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   285篇
  免费   2篇
  国内免费   6篇
安全科学   10篇
废物处理   19篇
环保管理   39篇
综合类   40篇
基础理论   57篇
污染及防治   91篇
评价与监测   17篇
社会与环境   18篇
灾害及防治   2篇
  2023年   3篇
  2022年   10篇
  2021年   11篇
  2020年   5篇
  2019年   4篇
  2018年   5篇
  2017年   9篇
  2016年   8篇
  2015年   14篇
  2014年   15篇
  2013年   20篇
  2012年   16篇
  2011年   22篇
  2010年   15篇
  2009年   24篇
  2008年   11篇
  2007年   12篇
  2006年   18篇
  2005年   12篇
  2004年   12篇
  2003年   8篇
  2002年   10篇
  2001年   3篇
  2000年   2篇
  1998年   1篇
  1997年   2篇
  1996年   2篇
  1995年   3篇
  1993年   4篇
  1992年   1篇
  1991年   1篇
  1989年   2篇
  1986年   1篇
  1985年   1篇
  1981年   1篇
  1966年   1篇
  1964年   1篇
  1962年   1篇
  1960年   1篇
  1958年   1篇
排序方式: 共有293条查询结果,搜索用时 15 毫秒
171.
Mitigation and Adaptation Strategies for Global Change - A new process to remove carbon dioxide (CO2) from the atmosphere, by combining commercial industrial technologies with ocean liming and CO2...  相似文献   
172.
173.
High energy prices and the growing concern for “Peak Oil” have put energy analysis, once again, on the front burner. However, before speculating about possible roadmaps regarding our energy future, it would be wise to develop better quantitative analyses. This paper flags the existence of systemic epistemological flaws in the current use of aggregate energy indicators and presents an alternative approach capable of dealing with the issue of multiple dimensions and multiple scales. Starting from a critical appraisal of the aggregate indicator “Economic Energy Intensity” it shows that economic and biophysical variables are often correlated and that their value is determined by characteristics which can only observed across different levels and scales. Complex metabolic systems (systems that use energy to maintain and reproduce themselves) are operating simultaneously at different scales. This implies that changes in the characteristics of parts, defined at the local scale, and changes in the characteristics of the whole, defined at the large scale can only be obtained after establishing a scaling mechanism in the analysis. In order to deal with the issue of scale in energy accounting, we propose to make a distinction between three different categories: (i) primary energy sources (PES) - establishing a link between energy quantities and the associated requirement of biophysical gradients, at the large scale, on the interface black-box/context; (ii) energy carriers (EC) - defining the set of energy inputs required by technical devices for expressing useful functions, at the local scale, within the parts operating inside the black-box; (iii) end uses (EU) the set of functions to be expressed by society across hierarchical levels for reproducing itself. Finally, the paper presents examples of quantitative results obtained using an innovative method of analysis - Multi-Scale Integrated Analysis of Societal and Ecosystem Metabolism (MuSIASEM). We conclude that by using this new accounting method it is possible to generate a better understanding of external and internal constraints determining the desirability and viability of the metabolic pattern of societies.  相似文献   
174.
Environmental Science and Pollution Research - Radon exhalation from soil and ores is among the most dangerous risks for the public health care. The impact becomes even more powerful when...  相似文献   
175.
Although the concept of tropical birds as sedentary is pervasive, evidence suggests many are not. Our grasp of movement status in tropical birds is decidedly poor, but the successful long-term conservation of these birds depends on such information. Sedentariness will likely doom much tropical avian diversity, but increased vagility is a two-edged sword: beneficial in promoting immigration, but detrimental in that more than one habitat may be required. Birds requiring more than one habitat may be unable to locate a particular type as landscape modifications increase. Our long-term data set from the Sierra de Los Tuxtlas in southern Veracruz, México, reveals infrequent, large-scale movements in a local highland endemic. Wetmore's Bush-Tanager ( Chlorospingus ophthalmicus wetmorei) seems occasionally dependent upon lowland forests (now greatly diminished) as a refugium from temporarily unsuitable highlands. Our data and observations lead us to three conclusions: 1) assumptions of sedentariness in tropical birds should be made with extreme caution; 2) normal, but periodic phenomena may be easily overlooked, even in relatively long-term studies; and 3) missing such phenomena jeopardizes the success of any conservation plan because over the long term a population may be dependent upon refugia only occasionally occupied.  相似文献   
176.
177.
Environmental Science and Pollution Research - In the present paper, different types of pure and commercial plastic waste from different EU countries (UK, France, Italy, and Romania) were...  相似文献   
178.
Recent studies have demonstrated the antibacterial effect of micro and nanoparticles of chitosan (CS) crosslinked with sodium tripolyphosphate (TPP), and incorporating metallic ions, bringing that the size, shape, and zeta potential are related to the antimicrobial potential. However, there are few studies on the antifungal activity and the effect of TPP on the antimicrobial potential. Micro and nanoparticles were prepared from CS by ionotropic gelation with TPP, and structurally characterized by transmission and scanning electron spectroscopy, and Fourier transformed infrared spectroscopy. Depending on the concentration of CS and TPP, spherical particles were obtained from 80 nm to 20 μm. Subsequently, particles were evaluated for their antifungal potential against Aspergillus parasiticus assessing radial growth, spore germination, and morphological changes. An increase in the antifungal potential compared with CS in solution was observed, inhibiting the development of the fungus causing clear morphological changes in both, hyphae and spores. Particle size and the availability of functional groups of CS/TPP (amino group and phosphate), suggest a possible synergistic effect between CS and TPP.  相似文献   
179.
180.
Objective: The aim of this study was to (1) examine the psychological impact of non-invasive prenatal testing (NIPT) in women with a high-risk (≥1 : 300) and low-risk (≤1 : 301) result on combined first trimester screening (cFTS) and (2) to examine factors influencing anxiety and decision-making in both risk populations. Method: Questionnaires and structured interviews were administered to low (n = 50) and high (n = 63) risk women at the time of NIPT blood draw (point A) and again at least 1 week after receiving their NIPT result (point B). Anxiety levels were measured at these two time points using the State–Trait Anxiety Inventory. Results: Both high-risk and low-risk cFTS groups demonstrated similar intrinsic (trait) anxiety levels (36 ± 10 vs 35 ± 10; p = 0.70). High-risk women had significantly higher levels of state anxiety at point A than low-risk women (42 ± 11 vs 36 ± 11; p < 0.01). Both groups had a statistically significant reduction (p < 0.01), to similar final levels of state anxiety at point B (30 ± 11 vs 29 ± 8; p = 0.61). Conclusion: Women receiving a high-risk result on cFTS have higher levels of state anxiety than their low-risk counterparts. Following a low-risk NIPT result, the anxiety levels in both populations are reduced to similar levels. © 2017 John Wiley & Sons, Ltd.  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