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   706篇
  免费   69篇
  国内免费   122篇
安全科学   255篇
废物处理   10篇
环保管理   56篇
综合类   378篇
基础理论   49篇
污染及防治   26篇
评价与监测   37篇
社会与环境   20篇
灾害及防治   66篇
  2024年   4篇
  2023年   19篇
  2022年   24篇
  2021年   35篇
  2020年   26篇
  2019年   27篇
  2018年   23篇
  2017年   22篇
  2016年   24篇
  2015年   31篇
  2014年   82篇
  2013年   41篇
  2012年   43篇
  2011年   64篇
  2010年   38篇
  2009年   46篇
  2008年   42篇
  2007年   38篇
  2006年   27篇
  2005年   32篇
  2004年   21篇
  2003年   30篇
  2002年   22篇
  2001年   16篇
  2000年   7篇
  1999年   14篇
  1998年   11篇
  1997年   12篇
  1996年   13篇
  1995年   9篇
  1994年   14篇
  1993年   7篇
  1992年   6篇
  1991年   9篇
  1990年   6篇
  1989年   7篇
  1988年   3篇
  1987年   2篇
排序方式: 共有897条查询结果,搜索用时 31 毫秒
481.
针对电除尘器在运行中出现的问题,利用大小修的机会,先后对电除尘器采取了一些必要的改造措施,达到了提高电除尘器收尘效果和可靠性的目的。  相似文献   
482.
通过对某型号卫星贮箱支架的数控加工实践,研究了大型铝合金框架式薄壁结构件的高效数控加工工艺技术。通过合理选择机械加工规程和工艺参数,解决了这类零件加工过程中极易超差等难题,可靠地满足了型号研制的要求。同时利用MastercamX软件研究了高效数控加工问题。  相似文献   
483.
分析了蒸馏装置减压塔进料接管角焊缝开裂、泄漏原因,阐述了减压转油线冷紧的重要性及检修中应注意的问题。  相似文献   
484.
In an urban-transit bus,fueled by biodiesel in Toledo,Ohio,single inhalable particle samples in October 2008 were collected and detected by scanning electron microscopy and energy dispersive X-ray spectrometry(SEM/EDS).Particle size analysis found bimodal distribution at 0.2 and 0.5 μm.The particle morphology was characterized by 14 different shape clusters:square,pentagon,hexagon,heptagon,octagon,nonagon,decagon,agglomerate,sphere,triangle,oblong,strip,line or stick,and unknown,by quantitative order.The square particles were common in the samples.Round and triangle particles are more,and pentagon,hexagon,heptagon,octagon,nonagon,decagon,strip,line or sticks are less.Agglomerate particles were found in abundance.The surface of most particles was coarse with a fractal edge that can provide a suitable chemical reaction bed in the polluted atmospheric environment.The three sorts of surface patterns of squares were smooth,semi-smooth,and coarse.The three sorts of square surface patterns represented the morphological characteristics of single inhalable particles in the air inside the bus in Toledo.The size and shape distribution results were compared to those obtained for a bus using ultra low sulfur diesel.  相似文献   
485.
The sludge, which was collected from a biological coke wastewater treatment plant, was used as a low-cost adsorbent in the removal of reactive dyes (methylene blue (MB) and reactive red 4 (RR4)) from aqueous solution. The pH of dye solution played an important role on the dye uptake. As the solution pH increase, the MB uptake increased, while the RR4 uptake decreased. The maximum uptake of RR4 by protonated sludge was 73.7 mg/g at pH 1, and the maximum uptake of MB by sludge was 235.3 mg/g at pH 9. Three functional groups, including carboxyl, phosphonate, and amine group, were identified by potentiometric titration, fourier transform infrared (FT-IR) spectrometry, and X-ray photoelectron spectroscopy (XPS). The anionic functional groups, phosphonate and carboxyl group, were identified as the binding sites for the cationic MB. Amine groups were identified to bind RR4. The main mechanism of the reactive dyestuffs adsorption is electrostatic interaction.  相似文献   
486.
通过对不同土壤环境标准物质和留样进行实测比对,验证了不同品牌的便携式X荧光光谱仪在不同样品情况下的工作性能,然后根据测试结果的准确度、精密度、可比性和仪器的辐射安全性优选出可用的仪器品牌;并对便携式X荧光光谱仪在土壤监测中存在的问题进行了探讨。  相似文献   
487.
地铁隧道因地质条件及周边环境的复杂性、不确定性等特点,施工风险较高。本文根据武汉地铁2号线一期工程沿线遭遇的各类不良地质问题,结合工程地质及水文地质条件和周边环境特点,辨识出武汉地铁2号线一期工程矿山法施工区间隧道主要的风险事件并进行了风险分析;同时采用R=P×C的风险定级方法,定量得到各风险事件的风险等级;并根据风险评估的结果,对风险较高的事件提出了具体的风险控制措施,从而确保了工程的顺利进行。该研究可为其他类似工程提供参考。  相似文献   
488.
-PbO2 electrodes were prepared by electro-deposition and characterized by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and linear sweep voltammetry. We confirmed pure -PbO2 crystals were on the electrode and it had a high oxygen evolution potential. The photoactivity and photoelectrochemical (PEC) properties of the -PbO2 electrode were investigated under visible light irradiation ( > 420 nm) for the decolorization of Methylene Blue. Pseudo first-order kinetics parameter (Kapp) for dye decolorization using the -PbO2 electrode achieved 6.71×10?4 min?1 under visible light irradiation, which indicated its excellent visible light-induced photoactivity. The Kapp of the PEC process was as much as 1.41×10?3 min?1 and was 1.71 times that of visible light irradiation or electrolysis even in the presence of the -PbO2 electrode. A significant synergetic effect was observed in the PEC system. We also employed TiO2 modified -PbO2 electrodes in this test, which revealed that the TiO2 immobilized on the -PbO2 electrode inhibited the visible light-induced PEC efficiency despite the amount of TiO2 used for electrode preparation. The -PbO2 electrode was also superior to the dimensionally stable anode (Ti/Ru0:3Ti0:7O2) in visible light-induced photoactivity and PEC efficiency.  相似文献   
489.
An improved watershed criteria model was developed in light of research on payment for ecosystem services outflows theory.  相似文献   
490.
基于某尾矿库目前标高和最终标高的概化模型,在正常水位和洪水位两种工况下,采用GeoStudio软件中的SEEP/W模块进行渗流场模拟,并应用SLOPE/W模块对每种条件下尾矿坝的稳定性进行数值计算,得到最危险滑动面和最小抗滑稳定系数。结果表明,在排渗设施正常工作的情况下,尾矿坝边坡稳定性均满足规范要求的最小安全系数,但终高洪水位时坝体安全系数的富余不是很大。同时验证了尾矿坝安全系数随着库内水位的上升以及浸润线深度的变化规律。  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