presence of eggs and dependent siblings. We found no indication that female offspring reproduce in their natal gallery,
as colonies with many mature daughters do not contain more eggs than those with few or no daughters. There is a significant
positive relationship between the number of females present and the number of dependent siblings (but not eggs), which suggests
that cooperative brood care of female offspring raises colony productivity by improving survival rates of immatures. Our results
suggest that cooperative breeding is likely to occur in X. saxeseni and possibly other xyleborine species. We argue that a closer look at sociality within this tribe may yield important information
on the factors determining the evolution of cooperative breeding and advanced social organization. 相似文献
774.
Predation and hunger are threats for most organisms, and appropriate behavioural responses to both factors should be shaped by natural selection. In combination, however, the behavioural demands of predation avoidance and effective foraging often cannot be satisfied at the same time and lead to a conflict within organisms. We examined the behavioural responses of two closely-related species of tadpoles, Rana lessonae and R. esculenta, to simulated predation by fish and hunger. Tadpoles, hatched and reared in the laboratory, were tested in a three-way factorial (predation risk × hunger × species) experiment with four predation levels and four hunger levels. Both species decreased their swimming activity with increasing predation risk. Predation risk did not influence the amount of activity time invested in feeding but caused the tadpoles to spend less time in patches with food. Refuges were not used to avoid predation. R. esculenta was more sensitive to predation risk than R. lessonae. Hunger increased both the activity of tadpoles and the amount of activity time invested in feeding, thus indicating an increased energy intake. No interactions were observed between predation risk and hunger. These results show that tadpoles possess genetically-based behavioural mechanisms that allow them to respond in a graded manner to predation and hunger. However, they did not balance the two conflicting demands of predation avoidance and effective foraging; the two mechanisms appeared to act independently.
Correspondence to: R.D. Semlitsch 相似文献
775.
An important topic in the registration of pesticides and the interpretation of monitoring data is the estimation of the consequences of a certain concentration of a pesticide for the ecology of aquatic ecosystems. Solving these problems requires predictions of the expected response of the ecosystem to chemical stress. Up until now, a dominant approach to come up with such a prediction is the use of simulation models or safety factors. The disadvantage of the use of safety factors is a crude method that does not provide any insight into the concentration–response relationships at the ecosystem level. On the other hand, simulation models also have serious drawbacks like that they are often very complex, lack transparency, their implementation is expensive and there may be a compilation of errors, due to uncertainties in parameters and processes. In this paper, we present the expert model prediction of the ecological risks of pesticides (PERPEST) that overcomes these problems. It predicts the effects of a given concentration of a pesticide based on the outcome of already performed experiments using experimental ecosystems. This has the great advantage that the outcome is more realistic. The paper especially discusses how this model can be used to translate measured and predicted concentrations of pesticides into ecological risks, by taking data on measured and predicted concentrations of atrazine as an example. It is argued that this model can be of great use to evaluate the outcome of chemical monitoring programmes (e.g. performed in the light of the Water Framework Directive) and can even be used to evaluate the effects of mixtures. 相似文献
776.
Statistical inference on patch-specific survival and movement rates from marked animals 总被引:1,自引:0,他引:1
Michael J. Conroy Jon E. Anderson Stephen L. Rathbun David G. Krementz 《Environmental and Ecological Statistics》1996,3(2):99-116
Empirical estimates of patch-specific survival and movement rates are needed to parametrize spatially explicit population
models, and for inference on the effects of habitat quality and fragmentation on populations. Data from radio-marked animals,
in which both the fates and habitat locations of animals are known over time, can be used in conjunction with continuous-time
proportional hazards models to obtain inferences on survival rates. Discrete-time conditional logistic models may provide
inference on both survival and movement rates. We use Monte Carlo simulation to investigate accuracy of estimates of survival
from both approaches, and movement rates from conditional logistic regression, for two habitats. Bias was low (relative bias
< 0.04) and interval coverage accurate (close to the nominal 0.95) for estimates of habitat effect on survival based on proportional
hazards. Bias was high (
relative bias 0.60) and interval coverage poor (
= 0.26 vs. nominal 0.95) for estimates of habitat effect based on conditional logistic regression; bias was especially influenced
by heterogeneity in survival and the shape of the hazard function, whereas both bias and coverage were affected by ‘memory’
effects in movement patterns. Bias estimates of movement rate was low (
relative bias < 0.05), but interval coverage was poor (
= 0.48–0.80), possibly as a result of poor performance of a Taylor series estimate of variance. An example is provided from
a radio-telemetry study of 47 wintering American woodcock (Scolopax minor), illustrating practical difficulties in field studies to parametrize these models. We also discuss extensions of continuous-time
models to explicitly include a movement process, and further examine tradeoffs between continuous and discrete models. 相似文献
777.
