首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   216篇
  免费   6篇
  国内免费   5篇
安全科学   6篇
废物处理   10篇
环保管理   16篇
综合类   60篇
基础理论   53篇
污染及防治   57篇
评价与监测   14篇
社会与环境   10篇
灾害及防治   1篇
  2023年   4篇
  2022年   8篇
  2021年   17篇
  2020年   10篇
  2019年   6篇
  2018年   16篇
  2017年   11篇
  2016年   17篇
  2015年   9篇
  2014年   10篇
  2013年   13篇
  2012年   15篇
  2011年   18篇
  2010年   6篇
  2009年   10篇
  2008年   13篇
  2007年   9篇
  2006年   5篇
  2005年   2篇
  2004年   4篇
  2003年   2篇
  2002年   4篇
  2001年   2篇
  2000年   5篇
  1999年   5篇
  1997年   1篇
  1996年   1篇
  1994年   1篇
  1992年   1篇
  1991年   1篇
  1981年   1篇
排序方式: 共有227条查询结果,搜索用时 15 毫秒
71.
Despite a significant decrease in the metallic waste emissions from an industrial site and a remediation process initiated in 2007, the Riou-Mort watershed (southwest France) still exhibits high Cd and Zn concentrations. Metal wastes have long been proven to significantly disturb aquatic communities. In this study, bioaccumulation capacities and responses to the chemical improvement of the hydrosystem were assessed for a year along the contamination gradient through the comparison of two biological models: Corbicula fluminea and periphytic biofilms, both considered as good bioindicators. Bioaccumulation results confirmed the persistence of water contamination in Corbicula fluminea and biofilms with, respectively, maximum Cd concentrations reaching 80.6 and 861.2 μg gDW(-1), and Zn concentrations 2.0 and 21.3 mg gDW(-1). Biofilms exhibited bioaccumulation in close correlation with water contamination, while Corbicula fluminea presented Cd bioaccumulation clearly regulated by water temperature and metal concentrations, affecting the ventilatory activity, as revealed by condition indices measurements. Also, a linear regression using Cd bioaccumulation and temperature () showed that below approximately 6 °C Corbicula fluminea did not appear to accumulate metals. Bioconcentration factors (BCFs) were higher in biofilms in comparison with Corbicula fluminea and showed the great accumulation capacity of suspended particulate matter in biofilms. However, bioaccumulation capacities are known to be influenced by many factors other than metal concentrations, such as temperature, water oxygenation or plankton and nutrient concentrations. Thus, this study demonstrates the power of a combined assessment using both Corbicula fluminea and biofilms as bioindicators to give a more integrated view of water quality assessment. Finally, when comparing our results with previous studies, the start of hydrosystem restoration could be shown by decreasing bioaccumulation in organisms.  相似文献   
72.
Europe has a long history of human pressure on freshwater ecosystems. As pressure continues to grow and new threats emerge, there is an urgent need for conservation of freshwater biodiversity and its ecosystem services. However, whilst some taxonomic groups, mainly vertebrates, have received a disproportionate amount of attention and funds, other groups remain largely off the public and scientific radar. Freshwater mussels (Bivalvia, Unionida) are an alarming example of this conservation bias and here we point out six conceptual areas that need immediate and long-term attention: knowledge, threats, socioeconomics, conservation, governance and education. The proposed roadmap aims to advance research, policy and education by identifying the most pressing priorities for the short- and long-term conservation of freshwater mussels across Europe.  相似文献   
73.
Evaluating the effects of fishing and environmental factors on fish populations are fundamental tenets of fisheries science. In this study, we assess associations between environmental variables (sea surface temperature; North Atlantic Oscillation index; upwelling; wind magnitude; westerly winds; northerly winds; river discharge) and fishing variables (fishing effort) in Diplodus sagus catch rates accounting for regional analyses (northwest coast; southwest coast and Algarve—Algarve south coast). Different time series models for data fitting (multi-model approach) were used. The models were lagged, according to species fishing recruitment age based on the hypothesis that fisheries catches depend on larvae recruitment and survivorship. D. sargus catch rates across areas were unrelated to fishing effort but correlated to environmental variables, with seasonal events explaining much of the variability in trends. On the northwestern coast, the catch rates were mainly set by sea surface temperature (SST) and wind magnitude; however, southwestern coast catch rates were set by NAO winter. On the south coast, only one statistical model (SST, upwelling and westerly winds) associated spring conditions with D. sargus catch rates. The multi-model approach revealed autumn, winter and spring seasonal effects to be related with northwest, southwest and Algarve coastal catch rates, respectively, indicating a possible coastal longitudinal gradient related with given periods of spawning and larval availability. The metadata analysis yielded different results from the regional analyses. In summary, marine resource management should take regional environment characteristics and variability into account when determining sustainable catch rates in given areas for species with high habitat site fidelity.  相似文献   
74.
