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611.
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613.
Local authorities in the United Kingdom are currently changing their approach towards recycling as they attempt to meet legislative
targets. An important part of this drive is the provision of an effective curbside recycling service and it is vital to understand
the parameters that influence the performance of the system offered. In this article, three primary datasets, collected from
over 1400 households each, are examined for parameters correlated to participation rates. Two measured parameters were found
that are not commonly identified in previous studies of curbside recycling schemes, and they are shown to merit further investigation
as useful tools for planning purposes. One is the number of types of material collected; participation rates are greater for
schemes collecting more materials. The second is the number of households situated on the same road; the lower the number,
the higher the participation rate. In both cases, evidence of the measured correlation is presented, justifying their usefulness
for planning. The multiple underlying factors causing the correlations are not identified here, but suggestions are made for
further studies. 相似文献
614.
Within fluvial systems, the spatial variability of geomorphological characteristics of stream channels and associated streambed properties can affect many biogeochemical processes. In agricultural streams of the midwestern USA, it is not known how geomorphological variability affects sediment denitrification rates, a potentially important loss mechanism for N. Sediment denitrification was measured at channelized and meandering headwater reaches in east-central Illinois, a region dominated by intensive agriculture and high NO(3)-N stream export, between June 2003 and February 2005 using the chloramphenicol-amended acetylene inhibition procedure. Sediment denitrification rates were greatest in separation zones, ranging from 0.6 to 76.4 mg N m(-2) h(-1), compared with riffles, point bars, pools, and a run ranging from 0 to 36.5 mg N m(-2) h(-1). Differences in benthic organic matter (r = 0.70) and the percentage of fine-grained sediments (r = 0.93) in the streambeds controlled much of the spatial variations in sediment denitrification among the geomorphological features. Although two meandering study reaches removed 390 and 99% more NO(3)-N by sediment denitrification than adjacent channelized reaches, NO(3)-N loss rates from all reaches were between 0.1 and 15.7% d(-1), except in late summer. Regardless of geomorphological characteristics, streams in east-central Illinois were not able to process the high NO(3)-N loads, making sediment denitrification in this region a limited sink for N. 相似文献
615.
Role of protein, amino acids, and enzyme activity on odor production from anaerobically digested and dewatered biosolids. 总被引:2,自引:0,他引:2
Matthew J Higgins Gregory Adams Yen-Chih Chen Zeynep Erdal Robert H Forbes Dietmar Glindemann J Ronald Hargreaves David McEwen Sudhir N Murthy John T Novak Jay Witherspoon 《Water environment research》2008,80(2):127-135
The main objective of this research was to test the hypothesis that bioavailable protein and, more specifically, the sulfur-containing amino acids within the protein, can be degraded by proteolytic enzymes to produce odor-causing compounds--mainly volatile sulfur compounds (VSCs)--during biosolids storage. To achieve these objectives, samples of digester effluent and cake solids were collected at 11 different wastewater treatment plants in North America, and the samples were analyzed for protein and amino acid content and general protein-degrading enzyme activity. At the same time, cake samples were stored using headspace bottles, the concentration of VSCs were measured using gas chromatography, and olfactometry measurements were made by a trained odor panel. The results showed that the bound cake protein content and methionine content was well-correlated with VSC production and the detection threshold measured by the odor panel. 相似文献
616.
Soil erosion is a serious problem in areas with expanding construction, agricultural production, and improper storm water
management. It is important to understand the major processes affecting sediment delivery to surficial water bodies in order
to tailor effective mitigation and outreach activities. This study analyzes how naturally occurring and anthropogenic influences,
such as urbanization and soil disturbance on steep slopes, are reflected in the amount of soil erosion and sediment delivery
within sub-watershed-sized areas. In this study, two sub-watersheds of the Rappahannock River, Horsepen Run and Little Falls
Run, were analyzed using the Revised Universal Soil Loss Equation (RUSLE) and a sediment delivery ratio (SDR) to estimate
annual sediment flux rates. The RUSLE/SDR analyses for Horsepen Run and Little Falls Run predicted 298 Mg/y and 234 Mg/y,
respectively, but nearly identical per-unit-area sediment flux rates of 0.15 Mg/ha/y and 0.18 Mg/ha/y. Suspended sediment
sampling indicated greater amounts of sediment in Little Falls Run, which is most likely due to anthropogenic influences.
Field analyses also suggest that all-terrain vehicle crossings represent the majority of sediment flux derived from forested
areas of Horsepen Run. The combined RUSLE/SDR and field sampling data indicate that small-scale anthropogenic disturbances
(ATV trails and construction sites) play a major role in overall sediment flux rates for both basins and that these sites
must be properly accounted for when evaluating sediment flux rates at a sub-watershed scale. 相似文献
617.
