全文获取类型
收费全文 | 712篇 |
免费 | 75篇 |
国内免费 | 193篇 |
专业分类
安全科学 | 101篇 |
废物处理 | 26篇 |
环保管理 | 61篇 |
综合类 | 361篇 |
基础理论 | 241篇 |
污染及防治 | 81篇 |
评价与监测 | 19篇 |
社会与环境 | 79篇 |
灾害及防治 | 11篇 |
出版年
2024年 | 5篇 |
2023年 | 14篇 |
2022年 | 28篇 |
2021年 | 28篇 |
2020年 | 30篇 |
2019年 | 30篇 |
2018年 | 24篇 |
2017年 | 33篇 |
2016年 | 32篇 |
2015年 | 46篇 |
2014年 | 35篇 |
2013年 | 90篇 |
2012年 | 66篇 |
2011年 | 93篇 |
2010年 | 50篇 |
2009年 | 45篇 |
2008年 | 39篇 |
2007年 | 43篇 |
2006年 | 38篇 |
2005年 | 22篇 |
2004年 | 22篇 |
2003年 | 33篇 |
2002年 | 20篇 |
2001年 | 22篇 |
2000年 | 17篇 |
1999年 | 17篇 |
1998年 | 11篇 |
1997年 | 12篇 |
1996年 | 7篇 |
1995年 | 4篇 |
1994年 | 7篇 |
1993年 | 6篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1975年 | 1篇 |
1971年 | 2篇 |
1970年 | 1篇 |
排序方式: 共有980条查询结果,搜索用时 234 毫秒
1.
汞污染具有生物积累性,因而得到社会广泛关注。研究监测和评估了郑州市城区土壤和绿色植物叶片中汞浓度、分布、污染水平等。研究发现郑州市主城区土壤总汞浓度为0. 150~0. 958 mg/kg,平均浓度为0. 448 mg/kg;郑州市主城区绿色植物叶片总汞浓度为0. 017~0. 249 mg/kg,平均浓度为0. 107 mg/kg;土壤和叶片中汞浓度按功能区排序为交通枢纽区工业区商业区行政区高教区住宅区。采用地累积指数法对郑州市80个土壤样品的汞污染水平进行评估,结果显示60%受到轻度污染,35%受到偏中度污染,5%受到中度污染。研究较为全面地分析了土壤汞污染的现状及浓度,为郑州市土壤汞污染防治提供参考。 相似文献
2.
通过实验考察了酸性条件下纳米铁催化分解高氯酸盐过程中的影响因素,对其分解的动力学进行了研究,并对纳米铁催化剂结构及微观形貌进行SEM、EDS和XRD表征分析。利用阿仑尼乌斯方程和幂指数方程拟合反应动力学方程,获得了高氯酸盐分解动力学方程Ct=C0exp{-0.03773exp(-201.65/T)[H]0.191t},理论的计算值与实验值吻合较好,误差在15%以内。 相似文献
3.
The performance of Ce-OMS-2 catalysts was improved by tuning the fill percentage in the hydrothermal synthesis process to increase the oxygen vacancy density. The Ce-OMS-2 samples were prepared with different fill percentages by means of a hydrothermal approach (i.e. 80%, 70%, 50% and 30%). Ce-OMS-2 with 80% fill percentage (Ce-OMS-2-80%) showed ozone conversion of 97%, and a lifetime experiment carried out for more than 20?days showed that the activity of the catalyst still remained satisfactorily high (91%). For Ce-OMS-2-80%, Mn ions in the framework as well as K ions in the tunnel sites were replaced by Ce4+, while for the others only Mn ions were replaced. O2-TPD and H2-TPR measurements proved that the Ce-OMS-2-80% catalyst possessed the greatest number of mobile surface oxygen species. XPS and XAFS showed that increasing the fill percentage can reduce the AOS of Mn and augment the amount of oxygen vacancies. The active sites, which accelerate the elimination of O3, can be enriched by increasing the oxygen vacancies. These findings indicate that increasing ozone removal can be achieved by tuning the fill percentage in the hydrothermal synthesis process. 相似文献
4.
