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   2207篇
  免费   99篇
  国内免费   823篇
安全科学   186篇
废物处理   130篇
环保管理   178篇
综合类   1199篇
基础理论   359篇
污染及防治   833篇
评价与监测   77篇
社会与环境   79篇
灾害及防治   88篇
  2024年   3篇
  2023年   43篇
  2022年   115篇
  2021年   102篇
  2020年   71篇
  2019年   55篇
  2018年   84篇
  2017年   108篇
  2016年   130篇
  2015年   129篇
  2014年   158篇
  2013年   203篇
  2012年   213篇
  2011年   174篇
  2010年   150篇
  2009年   153篇
  2008年   160篇
  2007年   146篇
  2006年   113篇
  2005年   93篇
  2004年   52篇
  2003年   73篇
  2002年   80篇
  2001年   67篇
  2000年   49篇
  1999年   67篇
  1998年   62篇
  1997年   51篇
  1996年   47篇
  1995年   43篇
  1994年   24篇
  1993年   28篇
  1992年   22篇
  1991年   18篇
  1990年   5篇
  1989年   9篇
  1988年   13篇
  1987年   3篇
  1986年   3篇
  1985年   1篇
  1984年   2篇
  1982年   4篇
  1981年   1篇
  1973年   1篇
  1972年   1篇
排序方式: 共有3129条查询结果,搜索用时 0 毫秒
711.
云南雷暴的时空分布特征分析   总被引:16,自引:0,他引:16  
利用1971~2005年云南132个气象站的逐日气象观测资料,对云南雷暴的时间、空间分布特点和变化特征进行分析研究,运用保证率公式计算了云南不同地区的雷暴可能初终日时空分布。分析结果表明:云南雷暴天气35年来在波动中呈减少趋势,年平均雷暴日滇西北最少,滇西南最多。滇东北、滇西北雷暴初日开始较晚,雷暴终日结束较早。全省雷暴集中发生在4~9月。全省雷暴日变化基本相同,呈两峰一谷的变化趋势,最大峰值发生在午后14~22时。  相似文献   
712.
城市高温灾害及其预防   总被引:4,自引:0,他引:4  
谢德寿 《灾害学》1994,9(3):29-33
本文通过实例阐述了大城市高温灾害的主要成因是热岛效应;分析了高温对工业生产、人民生活的影响和危害,进而提出了城市高温灾害的预防措施和对策。  相似文献   
713.
论灾区开放政策   总被引:1,自引:1,他引:1  
本文论述了在我国实行灾区开放政策的重要意义,并以我国唐山、澜沧-耿马地震、原苏联亚美尼亚地震的震后救灾活动为例,以实行不同对外开放政策的效果对比,说明实行灾区开放政策的必要性;用通讯调查的结果和国际救灾组织及主要援助国对外救援情况,反映实行灾区开放政策的可行性。最后,提出灾情开放、救灾开放、灾害的考察研究开放和灾区重建开放的四项灾区开放政策的建议。  相似文献   
714.
岩石边坡稳定性的可靠性理论评价研究   总被引:2,自引:0,他引:2  
本文撇开了传统的整体刚性极限平衡法和条分法等安全每当法评价边坡的稳定性,采用可靠性理论对边坡稳定性进行评价,实践证明它是一种更符合工程实际的新方法。  相似文献   
715.
A series of processes by biofilter and Fenton oxidation to treat mature landfill leachate has been devised. At a hydraulic loading rate of 20 l m?3 d?1, a biofilter packed with aged refuse is found to remove 80% of chemical oxygen demand (COD), 89% of ammonia nitrogen and 96% of total phosphorus (TP). Particularly, TP levels dropped below 1 mg l?1. The optimal condition for Fenton oxidation was selected to be an initial pH of 5, a dosage of 0.01 and 0.02 mol l?1 of FeSO4 and H2O2, respectively, and a duration of 3 h, where COD removal efficiency reaches 58.6%, and BOD5/COD ratio is raised from 0.05 to 0.20. Subsequent treatment by a biofilter packed with slag reduces COD, ammonia nitrogen levels to less than 100, 25 mg l?1, respectively. A pilot scale experiment conducted in situ demonstrates that this series of processes exhibits a high efficiency in removing pollutants from mature landfill leachate and it is viable for application.  相似文献   
716.
