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51.
52.
Procedures are developed and summarized that allow the calculation of the energy required to manufacture and install capital equipment, such as the material needed for a coalfired power plant. Three methods are available, each with certain strengths and weaknessess The first uses both literature value and national manufacturing statistics, the second uses a previously developed technique that disaggregates energy use according to how much each industry buys from all other industries, and the third technique is based on the average national relation between energy use and dollar flow. The most important differences between estimates of energy use by the different techniques relates to the inclusion or exclusion of labor and indirect expenditures rather than to differences in the data bases of the three techniques.  相似文献   
53.
PROBLEM: Injuries resulting from lifting are costly, and create significant pain and discomfort. While engineering controls are the most effective means of reducing risks, most organizations continue to rely on manual lifting techniques. The problem, however, is that the use of safe-lifting techniques is inconsistent and managers have a difficult time motivating use of these techniques. Consequently, it is important to understand the factors driving safe-lifting behaviors. METHODS: This study used a survey to apply the theory of planned behavior (Ajzen., I., 1991. The theory of planned behavior. Organization Behavior and Human Processes, 50, 179-211) to safe-lifting among 136 materials management employees at a heavy manufacturing organization. Structural equation modeling and factor analysis were employed to analyze relationships among constructs. RESULTS: Results revealed that perceived behavioral control and intention were the strongest predictors of safe-lifting behavior. Subjective norms, to a lesser degree, were also important influences on intention. Attitudes did not surface as effective direct predictors of safe-lifting behavior, but did affect behavior and intent via mediating factors (subjective norms and perceived behavioral control). Finally, the theory of planned behavior was supported as an effective model explaining safe-lifting behavior, and had potential application for many other safety-related behaviors. IMPACT ON INDUSTRY: Results from this study emphasize the importance of perceived behavioral control as a factor associated with safety-related behavior.  相似文献   
54.
Parasites are integral parts of most ecosystems, yet attention has only recently focused on how community structure and abiotic factors impact host-parasite interactions. In lakes, both factors are influenced by habitat morphology. To investigate the role of habitat structure in mediating parasitism in the plankton, we quantified timing and prevalence of a common microparasite (Metschnikowia bicuspidata) in its host, Daphnia dentifera, in 18 lakes that vary in basin size and shape. Over three years, we found substantial spatial and temporal variation in the severity of epidemics. Although infection rates reached as high as 50% in some lakes, they did not occur in most lakes in most years. Host density, often considered to be a key determinant of disease spread, did not explain a significant amount of variation in the occurrence of epidemics. Furthermore, host resistance does not fully explain this parasite's distribution, since we easily infected hosts in the laboratory. Rather, basin shape predicted epidemics well; epidemics occurred only in lakes with steep-sided basins. In these lakes, the magnitude of epidemics varied with year. We suggest that biological (predation) and physical (turbulence) effects of basin shape interact with annual weather patterns to determine the regional distribution of this parasite.  相似文献   
55.
The European waste sector is undergoing a period of unprecedented change driven by business consolidation, new legislation and heightened public and government scrutiny. One feature is the transition of the sector towards a process industry with increased pre-treatment of wastes prior to the disposal of residues and the co-location of technologies at single sites, often also for resource recovery and residuals management. Waste technologies such as in-vessel composting, the thermal treatment of clinical waste, the stabilisation of hazardous wastes, biomass gasification, sludge combustion and the use of wastes as fuel, present operators and regulators with new challenges as to their safe and environmentally responsible operation. A second feature of recent change is an increased regulatory emphasis on public and ecosystem health and the need for assessments of risk to and from waste installations. Public confidence in waste management, secured in part through enforcement of the planning and permitting regimes and sound operational performance, is central to establishing the infrastructure of new waste technologies. Well-informed risk management plays a critical role. We discuss recent developments in risk analysis within the sector and the future needs of risk analysis that are required to respond to the new waste and resource management agenda.  相似文献   
56.
We sampled understory hummingbirds in Amazonian forest fragments from before isolation through nine years after isolation. We recorded 377 captures of eight species in five 1-ha fragments and four 10-ha fragments. The three species netted before isolation, Phaethornis superciliosus, Phaethornis bourcieri , and Thalurania furcata , were nearly equally abundant at that time. After isolation abundance of P. bourcieri and T. furcata did not change, but P. superciliosus became nearly twice as common. Five additional species that were netted only after isolation represented about 10% of the post-isolation sample. The species recorded only after isolation were forest species usually found above the levels of nets; fragments were not colonized by nonforest species. Use of fragments did not differ between 1- and 10-ha fragments. The landscape surrounding the fragments included active cattle pasture, abandoned pasture, and Cecropia -dominated second growth, but this variation had little effect on use of fragments by hummingbirds. The results suggest that these understory hummingbirds can persist in a matrix of fragments, secondary growth, and large forest patches. This response is much different than that of the insectivorous birds that dominate the understory bird community at the site, which are much more vulnerable to fragmentation.  相似文献   
57.
