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   12546篇
  免费   491篇
  国内免费   4448篇
安全科学   826篇
废物处理   801篇
环保管理   938篇
综合类   6912篇
基础理论   2057篇
环境理论   6篇
污染及防治   4405篇
评价与监测   495篇
社会与环境   471篇
灾害及防治   574篇
  2024年   1篇
  2023年   197篇
  2022年   576篇
  2021年   479篇
  2020年   352篇
  2019年   359篇
  2018年   483篇
  2017年   559篇
  2016年   526篇
  2015年   701篇
  2014年   982篇
  2013年   1276篇
  2012年   1019篇
  2011年   1191篇
  2010年   855篇
  2009年   848篇
  2008年   892篇
  2007年   702篇
  2006年   662篇
  2005年   489篇
  2004年   359篇
  2003年   457篇
  2002年   414篇
  2001年   349篇
  2000年   362篇
  1999年   406篇
  1998年   333篇
  1997年   311篇
  1996年   296篇
  1995年   260篇
  1994年   178篇
  1993年   156篇
  1992年   113篇
  1991年   94篇
  1990年   64篇
  1989年   54篇
  1988年   44篇
  1987年   19篇
  1986年   23篇
  1985年   11篇
  1984年   11篇
  1983年   10篇
  1982年   10篇
  1981年   2篇
排序方式: 共有10000条查询结果,搜索用时 748 毫秒
781.
根据秦岭保护区群的生物多样性和保护管理现状 ,提出了加强保护区群生物多样性保护和促进保护区发展的对策 ,其主要措施为 :一、合理划分和调整功能区 ;二、强化内部管理 ,加强对自然资源的巡护、监测 ;三、协调周边社区关系 ,积极开展社区共管工作 ;四、加强对外合作 ,积极开展科学研究 ;五、开展环境教育 ,提高全民保护意识 ;六、开展资源适度开发利用 ,增强自养能力。  相似文献   
782.
论社区可持续发展规划与调控   总被引:11,自引:1,他引:10  
本文对社区可持续发展规划的原则、步骤、主要内容以及可持续发展系统调控的手段等问题进行了研究。  相似文献   
783.
Yang  W.  Deng  D. G.  Meng  X. L.  Zhang  S. 《Russian Journal of Ecology》2019,50(4):352-360
Russian Journal of Ecology - Temporal and spatial variations of phytoplankton community in Lake Erhai were investigated from May 2010 to April 2011. A total of 124 species belonging to 8 phyla and...  相似文献   
784.
785.
介绍了含油污泥热解技术及热解实验方法,提出热解产生的残渣进行适当处理可成为具有吸附性的材料。进行了含油污泥热解正交实验,得出影响最大的因素分别是热解温度、热解时间、升温速率,并得出最佳的热解温度、热解时间、升温速率等。分析了含油污泥热解的机理,探讨了热解含油污泥制备吸附材料的活化改性,并在此基础上对所制备吸附材料的脱硫性和除油性进行了研究。  相似文献   
786.
针对传统Fenton体系Fe(Ⅲ)累积和pH适用范围过窄等缺点,采用羟胺(HA)强化的HA-Fenton体系,以对氯苯酚(4-CP)为目标污染物进行降解实验,考察了Fe(Ⅱ)投加量、H2O2投加量、HA投加量和溶液pH等工艺条件对4-CP去除率的影响。实验结果表明:HA-Fenton体系适用于酸性和弱酸性条件,最佳pH范围为3.0~4.0;在溶液pH为3.0、Fe(Ⅱ)投加量为5.0 μmol/L、H2O2投加量为0.4 mmol/L、HA投加量为0.20 mmol/L的最适条件下,反应10 min, 4-CP去除率达64.25 %。  相似文献   
787.
Poly(aspartic acid-itaconic acid) copolymers (PAI) is a new scale inhibitor for water treatment. Thus, it is necessary to investigate its biodegradability. The biodegradability of PAI was investigated through CO2 evolution tests under different conditions based on determination of carbon dioxide production. The investigation results showed that the degradation rate of PAI on day 10 and day 28 were respectively 38.7 and 79.5%, indicating that PAI was one kind of easily biodegradable scale inhibitors. With the increase in the content of itaconic acid in copolymerization process, the biodegradability of PAI was significantly reduced. In addition, the high biodegradability might be attributed to the existence of C–N bone-structure and more –COO–. Finally, Cu2+ could decrease the degradation percentage and the enzyme inhibition effect of Cu2+ was not the linear effect, but the “low-dosage effect”.  相似文献   
788.
Journal of Material Cycles and Waste Management - To evaluate the agronomic potential of biochar, we prepared a series of biochars using rice straw waste under the limited oxygen cracking condition...  相似文献   
789.
Sb release characteristics of blast furnace slag, mining waste rock and tailing sand were investigated in static immersion and dynamic leaching test. These three kinds of waste samples were collected from the antimony mine in Lengshuijiang, China, produced in mining smelting process. Effects of solid/liquid ratio, sample size and pH of leaching solution on Sb release characteristics were inspected based on the analysis of scanning electron microscope, pH and EC of leachate. The optimal parameters for Sb leaching of each sample were analyzed. For blast furnace slag and mining waste rock, Sb release contents increased along with the decline of solid/liquid ratio. The maximum accumulative release contents were 42.13, 34.26 mg/kg at the solid/liquid ratio of 1:20. While Sb release content for tailing sand decreased first and then increased with the reduction of solid/liquid ratio. When the solid/liquid ratio was 1:5, the accumulative Sb release content reached the most (24.30 mg/kg). Sb release content of mining waste rock increased with the drop of leaching solution pH, with the highest accumulative release content of 26.01 mg/kg at pH 2.0. Sb release contents of blast furnace slag and tailing sand showed positive correlation with the variation of leaching solution pH. The maximum accumulative release contents of these two samples were 215.91 and 147.83 mg/kg, respectively, when leaching solution pH was 7.0. In summary, Sb release capacity of the three samples in descending order was tailing sand, blast furnace slag and mining waste rock. pH and EC of the leachate in dynamic test varied independently with the initial pH of leaching solution while showing close relationship with mineral hydrolysis in the waste.  相似文献   
790.
Channa argus, a type of snakehead fish native to China, is a popular food fish in certain Asian countries but is a known destructive invasive species in the US. In this study, the two collagens, i.e. acid-soluble collagen (ASC) and pepsin-solubilized collagen (PSC), were obtained from C. argus skin. The yield of ASC was 28.0% and that of PSC was 16.8% on the dry bases. The collagens were identified as the collagen of type I by SDS–PAGE patterns. The Tds were approximately 27.0?°C. Similar ultraviolet spectra of both collagens were observed. Fourier Transform infrared spectra indicated PSC structure had a little change due to the loss of terminal domains by pepsin digestion. The results of XRD proved that the two collagens retained their helical structures. The results suggest that the collagens isolated from C. argus can potentially be alternative sources of vertebrate collagens for use in the food and other industries.  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