5.
In the present study, the influence of aluminium on the regeneration potential of leaf and stem-cuttings of Portulaca oleracea was studied in order to identify a terrestrial plant species as an alternate biomonitoring toolof fresh water environment. The leaves and stem cuttings of theterrestrial plant, P. oleracea grew well in the distilled water producing adventitious and lateral roots. The aluminium treated leaves and stem cuttings showed a reduction in the growthof the adventitious and lateral roots and increase in the decay of leaves and stem cuttings with increasing aluminium concentration. The tolerance index calculated for the leaves and the stem cuttings showed that the leaves were more sensitivethan stems to aluminium. Since all the parameters studied showedconcentration dependent changes, the terrestrial plant, P. oleracea can be considered a suitable biomonitoring tool of fresh water environment besides its usage in the Al toxicity testing. 相似文献
6.
B. Beck-Friis M. Pell U. Sonesson H. Jönsson H. Kirchmann 《Environmental monitoring and assessment》2000,62(3):317-331
Composting can be a source of N2O andCH4 production. In this investigation, differentcompost heaps of organic household waste weremonitored with the focus on potential formation ofCH4 and N2O in the heaps and emission ofthese gases from the heaps. The studied compost heapshad different compost ages, turning intervals andcompost sizes. The analysed compost gases containedbetween 1–3421 L of N2O-N L-1 and 0–470 mL of CH4 L-1. The emission rates ofN2O and CH4 from the compost heaps werebetween 1–1464 mg N2O m-2 day-1 and0–119 000 mg CH4 m-2 day-1. These verylarge differences in compost gas composition andemission indicate the importance of compostmanagement. The results also give an understanding ofwhere in the composting process an increasing emissionof N2O and CH4 can occur. 相似文献
7.
A. Haurie J.J.E. Kübler A. Clappier H. van den Bergh 《Environmental Modeling and Assessment》2004,9(1):1-12
A method is proposed to build integrated models (also called Metamodels) aimed at quantifying the economic efficiency of air quality policies. This Metamodeling approach is based on the coupling of two complementary models, that operate at different scales in space and time, and which represent the economic and the physical and chemical processes, respectively. The joint consideration of the physico-chemical and techno-economic structure of the pollution control problems permits a comprehensive evaluation of air pollution abatement strategies. The motivating pollution control problems include urban-regional air quality management through efficient energy and traffic control policies. A pilot study, exploiting data collected in the Geneva canton (Switzerland), is used to demonstrate the potential of the approach. 相似文献
8.
9.
The effects of different aluminium chloride concentrations together with varying calciumchloride concentrations on root growth, cell division and nucleoli in root tip cells of Allium cepa werestudied. The concentrations used for aluminium chloride were 10-4, 10-3 and 10-2 mol/L ; and for calcium chloride were 10-5 , 10-4 , 10-3 and 10-2 mol/L, respectively. The results showed that after thetreatments with 10-2 to 10-3 mol/L Al3+ , root growth was severely inhibited , a large nurnber of thecells with c-mitosis were induced and the nucleolar material was extruded from the nucleus into the cytoplasm. However , the treatments with 10-2 to 10-3 mol/L of Al3+ together with 10-2)to 10-5 mol/LCa2+ suggested that Ca2+ gave the obviously protective effects against Al3+ poisoning in root growth.cell division and nucleoli of the root tip cells in A. cepa. The possible mechanism of these protective effects of Ca2+) is also briefly discussed. 相似文献
10.
TiO2膜固载型多孔催化剂的光催化分解试验 总被引:3,自引:0,他引:3
以多孔基质为载体,用溶胶-凝胶法制备出载TiO2薄膜的多孔型光催化剂。用X射线衍射和扫描电镜对催化剂的物相和形貌进行了表征,此催化剂能在光照下分解水溶液中四环素抗菌素。经1h光照,四环素的分解率可达85%左右。 相似文献