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   97篇
  免费   5篇
  国内免费   13篇
安全科学   6篇
废物处理   1篇
环保管理   7篇
综合类   50篇
基础理论   27篇
污染及防治   15篇
评价与监测   2篇
社会与环境   1篇
灾害及防治   6篇
  2022年   8篇
  2021年   4篇
  2020年   3篇
  2019年   1篇
  2018年   1篇
  2017年   4篇
  2016年   2篇
  2015年   4篇
  2014年   5篇
  2013年   9篇
  2012年   6篇
  2011年   12篇
  2010年   5篇
  2009年   4篇
  2008年   12篇
  2007年   11篇
  2006年   13篇
  2003年   1篇
  2002年   3篇
  2001年   1篇
  2000年   1篇
  1998年   2篇
  1997年   1篇
  1996年   1篇
  1995年   1篇
排序方式: 共有115条查询结果,搜索用时 281 毫秒
31.
持久性有机污染物可以通过大气、洋流等各种长距离传输途径进入北极地区,其中有机氯农药和多氯联苯对生态环境影响持久。采集夏季北极不同纬度地区的环境水样,并对北极地区表层水中这两类物质进行分析,以揭示北极地区表层水体中有机氯农药和多氯联苯的浓度水平。结果表明,所有水样均未检出多氯联苯;部分有机氯农药有检出,但处于极低的浓度水平,远低于国内外饮用水标准限值。  相似文献   
32.
We assessed the transportation tendency of dioxins and predict locations at high risk for dioxin pollution. A new parameter, the compartment distribution coefficient DC, was created to account for the tendency of dioxins to preferentially accumulate in particular compartments. It was obtained by a model using levels of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) in four countries: Japan, the United States, the United Kingdom, and Australia. The comparison with the temporal and spatial variation of DC indicated whether the location release or long-range transportation caused the changes. This study showed that PCDD/Fs have the greatest tendency to remain in soil among studied media. A higher DC value in Australia may indicate that this location is a potential future reservoir source of dioxins.  相似文献   
33.
第二十六类 有机过氧化物 活性特点: 有机过氧化物为有机物分子中含有过氧链(-O-O-)的一类物质,如过氧酸O=C-O-OH,烷基过氧化物(R-O-O-R)等.有机过氧化物具有很强的氧化性,尤其过氧酸被认为所有有机物中最强的氧化剂,由于过氧酸中比一般的羧酸多一个氧原子,因此其氧化性极强.  相似文献   
34.
潮白河顺义段断流的生态损失评估   总被引:1,自引:0,他引:1  
潮白河是北京市最重要的自然湿地之一。由于人类不合理的开发利用,河流生态系统严重退化,其中顺义段河道从1999年断流至今。在实地调研的基础上,建立了一套河道断流对区域社会-经济-自然复合生态系统发展造成的综合损失的定量评估方法体系,从社会-经济系统的年度产值损失、用于治理断流河道的年度恢复费用、断流河道非使用价值的年度损失三个方面,评价潮白河顺义段断流对研究区域造成的生态损失。研究结果表明,潮白河顺义段断流对研究区域复合生态系统造成的年度生态损失达8786.5万元,1995—2005年的十年间生态损失总值达87865万元。  相似文献   
35.
This study focused on the water quality of the Guanting Reservoir, a possible auxiliary drinking water source for Beijing. Through a remote sensing (RS) approach and using Landsat 5 Thematic Mapper (TM) data, water quality retrieval models were established and analyzed for eight common water quality variables, including algae content, turbidity, and concentrations of chemical oxygen demand, total nitrogen, ammonia nitrogen, nitrate nitrogen, total phosphorus, and dissolved phosphorus. The results show that there exists a statistically significant correlation between each water quality variable and remote sensing data in a slightly-polluted inland water body with fairly weak spectral radiation. With an appropriate method of sampling pixel digital numbers and multiple regression algorithms, retrieval of the algae content, turbidity, and nitrate nitrogen concentration was achieved within 10% mean relative error, concentrations of total nitrogen and dissolved phosphorus within 20%, and concentrations of ammonia nitrogen and total phosphorus within 30%. On the other hand, no effective retrieval method for chemical oxygen demand was found. These accuracies were acceptable for the practical application of routine monitoring and early warning on water quality safety with the support of precise traditional monitoring. The results show that performing the most traditional routine monitoring of water quality by RS in relatively clean inland water bodies is possible and effective.  相似文献   
36.
Copper and zinc interaction on clearance from water and distribution in different tissues was investigated for the freshwater mussel, Cristaria plicata, under laboratory conditions. Clearance rate of Cu or Zn from water was highly dependent on exposure concentration. Interaction effect was most evident at 300 μg·L−1 Cu exposure and depressed the Zn clearance rate significantly (p<0.05). However, the presence of 100 μg·L−1 and 300 μg·L−1 Zn hardly affected the Cu clearance rate. The 300 μg·L−1 Cu presence enhanced Cu accumulation in each tissue most significantly (p<0.01), but caused Zn content to decrease in the gills by 62% (p<0.05), viscera by 49% (p<0.05) and foot by 31% (p<0.05), and increase in the mantle by 97% (p<0.05) and the muscles by 243% (p<0.05) for different Zn exposure treatments. The response of metal accumulation in various tissues of the test mussels indicated that Zn transferred from the gills, viscera and foot to the mantle and muscles might be one of the important characteristics of the Zn regulatory mechanism by leading to a narrow range of Zn concentration in the different tissues.  相似文献   
37.
38.
如何在国民经济发展计划中体现资源环境因素的影响?如何用现实可行的方法制定出符合可持续发展要求的国民经济发展计划?是目前环境经济领域急待解决的问题。本文从物质平衡的角度,探讨可持续经济发展计划的研究方法。  相似文献   
39.
以单壁碳纳米管(SWCNTs)为固定相,采用高压匀浆法,制备HPLC色谱柱.测定乙腈相中18种有机化合物在SWCNTs色谱柱上的保留因子,研究SWCNTs与化合物的相互作用.结果表明,有机化合物取代基的种类和个数、杂原子的个数影响乙腈相中有机化合物与SWCNTs的相互作用.采用线性溶解能关系(LSER)定量表征SWCNTs与有机化合物的相互作用,所构建的LSER模型具有较强的拟合能力(R2=0.844)和稳健性(Q2LOO=0.768),发现π-/n-电子对作用和空穴/弥散作用是控制SWCNTs与有机化合物相互作用的主要因素.  相似文献   
40.
When fully-mechanized caving face passed fault, rock burst accidence easily occurred. The SOS microseism monitoring system was applied to monitor the microseismic activities all time occurred in the coal and rock mass near the fault area. Variation features of microseismic energy releasing and microseismic frequency were analyzed. Numerical simulation method was used to research the abutment stress distribution when coal face passed fault, which was compared with microseism occurrence rules. When the coal face approached to fault, the abutment stress increases gradually, so the high stress would accumulate near the fault region. When the coal face left fault, the abutment stress decreased. The SOS microseism monitoring results showed that microseismic activity in the fault area had a high instability. When the coal face neared to the fault, total energy value and frequency released by the microseism steadily increased. The maximum energy peak value also had the tendency to rapidly increase. Before the strong shock occurred, there was a period of weak seismic activity. The weak seismic activity showed energy accumulation for strong shock, which can be used to forecast the danger of rock burst.  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