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   357篇
  免费   65篇
  国内免费   161篇
安全科学   61篇
废物处理   16篇
环保管理   23篇
综合类   278篇
基础理论   84篇
污染及防治   74篇
评价与监测   22篇
社会与环境   7篇
灾害及防治   18篇
  2024年   4篇
  2023年   22篇
  2022年   40篇
  2021年   33篇
  2020年   43篇
  2019年   31篇
  2018年   29篇
  2017年   33篇
  2016年   27篇
  2015年   35篇
  2014年   41篇
  2013年   37篇
  2012年   42篇
  2011年   25篇
  2010年   29篇
  2009年   24篇
  2008年   28篇
  2007年   18篇
  2006年   17篇
  2005年   10篇
  2004年   1篇
  2003年   5篇
  2002年   5篇
  2001年   2篇
  2000年   2篇
排序方式: 共有583条查询结果,搜索用时 390 毫秒
41.
Miyun County,located in the northeast of Chinese capital Beijing,was underwent remarkable variations in land use in recent years.This paper aimed to detect changes in land use of Miyun from 1997 to 2005,and to qualify the response of ecosystem to LUCC based on ecosystem services valuation.With two-periods TM images,we got land use change data,and then ecosystem services values were calculated using ecosystem services valuation coefficients proposed by Chinese scholar Xie Gaodi.Results showed that water area,farm land and unused land decreased while residential land,forest land,grassland and orchard land increased during the study period.The loss of ESV was RMB 206 million and the main reason was the decrease of water area and farm land area.As for spatial variation,there were most dramatically land use change and ESV decline in reservoir ecological protection region.The coefficient sensitivity analysis indicates that valuation coefficients used in the study are suitable and results are reasonable.The driving forces of ESV loss were rapid population growth and economic development.More work should be done to make eco-environment stay healthy.  相似文献   
42.
固定CO2氢细菌的筛选及其培养条件优化   总被引:7,自引:0,他引:7  
从土壤中分离筛选到一株高效固定CO2 的氢氧化细菌—专性化能自养菌BHA 15 ,在最佳培养条件下(培养基 ρ/gL-1:NH4 Cl 4.0 ,Na2 HPO4 ·12H2 O 0 .75 ,KH2 PO4 0 .5 ,MgSO4 ·7H2 O 0 .3;V(H2 )∶V(O2 )∶V(CO2 ) =3 .5∶1∶1;pH =7;最适生长温度θ =30℃ ) ,密闭摇瓶中恒温 (30℃ )培养 40h后 ,菌体浓度 ρ(DW)达 1.6mg/mL ,菌体蛋白含量 71.8% .图 7表 2参 12  相似文献   
43.
44.
45.
46.
施工安全生产风险是由风险事件概率和风险后果2个要素决定的。从施工安全风险后果,即潜在安全风险后果影响的人员角度,介绍了施工现场安全生产人员聚集性活动安全专项的系统管理方法。施工安全风险跟踪监控实践,表明该方法对促进安全生产绩效具有重要意义。  相似文献   
47.
生物质炭对土壤重金属形态转化及其有效性的影响   总被引:31,自引:0,他引:31  
为了解土壤重金属形态转化及其有效性对生物质炭修复措施的响应,以Cd、Cu、Pb和Zn复合污染水稻土为供试土样,添加不同粒径(1 mm和0.25 mm)和不同施用量(0、1%和5%)的竹炭(BB)、稻草炭(RSB)进行为期1年的恒温((25±1)℃)培养试验后,检测土壤p H、有效磷含量及重金属DTPA有效态含量的变化,并采用BCR连续浸提法分析生物质炭对土壤中重金属元素化学形态再分配的影响.结果表明:稻草炭的施用显著(p0.05)提高了土壤的p H值,且在RSB-5%(0.25 mm)处理下效果最显著;稻草炭的施用显著(p0.05)提高了土壤的有效磷含量,且5%用量比1%用量效果更明显;而竹炭的施用对土壤p H值和有效磷含量均无显著性影响;RSB-5%(0.25 mm)处理对降低土壤中Cd、Cu、Pb和Zn有效态含量的效果最佳,分别减少了34.5%、50.1%、52.5%和52.1%;在细粒径(0.25 mm)稻草炭处理下,酸溶态Cd和Cu向可还原态和可氧化态转化,酸溶态Zn向可还原态转化;在粗粒径(1 mm)竹炭处理下,酸溶态Cu和Zn向可还原态、可氧化态和残渣态转化;酸溶态Pb在稻草炭处理下向可还原态和可氧化态转化,且细粒径比粗粒径效果更佳;竹炭和稻草炭的施用改变了土壤中上述重金属各形态的分配,且5%用量比1%用量效果更明显.  相似文献   
48.