Hall  J. R. 《Marine Biology》1972,12(1):42-52
Mystacocarid crustaceans are characteristic members of the mesopsammon of many marine beaches. A detailed investigation of the distribution of Derocheilocaris typica Pennak and Zinn, 1943, shows that this species is most abundant on open ocean, high-energy beaches, with only scattered occurrence in estuarine beaches. A characteristic distribution pattern in beaches is shown, with maximum density occurring between mid and high-water levels. This pattern changes seasonally, with the position of maximum density moving deeper into the beach and more landward during winter months. Short-term changes in distribution also occur, resulting from tidal migrations and abnormal hydrodynamic patterns (i.e., storms). Longshore variability in abundance suggests the occurrence of clumps of crustaceans arranged much like beads on a string. Changes in abundance or segregation of sexes and stages seasonally are not found.  相似文献   
58.
Disturbances such as fire play a key role in controlling ecosystem structure. In fire-prone forests, organic detritus comprises a large pool of carbon and can control the frequency and intensity of fire. The ponderosa pine forests of the Colorado Front Range, USA, where fire has been suppressed for a century, provide an ideal system for studying the long-term dynamics of detrital pools. Our objectives were (1) to quantify the long-term temporal dynamics of detrital pools; and (2) to determine to what extent present stand structure, topography, and soils constrain these dynamics. We collected data on downed dead wood, litter, duff (partially decomposed litter on the forest floor), stand structure, topographic position, and soils for 31 sites along a 160-year chronosequence. We developed a compartment model and parameterized it to describe the temporal trends in the detrital pools. We then developed four sets of statistical models, quantifying the hypothesized relationship between pool size and (1) stand structure, (2) topography, (3) soils variables, and (4) time since fire. We contrasted how much support each hypothesis had in the data using Akaike's Information Criterion (AIC). Time since fire explained 39-80% of the variability in dead wood of different size classes. Pool size increased to a peak as material killed by the fire fell, then decomposed rapidly to a minimum (61-85 years after fire for the different pools). It then increased, presumably as new detritus was produced by the regenerating stand. Litter was most strongly related to canopy cover (r2 = 77%), suggesting that litter fall, rather than decomposition, controls its dynamics. The temporal dynamics of duff were the hardest to predict. Detrital pool sizes were more strongly related to time since fire than to environmental variables. Woody debris peak-to-minimum time was 46-67 years, overlapping the range of historical fire return intervals (1 to > 100 years). Fires may therefore have burned under a wide range of fuel conditions, supporting the hypothesis that this region's fire regime was mixed severity.  相似文献   
59.
Infrastructure and Conservation Policy in Brazil   总被引:1,自引:0,他引:1  
Abstract:  The development of transportation and energy infrastructure has been a major driver in the conversion of natural ecosystems in Brazil since the nineteenth century. Although this pattern is present in most countries, Brazil differs in the scale of opportunities that are still available to build its physical infrastructure while pursuing an ambitious conservation agenda. This advantage stems from the magnitude of intact ecosystems, a dynamic policy environment, and the increasing availability of biological and economic data needed to harmonize conservation with public works. Success depends on integrating conservation and infrastructure planning, rather than relying on the project based, largely ineffective environmental assessment process. Front-loading environmental mitigation and compensation will also help, as will improving public access to, and understanding of, information on the environmental and economic values at stake in major infrastructure decisions.  相似文献   
60.
Abstract:  Land-reform and environmental movements, revitalized by the democratization of civil society in Brazil in the 1990s, found their objectives in conflict over forested parcels that settlers want for conversion to agriculture but that are important for wildlife conservation. In the Atlantic Forest, where 95% of the forest is gone, we reviewed three cases of Brazilian nongovernmental organization (NGOs) engagement with the land-reform movement with respect to forest remnants neighboring protected areas that have insufficient habitat for the long-term survival of unique endangered species. In the Pontal do Paranapanema (São Paulo), Poço das Antas (Rio de Janeiro), and southern Bahia, environmental NGOs have supported agricultural alternatives that improve livelihood options and provide incentives for habitat conservation planning. Where land-reform groups were better organized, technical cooperation on settlement agriculture permitted the exploration of mutual interests in conciliating the productive landscape with conservation objectives. Processes of regular consultation among NGOs, environmental agencies, and the private sector revealed that there was less zero-sum conflict over the same lands than commonly perceived. In both groups, technicians found forested lands less suitable for small-scale agriculture, and leaders took risks to justify and support claims to alternative existing agricultural lands. Based on the cases we examined, the construction of landscapes with both forest stewardship and poverty-reducing agrarian reform faces continued obstacles from contradictory agrarian and environmental sector policies and inadequate economic incentives for forest stewardship on private lands.  相似文献   
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