全文获取类型
收费全文 | 1269篇 |
免费 | 298篇 |
国内免费 | 28篇 |
专业分类
安全科学 | 27篇 |
废物处理 | 133篇 |
环保管理 | 352篇 |
综合类 | 681篇 |
基础理论 | 179篇 |
污染及防治 | 121篇 |
评价与监测 | 36篇 |
社会与环境 | 65篇 |
灾害及防治 | 1篇 |
出版年
2025年 | 9篇 |
2024年 | 26篇 |
2023年 | 36篇 |
2022年 | 42篇 |
2021年 | 40篇 |
2020年 | 45篇 |
2019年 | 46篇 |
2018年 | 39篇 |
2017年 | 42篇 |
2016年 | 60篇 |
2015年 | 64篇 |
2014年 | 100篇 |
2013年 | 105篇 |
2012年 | 117篇 |
2011年 | 113篇 |
2010年 | 79篇 |
2009年 | 84篇 |
2008年 | 91篇 |
2007年 | 69篇 |
2006年 | 67篇 |
2005年 | 59篇 |
2004年 | 52篇 |
2003年 | 37篇 |
2002年 | 22篇 |
2001年 | 30篇 |
2000年 | 24篇 |
1999年 | 12篇 |
1998年 | 11篇 |
1997年 | 10篇 |
1996年 | 8篇 |
1995年 | 7篇 |
1994年 | 5篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1984年 | 4篇 |
1983年 | 1篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 2篇 |
排序方式: 共有1595条查询结果,搜索用时 15 毫秒
51.
宁阳县发展循环经济过程中所取得的初步成果,同时对当前存在的突出问题,提出了相应的对策和改进措施:制定促进循环经济发展的相关政策;构筑循环经济基本模式,推动建立生态工业园;建立循环经济发展的技术支撑体系;制定发展循环经济的长远规划;提高全民发展循环经济意识和公众参与水平. 相似文献
52.
Michael W. Suplee Rosie Sada David L. Feldman 《Journal of the American Water Resources Association》2019,55(3):700-719
Effects of controlled nutrient additions on a prairie stream were studied using a before‐after‐control‐impact paired design. The site is in a reference condition with low soluble nitrate (NO3) and phosphate (soluble reactive phosphorus [SRP]) in summer (3 μg NO3‐N/L, 4 μg SRP/L). Nutrients were added to two reaches over the growing season at two levels (Low Dose — 39 μg NO3‐N/L and 4.4 SRP/L; High Dose — 119 μg NO3‐N/L and 15.6 μg SRP/L). Continuously measured dissolved oxygen (DO) and changes in aquatic flora were compared to an upstream Control. Enrichment led microalgae and filamentous algae to increase in density, areal coverage, and thickness, and the magnitude of the changes were largely concordant with dosing (more in the High Dose); algal growth also suppressed macrophytes in the High Dose. Enrichment caused significant increases in diel DO swings whose magnitudes were consistent with dosing level. In the High Dose, benthic algae flourished in the growing season and then senesced en masse in fall. The decomposing algae led DO to crash (ca. 0 mg/L on the bottom), but DO impacts were out‐of‐sync with peak algal growth and photosynthesis, which occurred weeks earlier. This finding provides a plausible explanation as to why high DO delta in streams impacts aquatic life even when concurrently measured DO is not low. When DO crashed, DO was longitudinally patchy, some areas having low DO near the bottom, others near saturation. Geomorphology and exposure to wind may have caused this pattern. 相似文献
53.
54.