基因组学、蛋白组学和代谢组学技术为生态毒理学的发展提供了生物高通量的技术手段,构成了新的交叉学科——生态毒理基因组学.生态毒理基因组学着重研究环境毒物暴露下非靶生物基因和蛋白的表达,能够在基因组水平上更深入地理解环境污染物的致毒机制,同时,它引进生物标志物为生态风险评价提供了平台.论文对生态毒理基因组学的发展历程、技术支持、模式生物及其在生态风险评价方面的应用进行了综述,以推动生态毒理基因组学技术在我国的进一步发展. 相似文献
778.
Adam R. Smith William T. Wcislo Sean O’Donnell 《Behavioral ecology and sociobiology》2007,61(7):1111-1120
Facultatively solitary and eusocial species allow for direct tests of the benefits of group living. We used the facultatively
social sweat bee Megalopta genalis to test several benefits of group living. We surveyed natural nests modified for observation in the field weekly for 5 weeks
in 2003. First, we demonstrate that social and solitary nesting are alternative behaviors, rather than different points on
one developmental trajectory. Next, we show that solitary nests suffered significantly higher rates of nest failure than did
social nests. Nest failure apparently resulted from solitary foundress mortality and subsequent brood orphanage. Social nests
had significantly higher productivity, measured as new brood cells provisioned during the study, than did solitary nests.
After accounting for nest failures, per capita productivity did not change with group size. Our results support key predictions
of Assured Fitness Return models, suggesting such indirect fitness benefits favor eusocial nesting in M. genalis. We compared field collections of natural nests to our observation nest data to show that without accounting for nest failures,
M. genalis appear to suffer a per capita productivity decrease with increasing group size. Calculating per capita productivity from
collected nests without accounting for the differential probabilities of survival across group sizes leads to an overestimate
of solitary nest productivity. 相似文献
779.
POLLUTION THREATS IN THE MEDITERRANEAN SEA: AN OVERVIEW 总被引:3,自引:0,他引:3
Roberto Danovaro 《Chemistry and Ecology》2003,19(1):15-32
This overview summarises the present knowledge on major sources of pollution, which are of concern for the Mediterranean Sea. Eutrophication, red tides, organic loads, hydrocarbon spills, heavy metal contamination and their biological effects are described on the light of the ecological characteristics of the Mediterranean. In particular special attention is paid to the "new pollution" processes; i.e. , the introduction of novel substances with biological activity that might have synergetic effects with "classical pollutants". Different compartments and marine ecosystems are considered and compared. The degree of anthropogenic impact and its apparent trends are discussed. Possible monitoring plans and remedial actions for a sustainable management of coastal zones subjected to increasing pollution are also suggested. 相似文献
780.
Gilberto Pasinelli Mathis Müller Michael Schaub Lukas Jenni 《Behavioral ecology and sociobiology》2007,61(7):1061-1074
Studies of animal breeding dispersal have often focused on possible causes, whereas its adaptive significance has received
less attention. Using an information-theoretic approach, we assessed predictions of four hypotheses relating to causes and
consequences of breeding dispersal in a migratory passerine, the red-backed shrike Lanius collurio. As predicted by the reproductive performance hypothesis, probability of breeding dispersal in females (though not in males)
decreased with increasing annual average number of fledglings produced in the past year, but there was no association with
conspecific reproductive performance in either sex. The site choice hypothesis, stating that individuals disperse to improve
breeding site quality, received support in males only, as dispersal probability was positively associated to a measure indicating
low territory quality. The social constraints hypothesis, referring to dispersal in relation to intraspecific interactions,
received little support in either sex. The predation risk hypothesis was hardly supported either. Consequences of dispersal
were marginal in both sexes because neither fledgling production in females, nor territory quality in males improved after
dispersal. In addition, males settled on territories closer to the forest edge than those occupied predispersal, which is
opposite to the prediction of the predation risk hypothesis. We conclude that own reproductive success was the major factor
determining dispersal behavior in females, whereas territory quality and possibly predation risk were most important in males.
Overall, breeding dispersal appeared not to be adaptive in this dense population inhabiting an optimal habitat. 相似文献