Sulfonamides (SAs) are one of the most widely used antibiotics and their residuals in the environment could cause some negative environmental issues. Advanced oxidation such as Fenton-like reaction has been widely applied in the treatment of SAs polluted water. Degradation rates of 95%-99.7% were achieved in this work for the tested 8 SAs, including sulfisomidine, sulfameter (SME), phthalylsulfathiazole, sulfamethoxypyridazine, sulfamonomethoxine, sulfisoxazole, sulfachloropyridazine, and sulfadimethoxine, in the Fe3O4/peroxodisulfate (PDS) oxidation system after the optimization of PDS concentration and pH. Meanwhile, it was found that a lot of unknown oxidation products were formed, which brought up the uncertainty of health risks to the environment, and the identification of these unknown products was critical. Therefore, SME was selected as the model compound, from which the oxidation products were never elucidated, to identify these intermediates/products. With liquid chromatography-high resolution tandem mass spectrometry (LC-HRMS/MS), 10 new products were identified, in which 2-amino-5-methoxypyrimidine (AMP) was confirmed by its standard. The investigation of the oxidation process of SME indicated that most of the products were not stable and the degradation pathways were very complicated as multiple reactions, such as oxidation of the amino group, SO2 extrusion, and potential cross-reaction occurred simultaneously. Though most of the products were not verified due to the lack of standards, our results could be helpful in the evaluation of the treatment performance of SAs containing wastewater.  相似文献   
49.
Microbial application is an efficient, economical, and ecofriendly method for remediating black-odorous rivers. In this study, the field treatment effect and microbial community changes were monitored during remediation by the acclimated complex microorganisms of a typical black-odorous stream. After the treatment, the total phosphorus and ammonia contents decreased by 74.0% and 76.3% and the concentrations of dissolved oxygen increased from 1.65 to 4.90 mg/L, indicating the effectiveness of the acclimated composite microorganisms. The proportion of Bacteroidetes decreased significantly by 48.1% and that of Firmicutes increased by 2.23% on average, and the microbial diversity index first increased and then tended to be uniform. Redundancy analysis demonstrated that the pH, dissolved oxygen, and oxidation-reduction potential together determined the composition of the microbial communities (p < 0.05). These findings showed that the acclimated composite microorganisms can effectively remediate the black odor.  相似文献   
50.
及时掌握污染场地修复过程中所关注污染物和修复后再利用土地类型信息对深化建设用地环境管理具有重要意义. 本文基于文献调研和信息公示平台资料查询等途径获取了我国537个污染场地案例信息数据,分析了我国近10年来污染场地修复与再利用的变化情况. 统计分析结果表明:我国537个污染场地中约有66%集中在北京市、上海市、浙江省、江苏省和重庆市等先行地区;从2016年《土壤污染防治行动计划》颁布实施开始,场地修复管控数量增势凸显,2018年污染场地修复管控数量达到峰值;原用地类型归属化学工业、金属制品、冶炼等行业的比例较大,且重金属、苯系物为主的再利用挥发性有机物、多环芳烃类为主的半挥发性有机物和总石油烃是典型污染物;在GB 36600—2018《土壤环境质量 建设用地土壤污染风险管控标准(试行)》实施前后,包含苯系物、多环芳烃类和总石油烃等污染物的出现频次增加趋势最为明显,而有机农药类和多氯联苯(总量)的出现频次有所减少;污染场地用途大部分是敏感用地类型中的居住用地,且这类场地的原行业类型为化学工业、金属制品等特征污染物危害较大的行业. 研究显示,利好政策和标准的颁布与实施促进了我国经济欠发达地区污染场地的修复管控工作,以多环芳烃类为主的半挥发性有机物是我国未来场地土壤环境治理工作的重点,需要进一步提升对再利用类型为敏感用地类型场地的关注.   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