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411.
John Zamurs Ronald J. Piracci 《Journal of the Air & Waste Management Association (1995)》2013,63(9):947-953
This paper describes the results of a measurement and modeling study of carbon monoxide (CO) concentrations In the proximity of intersections. Analysis for model performance of paired observed and predicted CO concentrations are presented. Two methodologies of pollutant prediction were used: the Intersection Midblock Model (IMM) and a statistical multiple linear regression. The results showed that both methods underpredicted frequently and dispensed results that were site specific. In addition, correlations of IMM predicted concentrations to observed concentrations were poor (typically r2 values <0.25). Various explanations for this observation are proposed. The statistical approach exhibited an improved accuracy over that of IMM. However, some of the independent variables used might be difficult to obtain as a routine measurement, and use of a one or two independent parameter model yielded adjusted R2 values comparable to the r2 values observed with IMM. Based on these results, an Intersection model applicable under a wide range of conditions of traffic, meteorology, and geometry is not available. Research Is needed to develop one, since its use would often be called on in the development of air quality sections of Environmental Assessments or Environmental Impact Statements. 相似文献
412.
Souzana Achilleos John S. Evans Panayiotis K. Yiallouros Savvas Kleanthous Joel Schwartz Petros Koutrakis 《Journal of the Air & Waste Management Association (1995)》2014,64(12):1352-1360
Air quality in Cyprus is influenced by both local and transported pollution, including desert dust storms. We examined PM10 concentration data collected in Nicosia (urban representative) from April 1, 1993, through December 11, 2008, and in Ayia Marina (rural background representative) from January 1, 1999, through December 31, 2008. Measurements were conducted using a Tapered Element Oscillating Micro-balance (TEOM). PM10 concentrations, meteorological records, and satellite data were used to identify dust storm days. We investigated long-term trends using a Generalized Additive Model (GAM) after controlling for day of week, month, temperature, wind speed, and relative humidity. In Nicosia, annual PM10 concentrations ranged from 50.4 to 63.8 μg/m3 and exceeded the EU annual standard limit enacted in 2005 of 40 μg/m3 every year. A large, statistically significant impact of urban sources (defined as the difference between urban and background levels) was seen in Nicosia over the period 2000–2008, and was highest during traffic hours, weekdays, cold months, and low wind conditions. Our estimate of the mean (standard error) contribution of urban sources to the daily ambient PM10 was 24.0 (0.4) μg/m3. The study of yearly trends showed that PM10 levels in Nicosia decreased from 59.4 μg/m3 in 1993 to 49.0 μg/m3 in 2008, probably in part as a result of traffic emission control policies in Cyprus. In Ayia Marina, annual concentrations ranged from 27.3 to 35.6 μg/m3, and no obvious time trends were observed. The levels measured at the Cyprus background site are comparable to background concentrations reported in other Eastern Mediterranean countries. Average daily PM10 concentrations during desert dust storms were around 100 μg/m3 since 2000 and much higher in earlier years. Despite the large impact of dust storms and their increasing frequency over time, dust storms were responsible for a small fraction of the exceedances of the daily PM10 limit.
ImplicationsThis paper examines PM10 concentrations in Nicosia, Cyprus, from 1993 to 2008. The decrease in PM10 levels in Nicosia suggests that the implementation of traffic emission control policies in Cyprus has been effective. However, particle levels still exceeded the European Union annual standard, and dust storms were responsible for a small fraction of the daily PM10 limit exceedances. Other natural particles that are not assessed in this study, such as resuspended soil and sea salt, may be responsible in part for the high particle levels. 相似文献
413.
Polychlorinated biphenyl contamination trends in Lake Hartwell, South Carolina (USA): sediment recovery profiles spanning two decades 总被引:1,自引:0,他引:1
To assess the ca. 20-year polychlorinated biphenyl (PCB) contamination trends in Lake Hartwell, SC, sediment cores from the Twelve Mile Creek arm were collected in July 2004 at two sites (G30 and G33) first sampled in the mid-1980s. Congener-specific PCB data as a function of depth from the sediment-water interface for the 2004 sediment samples were compared to data obtained from 1987 and 1998 samples taken from the same locations. Despite modest decreases in total PCB levels near the G30 sediment-water interface, historical increases in average degrees of chlorination may elevate the overall toxic risk at this site. Unlike G30, the more rapid recovery in the near-surface sediment of G33 suggests that the effectiveness of the U.S. EPA natural attenuation record of decision is site-specific and is unlikely to result in uniform surface sediment recovery throughout the most contaminated regions of Lake Hartwell. 相似文献
414.
