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921.
Margaret A. Palmer Dennis P. Lettenmaier N. LeRoy Poff Sandra L. Postel Brian Richter Richard Warner 《Environmental management》2009,44(6):1053-1068
Rivers provide a special suite of goods and services valued highly by the public that are inextricably linked to their flow
dynamics and the interaction of flow with the landscape. Yet most rivers are within watersheds that are stressed to some extent
by human activities including development, dams, or extractive uses. Climate change will add to and magnify risks that are
already present through its potential to alter rainfall, temperature, runoff patterns, and to disrupt biological communities
and sever ecological linkages. We provide an overview of the predicted impacts based on published studies to date, discuss
both reactive and proactive management responses, and outline six categories of management actions that will contribute substantially
to the protection of valuable river assets. To be effective, management must be place-based focusing on local watershed scales
that are most relevant to management scales. The first priority should be enhancing environmental monitoring of changes and
river responses coupled with the development of local scenario-building exercises that take land use and water use into account.
Protection of a greater number of rivers and riparian corridors is essential, as is conjunctive groundwater/surface water
management. This will require collaborations among multiple partners in the respective river basins and wise land use planning
to minimize additional development in watersheds with valued rivers. Ensuring environmental flows by purchasing or leasing
water rights and/or altering reservoir release patterns will be needed for many rivers. Implementing restoration projects
proactively can be used to protect existing resources so that expensive reactive restoration to repair damage associated with
a changing climate is minimized. Special attention should be given to diversifying and replicating habitats of special importance
and to monitoring populations at high risk or of special value so that management interventions can occur if the risks to
habitats or species increase significantly over time. 相似文献
922.
Improving the Evaluation of Conservation Programs 总被引:5,自引:0,他引:5
Devra G. Kleiman Richard P. Reading † Brian J. Miller † Tim W. Clark ‡ J. Michael Scott § John Robinson Richard L. Wallace ‡§ Robert J. Cabin †† and Fred Felleman‡‡ 《Conservation biology》2000,14(2):356-365
Abstract: The evaluation of conservation programs is rare but increasingly important in improving their effectiveness. Regular evaluations of conservation programs and the implementation of recommendations resulting from such assessments are infrequent because of resistance by participants and lack of funding. Evaluations may be internal or external, depending on the purpose of the review and how broadly it is focused. We strongly recommend external peer review of long-term complex conservation programs every 5 years, supported by more frequent (annual) internal reviews. Criteria for success must encompass both biological and social measures and include learning and the application of new knowledge to management. Evaluations must also go beyond monitoring to assess the value of the program. We emphasize the need to include the organization and function of a conservation program (the process) in any evaluation in addition to substantive criteria for success, which usually involve biological measures (numbers). A dysfunctional program organization and process can as effectively cripple a conservation effort as can a major biological catastrophe. We provide examples of different types of conservation program evaluations, including moderated workshops and case-study analysis, and provide advice on the logistics and organization of the review, emphasizing the importance of the evaluation process itself to a successful outcome. One important aspect of an evaluation is having an individual with leadership ability and considerable expertise to organize the format and oversee the review process itself. Second, it is essential at the outset to ensure agreement among the program participants and the review committee on the goals and objectives of the conservation program, what is to be evaluated, and the criteria for defining success. Finally, the best evaluations are inclusive and involve all participants and stakeholders. 相似文献
923.
Estimate of the Area Affected Ecologically by the Road System in the United States 总被引:45,自引:0,他引:45
Richard T. T. Forman 《Conservation biology》2000,14(1):31-35
Abstract: In view of an extensive road system, abundant and rapidly growing vehicular traffic, and a scattered literature indicating that some ecological effects of roads extend outward for > 100 m, it seems likely that the cumulative ecological effect of the road system in the United States is considerable. Two recent studies in The Netherlands and Massachusetts ( U.S.A.) evaluated several ecological effects of roads, including traffic noise effects, and provide quantitative evidence for a definable "road-effect zone." Based on the approximate width of this asymmetric convoluted zone, I estimate that about one-fifth of the U.S. land area is directly affected ecologically by the system of public roads. I identify a series of assumptions and variables suggesting that over time this preliminary estimate is more likely to rise than drop. Several transportation planning and policy recommendations, ranging from perforating the road barrier for wildlife crossings to closing certain roads, offer promise for reducing this enormous ecological effect. 相似文献
924.