In regions with high livestock densities, the usage of antibiotics and metals for veterinary purposes or as growth promoters poses a risk in manured soils. We investigated to which degree the concentrations and depth distributions of Cu, Zn, Cr and As could be used as a tracer to discover contaminations with sulfonamides, tetracyclines and fluoroquinolones. Besides, we estimated the potential vertical translocation of antibiotics and compared the results to measured data. In the peri-urban region of Beijing, China, soil was sampled from agricultural fields and a dry riverbed contaminated by organic waste disposal. The antibiotic concentrations reached 110 μg kg?1 sulfamethazine, 111 μg kg?1 chlortetracycline and 62 μg kg?1 enrofloxacin in the topsoil of agricultural fields. Intriguingly, total concentrations of Cu, Zn, Cr and As were smaller than 65, 130, 36 and 10 mg kg?1 in surface soil, respectively, therewith fulfilling Chinese quality standards. Correlations between sulfamethazine concentrations and Cu or Zn suggest that in regions with high manure applications, one might use the frequently existing monitoring data for metals to identify potential pollution hotspots for antibiotics in topsoils. In the subsoils, we found sulfamethazine down to ≥2 m depth on agricultural sites and down to ≥4 m depth in the riverbed. As no translocation of metals was observed, subsoil antibiotic contamination could not be predicted from metal data. Nevertheless, sulfonamide stocks in the subsoil could be estimated with an accuracy of 35–200 % from fertilisation data and potential leaching rates. While this may not be sufficient for precise prediction of antibiotic exposure, it may very well be useful for the pre-identification of risk hotspots for subsequent in-depth assessment studies.  相似文献   
75.
Air quality impacts of volatile organic compound (VOC) and nitrogen oxide (NOx) emissions from major sources over the northwestern United States are simulated. The comprehensive nested modeling system comprises three models: Community Multiscale Air Quality (CMAQ), Weather Research and Forecasting (WRF), and Sparse Matrix Operator Kernel Emissions (SMOKE). In addition, the decoupled direct method in three dimensions (DDM-3D) is used to determine the sensitivities of pollutant concentrations to changes in precursor emissions during a severe smog episode in July of 2006. The average simulated 8-hr daily maximum O3 concentration is 48.9 ppb, with 1-hr O3 maxima up to 106 ppb (40 km southeast of Seattle). The average simulated PM2.5 (particulate matter with an aerodynamic diameter <2.5 μm) concentration at the measurement sites is 9.06 μg m?3, which is in good agreement with the observed concentration (8.06 μg m?3). In urban areas (i.e., Seattle, Vancouver, etc.), the model predicts that, on average, a reduction of NOx emissions is simulated to lead to an increase in average 8-hr daily maximum O3 concentrations, and will be most prominent in Seattle (where the greatest sensitivity is??0.2 ppb per % change of mobile sources). On the other hand, decreasing NOx emissions is simulated to decrease the 8-hr maximum O3 concentrations in remote and forested areas. Decreased NOx emissions are simulated to slightly increase PM2.5 in major urban areas. In urban areas, a decrease in VOC emissions will result in a decrease of 8-hr maximum O3 concentrations. The impact of decreased VOC emissions from biogenic, mobile, nonroad, and area sources on average 8-hr daily maximum O3 concentrations is up to 0.05 ppb decrease per % of emission change, each. Decreased emissions of VOCs decrease average PM2.5 concentrations in the entire modeling domain. In major cities, PM2.5 concentrations are more sensitive to emissions of VOCs from biogenic sources than other sources of VOCs. These results can be used to interpret the effectiveness of VOC or NOx controls over pollutant concentrations, especially for localities that may exceed National Ambient Air Quality Standards (NAAQS).