Michael Lasithiotakis;Christodoulos Psanis;Eleni Triantafyllou;Panagiotis Sinioros; 《环境质量管理》2024,33(3):195-208
Emission of airborne particulate matter is produced by the industrial processes of metal extraction from electronic waste (e-waste). These aerosols can transport organic contaminants, such as polyaromatic hydrocarbons (PAHs) and polybrominated biphenyls. These pollutants are proven to have long-term effects on workers' health. In this work, we characterize aerosol particles and dust deposited from a recycling process of printed circuit boards in a recycling plant. This study also explores the significance of the secondary aerosol sources, and their importance, as an additional burden compared to primary sources. A Scanning Mobility Particles Counter and Sizer (SMPCS) was used to measure the size distributions of ultrafine particles. A Micro-Orifice Uniform Deposition Impactor (MOUDI) collected aerosol particle samples for chemical analysis. All plant compartments checked are subject to high particulate matter concentrations during work hours. Concentrations of organic pollutants in the machinery compartments do not pose a short or long-term health risk according to US Occupational Safety and Health Administration (OHSA). The application of the model presented in this work revealed that the accumulation of contaminants in other compartments should be considered in an occupational exposure assessment because it can present an equally important burden to workers’ health. 相似文献
55.
Long-term depletion of calcium and other nutrients in eastern US forests 总被引:10,自引:0,他引:10
C. Anthony Federer James W. Hornbeck Louise M. Tritton C. Wayne Martin Robert S. Pierce C. Tattersall Smith 《Environmental management》1989,13(5):593-601
Both harvest removal and leaching losses can deplete nutrient capital in forests, but their combined long-term effects have not been assessed previously. We estimated changes in total soil and biomass N, Ca, K, Mg, and P over 120 years from published data for a spruce-fir site in Maine, two northern hardwood sites in New Hampshire, central hardwood sites in Connecticut and Tennessee, and a loblolly pine site in Tennessee. For N, atmospheric inputs counterbalance the outputs, and there is little long-term change on most sites. For K, Mg, and P, the total pool may decrease by 2%–10% in 120 years depending on site and harvest intensity. For Ca, net leaching loss is 4–16 kg/ha/yr in mature forests, and whole-tree harvest removes 200–1100 kg/ha. Such leaching loss and harvest removal could reduce total soil and biomass Ca by 20%–60% in only 120 years. We estimated unmeasured Ca inputs from rock breakdown, root-zone deepening, and dry deposition; these should not be expected to make up the Ca deficit. Acid precipitation may be the cause of current high leaching of Ca. Although Ca deficiency does not generally occur now in acid forest soils, it seems likely if anthropogenic leaching and intensive harvest removal continue. 相似文献
56.
David A. Saad Gregory E. Schwarz Dale M. Robertson Nathaniel L. Booth 《Journal of the American Water Resources Association》2011,47(5):933-949
Saad, David A., Gregory E. Schwarz, Dale M. Robertson, and Nathaniel L. Booth, 2011. A Multi‐Agency Nutrient Dataset Used to Estimate Loads, Improve Monitoring Design, and Calibrate Regional Nutrient SPARROW Models. Journal of the American Water Resources Association (JAWRA) 47(5):933‐949. DOI: 10.1111/j.1752‐1688. 2011.00575.x Abstract: Stream‐loading information was compiled from federal, state, and local agencies, and selected universities as part of an effort to develop regional SPAtially Referenced Regressions On Watershed attributes (SPARROW) models to help describe the distribution, sources, and transport of nutrients in streams throughout much of the United States. After screening, 2,739 sites, sampled by 73 agencies, were identified as having suitable data for calculating long‐term mean annual nutrient loads required for SPARROW model calibration. These sites had a wide range in nutrient concentrations, loads, and yields, and environmental characteristics in their basins. An analysis of the accuracy in load estimates relative to site attributes indicated that accuracy in loads improve with increases in the number of observations, the proportion of uncensored data, and the variability in flow on observation days, whereas accuracy declines with increases in the root mean square error of the water‐quality model, the flow‐bias ratio, the number of days between samples, the variability in daily streamflow for the prediction period, and if the load estimate has been detrended. Based on compiled data, all areas of the country had recent declines in the number of sites with sufficient water‐quality data to compute accurate annual loads and support regional modeling analyses. These declines were caused by decreases in the number of sites being sampled and data not being entered in readily accessible databases. 相似文献
57.
