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891.
Abstract: Due to the structuring forces and large-scale physical processes that shape our biosphere, we often find that environmental and ecological data are either spatially or temporally—or both spatially and temporally—dependent. When these data are analyzed, statistical techniques and models are frequently applied that were developed for independent data. We describe some of the detrimental consequences, such as inefficient parameter estimators, biased hypothesis test results, and inaccurate predictions, of ignoring spatial and temporal data dependencies, and we cite an example of adverse statistical results occurring when spatial dependencies were disregarded. We also discuss and recommend available techniques used to detect and model spatial and temporal dependence, including variograms, covariograms, autocorrelation and partial autocorrelation plots, geostatistical techniques, Gaussian autoregressive models, K functions, and ARIMA models, in environmental and ecological research to avoid the aforementioned difficulties. 相似文献
892.
Kenneth J. Goldstein Andrew R. Vitolins Daria Navon Beth L. Parker Steven Chapman Grant A. Anderson 《补救:环境净化治理成本、技术与工艺杂志》2004,14(4):19-37
The distribution of volatile organic compounds (VOCs) in fractured shale overlain by thin (< 10 feet) overburden at the Watervliet Arsenal near Albany, New York, was initially determined by sampling water from the fracture network using packer systems in boreholes and also using conventional monitoring wells. Furthermore, short‐term pumping and injection tests were conducted and the boreholes were logged using a variety of geophysical and hydrophysical tools. Tetrachloroethene is the dominant VOC in the groundwater, with lesser concentrations of trichloroethene and degradation products (cis‐1,2‐dichloroethene, trans‐1,2‐dichloroethene, and vinyl chloride). The vertical VOC distributions in the rock matrix were obtained from continuous‐cored holes from which small rock samples, collected at many depths between 18 and 150 feet below ground surface, were analyzed. The rock core VOC concentrations were determined by methanol extraction of crushed rock followed by direct methanol injection onto a gas chromatograph and subsequent estimation of rock porewater VOC concentrations. The rock core data support the concept that diffusion‐driven mass transfer has caused nearly all the VOC mass initially present in the fractures to now reside in the rock matrix, which has a porosity three or four orders of magnitude larger than the bulk fracture porosity. The results of the site characterization indicate that an effective site investigation strategy in fractured shale must include characterization of both the fracture and matrix contaminant distribution. These results also indicate that the most favorable remediation technologies for this fractured shale are those that will destroy VOCs in the rock matrix, particularly contaminants in the sorbed phase, and also destroy the VOC mass in the fractures including both dissolved and immiscible phases. The site characterization resulted in the selection of potassium permanganate for an in situ chemical oxidation pilot study. © 2004 Wiley Periodicals, Inc. 相似文献
893.
Social information processing and social learning theories were utilized to hypothesize that an employee's organizational citizenship behavior (OCB) is influenced by the collective OCB in one's workgroup. An aggregate measure of OCB was constructed based upon Podsakoff, MacKenzie, and Fetter's (1993) measures of Organ's (1988) typology of OCB, and the study was replicated using both supervisor and employee‐provided ratings of OCB. The sample for this study included 566 employees (488 for the supervisor‐rated analysis) from 56 workgroups in a manufacturing organization. The mean level of OCB for other members of one's workgroup explained significant variance in individual levels of OCB. We also found that this effect is moderated by the consistency of the display of the OCB within the workgroup. The consistency of OCB across coworkers was associated with more OCB by individuals and this effect was replicated across both supervisor and employee ratings. Explanations and uses for our findings are discussed. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
894.
Many publicly owned treatment works in North America are exceeding permitted limits for total cyanide in their wastewater treatment effluents. A recently introduced rapid, segmented, flow-injection analysis procedure using UV digestion and amperometric detection of the membrane-separated cyanide was used to investigate the various scenarios by which elevated cyanide levels might be present in wastewater treatment plant effluent. A number of significant interferences can produce false positive bias during sample analysis with the traditional acid distillation technique, but are minimized or absent with the new analytical method. However, increased levels of cyanide were found in some chlorinated wastewaters compared to the levels before chlorination, suggesting a fast reaction mechanism associated with the disinfectant and some precursor in the wastewater. In particular, the contact of chlorine with nitrite in the presence of a carbon precursor appears to contribute to cyanide formation during wastewater treatment and sample handling. This paper explores the scenarios under which cyanide can form during wastewater treatment as well as those in which a false bias for total cyanide can be obtained during sample processing and provides guidance for appropriate sample handling, screening, and processing to ensure valid analytical results. 相似文献
895.
