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   1586篇
  免费   23篇
  国内免费   254篇
安全科学   69篇
废物处理   93篇
环保管理   121篇
综合类   401篇
基础理论   334篇
污染及防治   649篇
评价与监测   99篇
社会与环境   72篇
灾害及防治   25篇
  2023年   12篇
  2022年   67篇
  2021年   22篇
  2020年   27篇
  2019年   24篇
  2018年   88篇
  2017年   45篇
  2016年   67篇
  2015年   71篇
  2014年   74篇
  2013年   127篇
  2012年   77篇
  2011年   111篇
  2010年   82篇
  2009年   78篇
  2008年   91篇
  2007年   108篇
  2006年   85篇
  2005年   56篇
  2004年   87篇
  2003年   80篇
  2002年   44篇
  2001年   107篇
  2000年   52篇
  1999年   30篇
  1998年   21篇
  1997年   18篇
  1996年   20篇
  1995年   25篇
  1994年   17篇
  1993年   9篇
  1992年   8篇
  1991年   8篇
  1990年   4篇
  1989年   5篇
  1988年   4篇
  1987年   1篇
  1986年   1篇
  1985年   3篇
  1981年   1篇
  1980年   1篇
  1977年   1篇
  1975年   1篇
  1964年   1篇
  1960年   1篇
  1951年   1篇
排序方式: 共有1863条查询结果,搜索用时 31 毫秒
971.
This study is to modify the ecological footprint methodology by incorporating non-renewable or abiotic resources as an additional category. The use of abiotic resources can be quantified as global hectare by using thermodynamic approaches. A detailed case study on various countries including Australia, Belgium, Brazil, Canada, Japan, USA, and Vietnam shows the advantage of using the new modified ecological footprint (EF) as an indicator for sustainable development. The modified EF includes not only biotic resources, but also the abiotic resources. The case study indicates that the modified EF differs from the traditional EF up to 123% in the case of Belgium, and 90% in the case of Australia. For developing countries such as Brazil and Vietnam, the differences are relatively smaller (21% for Brazil and 9.4% for Vietnam). The estimated total ecological footprint of the world using the new method implies more serious problems associated with over consumption than using results from the original ecological footprint method.  相似文献   
972.
固相萃取-气相色谱法检测水中的邻苯二甲酸酯   总被引:7,自引:0,他引:7  
利用固相萃取技术富集了水中4种邻苯二甲酸酯类(PAEs)化合物:邻苯二甲酸二甲酯(DMP)、邻苯二甲酸二乙酯(DEP)、邻苯二甲酸二丁酯(DBP)、邻苯二甲酸二(2-乙基己基)酯(DEHP)。借助均匀设计法及计算机回归建模优化技术对4种PAEs的固相萃取条件进行了设计与优化,得到的最佳固相萃取条件:洗脱剂配比(正己烷与丙酮的体积比)30:1,洗脱体积2mL,洗脱速率4mL/min,上样速率8mL/min。富集后的试样用带电子捕获器的毛细管气相色谱仪检测,方法的线性范围为1~1000μg/L(DMP,DEP),0.2—100μg/L(DBP,DEHP),线性回归方程的相关系数为0.9970~1.0000,检出限为0.02-0.4μg/L,4种PAEs的回收率为69%~117%,相对标准偏差为2.5%~9.5%。[关键词]  相似文献   
973.
974.
Peroxidases and other lignin‐degrading enzymes and chemicals can potentially degrade persistent pollutants. Fifty vascular plant species were hydroponically tested for the capability of decolorization of Poly R‐478, a lignolytic indicator dye. The top six species that had less than 50 percent of control color at the end of the experiments were Pennisetum purpureum, Rumex crispus, Fimbristylis cymosa, Eleocharis calva, Hibiscus furcellatus, and Cyperus javanicus, in an order from high to low decolorization activity. F. cymosa, E. calva, and C. javanicus are in the Cyperaceae family. Extracellular peroxidase activity was found in vascular plants and correlated to decolorization of polymeric dyes. The plant R. crispus provided the highest guaiacol peroxidase enzyme activity among four of the top six plant species. The Poly R‐478 decolorization could be used as a fast screening technique for vascular plants that may have phytoremediation capability. © 2006 Wiley Periodicals, Inc.  相似文献   
975.