Davis JW Odom JM Deweerd KA Stahl DA Fishbain SS West RJ Klecka GM DeCarolis JG 《Journal of contaminant hydrology》2002,57(1-2):41-59
A polyphasic approach based on cultivation and direct recovery of 16S rRNA gene sequences was utilized for microbial characterization of an aquifer contaminated with chlorinated ethenes. This work was conducted in order to support the evaluation of natural attenuation of chlorinated ethenes in groundwater at Area 6 at Dover Air Force Base (Dover, DE). Results from these studies demonstrated the aquifer contained relatively low biomass (e.g. direct microscopic counts of < 10(7) bacteria/g of sediment) comprised of a physiologically diverse group of microorganisms including iron reducers, acetogens, sulfate reducers, denitrifiers, aerobic and anaerobic heterotrophs. Laboratory microcosms prepared with authentic sediment and groundwater provided direct microbiological evidence that the mineralization of vinyl chloride and cis-dichloroethene as well as each step in the complete reductive dechlorination of tetracloroethene to ethene can occur in the Area 6 aquifer. Enrichment cultures capable of the oxidative degradation of cis-1,2-dichloroethene (cis-DCE) and vinyl chloride (VC) were obtained from groundwater across the aquifer demonstrating the possible importance of direct, non-cometabolic oxidation of cis-DCE and VC in natural attenuation. Culture-independent analyses based upon recovery of 16S rRNA gene sequences revealed the presence of anaerobic organisms distributed primarily between two major bacterial divisions: the delta subdivision of the Proteobacteria and low-G + C gram positive. Recovery of sequences affiliated with phylogenetic groups containing known anaerobic-halorespiring organisms such as Desulfitobacterium, Dehalobacter, and certain groups of iron reducers provided qualitative support for a role of reductive dechlorination processes in the aquifer. This molecular data is suggestive of a functional linkage between the microbiology of the site and the apparent natural attenuation process. The presence and distribution of microorganisms were found to be consistent with a microbially driven attenuation of chlorinated ethenes within the aquifer and in accord with a conceptual model of aquifer geochemistry which suggest that both reductive and oxidative mechanisms are involved in heterogeneous, spatially distributed processes across the aquifer. 相似文献
415.
Cliff I. Davidson Chris T. Hendrickson H. Scott Matthews Michael W. Bridges David T. Allen Cynthia F. Murphy Braden R. Allenby John C. Crittenden Sharon Austin 《Journal of Cleaner Production》2010,18(7):698-701
The field of engineering is changing rapidly as the growing global population puts added demands on the earth's resources: engineering decisions must now account for limitations in materials and energy as well as the need to reduce discharges of wastes. This means educators must revise courses and curricula so engineering graduates are prepared for the new challenges as practicing engineers. The Center for Sustainable Engineering has been established to help faculty members accommodate such changes through workshops and new educational materials, including a free access website with peer-reviewed materials. 相似文献
416.
Wahidul K. Biswas John Graham Kevin Kelly Michele B. John 《Journal of Cleaner Production》2010,18(14):1386-1392
This paper compares the life cycle global warming potential of three of Australia’s important agricultural production activities – the production of wheat, meat and wool in grazed subterranean clover (sub-clover) dominant pasture and mixed pasture (perennial ryegrass/phalaris/sub-clover/grass and cape weed) systems. Two major stages are presented in this life cycle assessment (LCA) analysis: pre-farm, and on-farm. The pre-farm stage includes greenhouse gas (GHG) emissions from agricultural machinery, fertilizer, and pesticide production and the emissions from the transportation of these inputs to paddock. The on-farm stage includes GHG emissions due to diesel use in on-farm transport and processing (e.g. seeding, spraying, harvesting, topdressing, sheep shearing), and non-CO2 (nitrous oxide (N2O), and methane (CH4)) emissions from pastures and crop grazing of lambs.The functional unit of this life cycle analysis is the GHG emissions (carbon dioxide equivalents – CO2 -e) from 1 kg of wheat, sheep meat and wool produced from sub-clover, wheat and mixed pasture plots. The GHG emissions (e.g. CO2, N2O and CH4 emission) from the production, transportation and use of inputs (e.g. fertilizer, pesticide, farm machinery operation) during pre-farm and on-farm stages are also included. The life cycle GHG emissions of 1 kg of wool is significantly higher than that of wheat and sheep meat. The LCA analysis identified that the on-farm stage contributed the most significant portion of total GHG emissions from the production of wheat, sheep meat and wool. This LCA analysis also identified that CH4 emissions from enteric methane production and from the decomposition of manure accounted for a significant portion of the total emissions from sub-clover and mixed pasture production, whilst N2O emissions from the soil have been found to be the major source of GHG emissions from wheat production. 相似文献
417.
