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91.
Kate M. Millar 《Journal of Agricultural and Environmental Ethics》2000,12(1):41-50
An analysis of the ethical impacts of the use of anAutomatic Milking System (AMS) is employed as a casestudy to illustrate the use of a form of bioethicalanalysis in technology assessment. The approach isbased on the Ethical Matrix, where `impacts' areassessed in terms of (lack of) respect for threeethical principles as applied to interest groups. Inthis case, only impacts on dairy cows are examined,and principally in terms of their behaviouralfreedom.In contrast to traditional milking systems, AMS, inprinciple, allow cows to present for milkingvoluntarily. So with AMS, it is claimed that dairymanagement relies on the autonomous interaction of thecow with her environment.One of the roles of bioethical analysis is to identifythe influence of rhetoric and symbolism in technologyassessment, e.g., with respect to the claimed`voluntariness' of cows' presentation. The AMS can beinstalled to allow cows three types of access, viz., i)free choice ii) rewarded access (RA) iii) obligatoryaccess (OA). Studies suggest the desire for milkremoval per se is not critical in the cow'sattendance at the AMS. Continued motivation to bemilked, required for the system to function,principally relies on RA and OA. Both RA and OA aresubject to numerous factors, such as: design of theAMS, location, etc. In turn, these can affect thecows' behavioural freedom and welfare.One of the aims of this approach is to illustrate theethical basis on which public policy is or can beformulated. 相似文献
92.
Kate A. Rawlinson 《Marine Biology》2008,153(5):769-778
Polyclads are mobile predators and possibly an important functional component of hard substrate marine environments globally.
To understand the natural patterns of spatial differences, polyclad assemblages were sampled in seven coastal regions across
the wider Caribbean spanning 15° latitude and 24° longitude between May and June 2005 and May and September 2006. In total,
67 species in 28 genera and 17 families were recorded from 62 sites. Only two species were found in all surveyed regions,
Melloplana ferruginea and Pseudoceros bicolor. Conversely, 41 species were restricted to one or two sites, and 34 species were represented by one or two individuals. The
distribution and abundance of species varied between the two suborders. Cotyleans were most species rich and had a higher
number of species of restricted range, while Acotylea showed a higher proportion of rare species; however, two species were
highly abundant comprising over half of the individuals counted. In most habitats, polyclads were rare, but in some intertidal
habitats two species, Styloplanocera fasciata and Boninia divae were densely aggregated and dominant members of the benthic epifauna. Alpha diversity was variable but showed no evidence
of a relationship with latitude, longitude or depth. Beta diversity increased with the number of habitats sampled and was
highest for cotyleans. Highest gamma diversity was recorded in Jamaica and the US Virgin Islands and was not significantly
correlated to alpha diversity. Overall assemblages from the seven regions were similar, revealing faunal homogeneity across
the wider region. Reef assemblages were distinct from other habitats dominated by species of the Cotylea. Reefs from Panama
and the US Virgin Islands were the most species rich.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
93.
To study forest dynamics without relying on the space-for-time substitution, one must be able to follow a population or stand of trees back or forward in time. The method of stand reconstruction looks back in time by aging all the live trees and aging and dating the time of death of dead standing and fallen trees. However, dead trees are lost by decomposition so the record becomes increasingly incomplete with passage of time. Here we present a model of the passage of trees from dead standing to dead decomposed but still datable to completely decomposed and thus undatable or lost. We then generalize a method for calculating the falling rate of dead trees originally proposed in 1985 by A. P. Gore, E. A. Johnson, and H. P. Lo. We do this by removing the assumption that no trees are lost by decomposition, i.e., by using the decomposition rate. Finally, in the most important result, the model allows estimation of how far back a good estimate of the numbers in the population can be made if the decomposition rates are known. 相似文献
94.
The effects of landscape structure on space competition and alternative stable states 总被引:1,自引:0,他引:1
Many species that compete for space live on heterogeneous landscapes and interact at local scales. The quality, amount, and structure of landscapes may have considerable impact on the ability of species to compete or coexist, yet basic models of space competition do not include that level of detail. We model space competition between two species with positive feedback through recruitment facilitation, which creates the potential for alternative stable states to occur. We compare the predictions of a spatially implicit model with a simulation model that includes explicit space and landscape structure. We create structured landscapes in which we specify the amount of habitat and degree of fragmentation and ask how landscape structure, dispersal strategy, and scale affect the presence of alternative stable states, or bistability. We find that structured landscapes can reduce the range of parameter values that lead to bistability in our model, but they do not eliminate bistability. The type of landscape and the dispersal distance for each species also influence the amount of environmental change needed for abrupt community shifts to occur. Coexistence of the two competitors is possible under certain conditions when connectivity is low. Consequently, landscape structure may lead to considerable disparity between the predictions of simple models and actual dynamics on complex landscapes during environmental change. 相似文献
95.
