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   1433篇
  免费   45篇
  国内免费   427篇
安全科学   106篇
废物处理   88篇
环保管理   104篇
综合类   673篇
基础理论   279篇
污染及防治   510篇
评价与监测   48篇
社会与环境   39篇
灾害及防治   58篇
  2023年   20篇
  2022年   73篇
  2021年   59篇
  2020年   32篇
  2019年   35篇
  2018年   60篇
  2017年   49篇
  2016年   61篇
  2015年   69篇
  2014年   113篇
  2013年   134篇
  2012年   106篇
  2011年   106篇
  2010年   99篇
  2009年   100篇
  2008年   99篇
  2007年   62篇
  2006年   73篇
  2005年   44篇
  2004年   54篇
  2003年   64篇
  2002年   42篇
  2001年   36篇
  2000年   41篇
  1999年   29篇
  1998年   59篇
  1997年   41篇
  1996年   24篇
  1995年   25篇
  1994年   25篇
  1993年   26篇
  1992年   18篇
  1991年   11篇
  1990年   5篇
  1989年   5篇
  1988年   2篇
  1987年   2篇
  1984年   2篇
排序方式: 共有1905条查询结果,搜索用时 250 毫秒
841.
We studied the energy and economic flow of six types of homegardens in Sanjia village, SW China. Our study showed that the energy input of six types of homegardens averaged 99.11-175.65 x 1010J/ha, the energy output was 102.30-159.83 x 1010J/ha and the ratio of input/output ranged between 1:0.880-1:1.416. The ratios of input to output of home-gardens that prioritized cultivation of crops were higher than for homegardens that prioritized animal husbandry or other economic activities. The economic ratio of input/ output of six types of homegardens varied between 1:0.997-1:1.376 and the economic output ranged between 2480.0-10131.5 RMB/yr. We concluded that the homegarden systems of Sanjia village are high in the input and output of energy and cash flow, and can provide a basis for designing models of farm economy in rural subtropical areas.  相似文献   
842.
Anaerobic co-digestion of corn stalk and vermicompost (VC) as well as mono-digestion of corn stalk were investigated. Batch mono-digestion experiments were performed at 35 ± 1 °C and initial total solid loading (TSL) ranged from 1.2% to 6.0%. Batch co-digestion experiments were performed at 35 ± 1 °C and initial TSL of 6% with VC proportions ranged from 20% to 80% of total solid (TS). For mono-digestion of corn stalk, a maximum methane yield of 217.60 ± 13.87 mL/g TSadded was obtained at initial TSL of 4.8%, and acidification was found at initial TSL of 6.0% with the lowest pH value of 5.10 on day 4. Co-digestion improved the methane yields by 4.42–58.61% via enhancing volatile fatty acids (VFAs) concentration and pH value compared with mono-digestion of corn stalk. The maximum biogas yield of 410.30 ± 11.01 mL/g TSadded and methane yield of 259.35 ± 13.85 mL/g TSadded were obtained for 40% VC addition. Structure analysis by X-ray diffractometry (XRD) showed that the lowest crystallinity of 35.04 of digested corn stalk was obtained from co-digestion with 40% VC, which decreased 29.4% compared to 49.6 obtained from un-treated corn stalk. It is concluded that co-digestion with VC is beneficial for improving biodigestibility and methane yield from corn stalk.  相似文献   
843.
本文主要介绍国家标准GB/T28409—2012的制订背景以及防护鞋(靴)的选择、使用和维护指南,并提出标准实施的建议。  相似文献   
844.
党的十八大以科学发展观为指导,提出了推进生态文明、建设美丽中国的战略任务,生态文明是我党创造性地回答经济发展与资源环境关系问题所取得的最新理论成果,为统筹人与自然和谐发展指明了前进方向。改革开放的中国,社会经济高速发  相似文献   
845.
为了提高试采放空天然气的利用率,考虑将不能输送的放空低压气进行技术增压,达到输送压力后,使其进入油气处理装置进行分离,其中一部分通过注气压缩机回注至地层,保持地层压力,提高油田凝析油采收率和延长油气田开发时间,实现低压气的高效利用。对站外试采井的低压放空气进行增压回收,减少了天然气资源浪费,实现了向资源节约型、环境保护企业的健康发展。  相似文献   
846.
在水质检测工作中,质量控制方法是确保检测数据准确的一种重要手段。当前水质检测实验室中常用的质控手段有盲样考核、平行测定、加标回收、比对试验、期间核查、相关性分析与质量监督六类,通过分析比较这些质控手段在分析检测中的差异及其对检测结果的影响,为提升水质检测工作质量,出具科学、公正的检测报告提供保障。  相似文献   
847.
随着经济全球化、城市化进程的加剧,城市生态的规划建设对社会经济发展起着至关重要的作用。从可持续发展视域探讨当前城市规划建设中存在的由规划滞后、规划重复、规划片面、执法不严等造成的城市规划环境污染、资源浪费和生态破坏的问题,提出构建城市生态规划的现实必然性和基本原则,从强化机制、转变观念、以人为本、健全法制、合理规划等角度探讨可持续发展视阈下城市生态规划的途径。  相似文献   
848.
在磷酸盐缓冲液(PB)中考察了特定条件下超声/过硫酸盐(US/PS)降解阿特拉津(又称莠去津,ATZ)的效果并对其降解机理及动力学进行了探讨.结果显示,在恒温水浴20℃的pH7的PB中,PS、ATZ浓度分别为200、0.928μmol/L,US强度为0.88 W/mL,反应时间为60 min时,US/PS对ATZ的降解...  相似文献   
849.
• The PNA, denitratation/anammox, and DAMO/anammox process are reviewed together. • Denitratation/anammox-based process is promising in mainstream treatment. • DAMO and denitratation processes realize the higher nitrogen removal efficiency. • The utilization of metabolism diversity of functional microbe is worth exploring. • An effective waste treatment system concept is proposed. Anammox technology has been widely researched over the past 40-year from the laboratory-scale to full-scale. It is well-known that in actual applications, the solo application of anammox is not feasible. Since both ammonium and nitrite are prerequisites based on the reaction mechanism, the pre-treatment of wastewater is necessary. With the combination of anammox process and other pre-treatment processes to treat the actual wastewater, many types of anammox-based processes have been developed with distinct nitrogen removal performance. Thus, in order to heighten the awareness of researchers to the developments and accelerate the application of these processes to the treatment of actual wastewater, the main anammox-based processes are reviewed in this paper. It includes the partial nitritation/anammox process, the denitratation/anammox (PD/A) process, the denitrifying anaerobic methane oxidation/anammox (DAMO/A) process, and more complex deuterogenic processes. These processes have made the breakthroughs in the application of the anammox technology, such as the combination of nitrification and PD/A process can achieve stability and reliability of nitrogen removal in the treatment of mainstream wastewater, the PD/A process and the DAMO/A have brought about further improvements in the total nitrogen removal efficiency of wastewater. The diversity of functional microbe characteristics under the specific condition indicate the wide application potential of anammox-based processes, and further exploration is necessary. A whole waste treatment system concept is proposed through the effective allocation of above mentioned processes, with the maximum recovery of energy and resources, and minimal environmental impact.  相似文献   
850.
Environmental Science and Pollution Research - The motivation of this fundamental research is to reveal the response of ecosystem services to land use change and to support the sustainable...  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