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   590篇
  免费   13篇
  国内免费   7篇
安全科学   16篇
废物处理   39篇
环保管理   43篇
综合类   65篇
基础理论   161篇
污染及防治   186篇
评价与监测   54篇
社会与环境   44篇
灾害及防治   2篇
  2023年   8篇
  2022年   20篇
  2021年   15篇
  2020年   8篇
  2019年   12篇
  2018年   28篇
  2017年   26篇
  2016年   36篇
  2015年   14篇
  2014年   32篇
  2013年   49篇
  2012年   43篇
  2011年   55篇
  2010年   34篇
  2009年   38篇
  2008年   29篇
  2007年   36篇
  2006年   24篇
  2005年   26篇
  2004年   17篇
  2003年   16篇
  2002年   5篇
  2001年   8篇
  2000年   9篇
  1999年   3篇
  1997年   3篇
  1996年   3篇
  1993年   3篇
  1992年   1篇
  1991年   3篇
  1990年   2篇
  1989年   1篇
  1988年   1篇
  1986年   1篇
  1972年   1篇
排序方式: 共有610条查询结果,搜索用时 250 毫秒
511.
The paper aims to explore the implementation of an eco-design methodology and the related software platform (G.EN.ESI – Green ENgineering dESIgn) within technical departments of a manufacturing firm. The G.EN.ESI eco-design methodology is based on the life cycle thinking concept and the software platform is conceived as a set of inter-operable software tools able to efficiently exchange data among them and with the traditional design systems (i.e. CAD, PDM and PLM). A multinational company, designing and producing household appliances, adopted the proposed methodology and related software platform for redesigning two cooker hood models with the aim to improve their environmental performances. Design and engineering departments evaluated the methodology and platform impact on the product development process, as well as the platform inter-operability with traditional design tools. The results indicate that methodology and software platform satisfy the requirements of the enterprise in terms of: (i) degree of expertise and training requirement on this subject, (ii) low impact in a consolidated design process and, (ii) good level of inter-operability among heterogeneous tools. However, the testing results highlight the necessity of a further platform optimisations in terms of software integration (single workbench made by integrated software tools with the same graphical user interface).  相似文献   
512.
The paper presents the first comprehensive survey of congener profiles of polychlorinated biphenyls (PCBs) in core sediment samples (<63 microm particle size) covering seven sites in Sunderban mangrove Wetland, north-eastern part of the Bay of Bengal. Results pointed out a non-homogenous contamination of the wetland with Sigma23PCB values ranging from 0.5 to 26.9 ng g(-1) dry weight, reflecting very low to moderate contamination closely in conformity to other Asian coastal environment. The general decreasing order of the dominant congeners to the total load was: CB138 > 153 > 149 > 101, indicating the predominance of hexa-chlorinated congeners. The spatial distribution revealed significant differences in concentration related to local urbanization with industrial and land-based sources. No uniform temporal trend on PCB levels was recorded probably due to particular hydrological characteristics of the wetland and/or non-homogenous inputs from point sources. Strong positive correlations between the seven dominant congeners suggest their common sources and similar environmental behaviors. These results were also used for a risk assessment evaluation in the Sunderban wetland, showing that the present PCB levels were exceeding in few cases the lower limit of sediment quality guidelines of Environmental Protection Agency and Canadian Council of Ministers of the Environment.  相似文献   
513.
A specific 2-year program to monitor and test both the vadose zone and the saturated zone, coupled with a numerical analysis, was performed to evaluate the overall performance of slurry wall systems for containment of contaminated areas. Despite local physical confinement (slurry walls keyed into an average 2-m-thick aquitard), for at least two decades, high concentrations of chlorinated solvents (up to 110 mg l − 1) have been observed in aquifers that supply drinking water close to the city of Milan (Italy). Results of monitoring and in situ tests have been used to perform an unsaturated-saturated numerical model. These results yielded the necessary quantitative information to be used both for the determination of the hydraulic properties of the different media in the area and for the calibration and validation of the numerical model. Backfill material in the shallower part of the investigated aquifer dramatically affects the natural recharge of the encapsulated area. A transient simulation from wet to drought periods highlights a change in the ratio between leakages from lateral barriers that support a specific scenario of water loss through the containment system. The combination of monitoring and modelling allows a reliable estimate of the overall performance of the physical confinement to be made without using any invasive techniques on slurry wall.  相似文献   
514.
