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   579篇
  免费   20篇
  国内免费   167篇
安全科学   37篇
废物处理   33篇
环保管理   42篇
综合类   320篇
基础理论   80篇
污染及防治   195篇
评价与监测   18篇
社会与环境   16篇
灾害及防治   25篇
  2023年   6篇
  2022年   24篇
  2021年   23篇
  2020年   11篇
  2019年   14篇
  2018年   21篇
  2017年   21篇
  2016年   16篇
  2015年   35篇
  2014年   29篇
  2013年   63篇
  2012年   46篇
  2011年   41篇
  2010年   41篇
  2009年   32篇
  2008年   36篇
  2007年   30篇
  2006年   44篇
  2005年   34篇
  2004年   11篇
  2003年   21篇
  2002年   21篇
  2001年   23篇
  2000年   26篇
  1999年   11篇
  1998年   17篇
  1997年   14篇
  1996年   11篇
  1995年   10篇
  1994年   10篇
  1993年   6篇
  1992年   3篇
  1991年   1篇
  1990年   5篇
  1989年   2篇
  1986年   2篇
  1984年   1篇
  1982年   1篇
  1981年   2篇
  1979年   1篇
排序方式: 共有766条查询结果,搜索用时 31 毫秒
171.
我是中央电视台这棵大树上的一片叶子,我为这个机体输送过经光合作用而形成的养分,也受这棵大树的支撑能在阳光下闪烁。尽管任何一片叶子都迟早会脱落,但是,这棵大树注定根深叶茂,日益繁盛。没有中央电视台就没有我。  相似文献   
172.
在活性污泥系统中,由丝状菌过度繁殖引起的污泥膨胀是最难解决的问题之一。文章对与丝状菌污泥膨胀相关的微生物学和丝状菌生理生态学进行了讨论;介绍了现有的解释污泥膨胀的基本理论,并对丝状菌膨胀的控制措施进行了探讨。  相似文献   
173.
邹晶 《世界环境》2005,(4):94-95
自然保护选民联合会(LCV)是美国一家旨在反映全国环保运动,并略带有政治观点的非政府组织,也是美国唯一一个竭力促使国会和白宫成为对环境负责任的国家权利机构的无党派和非营利组织。因而,也被称之为环境政治压力团体。  相似文献   
174.
此文用自行编制的弹塑性有限元程序对承受内压的厚壁圆筒进行了分析,考虑了材料的应变强化,分析了小变形情况下达到塑性极限点以后内压与径向位移之间的关系。并将其应用于焊管管端定径工艺分析中,得出了主要工艺参数。  相似文献   
175.
拟菊酯杀虫剂的光敏降解研究   总被引:19,自引:5,他引:19  
研究了哒嗪硫磷、多菌灵和克百威对三种菊酯杀虫剂(氯氰菊酯、溴氰菊酯、氰戊菊酯)的光敏降解效应.在0.03—2.66μg/cm~2剂量范围内,哒嗪硫磷,多菌灵对3种拟菊酯杀虫剂有极显著的光敏效应,光解速度常数分别是拟菊酯杀虫剂单独照光的1.54—1.88倍和1.41—1.72倍.克百威对氯氰菊酯和溴氰菊酯有显著的光猝灭效应.当克百威和哒嗪硫磷共存时,克百威明显减弱哒嗪硫磷对氯氰菊酯和嗅氰菊酯的光敏效应,而增强对氰戊菊酯的光敏效应.  相似文献   
176.
Water resources have become a barrier hampering socioeconomic development. Changes in the spatial distribution of water use profile have direct impacts to regional water use efficiency. However, the related research is inadequate, and a more suitable way to analyze regional water use profile is necessary. The Gini coefficient and location quotient, two reliable methods commonly used in discussing the spatial distribution of elements, were introduced and calculated. Taking Gansu Province as the study area, the concentration effect of industrial water use was the strongest, followed by domestic, environmental, and agricultural water use. However, a balanced distribution of agricultural water use failed to be coordinated with the production conditions, the center of Gansu’s grain production should be established to enhance the scale effect of agricultural production. The industrial agglomeration effect remained weak, and each region’s dominant industries need to be developed vigorously. Gansu’s domestic water use was consistent with its population distribution, but it is necessary to reduce the water use gap between urban and rural areas. With a growing awareness of environmental protection, environmental water use exhibited a more balanced distribution. Overall, the methods are simple and have good applicability, and the results can provide a reference in water use optimization.  相似文献   
177.
针对硫化氢气体的特点,研制了在泄漏事故中用于清除硫化氢气体的硫化氢捕消剂;开展了密闭空间和开放空间硫化氢清除应用试验,结果表明,硫化氢捕消剂能够有效地清除泄漏在空气中的硫化氢气体。  相似文献   
178.
Previous studies on environmental antibiotics resistance genes(ARGs) have focused on the pollution sources such as wastewater treatment plants, aquaculture and livestock farms,etc. Few of them had addressed this issue in a regional scale such as river catchment. Hence,the occurrence and abundances of 23 ARGs were investigated in surface water samples collected from 38 sites which located from the river source to estuary of the Beijiang River.Among them, 11 ARGs were frequently detected in this region and 5 ARGs(sul I, sul II, tet B,tet C, and tet W) were selected for their distribution pattern analysis. The abundances of the selected ARGs were higher in the upstream(8.70 × 10~6 copies/ng DNA) and downstream areas(3.17 × 10~6 copies/ng DNA) than those in the midstream areas(1.23 × 10~6 copies/ng DNA), which was positively correlated to the population density and number of pollution sources. Pollution sources of ARGs along the Beijiang River not only had a great impact on the abundances and diversity, but also on the distribution of specific ARGs in the water samples. Both sul I and sul II were likely originated from aquaculture farms and animal farms,tet W gene was possibly associated with the mining/metal melting industry and the electric waste disposal and tet C gene was commonly found in the area with multiple pollution sources.However, the abundance of tet B was not particularly related to anthropogenic impacts. These findings highlight the influence of pollution sources and density of population on the distribution and dissemination of ARGs at a regional scale.  相似文献   
179.
制备了锰粉改进的规整化微电解填料,采用电化学辅助改进微电解填料处理初始COD为6 153.6 mg/L、ρ(NH_3-N)为182.6 mg/L的焦化废水,优化了工艺条件。实验结果表明,电化学辅助微电解法处理焦化废水的最佳工艺条件为电压8 V,填料投加量20 g/L,初始废水pH 6,反应时间30 min。在此条件下废水COD去除率为75.3%,NH_3-N去除率为65.4%;在其他工艺条件相同的情况下,未通过电化学辅助的填料微电解反应的COD去除率为33.0%,NH_3-N去除率为16.2%,电化学辅助后的COD去除率和NH_3-N去除率均明显提高。  相似文献   
180.
The potential of three varieties of Italian ryegrass (Lolium multiflorum Lam.), Dryan, Tachimasari and Waseyutaka, to improve the water quality of swine wastewater was evaluated using a constructed macrophyte floating bed system. With respect to reductions in levels of nutrients, chemical oxygen demand (COD), and sulfonamide antimicrobials (SAs, including sulfadiazine, sulfamethazine, and sulfamethoxazole), Dryan performed better than Tachimasari and Waseyutaka. For Dryan, total N was reduced by 84.0%, total P by 90.4%, COD by 83.4% and sulfonamide antimicrobials by 91.8–99.5%. Similar results were observed for Tachimasari and Waseyutaka. The results indicated that the treatment of swine wastewater using the constructed macrophyte floating bed system was effective in the removal of nutrients and veterinary antibiotics.  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