Vector-borne diseases are feared to extend their range in a future where global warming has occurred. There is considerable
concern about scourges such as malaria re-invading currently temperate regions and reaching into higher altitudes in Africa.
In this paper we examine the various factors thought to determine potential infectivity of malaria, and its actual outbreak
in the context of a dynamic integrated assessment model. We quantify: (i) the role of demographics in placing a larger population
in harms way; (ii) the role of climate change in increasing the potential geographic range and severity of the risk of infection;
and (iii) the role of economic and social development in limiting the occurrence of malaria. We then explore the climate and
economic implications of various climate policies in their effectiveness to limit potential infectivity of malaria. In illustration
of these issues we present the climate-related and economics-related impacts of unilateral CO2 control by OECD on incidence of malaria in non-OECD nations. The model presented here, although highly stylized in its representation
of socio-economic factors, provides strong evidence of the role of socio-economic factors in determination of malaria incidence.
The case study offers insights into unintended adverse consequences of well-meaning climate policies.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
925.
Wang L Brenden T Seelbach P Cooper A Allan D Clark R Wiley M 《Environmental monitoring and assessment》2008,141(1-3):1-17
Identification of reference streams and human disturbance gradients are crucial steps in assessing the effects of human disturbances
on stream health. We describe a process for identifying reference stream reaches and assessing disturbance gradients using
readily available, geo-referenced stream and human disturbance databases. We demonstrate the utility of this process by applying
it to wadeable streams in Michigan, USA, and use it to identify which human disturbances have the greatest impact on streams.
Approximately 38% of cold-water and 16% of warm-water streams in Michigan were identified as being in least-disturbed condition.
Conversely, approximately 3% of cold-water and 4% of warm-water streams were moderately to severely disturbed by landscape
human disturbances. Anthropogenic disturbances that had the greatest impact on moderately to severely disturbed streams were
nutrient loading and percent urban land use within network watersheds. Our process for assessing stream health represents
a significant advantage over other routinely used methods. It uses inter-confluence stream reaches as an assessment unit,
permits the evaluation of stream health across large regions, and yields an overall disturbance index that is a weighted sum
of multiple disturbance factors. The robustness of our approach is linked to the scale of disturbances that affect a stream;
it will be less robust for identifying less degraded or reference streams with localized human disturbances. With improved
availability of high-resolution disturbance datasets, this approach will provide a more complete picture of reference stream
reaches and factors contributing to degradation of stream health. 相似文献
926.
Chow JC Watson JG Lowenthal DH Park K Doraiswamy P Bowers K Bode R 《Environmental monitoring and assessment》2008,144(1-3):179-189
PM(2.5) nitrate [Formula: see text] and sulfate ([Formula: see text]) were measured continuously with R&P8400N and R&P8400S instruments, respectively, and compared with filter-based measurements at the Fresno Supersite from October, 2000 through December, 2005. [Formula: see text] concentrations were higher in winter than summer with a long-term decreasing trend. Correlations between 24-h average continuous and filter-based [Formula: see text] were greater than 0.96 in 4 out of 5 years. Continuous [Formula: see text] was generally lower than filter-based [Formula: see text] although the difference decreased over time, from -52% in 2001 to +13% in 2005. These differences were similar in winter (-23%) and summer (-19%) while the corresponding differences between ambient and instrument temperature were -12 and 0.7 degrees C, respectively. Neither seasonal nor long-term trends in [Formula: see text] can be explained by variations in ambient temperature, the difference between ambient and instrument temperature, or changes in aerosol chemical composition. There were no seasonal or long-term trends in [Formula: see text] concentrations, partially due to low concentrations observed in Fresno. Long-term variability in the performance of R&P8400 [Formula: see text] and [Formula: see text] instruments suggest that collocation with filter measurements is needed for long-term measurements. 相似文献
927.