Mark Dougherty Randel L. Dymond Thomas J. Grizzard Adil N. Godrej Carl E. Zipper John Randolph Christine M. Anderson‐Cook 《Journal of the American Water Resources Association》2006,42(5):1405-1419
ABSTRACT: Long term effects of precipitation and land use/land cover on basin outflow and nonpoint source (NFS) pollutant flux are presented for up to 24 years for a rapidly developing headwater basin and three adjacent headwater basins on the urban fringe of Washington, D.C. Regression models are developed to describe the annual and seasonal responses of basin outflow and IMPS pollutant flux to precipitation, mean impervious surface (IS), and land use. To quantify annual change in mean IS, a variable called delta IS is created as a temporal indicator of urban soil disturbance. Hydrologic models indicate that total annual surface outflow is significantly associated with precipitation and mean IS (r2= 0.65). Seasonal hydrologic models reveal that basin outflow is positively associated with IS during the summer and fall growing season (June to November). NPS pollutant flux models indicate that total and storm total suspended solids (TSS) flux are significantly associated with precipitation and urban soil disturbance in all seasons. Annual NPS total nitrogen flux is significantly associated with both urban and agricultural soil disturbance (r2= 0.51). Seasonal models of phosphorus flux indicate a significant association of total phosphorus flux with urban soil disturbance during the growing season. Total soluble phosphorus (TSP) flux is significantly associated with IS (r2= 0.34) and urban and agricultural soil disturbance (r2= 0.58). In urbanizing Cub Run basin, annual TSP concentrations are significantly associated with IS and cultivated agriculture (r2= 0.51). 相似文献
58.
Spent hydroprocessing catalysts from refineries have been classified as hazardous solid waste by the United States Environmental Protection Agency (USEPA), refiners must find a viable but economical solution to solve this serious environmental issue. Catalyst rejuvenation is an attractive option for minimizing the environmental problems associated with spent catalysts. In this study, a preliminary design for such a process and the corresponding economic analysis are performed to assess the proposed catalyst rejuvenation process for metal-fouled spent catalysts generated in residue hydroprocessing units. The scenarios used in the economic assessment are based on three options of process synthesis and two operator modes. It is found that the option of rejuvenating medium and lightly fouled spent catalyst produced by the refinery will be the best solution for refiners, both environmentally and economically. 相似文献
59.
ABSTRACT: As part of a basinwide water-quality study, nitrogen and phosphorus data for the Upper Colorado River Basin from the Colorado-Utah State line to the Continental Divide were analyzed for spatial distributions, concentrations associated with various land uses, and temporal trends. Nitrogen and phosphorus concentrations generally increased in a downstream direction. Some nutrient concentrations were elevated at some sites in the upper parts of the basin in areas influenced by increasing urbanization. Sites were grouped according to land use and site type, and median nutrient concentrations were compared among groups. Sites within the agricultural areas of the basin generally had the highest concentrations of nitrogen and phosphorus; concentrations for main-stem, tributary, and urbanization sites were slightly lower than for the agricultural sites. Background sites, or sites with minimal land-use impacts, had very low median nutrient concentrations. Several sites with long-term data were analyzed for temporal trends in concentrations. Several statistically significant downward trends of low and moderate magnitude were observed for nitrogen and phosphorus species. No upward trends were observed in the data at any site. 相似文献
60.
Fbio Lazzarotti Darlan Roman Simone Sehnem Fernando Fantoni Bencke Analisa Tiburski Sommer 《环境质量管理》2019,29(2):37-49
The purpose of the study was to analyze the social phenomenon of collecting animal carcasses from rural properties using the perspective of the ecological modernization theory. The results show that the success of the Recolhe pilot project is associated with users’ engagement in environmental awareness, environmental regulations, sanitary and environmental risk management, minimization of labor in rural properties, and municipal legal pressures. 相似文献