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   257篇
  免费   1篇
  国内免费   10篇
安全科学   5篇
废物处理   14篇
环保管理   37篇
综合类   43篇
基础理论   55篇
污染及防治   63篇
评价与监测   35篇
社会与环境   16篇
  2023年   2篇
  2022年   26篇
  2021年   13篇
  2020年   8篇
  2019年   6篇
  2018年   7篇
  2017年   13篇
  2016年   5篇
  2015年   6篇
  2014年   11篇
  2013年   22篇
  2012年   9篇
  2011年   17篇
  2010年   11篇
  2009年   15篇
  2008年   10篇
  2007年   9篇
  2006年   11篇
  2005年   10篇
  2004年   7篇
  2003年   3篇
  2002年   4篇
  2001年   1篇
  1997年   1篇
  1996年   1篇
  1995年   2篇
  1994年   3篇
  1992年   1篇
  1991年   1篇
  1989年   1篇
  1988年   1篇
  1980年   2篇
  1979年   4篇
  1978年   1篇
  1976年   5篇
  1975年   1篇
  1974年   4篇
  1973年   3篇
  1972年   2篇
  1971年   2篇
  1967年   1篇
  1965年   1篇
  1964年   1篇
  1962年   1篇
  1961年   1篇
  1959年   1篇
  1955年   1篇
排序方式: 共有268条查询结果,搜索用时 15 毫秒
171.
172.
There is increasing optimism regarding the possible role that renewable energy technologies can play in the coming decade in the energy sector in India. Some recent developments and trends within the renewable energy sector that are responsible for this optimism, and the likely investments of the order of US$1210 million in the next four to five years, are discussed. The paper includes discussion of the recent changes in the implementing institutions, innovation in financing renewable technology investments, and a shift from financial to fiscal incentives. In addition, wind power generation, small hydro, photovoltaic and gasifier programmes are analysed in some detail.  相似文献   
173.
Environment, Development and Sustainability - The large-scale water-induced erosion is one of the most determining elements on land degradation in subtropical monsoon-dominated region. From this...  相似文献   
174.
Investigations were conducted into the treatment of effluents produced during manufacturing processes at both a chemicals production facility and a paint manufacturing facility. A comparison of costs of wastewater treatment at both facilities was also performed. The untreated effluents from both facilities were high in biological oxygen demand (BOD), chemical oxygen demand (COD), and total dissolved solids (TDS). In addition, the effluents from the two facilities deviated significantly in dissolved oxygen (DO) content and pH levels. However, both facilities ultimately released treated wastewater with allowable amounts or levels of BOD, COD, TDS, DO, and pH as permitted by the Department of the Environment, Ministry of Environment and Forests, Bangladesh (DOE). The effluent treatment plants (ETP) at both facilities contained combinations of chemical and biological treatment processes. The treatment processes used at the chemicals production facility and at the paint manufacturing facility were continuous and semi‐batch processes, respectively. The biological treatment section of the ETP at the chemicals production facility has both anaerobic and aerobic units, while the paint manufacturing facility has only an aerobic unit. Annual installation and operation costs of the ETP at the chemicals production facility was Bangladeshi Taka (Tk) 1,300,000 ($16,667 US dollars) and Tk 800,000 ($10,257), respectively. The annual installation and operation costs of the ETP at the paint manufacturing facility were Tk 3,050,000 ($39,103) and Tk 6,200,000 ($79,488), respectively.  相似文献   
175.
Toxicity assessment of heavy metals with Nostoc muscorum L   总被引:1,自引:0,他引:1  
Heavy metals in aquatic ecosystem (Mn, Ni, Zn, Cu) were tested for their toxicity against Nostoc muscorum L., a common fresh water phytoplankton, with respect to chlorophyll, protein, total carbohydrate and starch contents along with growth (OD). Mn showed stimulatory effect up to 1.5 ppm for all the observed parameters. However, Ni, Zn and Cu (0.1, 0.2, 0.3, 0.4 and 0.5 ppm) showed adverse effects even at 0.1 ppm. Chlorophyll was most sensitive parameter followed by carbohydrate, protein and starch. Ni was most toxic to N. muscorum followed by Cu and Zn. The IC50 for Ni was 0.1 ppm for growth, chlorophyll and protein, while total carbohydrate and starch showed IC50 at 0.3 and 0.4 ppm, respectively. The IC50 for Cu was recorded at 0.2 ppm for all the parameters. Zn showed IC50 at 0.3 ppm for growth, chlorophyll, protein and starch at 0.4 ppm for carbohydrate. This study can be applied as bioassay using cyanobacteria for toxicity assessment of various industrial wastes in aquatic ecosystem.  相似文献   
176.
The paper deals with the measurement of five heavy metals viz., Cd, Cu, Mn, Pb and Zn in water of the rivers Hooghly and Haldi at Haldia during June 1999 to October 2002. The industrial effluent out fall (OF) at Patikhali, Haldia was also taken as sampling site along with above out fall (AOF) and below out fall (BOF) sites. Most of the metals exhibited their least concentration at the sampling site above the Haldia industrial area of river Hooghly. The average concentrations of the studied metals were Cd 2-14, Cu 5-19, Mn 8-88, Pb 17-41 and Zn 22-37 microg l(-1). Comparison of the data with the Criterion Continuous Concentration (CCC) of USA revealed that Cd, Cu and Pb were the pollutants present at alarming level to disturb the aquatic life process in the zone. The effect was found to reflect on the tissue level aberrations in the residential fishes. The other two metals viz., Mn and Zn were probably less harmful to the aquatic ecosystem. In India, necessity is felt to develop the CCC values, which will be more appropriate for protection of aquatic environment than comparing with drinking water standards.  相似文献   
177.
The potential of Wolffia globosa, a profusely occurring rootless duckweed, was evaluated as an indicator of metal pollution in the water bodies. Plants of W. globosa were cultured in 3% Hoagland's nutrient medium which was supplemented with 0.05, 0.1, 1.0 and 2.0 mg/L of Cr and Cd. Plants showed substantial accumulation of both the metals at lowest concentrations. For example, at 0.05 ppm, the concentration factor (Cf) value for Cr was significantly higher (5616) than for Cd (1018). A high level of tolerance was shown by the plants to both Cr and Cd. The results show that the plants are sensitive to the variations in metal concentration and are capable of high metal enrichment at very low ambient concentration of the metals. This information may be useful for detecting metals in the water.NBRI Research Publication No. 401 (N.S.)  相似文献   
178.
179.
180.
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