Implications: The effect of NOx and VOC controls on ozone and PM2.5 concentrations in the northwestern United States is examined using the decoupled direct method in three dimensions (DDM-3D) in a state-of-the-art three-dimensional chemical transport model (CMAQ). NOx controls are predicted to increase PM2.5 and ozone in major urban areas and decrease ozone in more remote and forested areas. VOC reductions are helpful in reducing ozone and PM2.5 concentrations in urban areas. Biogenic VOC sources have the largest impact on O3 and PM2.5 concentrations.  相似文献   
76.
A 168-day period field study, carried out in Sisimiut, Greenland, assessed the potential to enhance soil remediation with the surplus heating from an incineration facility. This approach searches a feasible ex situ remediation process that could be extended throughout the year with low costs. Individual and synergistic effects of biostimulation were also tested, in parallel. An interim evaluation at the end of the first 42 days showed that biostimulation and active heating, as separate treatments, enhanced petroleum hydrocarbon (PHC) removal compared to natural attenuation. The coupling of both technologies was even more effective, corroborating the benefits of both techniques in a remediation strategy. However, between day 42 and day 168, there was an opposite remediation trend with all treatments suggesting a stabilization except for natural attenuation, where PHC values continued to decrease. This enforces the “self-purification” capacity of the system, even at low temperatures. Coupling biostimulation with active heating was the best approach for PHC removal, namely for a short period of time (42 days). The proposed remediation scheme can be considered a reliable option for faster PHC removal with low maintenance and using “waste heating” from an incineration facility.  相似文献   
77.
The Arctic marine ecosystem contains multiple elements that present alternative states. The most obvious of which is an Arctic Ocean largely covered by an ice sheet in summer versus one largely devoid of such cover. Ecosystems under pressure typically shift between such alternative states in an abrupt, rather than smooth manner, with the level of forcing required for shifting this status termed threshold or tipping point. Loss of Arctic ice due to anthropogenic climate change is accelerating, with the extent of Arctic sea ice displaying increased variance at present, a leading indicator of the proximity of a possible tipping point. Reduced ice extent is expected, in turn, to trigger a number of additional tipping elements, physical, chemical, and biological, in motion, with potentially large impacts on the Arctic marine ecosystem.  相似文献   
78.
人口迁徙、汇款、生活轨迹及社会应变能力   总被引:7,自引:0,他引:7  
我们认为,人口变化的方方面面,包括迁徙,都影响个人和团体的社会应变能力以及基本资源基础的可持续性.社会应变能力是应对和适应通过适当的制度调节的环境和社会变化的能力.我们调查了当今越南沿海地区人口变化、社会应变能力以及可持续发展之间关系的一个侧面:迁徙和汇款对依赖于资源的人口源区居民群的影响.利用有关生活来源的纵向运动数据,我们发现移民出境和汇款对一个逐渐形成的社会和政治范围内的应变能力有抵消作用.移民出境是与不可持续的沿海养殖业的发展同时并存的,而不是起推动作用.日益增加的经济不平等削弱了社会应变能力.同时,多种经营和收入水平的不断提高有助于应变能力的增强.  相似文献   
79.
旅游者们越来越意识到交通的负面影响(包括噪音和其他类型的污染).繁重的交通会影响旅游目的地的娱乐或其他价值.对于旅游胜地以赢利为目的的管理者来说,交通方式和参观者的满意程度及再访愿望之间的关系正越来越重要.  相似文献   
80.
The present study utilizes meta‐analytic techniques to examine the literature on sleep and work performance. In line with previous meta‐analytic research, results indicate that sleep and work performance have a positive relationship. However, more importantly, results from moderator analyses reveal that the type of sleep measurement (sleep quantity and sleep quality), work performance measurement (task performance, organizational citizenship behavior, and counterproductive work behavior), analysis method (between‐person and within‐person), sleep report source (self‐report, other report, and objective), sleep recall window (day, week/month, and more than 1 month), and study setting (field and laboratory) differentially influence the strength of the sleep–work performance relationship. Furthermore, meta‐analytic SEM results indicate that certain mediators (affect, job attitudes, and cognitive resources) provide stronger explanations (i.e., stronger indirect effects) for the relationship between sleep and work performance, depending on the specific type of performance being examined. In general, results highlight the importance of construct operationalization and methodology decisions when conducting sleep–work performance research and provide greater insight into explanations for the relationship between sleep and work performance. Research implications, practical implications, potential limitations, and future directions are also discussed.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号