Michael B. Griffith F. Bernard Daniel Matthew A. Morrison Michael E. Troyer James M. Lazorchak Joseph P. Schubauer‐Berigan 《Journal of the American Water Resources Association》2009,45(6):1475-1492
Griffith, Michael B., F. Bernard Daniel, Matthew A. Morrison, Michael E. Troyer, James M. Lazorchak, and Joseph P. Schubauer‐Berigan, 2009. Linking Excess Nutrients, Light, and Fine Bedded Sediments to Impacts on Faunal Assemblages in Headwater Agricultural Streams. Journal of the American Water Resources Association (JAWRA) 45(6):1475‐1492. Abstract: Biological impairments in streams are typically defined by regulatory agencies in terms of altered invertebrate or fish assemblages. While nutrients, canopy cover, and sediment fines contribute to these impairments, these stressors are often defined, at least in part, by their impacts on periphyton. Path analysis can extend these assessments to impacts on invertebrates and fish by characterizing the direct and indirect relationships among variables along defined model pathways. With data from headwater tributaries in the Little Miami River, Ohio, we tested models of the impacts of nutrients [total nitrogen (TN), total phosphorus (TP), and the nitrogen to phosphorus (N/P) ratio], the percentage of (%) open canopy, and the % sand and fines on three periphyton metrics [periphytic ash‐free dry mass (AFDM), the percent abundance of cyanobacteria (% cyanobacteria), and the percent abundance of Chlorophyta (% Chlorophyta)] and, in turn, on selected invertebrate or fish metrics. Our objective was to develop and evaluate a statistical model that assesses the direct and indirect impacts of excess nutrients on macroinvertebrate and fish in these streams and demonstrate how this approach might be applicable elsewhere. The results suggest indirect pathways for the influences of nutrients, canopy cover, and fine bedded sediments on invertebrates or fish that are mediated by their influences on periphyton. This is in addition to any direct impacts of these stressors on the invertebrate and fish metrics. In most models, all three periphyton metrics increased with % open canopy. Periphytic AFDM increased with TN, while % cyanobacteria decreased. The % cyanobacteria also decreased with % sand and fines, but % Chlorophyta increased. The metrics, percent abundance of (%) three most dominant (macroinvertebrate) taxa, % Trichoptera, and % herbivorous fish all increased with periphytic AFDM, while % climbers, % swimmers, and %Lepomis cyanellus Rafinesque decreased. Lepomis cyanellus is an indicator species, because it is generally common in these streams and relatively tolerant to various common environmental stressors. The % three most dominant macroinvertebrate taxa increased while % Hydropsychidae (Trichoptera) and %L. cyanellus decreased with % cyanobacteria. The % Trichoptera and %L. cyanellus increased with % Chlorophyta. Some macroinvertebrate metrics, such as the % burrowers and number of burrower taxa, did not have any statistically significant relationships with the periphyton metrics but did exhibit a direct pathway with % sand and fines. These analyses illustrate how path analysis can be used to estimate the relationships among the variables in a conceptual model, modify the model, assess the relative importance of different paths, and explore responses resulting from stressors with interacting and indirect impacts. 相似文献
618.
Noreen McDonald Author Vitae Matthew Trowbridge Author Vitae 《Journal of Safety Research》2009,40(3):177-183
Problem
Motor vehicle crashes are the most common cause of death for American adolescents. However, the impact of where teens live on when they begin driving has not been studied.Method
Data from the 2001 National Household Travel Survey were used to estimate the effect of residential density on the driver status of teens aged 16 to 19 years after matching on demographic characteristics.Results
Controlling for demographic characteristics, 16 and 17 year old teens in high density neighborhoods had driver rates 15 percentage points below teens living in less dense areas (p < 0.001). The effect for 18 and 19 year olds was a 9 percentage point decrease (p < 0.001).Summary
These results suggest teens living in less dense and more sprawling communities initiate driving at a younger age than comparable teens in compact areas, placing them at increased risk for crash related injuries. Impact on Industry: The role of environmental factors, such as neighborhood walkability and provision of transit, should be considered in young driver programs. 相似文献619.
Following international interventions in Bosnia-Herzegovina(1) and Iraq, non-governmental organisations (NGOs) have played a central role in delivering humanitarian relief, encouraging participation in new systems of government, and advocating on behalf of marginalised groups. Although intervening agencies have framed such autonomous organisations as unquestionably virtuous, scholars have increasingly questioned the agency of NGOs, pointing to the constraining effects of funding and regulatory mechanisms. This paper contributes to this body of work by offering a detailed examination of legislation requiring NGOs to register with nascent state institutions. Drawing on case study material from Bosnia and Iraq, it argues that NGO registration should not be dismissed as a technical or legal matter, but that it should be embraced as a significant political practice embedded in relations of power. Registration legislation has increased the transparency of NGO funding origins and institutional practices, yet it has simultaneously acted as a barrier to smaller organisations and led to the transmission of international objectives through civil society entities. 相似文献
620.
Ralstonia sp. SA-3, Ralstonia sp. SA-4 and Pseudomonas sp. SA-6 are natural strains with a novel capacity to utilize meta-substituted dichlorobiphenyls (diCBs) hitherto not known to serve as a sole source of carbon and energy for polychlorobiphenyl-degraders. In growth experiments, axenic cultures of isolates grew logarithmically on 3,3'-diCB with generation times that ranged insignificantly (t-test, P>0.05) from 30.4 to 33.8 h. Both 3-chlorobenzoate (3-CBA) and chloride produced as metabolites were recovered in non-stoichiometric quantities. The release of chloride by the cultures lagged substantially, indicating that the initial dioxygenase attack preceded cleavage of carbon-chloride bonds and that chloride must have been released from the chlorinated hydroxypentadienoate. In the case of 3,5-diCB, SA-3 and SA-6 metabolised this substrate primarily to 3,5-CBA. The lack of chloride in the culture media coupled with stoichiometric recovery of 3,5-CBA suggests that growth by these strains occurred predominantly at the expense of the unsubstituted phenyl ring. The unique metabolic properties of these three aerobic isolates point to their potential usefulness as seeds for bioremediation of PCBs polluted environments without the need for repeated inoculation or supplementation by a primary growth substrate such as biphenyl. 相似文献