Caged populations of Monellia caryella (Fitch) were observed to condition pecan leaves throughout the season resulting in the leaves being unsuitable for subsequent colonization. Aphid populations were greatest (peak of 70 aphids/leaf) and occurred for a longer period (25 days) compared to late season activity (peak of 37 aphids/leaf, lasting 11 days) before conditioning occurred in closed cages. Intrinsic rates of increase per day or per degree-day declined during the season. Population growth was best described using an exponential increase equation compared to a logistic equation. These results indicated that as pecan leaves aged they were a poorer substrate for M. caryella and more easily made unsuitable for subsequent colonization.  相似文献   
976.
977.
In an era of rapid environmental change, China is facing increasing problems in the management of its large rivers and water resources. The disastrous 1998 Yangtze floods and the emerging water shortages in north China raised further concerns about the potential impact of environmental change on extreme hydrological events such as floods and droughts. Over the past few decades, increasing water consumption by the domestic, industrial and agricultural sectors, as well as a number of human activities such as deforestation, agricultural land expansion, wetland reclamation, construction of reservoirs and roads, water diversion, and sand/stone excavation significantly affect hydro-geomorphic processes such as water discharge and sediment flux throughout China. This paper aims to provide an overview of recent research on the water discharge changes occurring in major Chinese rivers and their vulnerability to environmental change. Most of the rivers, notably in north China, have experienced significant changes in water discharge over the last few decades, indicating that they are vulnerable to climatic variations and human activities. In contrast to north China, the rivers in south China have experienced less change, but some of the detected changes displayed similar trends to those in north China, though at a slower pace. These profound changes, in addition to the on-going projects such as the Three Gorges Dam Project and the South-North Water Transfer Project, will completely alter Chinas waterscape.  相似文献   
978.
A simple size-dependent compartmental model was developed to describe airborne dust exposure dynamics for the human respiratory tract (HRT) in mechanically ventilated swine buildings. Transport mechanisms of airborne dust for HRT include respiration, gravitational settling, turbulent diffusive deposition, inertial impaction, interception deposition loss, and dust clearance. The dominant deposition mechanism in the lung regions was found to be the inertial impaction rate, in which the order of magnitude ranged from 10(-3) to 10(-1) sec(-1). Results demonstrate that the extrathoracic region has a higher airborne dust mass lung/indoor ratios (0.71-0.87) than do the bronchial regions (0.41-0.74), the bronchiolar region (0.12-0.61), and the alveolar-interstitial region (0.01-0.49). The predictions from the HRT model agreed favorably with the experimental deposition profiles in the nasal passage, pharynx, bronchial, bronchiolar, and alveolar-interstitial regions, whereas the rms errors of the total deposition fraction between predicted values and ICRP66 and Non-ICRP66 were 0.15 and 0.07, respectively. Simulation results show that breathing via the nose has both a higher deposition fraction and a higher exposure dose in the size ranges 0.01-10 microm than does breathing orally.  相似文献   
979.
This paper investigates the relationship between pupils' environmental perception (in terms of preservation and utilisation of nature) and personality (in terms of risk-taking). 713 secondary school pupils in Switzerland were investigated. Environmental perception was assessed via three factors: Preservation, Utilisation of Nature and Consideration for Conservation. Risk-taking was evaluated via six factors: Positive Risking, Ambivalence, Thrill in Gambling, Ineffective Control, Effective Control, and Anger Reaction. Analysis of the correlation matrix between Risk-taking and Environmental perception revealed three profiles (types): the high scorer on Preservation is the controlled and cautious gambler. The Utiliser (anthropocentric) profile is essentially a mirror image of the first: the Utiliser does not enjoy unpredictable risks, reacts with anger when risks fail and has little control over his/her own risk-taking behaviour. The Consideration for Conservation (ecocentric) profile assumes a position between these two profiles.  相似文献   
980.
We propose a source of aerosols in the lower atmosphere associated with the creation, growth, and recombination of ubiquitous cosmogenically generated ions. This particle source should be favorable in the relatively clean, stable marine boundary layer, providing a uniform, continuous fine particle generator in the presence of dimethylsulfide emissions. Through this mechanism, new sulfate aerosols can be formed at sulfuric acid vapor partial pressures well below the supersaturations required for homogeneous binary nucleation of sulfuric acid/water solutions, which is consistent with numerous observations of new particle formation under sub-saturated conditions. The evolving aerosols in turn control the acid vapor concentration and thus modulate the sizes of the precursor ions and the rate of new particle formation. A simple model representing this nonlinear coupled system predicts that the physical and chemical processes connecting ions, vapors, and aerosols effectively constrain the particle population to a relatively narrow range of values. This self-limiting behavior may explain in part the apparent stability of the marine sulfate aerosol, with mean concentrations of the order of several hundred per cubic centimeter.  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