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   374篇
  免费   3篇
  国内免费   1篇
安全科学   10篇
废物处理   25篇
环保管理   36篇
综合类   55篇
基础理论   46篇
污染及防治   138篇
评价与监测   46篇
社会与环境   21篇
灾害及防治   1篇
  2024年   2篇
  2023年   12篇
  2022年   13篇
  2021年   20篇
  2020年   8篇
  2019年   8篇
  2018年   7篇
  2017年   10篇
  2016年   24篇
  2015年   13篇
  2014年   19篇
  2013年   40篇
  2012年   27篇
  2011年   28篇
  2010年   22篇
  2009年   18篇
  2008年   20篇
  2007年   12篇
  2006年   27篇
  2005年   11篇
  2004年   19篇
  2003年   2篇
  2002年   4篇
  2001年   1篇
  2000年   3篇
  1998年   1篇
  1997年   1篇
  1994年   1篇
  1992年   2篇
  1986年   1篇
  1985年   1篇
  1964年   1篇
排序方式: 共有378条查询结果,搜索用时 0 毫秒
81.
         下载免费PDF全文
We report on the biodegradation of pure hydrocarbons and chemotaxis towards these compounds by an isolated chlorophenol degrader,Pseudomonas strain H.The biochemical and phylogenetic analysis of the 16S rDNA sequence identified Pseudomonas strain H as having 99.56% similarity with P.aeruginosa PA01.This strain was able to degrade n-hexadecane,1-undecene,1-nonene,1-decene,1-dodecene and kerosene.It grew in the presence of 1-octene,while this hydrocarbons is toxic to other hydrocarbons degraders.Pseudomonas strain H was also chemotactic towards n-hexadecane,kerosene,1-undecene and 1-dodecene.These results show that this Pseudomonas strain H is an attractive candidate for hydrocarbon-containing wastewater bioremediation in controlled environments.Since the classical standard techniques for detecting chemotaxis are not efficient at low bacterial concentrations,we demonstrate the use of the dynamic speckle laser method,which is simple and inexpensive,to confirm bacterial chemotaxis at low cell concentrations (less than 105 colony-forming unit per millilitre (CFU/mL)) when hydrocarbons are the attractants.  相似文献   
82.
83.
         下载免费PDF全文
n-Alkanes and polycyclic aromatic hydrocarbons (PAHs) bound to atmospheric particulate matter (PM1) were investigated in a traffic site located in an urban area of Venice Province (Eastern Po Valley, Italy) during the cold season. Considering the critical situation affecting the Veneto Region concerning the atmospheric pollution and the general lack of information on PM1 composition and emission in this area, this experimental study aims at determining the source profile, their relative contributions and the dispersion of finer particles. Four sources were identified and quantified using the Positive Matrix Factorization receptor model: (1) mixed combustions related to the residential activities, (2) agricultural biomass burning in addition to the resuspension of anthropogenic and natural debris carried by the wind, (3) gasoline and (4) diesel traffic-related combustions. The role of local atmospheric circulation was also investigated to identify the pollutant sources.  相似文献   
84.
The survival of hymenopteran populations especially that of ecologically and economically important pollinators and parasitoids, has become a major topic for empirical and theoretical studies. Complementary sex determination (CSD) in Hymenoptera may impose a substantial genetic load through the production of inviable or sterile diploid males. Modelling and laboratory studies have indicated that this genetic load may trigger a ‘diploid male vortex’ leading to rapid extinction of populations.Here we take a broader theoretical approach to analyze why populations exhibiting CSD persist in nature, even if they contain large proportions of homozygous diploid individuals. Using an individual-based model of spatially structured hymenopteran populations, we show that (i) inviability or reduced fertility of homozygous individuals, (ii) female-biased sex ratio, and (iii) strong intra-specific competition can mitigate the negative influence of CSD on population persistence and that (iv) already extremely low dispersal rates will result in long term survival. These findings underline the importance of life history traits for population survival and demonstrate that rather specific conditions must be met to initiate the ‘diploid male vortex’.  相似文献   
85.
A phylogenetic analysis based on rDNA internal transcribed spacers (ITS) sequences was performed on 15 species of black corals assigned to the genera Antipathes, Stichopathes, Cirrhipathes, Rhipidipathes, Antipathella, Myriopathes and Cupressopathes recorded from the Messina Strait (Mediterranean Sea) and the Bunaken Marine Park (Celebes Sea, Indonesia). The phylogenetic analysis shows that the examined species are grouped in two main branches corresponding to the families Antipathidae-Aphanipathidae and Myriopathidae. While among the Myriopathidae species there is a very small genetic distance, the Antipathidae-Aphanipathidae clade shows a high degree of divergence between different genera. According to this study, the taxon Antipathes? sp. 3 characterised by a bush-like corallum without a well-defined axis, probably belongs to a new undescribed genus of the family Antipathidae.  相似文献   
86.
87.
Environmental Geochemistry and Health - Thermal caves represent an environment characterized by unique chemical/physical properties, often used for treatment and care of musculoskeletal,...  相似文献   
88.
    
The literature on the subject of corporate social responsibility and environmental management in small‐ and medium‐sized enterprises (SMEs) has theorized about the different factors influencing the propensity of business owners/managers towards sustainability. However, the varying results and some gaps in these previous studies have highlighted the need to search for new models for the relationships among these drivers. This study theorizes and tests a model in which the decision flow of SME owners/managers is described as a multistep process in which the first push felt from internal and external pressures is mediated by two opposite forces: the positive influence exerted by the perceived benefits of sustainability and the negative influence exerted by the perceived barriers of implementing it. Data were collected from an Italian SME survey and analyzed through structural equation modelling. The results confirmed the hypotheses of a mediated path of influence, thus highlighting the different roles of factors that enable and block sustainability in SMEs, with prospective business and policy‐making implications in the light of the pursuit of the United Nation's recommended Sustainable Development Goals.  相似文献   
89.
    
ABSTRACT: The size, scale, and number of subwatersheds can affect a watershed modeling process and subsequent results. The objective of this study was to determine the appropriate level of subwatershed division for simulating flow, sediment, and nutrients over 30 years for four Iowa watersheds ranging in size from 2,000 to 18,000 km2 with the Soil and Water Assessment Tool (SWAT) model. The results of the analysis indicated that variation in the total number of subwatersheds had very little effect on streamflow. However, the opposite result was found for sediment, nitrate, and inorganic P; the optimal threshold subwatershed sizes, relative to the total drainage area for each watershed, required to adequately predict these three indicators were found to be around 3, 2, and 5 percent, respectively. Decreasing the size of the subwatersheds below these threshold levels does not significantly affect the predicted levels of these environmental indicators. These threshold subwatershed sizes can be used to optimize input data preparation requirements for SWAT analyses of other watersheds, especially those within a similar size range. The fact that different thresholds emerged for the different indicators also indicates the need for SWAT users to assess which indicators should have the highest priority in their analyses.  相似文献   
90.
Journal of Polymers and the Environment - Electrospinning of water-soluble polymers is considered a green process for encapsulating active compounds in polymeric nanofibers, but generally the...  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