In order to keep subscribers up-to-date with the latest developments in their field, John Wiley & Sons are providing a current awareness service in each issue of the journal. The bibliography contains newly published material in the field of prenatal diagnosis. Each bibliography is divided into 22 sections: 1 Reviews; 2 General Interest; 3 Normal Fetal Development; 4 Preimplantation Genetic Diagnosis; 5 First Trimester Diagnosis; 6 Second Trimester Diagnosis; 7 Fetal Imaging: General; Ultrasound; MRI; Doppler; 8 Maternal Serum Screening for Aneuploidy; 9 Screening for Carriers of Genetic Abnormality; 10 Molecular Cytogenetics: Metaphase Cytogenetics/FISH; Array CGH; 11 Fetal Cells in Maternal Circulation; 12 Fetal DNA/RNA in Maternal Body Fluids; 13 Fetal Therapy; 14 Psychosocial and Ethical Aspects; 15 Epidemiology and Environmental Factors; 16 Developmental and Placental Pathology; 17 Genetic Counseling. Within each section, articles are listed in alphabetical order with respect to author. If, in the preceding period, no publications are located relevant to any one of these headings, that section will be omitted 相似文献
418.
419.
Response of balanced network models to large-scale perturbation: Implications for evaluating the role of small pelagics in the Gulf of Maine 总被引:1,自引:0,他引:1
Jason Link Laurel Col Vincent Guida David Dow John O’Reilly Jack Green William Overholtz Debra Palka Chris Legault Joseph Vitaliano Carolyn Griswold Michael Fogarty Kevin Friedland 《Ecological modelling》2009
Exploring the response of an ecosystem, and subsequent tradeoffs among its biological community, to human perturbations remains a key challenge for the implementation of an ecosystem approaches to fisheries (EAF). To address this and related issues, we developed two network (or energy budget) models, Ecopath and Econetwrk, for the Gulf of Maine ecosystem. These models included 31 network “nodes” or biomass state variables across a broad range of trophic levels, with the present emphasis to particularly elucidate the role of small pelagics. After initial network balancing, various perturbation scenarios were evaluated to explore how potential changes to different fish, fisheries and lower trophic levels can affect model outputs. Categorically across all scenarios and interpretations thereof, there was minimal change at the second trophic levels and most of the “rebalancing” after a perturbation occurred via alteration of the diet matrix. Yet the model results from perturbations to a balanced energy budget fall into one of three categories. First, some model results were intuitive and in obvious agreement with established ecological and fishing theory. Second, some model results were counter-intuitive upon initial observation, seemingly contradictory to known ecological and fishing theory; but upon further examination the results were explainable given the constraints of an equilibrium energy budget. Finally, some results were counter-intuitive and difficult to reconcile with theory or further examination of equilibrium constraints. A detailed accounting of biomass flows for example scenarios explores some of the non-intuitive results more rigorously. Collectively these results imply a need to carefully track biomass flows and results of any given perturbation and to critically evaluate the conditions under which a new equilibrium is obtained for these types of models, which has implications for dynamic simulations based off of them. Given these caveats, the role of small pelagics as a prominent component of this ecosystem remains a robust conclusion. We discuss how one might use this approach in the context of further developing an EAF, recognizing that a more holistic, integrated perspective will be required as we continue to evaluate tradeoffs among marine biological communities. 相似文献
420.
Steven?J.?CookeEmail authorView authors OrcID profile Eduardo?G.?Martins Daniel?P.?Struthers Lee?F.?G.?Gutowsky Michael?Power Susan?E.?Doka John?M.?Dettmers David?A.?Crook Martyn?C.?Lucas Christopher?M.?Holbrook Charles?C.?Krueger 《Environmental monitoring and assessment》2016,188(4):239
Freshwater fish move vertically and horizontally through the aquatic landscape for a variety of reasons, such as to find and exploit patchy resources or to locate essential habitats (e.g., for spawning). Inherent challenges exist with the assessment of fish populations because they are moving targets. We submit that quantifying and describing the spatial ecology of fish and their habitat is an important component of freshwater fishery assessment and management. With a growing number of tools available for studying the spatial ecology of fishes (e.g., telemetry, population genetics, hydroacoustics, otolith microchemistry, stable isotope analysis), new knowledge can now be generated and incorporated into biological assessment and fishery management. For example, knowing when, where, and how to deploy assessment gears is essential to inform, refine, or calibrate assessment protocols. Such information is also useful for quantifying or avoiding bycatch of imperiled species. Knowledge of habitat connectivity and usage can identify critically important migration corridors and habitats and can be used to improve our understanding of variables that influence spatial structuring of fish populations. Similarly, demographic processes are partly driven by the behavior of fish and mediated by environmental drivers. Information on these processes is critical to the development and application of realistic population dynamics models. Collectively, biological assessment, when informed by knowledge of spatial ecology, can provide managers with the ability to understand how and when fish and their habitats may be exposed to different threats. Naturally, this knowledge helps to better evaluate or develop strategies to protect the long-term viability of fishery production. Failure to understand the spatial ecology of fishes and to incorporate spatiotemporal data can bias population assessments and forecasts and potentially lead to ineffective or counterproductive management actions. 相似文献