Fluoride (F) distribution and its effects (fluorosis) were investigated in Antarctica. Droppings (L) excreta selected of aquatic birds, lake water, soil and moss (Polytrichum alpinum) showed a high F concentration. Although bones of Adelie penguin (Pygiscelis adeliae) and skua (Catharacta maccormicki) showed exceptionally very high F concentration in the range of 832 to 7187 mg kg(-1), their radiographs did not show any evidence of skeletal fluorosis. The possible reason and geochemical aspects of F in Antarctica region are discussed.  相似文献   
717.
本文对位于亚热带丘岗区畜牧业生态经济亚系统的畜种结构和生态效率进行研究。因地制宜地调整和优化畜种结构,充分合理地利用当地饲料资源,改善饲料营养结构,增强亚系统的总体功能。  相似文献   
718.
广州市城市森林的空间特征与发展研究   总被引:10,自引:0,他引:10  
应用城市林业的基本理论和GIS技术,广州市城区森林的空间分布以两山(白云山、越秀山)两河(珠江、流溪河)为核心,辅之公共绿地和道路绿化,形成多功能、多类型的网络式结构。近郊森林建设好风暴旅游林以及环绕卫星城镇和重点工业镇的生态公益林。远郊森林保障了“菜蓝子”工程,促进森林旅游及其相关产业的发展。  相似文献   
719.
● Present a general concept called “salinity exchange”. ● Salts transferred from seawater to treated wastewater until completely switch. ● Process demonstrated using a laboratory-scale electrodialysis system. ● High-quality desalinated water obtained at ~1 mL/min consuming < 1 kWh/m 3 energy. Two-thirds of the world’s population has limited access to potable water. As we continue to use up our freshwater resources, new and improved techniques for potable water production are warranted. Here, we present a general concept called “salinity exchange” that transfers salts from seawater or brackish water to treated wastewater until their salinity values approximately switch, thus producing wastewater with an increased salinity for discharge and desalinated seawater as the potable water source. We have demonstrated this process using electrodialysis. Salinity exchange has been successfully achieved between influents of different salinities under various operating conditions. Laboratory-scale salinity exchange electrodialysis (SEE) systems can produce high-quality desalinated water at ~1 mL/min with an energy consumption less than 1 kWh/m3. SEE has also been operated using real water, and the challenges of its implementation at a larger scale are evaluated.  相似文献   
720.
● A crosslinked polyaniline/carbon nanotube NF membrane was fabricated. ● Electro-assistance enhanced the removal rate of the NF membrane for bisphenol A. ● Intermittent voltage-assistance can achieve nearly 100% removal of bisphenol A. ● Membrane adsorption–electro-oxidation process is feasible for micropollutant removal. Nanofiltration (NF) has attracted increasing attention for wastewater treatment and potable water purification. However, the high-efficiency removal of micropollutants by NF membranes is a critical challenge. Owing to the adsorption and subsequent diffusion, some weakly charged or uncharged micropollutants, such as bisphenol A (BPA), can pass through NF membranes, resulting in low removal rates. Herein, an effective strategy is proposed to enhance the BPA removal efficiency of a crosslinked polyaniline/carbon nanotube NF membrane by coupling the membrane with electro-assistance. The membrane exhibited a 31.9% removal rate for 5 mg/L BPA with a permeance of 6.8 L/(m2·h·bar), while the removal rate was significantly improved to 98.1% after applying a voltage of 2.0 V to the membrane. Furthermore, when BPA coexisted with humic acid, the membrane maintained 94% removal of total organic carbon and nearly 100% removal of BPA at 2.0 V over the entire filtration period. Compared to continuous voltage applied to the membrane, an intermittent voltage (2.0 V for 0.5 h with an interval of 3.5 h) could achieve comparable BPA removal efficiency, because of the combined effect of membrane adsorption and subsequent electrochemical oxidation. Density functional theory calculations and BPA oxidation process analyses suggested that BPA was adsorbed by two main interactions: π–π and hydrogen-bond interactions. The adsorbed BPA was further electro-degraded into small organic acids or mineralized to CO2 and H2O. This work demonstrates that NF membranes coupled with electro-assistance are feasible for improving the removal of weakly charged or uncharged micropollutants.  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