A correct characterization of the status and trend of forest condition is essential to support reporting processes at national and international level. An international forest condition monitoring has been implemented in Europe since 1987 under the auspices of the International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests). The monitoring is based on harmonized methodologies, with individual countries being responsible for its implementation. Due to inconsistencies and problems in sampling design, however, the ICP Forests network is not able to produce reliable quantitative estimates of forest condition at European and sometimes at country level. This paper proposes (1) a set of requirements for status and change assessment and (2) a harmonized sampling strategy able to provide unbiased and consistent estimators of forest condition parameters and of their changes at both country and European level. Under the assumption that a common definition of forest holds among European countries, monitoring objectives, parameters of concern and accuracy indexes are stated. On the basis of fixed-area plot sampling performed independently in each country, an unbiased and consistent estimator of forest defoliation indexes is obtained at both country and European level, together with conservative estimators of their sampling variance and power in the detection of changes. The strategy adopts a probabilistic sampling scheme based on fixed-area plots selected by means of systematic or stratified schemes. Operative guidelines for its application are provided.  相似文献   
515.
Ambio - The peregrine falcon (Falco peregrinus) and the gyrfalcon (Falco rusticolus) are top avian predators of Arctic ecosystems. Although existing monitoring efforts are well established for both...  相似文献   
516.
517.
Rheological Studies of Microfibrillar Cellulose Water Dispersions   总被引:2,自引:0,他引:2  
The rheological behaviour of microfibrillar cellulose (MFC) water dispersions has been investigated. For the first time a detailed study of shear dependent viscosity at low and high shear rate is presented. A peculiar time dependent behaviour measured in the area between 0 and 1000 s−1 was identified. The study shows a hysteresis loop in the shear rate–viscosity relationship at low shear rate. Additional time dependent shear rate measurements were performed, and a hypothesis for a mechanism of interaction and formation of a fibrils network was suggested. Higher temperature caused lower viscosity values, and this difference was increased at higher shear rate values. Oscillatory measurements showed how the closeness of the fibrils helps network creations. Data obtained from high shear measurements showed that 1% MFC water dispersions had a dilatant behaviour at ultra high shear rates with values increasing from 120 to 300 Pa s in the area between 180,000 and 330,000 s−1 .  相似文献   
518.
Environmental Science and Pollution Research - Making good environmental damage caused by industrial accidents and restoring impaired ecosystems may be associated with high costs. The European...  相似文献   
519.
Combined wastewater collection systems continue to serve as a common urban conveyance method in urban areas of Europe and older urban areas of the United States. This study uses combined wastewater collection system monitoring data from the urbanizing Liguori catchment and channel in Cosenza (Italy) to illustrate event-based delivery and distribution of conveyed pollutant indices. Motivated by recent European Union (EU) discharge control legislation, this study specifically differentiates the event-based delivery of these indices between dry and wet-weather flows. Although the relatively steady to diurnal-variable delivery phenomena in dry weather flows are known, transport limiting phenomena for wet-weather hydrology and mass delivery typically are not known for the same catchment. Limiting categories of transport for a pollutant phase are generated by variables such as flow volume and duration, stream power, hydrograph parameters, and previous dry hours (PDH). Transport limitations of wet and dry weather events from the 414-ha catchment were analyzed and characterized as limited by mass indices (first-order, first flush transport) or limited by flow (zero-order transport). Results indicated significant concentration differences between mass- and flow-limited events. Higher concentrations were associated with mass-limited events. Frequency distributions of flow, total suspended solids (TSS), chemical oxygen demand (COD), and five-day biochemical oxygen demand (BOD5) were consistently exponential for wet-weather and mass-limited events. In contrast, flow, TSS, and BOD5 concentrations were distributed normally for flow-limited events. Results indicated a reasonable linear relationship between discharged TSS, COD, and BOD5 (biochemical oxygen demand) for Liguori Channel discharges into the Crati River. Wet-weather event transport was predominately mass-limited for TSS, COD, and BOD5.  相似文献   
520.
INTRODUCTION: The reuse of wastewaters for agricultural purposes is a common practice in many countries and is increasingly recommended by organizations that promote sustainable development. Yet, it is restricted by the potential negative impact of these materials on soil and crops. The aim of this study was therefore to evaluate the environmental impact of walnut husk washing waters (WHWW) and their organic fractions, in order to conceive their agricultural exploitation. DISCUSSION: Phytotoxicity tests and morphological investigations on representative plant species of horticultural interest indicated that WHWW and their organic fractions can elicit a concentration-dependent stimulating effect on the growth of radish, lettuce cv. cavolo Napoli with effects up to 165 %. An opposite inhibitory effect up to 70 % was observed on spinach and lettuce cv. Gentilina. Proapoptotic effects were observed by acridine orange/ethidium bromide assay in the species inhibited by WHWW treatment. High-performance liquid chromatography-mass spectrometry analysis of the WHWW revealed the presence of a main component which was extracted selectively in organic solvents and purified by preparative chromatography. Complete spectral analysis allowed identification as 4,8-dihydroxy-1-tetralone, commonly known as regiolone. Regiolone exhibited the same concentration-dependent activity on root elongation with a stimulation in the case of radish up to 135 % with respect to control. These results open perspectives in the exploitation of WHWW and the main phenolic constituent readily available by a straightforward isolation procedure as a natural fertilizer for specific crops.  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