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391.
Feeding and aggressive behaviours in juvenile coho salmon (Oncorhynchus kisutch) under chemically-mediated risk of predation 总被引:1,自引:0,他引:1
Summary Juvenile coho salmon (Oncorhynchus kisutch) spend the first year of their lives in their natal streams, where they may often hold feeding territories. They also face significant risk of predation by birds and fish, and should alter their behaviour to reduce risk of mortality when these predators are present. Although there is laboratory evidence that coho react to predator visual stimuli, chemoreception of avian predator presence has not previously been reported. We tested the influence of chemical stimuli of common merganser (Mergus merganser), preying on juvenile coho, on two aspects of coho territorial behaviour, foraging and aggression, in flow-through aquaria. After a mixture of merganser- and coho-conditioned water was introduced into the system, juvenile coho significantly reduced their attack distance on drifting prey. The fish also significantly decreased their aggressive behaviour directed towards mirrors (total number of acts, intensity of acts and time spent) when the same odour was present. They did not change their behaviour in either experiment after control introductions of water treated with fish alone. These results are interpreted within the framework of a trade-off between juvenile growth and mortality. 相似文献
392.
Cesar Beltran N. R. Edwards A. B. Haurie J.-P. Vial D. S. Zachary 《Environmental Modeling and Assessment》2006,11(1):31-43
In this paper, we show how oracle-based optimization can be effectively used for the calibration of an intermediate complexity
climate model. In a fully developed example, we estimate the 12 principal parameters of the C-GOLDSTEIN climate model by using
an oracle-based optimization tool, Proximal-ACCPM. The oracle is a procedure that finds, for each query point, a value for
the goodness-of-fit function and an evaluation of its gradient. The difficulty in the model calibration problem stems from
the need to undertake costly calculations for each simulation and also from the fact that the error function used to assess
the goodness-of-fit is not convex. The method converges to a ‘best fit’ estimate over 10 times faster than a comparable test
using the ensemble Kalman filter. The approach is simple to implement and potentially useful in calibrating computationally
demanding models based on temporal integration (simulation), for which functional derivative information is not readily available. 相似文献
393.
Matthew Edwards Fiona McKenzie Stephen O'Callaghan David Somerset Phillip Woodford Jillian Spilsbury Michael Fietz Janice Fletcher 《黑龙江环境通报》2006,26(10):985-988
Blood was obtained by cordocentesis from a fetus with non-immune hydrops demonstrated by ultrasound scanning at 27 weeks' gestation. Abnormalities of serum transferrin isoelectric focussing (IEF) were identified, characteristic of a congenital disorder of glycosylation type I (CDG-Ia). A diagnosis of CDG-Ia was confirmed by enzyme analysis of cultured amniocytes. This is the first report of CDG-Ia diagnosed by serum analysis in a fetus. Previous reports have warned that diagnostic abnormalities do not appear in serum until several weeks after birth. The sensitivity of cordocentesis transferrin IEF is unknown but is less than 100% effective because cases have been diagnosed postnatally after normal prenatal or neonatal studies. Enzyme analysis or mutation analysis is required for diagnosis of congenital disorder of glycosylation (CDGs) regardless of whether a diagnostic transferrin pattern is identified prenatally. The analysis of a small sample of serum, from cordocentesis, performed to check for fetal anemia, simplified the investigation, diagnosis, and genetic counselling of a case of non-immune hydrops detected at 27 weeks' gestation. This might be a useful test for other cases in these circumstances, as fetal blood is usually collected to check for anemia. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
394.
395.
396.
Edwards AW 《Behavioral ecology and sociobiology》2011,65(3):421-430
Ernst Mayr called the first part of the evolutionary synthesis the ‘Fisherian synthesis’ on account of the dominant role played
by R.A. Fisher in forging a mathematical theory of natural selection together with J.B.S. Haldane and Sewall Wright in the
decade 1922–1932. It is here argued that Fisher’s contribution relied on a close reading of Darwin’s work to a much greater
extent than did the contributions of Haldane and Wright, that it was synthetic in contrast to their analytic approach and
that it was greatly influenced by his friendship with the Darwin family, particularly with Charles’s son Leonard. 相似文献
397.
The impact of granivores on coastal dune seed reserves may be high, increasing along a landward gradient from the littoral
zone as the structural complexity of the habitat increases. Seasonal removal rates of non-native seeds by nocturnal and diurnal
vertebrates and ants from experimental seed trays in two habitats within the Alexandria Coastal Dunefield, South Africa, were
determined. Overall, seed removal was higher in the dune-field bush-pocket habitat than the landward thicket habitat. Nocturnal
vertebrates were the most important seed removers within bush-pockets. The importance of nocturnal vertebrates decreased in
the thicket and there was a shift in the dominant seed removers to diurnal vertebrates. Seed removal by ants and diurnal vertebrates
did not differ significantly between the bush-pockets and thicket while that of nocturnal vertebrates showed a significant
change. This can be ascribed to the abundance of the omnivorous murid rodentGerbillurus paeba exilis in the bush-pockets which is absent from thicket vegetation. 相似文献
398.
399.
Anthony R. Olsen Joseph Sedransk Don Edwards Carol A. Gotway Walter Liggett Stephen Rathbun Kenneth H. Reckhow Linda J. Yyoung 《Environmental monitoring and assessment》1999,54(1):1-45
The United States funds a number of national monitoring programs to measure the status and trends of ecological and natural resources. Each of these programs has a unique focus; the scientific objectives are different as are the sample designs. However, individuals and committees, all well aware of the cost of ecological monitoring, have called for more effective monitoring programs. The objective of this paper is to summarize existing programs' statistical designs and discuss potential alternatives for improvement in national monitoring. Can we improve the current situation by providing an overall framework for the design or analysis of data from these disparate surveys? First, the paper summarizes the objectives of these surveys, compares and contrasts their survey designs as currently implemented, and determines what variables they collect. Through this process we identify commonalities and issues that impact our ability to combine information across one or more of the surveys. Three potential alternatives are presented, leading to comprehensive monitoring in the United States. 相似文献
400.
Weighted road density: A simple way of assigning traffic-related air pollution exposure 总被引:2,自引:0,他引:2
Nectarios Rose Christine Cowie Robert Gillett Guy B. Marks 《Atmospheric environment (Oxford, England : 1994)》2009,43(32):5009-5014
BackgroundExisting traffic variables used for predicting NO2 in epidemiological studies are either difficult to acquire or explain only a small proportion of the variance. The purpose of this study was to develop and validate a new predictor, weighted road density, which combines the maximum amount of information related to traffic into a single variable without the requirement of obtaining traffic counts for a given area.MethodTwo week NO2 samples were collected using the readings of up to 32 passive samplers on 3 separate rounds between September and December 2006 and again in 2007. Several types of traffic related explanatory variables based on traffic counts, distance to main road and the proposed weighted road density were constructed using GIS software, and tested for association with the NO2 samplers. Assessment of the best model was based on R2 values, as well as leave-one-out cross validation.ResultsThe weighted road density variable and the density variable based on traffic counts resulted in a similar R2 (0.59) for predicting NO2, although weighted road density was much easier to construct and outperformed other variables such as distance to main road.ConclusionAs well as being a powerful predictor for use in a land use regression model, weighted road density can be used as a proxy for exposure to traffic-related pollution, for use in circumstances where direct measurements of pollutant levels are not feasible or are not required. 相似文献