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   240篇
  免费   2篇
安全科学   9篇
废物处理   11篇
环保管理   15篇
综合类   38篇
基础理论   36篇
污染及防治   89篇
评价与监测   29篇
社会与环境   14篇
灾害及防治   1篇
  2023年   1篇
  2022年   6篇
  2021年   9篇
  2020年   1篇
  2019年   1篇
  2018年   11篇
  2017年   8篇
  2016年   10篇
  2015年   5篇
  2014年   9篇
  2013年   15篇
  2012年   16篇
  2011年   17篇
  2010年   12篇
  2009年   17篇
  2008年   25篇
  2007年   22篇
  2006年   14篇
  2005年   12篇
  2004年   7篇
  2003年   3篇
  2002年   9篇
  2001年   3篇
  2000年   1篇
  1999年   1篇
  1996年   1篇
  1995年   1篇
  1994年   1篇
  1990年   1篇
  1984年   1篇
  1983年   1篇
  1969年   1篇
排序方式: 共有242条查询结果,搜索用时 15 毫秒
131.
Environmental classification addresses issues involving the representation and analysis of continuous and variable ecological data. This study creates a methodology to define topo-climatic landscapes (TCL) in the north-west of Catalonia, which is situated in the north-east of the Iberian Peninsula. TCL provide data regarding the ecological behavior of a landscape in terms of its topography, physiognomy, and climate, which are the main drivers of an ecosystem. The variables selected are derived from a variety of different sources, such as remote sensing and climatic atlases. The methodology employed combines unsupervised iterative cluster classification with supervised fuzzy classification. Twenty eight TCL, which can be differentiated in terms of their vegetation physiognomy and vegetation altitudinal range type, were selected for the study area. Furthermore, a hierarchy among the TCL is established which permits the merging of clusters and allows for changes in thematic resolution. By using the topo-climatic landscape map, managers can identify patches with similar environmental conditions and at the same time assess the uncertainty involved in classification.  相似文献   
132.
Environmental Science and Pollution Research - This paper reports the development of a novel photoelectrochemical (PEC) oxidation technique based on UV-C irradiation and boron-doped diamond (BDD)...  相似文献   
133.
The debate concerning occupational safety and health (OSH) interventions has recently focused on the need of improving the evaluation of interventions, and in particular on the need for providing information about why the intervention worked or not, under what circumstances and in which context. Key concepts in the analysis of the context are the drivers, i.e., those factors enabling, fostering or facilitating OSH interventions. However, the concept of driver for an OSH intervention is both confused and contested. Although the term is widely used, there is little consensus on how drivers should be understood, how important they are in different contexts and how they can facilitate interventions. This exploratory study based on interviews with the owner-managers and the safety officers of small and medium-sized enterprises (SMEs) gives an overview of the most characteristic drivers for OSH interventions. The results will be used to make an initial evaluation of SMEs' needs, and will help orient interventions and future research.  相似文献   
134.
Conservation planning and biodiversity assessments need quantitative targets to optimize planning options and assess the adequacy of current species protection. However, targets aiming at persistence require population‐specific data, which limit their use in favor of fixed and nonspecific targets, likely leading to unequal distribution of conservation efforts among species. We devised a method to derive equitable population targets; that is, quantitative targets of population size that ensure equal probabilities of persistence across a set of species and that can be easily inferred from species‐specific traits. In our method, we used models of population dynamics across a range of life‐history traits related to species’ body mass to estimate minimum viable population targets. We applied our method to a range of body masses of mammals, from 2 g to 3825 kg. The minimum viable population targets decreased asymptotically with increasing body mass and were on the same order of magnitude as minimum viable population estimates from species‐ and context‐specific studies. Our approach provides a compromise between pragmatic, nonspecific population targets and detailed context‐specific estimates of population viability for which only limited data are available. It enables a first estimation of species‐specific population targets based on a readily available trait and thus allows setting equitable targets for population persistence in large‐scale and multispecies conservation assessments and planning.  相似文献   
135.
136.
We describe a model of forest flammability, based on daily satellite observations, for national to regional applications. The model defines forest flammability as the percent moisture content of fuel, in the form of litter of varying sizes on the forest floor. The model uses formulas from the US Forest Service that describe moisture exchange between fuel and the surrounding air and precipitation. The model is driven by estimates of temperature, humidity, and precipitation from the moderate resolution imaging spectrometer and tropical rainfall measuring mission multi-satellite precipitation analysis. We provide model results for the southern Amazon and northern Chaco regions. We evaluate the model in a tropical forest-to-woodland gradient in lowland Bolivia. Results from the model are significantly correlated with those from the same model driven by field climate measurements. This model can be run in a near real-time mode, can be applied to other regions, and can be a cost-effective input to national fire management programs.  相似文献   
137.
As part of a survey programme conducted by the Environment Department of the Autonomous Government of Catalonia in collaboration with the Spanish Council for Scientific Research (CSIC), dioxin concentrations in ambient air were measured in the four provinces of Catalonia (Spain). The study was also performed with the intention of providing data as a basis for future monitoring and evaluation of temporal trends in ambient air. Thus, 91 samples were collected in 25 different sites (rural, urban, suburban and industrial) between 1994 and 2000. The levels revealed a variable content of PCDDs/PCDFs depending both on the area and the contamination source. In particular, industrial areas presented levels ranging from 18 to 954 fg I-TEQ/m3. However, findings in urban and suburban sites varied between 13 and 357 fg I-TEQ/m3. As expected, the lowest levels were found in rural areas with levels between 5 and 125 fg I-TEQ/m3.  相似文献   
138.
139.
The ability of pine bark and almond shells to remove bisphenol A (BPA) from aqueous solutions was evaluated. Samples of these traditional agro-forestry by-products were milled, sieved into different particle size fractions (0.10–0.15 and 1.5–2.0 mm) and submitted to two different types of treatment. Sorption experiments were conducted in a batch system at room temperature and natural pH. Sorption equilibrium was attained after 48 h for all systems under study. Bisphenol A was adsorbed more effectively on the smaller particles of the sorbents. Pine bark and almond shell pretreated with formaldehyde presented higher sorption efficiency (95%), followed by almond shell (87%) and pine bark (82%) washed with hot water. All the sorption isotherms were found to fit a Freundlich equation, with correlation coefficients (R 2) between 0.823 and 0.989. The sorption coefficient (K F) ranged from 0.06 to 0.74 (mg1?1/n ·L 1/n ·g ?1). These results indicate that utilisation of both materials as an alternative sorbent for the removal of bisphenol A from contaminated waters is promising because they are available in large amounts and have an acceptable cost–efficiency ratio when compared with traditional adsorbents.  相似文献   
140.
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