Jarvie HP Neal C Withers PJ Baker DB Richards RP Sharpley AN 《Journal of environmental quality》2011,40(2):492-504
Extended end-member mixing analysis (E-EMMA) is presented as a novel empirical method for exploring phosphorus (P) retention and release in rivers and watersheds, as an aid to water-quality management. E-EMMA offers a simple and versatile tool that relies solely on routinely measured P concentration and flow data. E-EMMA was applied to two river systems: the Thames (U.K.) and Sandusky River (U.S.), which drain similar watershed areas but have contrasting dominant P sources and hydrology. For both the Thames and Sandusky, P fluxes at the watershed outlets were strongly influenced by processes that retain and cycle P. However, patterns of P retention were markedly different for the two rivers, linked to differences in P sources and speciation, hydrology and land use. On an annual timescale, up to 48% of the P flux was retained for the Sandusky and up to 14% for the Thames. Under ecologically critical low-flow periods, up to 93% of the P flux was retained for the Sandusky and up to 42% for the Thames. In the main River Thames and the Sandusky River, in-stream processes under low flows were capable of regulating the delivery of P and modifying the timing of delivery in a way that may help to reduce ecological impacts to downstream river reaches, by reducing ambient P concentrations at times of greatest river eutrophication risk. The results also suggest that by moving toward cleaner rivers and improved ecosystem health, the efficiency of P retention may actually increase. 相似文献
96.
97.
Pair-wise preference experiments were used to reveal predator discrimination by four tit species wintering in the Czech Republic.
The reactions of the tits to a more dangerous predator (sparrowhawk) and a less dangerous (kestrel) one were compared. The
number of visits to a feeder with a predator present expressed the perceived dangerousness of the predator. The tits' behaviour
towards the feeders was in agreement with predictions, according to dynamic risk assessment theory. The presence of any predator
at the feeder lowered the number of visits to the feeder. Similarly, the tits were judged to have evaluated the sparrowhawk
as being more dangerous than the kestrel, as its presence lowered the number of arrivals more than did the kestrel. The duration
of stay and number of pecks of individual birds were also used as measures of predator dangerousness. The results not only
confirm that tits behave according to dynamic risk assessment theory, but also show the exceptional suitability of preference
experiments for the research of predator differentiation and evaluation. 相似文献
98.
Organizational efforts to improve team effectiveness in crisis situations primarily have focused on team training initiatives and, to a lesser degree, on staffing teams with respect to members' ability, experience, and functional backgrounds. Largely neglected in these efforts is the emotional component of crises and, correspondingly, the notion of staffing teams with consideration for their affective makeup. To address this void, we examined the impact of team member dispositional positive affect (PA) on team crisis effectiveness and the role of felt negative emotion in transmitting that influence. A study of 21 nuclear power plant crews engaged in crisis training simulations revealed that homogeneity in PA, but not mean‐level PA, was associated with greater team effectiveness. Mediation analysis suggested that homogeneity in PA leads to greater team effectiveness by reducing the amount of negative emotions that team members experience during crises. Furthermore, homogeneity in PA compensated for lower mean‐level PA in predicting effectiveness. Discussion focuses on the implications of these findings for understanding and further exploring the importance of affective factors and especially team affective composition in team crisis performance. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
99.
Exchanges of carbon and nitrogen between the atmosphere and terrestrial ecosystems involve a complex set of interactions affected by both natural and management processes. Understanding these processes is important for managing ecosystem productivity and sustainability. Management processes also affect the net outcome of exchanges of greenhouse gases between terrestrial ecosystems and the atmosphere. In developing a national carbon accounting system (NCAS) for Australia to account for emissions and removal of greenhouse gases to and from the atmosphere, a carbon:nitrogen mass balance ecosystem model (FullCAM) was developed. The FullCAM model is a hybrid of empirical and process modelling. The approach enables application to a wide range of natural resource management issues, because it is at land-management-relevant spatial and temporal resolution
and captures the main process and management drivers. The scenario-prediction capability can be used to determine the emissions consequences of different management activities. Because, in Australia, emissions of greenhouse gases are closely related to the retention of dead organic matter and the availability of nitrogen for plant growth, the carbon and nitrogen cycling as modelled are good indicators of ecosystem productivity and condition. The NCAS also emphasizes the advantages of a comprehensive and integrated approach to developing a continental scale ecosystem-modelling system that has relevance both to estimation of greenhouse gas emissions and sustainable management of natural resources. 相似文献
100.
R.P.O. Schulte A.R. Melland O. Fenton M. Herlihy K. Richards P. Jordan 《Environmental Science & Policy》2010,13(6):472-484
Depletion of plant-available soil phosphorus (P) from excessive to agronomically optimum levels is a measure being implemented in Ireland to reduce the risk of diffuse P transfer from land to water. Within the Nitrates and Water Framework Directive regulations the policy tool is designed to help achieve good status by 2015 in water bodies at risk from eutrophication. To guide expectation, this study used soil plot data from eight common soil associations to develop a model of Soil Test P (STP) (Morgan's extract) decline following periods of zero P amendment. This was used to predict the time required to move from excessive (Index 4) to the upper boundary of the optimum (Index 3) soil P concentration range. The relative P balance (P balance : Total soil P) best described an exponential decline (R2 = 63%) of STP according to a backwards step-wise regression of a range of soil parameters. Using annual field P balance scenarios (?30 kg P ha?1, ?15 kg P ha?1, ?7 kg P ha?1), average time to the optimum soil P boundary condition was estimated from a range of realistic Total P and STP starting points. For worst case scenarios of high Total P and STP starting points, average time to the boundary was estimated at 7–15 years depending on the field P balance. However, uncertainty analysis of the regression parameter showed that variation can be from 3 to >20 years. Combined with variation in how soil P source changes translate to resulting P delivery to water bodies, water policy regulators are advised to note this inherent uncertainty from P source to receptor with regard to expectations of Water Framework Directive water quality targets and deadlines. 相似文献