896.
This paper addresses the issue of occupational safety and how the process of globalisation can potentially influence the attitudes, beliefs and behaviour of disparate ‘national’ workforces working across the globe for the same multi-national company. The paper reviews published literature on cross-cultural differences in attitudes, perceptions and beliefs regarding safety and presents details of a study examining the relationship between Hofstede’s [Hofstede, G., 1984. Culture’s Consequences; International Differences in Work-Related Values, Abridged edition. Sage Publications, London, Hofstede, G., 1991. Culture and Organisations; Software of the Mind. McGraw Hill, Maidenhead] cultural values dimensions (i.e., Power Distance, Individualism/Collectivism, Masculinity/Femininity); safety climate (perceived management commitment to safety) and risk-taking behaviour in workforce members of a multi-national engineering organisation operating in six countries. The results suggest that more proximal influences such as perceived management commitment to safety and the efficacy of safety measures exert more impact on workforce behaviour and subsequent accident rates than fundamental national values. 相似文献
897.
Steven H. Cadle Mark Carlock Richard E. Gibbs Kenneth T. Knapp Alan C. Lloyd William R. Pierson 《Journal of the Air & Waste Management Association (1995)》2013,63(6):817-820
A conference was held on October 30-31,1990 to examine discrepancies between the output of vehicle emission factor models (MOBILE and EMFAC), field and laboratory measurements of vehicle emissions, and observed ratios of pollutants in urban atmospheres dominated by vehicle emissions. There was a general consensus that significant discrepancies exist and that these discrepancies must be resolved. A number of research recommendations were made as to how models and model inputs could be improved, and what additional laboratory and field work should be conducted. 相似文献
898.
Dennis Finn Kirk L. Clawson Roger G. Carter Jason D. Rich Richard M. Eckman Steven G. Perry Vlad Isakov David K. Heist 《Atmospheric environment (Oxford, England : 1994)》2010,44(2):204-214
A roadway toxics dispersion study was conducted at the Idaho National Laboratory (INL) to document the effects on concentrations of roadway emissions behind a roadside sound barrier in various conditions of atmospheric stability. The homogeneous fetch of the INL, controlled emission source, lack of other manmade or natural flow obstructions, and absence of vehicle-generated turbulence reduced the ambiguities in interpretation of the data. Roadway emissions were simulated by the release of an atmospheric tracer (SF6) from two 54 m long line sources, one for an experiment with a 90 m long noise barrier and one for a control experiment without a barrier. Simultaneous near-surface tracer concentration measurements were made with bag samplers on identical sampling grids downwind from the line sources. An array of six 3-d sonic anemometers was employed to measure the barrier-induced turbulence. Key findings of the study are: (1) the areal extent of higher concentrations and the absolute magnitudes of the concentrations both increased as atmospheric stability increased; (2) a concentration deficit developed in the wake zone of the barrier with respect to concentrations at the same relative locations on the control experiment at all atmospheric stabilities; (3) lateral dispersion was significantly greater on the barrier grid than the non-barrier grid; and (4) the barrier tended to trap high concentrations near the “roadway” (i.e. upwind of the barrier) in low wind speed conditions, especially in stable conditions. 相似文献
899.
900.
Toronto is among the fastest-growing urban regions in North America. Regional efforts to preserve rural landscapes and remnant
habitat have had variable success. In the 1990s, significant conflict emerged over proposals to build large housing developments
on portions of the Oak Ridges Moraine, a 160-km stretch of environmentally sensitive land along the city’s northern edge.
After years of planning conflict, Ontario’s provincial government created the Oak Ridges Moraine Conservation Plan, an Act
of the Ontario Legislature. The Plan represents a dramatic change in Ontario’s approach to conservation planning. We examine
the development and implementation of the Conservation Plan as an example of environmental planning policy in a complex urban
setting. Data from interviews with policy actors, planning agency documents, and geospatial sources are used to construct
an analysis and discussion of the Plan and its implementation. From a policy research perspective, the evolution and implementation
of the Plan require analysis and monitoring to better understand how such approaches can best be implemented. The Conservation
Plan marks a change in policy in Ontario, and the implementation process highlights challenges in putting conservation plans
into practice. 相似文献