We developed an assessment model to quantify the wildlife habitat value of New England salt marshes based on marsh characteristics and the presence of habitat types that influence habitat use by terrestrial wildlife. Applying the model to 12 salt marshes located in Narragansett Bay, RI resulted in assessment scores that ranged over a factor of 1.5 from lowest to highest. Pre-classifying the results based on marsh size and morphology helped to compare assessment scores between marshes, and demonstrated that even the lower ranking marshes had substantial habitat value. Stepwise multiple regression analysis of assessment scores and model components demonstrated that salt marsh morphology, the degree of anthropogenic modification, and salt marsh vegetative heterogeneity were significant variables and accounted for 91.3% of the variability in component scores. Our results suggest that targeting these components for restoration may lead to improved assessment scores for our study marshes. We also examined the use of lower resolution remote sensing data in the assessment in order to minimize the time and effort required to complete the model. Scores obtained using smaller-scale, lower resolution data were significantly lower than those obtained using larger-scale, higher resolution data (df = 11; t = 2.2; p < 0.001). The difference was significantly positively correlated with the portion of the assessment score that could be attributed to trees, pools, and pannes and marsh size (r (2) =0.50, F = 4.6, p = 0.04), and could indicate a bias against smaller, more heterogeneous marshes. We conclude that potential differences need to be weighed against the time benefit of using this type of data, bearing in mind the marsh size and the goals of the assessment. Overall, our assessment can provide information to aid in prioritizing marshes for protection and restoration, identify marshes that may harbor significant biodiversity, or help monitor changes in habitat value over time. 相似文献
928.
929.
Compost impacts on dissolved organic carbon and available nitrogen and phosphorus in turfgrass soil 总被引:1,自引:0,他引:1
Wright AL Provin TL Hons FM Zuberer DA White RH 《Waste management (New York, N.Y.)》2008,28(6):1057-1063
Compost application to turfgrass soils may increase dissolved organic C (DOC) levels which affects nutrient dynamics in soil. The objectives of this study were to investigate the influence of compost source and application rate on soil organic C (SOC), DOC, NO(3), and available P during 29 months after a one-time application to St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] turf. Compost sources had variable composition, yet resulted in few differences in SOC, DOC, and NO(3) after applied to soil. Available NO(3) rapidly decreased after compost application and was unaffected by compost source and application rate. Available P increased after compost application and exhibited cyclical seasonal patterns related to DOC. Compost application decreased soil pH relative to unamended soil, but pH increased during the course of the study due to irrigation with sodic water. Increasing the compost application rate increased SOC by 3 months, and levels remained fairly stable to 29 months. In contrast, DOC continued to increase from 3 to 29 months after application, suggesting that compost mineralization and growth of St. Augustinegrass contributed to seasonal dynamics. Dissolved organic C was 75%, 78%, and 101% greater 29 months after application of 0, 80, and 160 Mg compostha(-1), respectively, than before application. Impacts of composts on soil properties indicated that most significant effects occurred within a few months of application. Seasonal variability of SOC, DOC, and available P was likely related to St. Augustinegrass growth stages as well as precipitation, as declines occurred after precipitation events. 相似文献
930.
Webb RM Wieczorek ME Nolan BT Hancock TC Sandstrom MW Barbash JE Bayless ER Healy RW Linard J 《Journal of environmental quality》2008,37(3):1145-1157
Pesticide leaching through variably thick soils beneath agricultural fields in Morgan Creek, Maryland was simulated for water years 1995 to 2004 using LEACHM (Leaching Estimation and Chemistry Model). Fifteen individual models were constructed to simulate five depths and three crop rotations with associated pesticide applications. Unsaturated zone thickness averaged 4.7 m but reached a maximum of 18.7 m. Average annual recharge to ground water decreased from 15.9 to 11.1 cm as the unsaturated zone increased in thickness from 1 to 10 m. These point estimates of recharge are at the lower end of previously published values, which used methods that integrate over larger areas capturing focused recharge in the numerous detention ponds in the watershed. The total amount of applied and leached masses for five parent pesticide compounds and seven metabolites were estimated for the 32-km2 Morgan Creek watershed by associating each hectare to the closest one-dimensional model analog of model depth and crop rotation scenario as determined from land-use surveys. LEACHM parameters were set such that branched, serial, first-order decay of pesticides and metabolites was realistically simulated. Leaching is predicted to be greatest for shallow soils and for persistent compounds with low sorptivity. Based on simulation results, percent parent compounds leached within the watershed can be described by a regression model of the form e(-depth) (a ln t1/2-b ln K OC) where t1/2 is the degradation half-life in aerobic soils, K OC is the organic carbon normalized sorption coefficient, and a and b are fitted coefficients (R2 = 0.86, p value = 7 x 10(-9)). 相似文献