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   559篇
  免费   47篇
  国内免费   223篇
安全科学   46篇
废物处理   33篇
环保管理   65篇
综合类   311篇
基础理论   117篇
污染及防治   192篇
评价与监测   22篇
社会与环境   16篇
灾害及防治   27篇
  2024年   2篇
  2023年   9篇
  2022年   57篇
  2021年   33篇
  2020年   33篇
  2019年   31篇
  2018年   33篇
  2017年   38篇
  2016年   32篇
  2015年   41篇
  2014年   39篇
  2013年   66篇
  2012年   61篇
  2011年   61篇
  2010年   38篇
  2009年   30篇
  2008年   34篇
  2007年   27篇
  2006年   41篇
  2005年   9篇
  2004年   13篇
  2003年   11篇
  2002年   10篇
  2001年   8篇
  2000年   13篇
  1999年   8篇
  1998年   7篇
  1997年   9篇
  1996年   10篇
  1995年   5篇
  1994年   5篇
  1993年   2篇
  1992年   3篇
  1991年   2篇
  1986年   3篇
  1985年   1篇
  1983年   1篇
  1978年   1篇
  1975年   1篇
  1974年   1篇
排序方式: 共有829条查询结果,搜索用时 234 毫秒
751.
介绍九江分公司炼化生产中的节水减排工作情况。通过合理的系统划分,优化机泵冷却水设计,清污分流,对不同水质的工艺冷凝液实施处理与回用,并结合提高循环水运行浓缩倍数以减少系统补充水量,回用正洗水以降低除盐水自耗水量等措施,实现全厂节水减排的目标。  相似文献   
752.
北京地区重金属在土壤中的纵向分布和迁移   总被引:32,自引:4,他引:32       下载免费PDF全文
本文讨论了重金属在土壤中的纵向分布和迁移及其对地下水污染的可能性.在典型褐土中,重金属在B层发生淀积,但在冲积性土壤中,重金属的含量随冲积层粘性增高而增多,土柱模拟试验表明,Cd仅在土壤表层聚积.野外研究表明,在旱作农田下,由于灌溉水和雨水不能渗入深层.重金属亦难于下移到深层.但在污泥沉淀池、污水渠或水稻田等长期存纳污水情况下,重金属会向下迁移并可能污染地下水.  相似文献   
753.
用废水污染驯化的菌种对邻苯二甲酸及邻苯二甲酸二甲酯进行降解,最优降解条件由四因子四水平正交试验得出。在最优条件下,浓度高达4000mg/L的邻苯二甲酸可在5d内降解99%以上。作为唯一的碳源和能源的邻苯二甲酸二甲酯也能够在好氧条件下降解,两种中间产物为邻苯二甲酸一甲酯及邻苯二甲酸,另外,在培养液中加入邻苯二甲酸作为共同底物时,可提高邻苯二甲酸二甲酯的降解速率。图2表3参14。  相似文献   
754.
畜粪污染处理与利用研究   总被引:4,自引:0,他引:4  
国内外对于粪便固体物的处理主要采用焚烧法、干燥法和堆肥法等,在粪便污水处理方面主要采用厌氧消化法,它将治污、产气和综合利用相结合,使废物资源化,达到环境效益、经济效益和社会效益相统一。  相似文献   
755.
756.
通过室内循环冻融循环试验和三轴不固结不排水(UU)压缩试验研究了循环冻融作用与细砾组含量(P_(2-5))对黏质粗粒土抗剪性能的影响。结果表明,冻融循环作用对黏质粗颗粒土的应力—应变曲线性状具有一定的影响,可使其由未冻融的应变软化向应变硬化转变的趋势,但随着细砾组P_(2-5)含量的增加,冻融作用对其影响逐渐减弱。随着冻融循环次数的增加,土样剪切强度呈现逐渐衰减,且在5~9次冻融循环次数后基本保持不变,多次循环冻融作用后剪切强度最大衰减幅度可达40%。弹性模量随冻融循环次数的增加上下波动较大但整体呈现下降趋势。在抗剪强度指标方面,冻融作用对黏聚力影响比较显著,随着冻融循环次数的增加,黏聚力逐渐减小,最大衰减幅度可达65%,而内摩擦角上下波动较大无明显趋势。此外,随着细砾组P_(2-5)含量的增加,剪切强度、弹性模量及抗剪强度指标均呈现不同程度的减小,这与粗粒土内部粗颗粒和细颗粒占比及其强度发挥机制有关。  相似文献   
757.
The Pb (II) adsorption/desorption mechanism onto a natural sandy loam soil was studied by batch experiments at different pHs (3.0, 4.5, 6.0), at different ionic strength (0, 0.02 and 0.1 M) and with different electrolytes solutions of NaCl, NaAcO and NaNO3. Pb was strongly adsorbed onto the soil due to the formation of a mix of inner-sphere and outer-sphere complexes. Experimental adsorption data fitted Freundlich and Langmuir isotherms. The desorption results with 0.1 M Mg (NO3)2 and 0.1 M NaAcO solutions corroborated the mechanisms proposed. The strong binding of Pb (II) to high affinity sites on soil minerals seems to be responsible for the extent of hysteresis. The sandy loam soil under study thus constitutes a natural control for Pb contamination.  相似文献   
758.
介绍了粮食筒仓粉尘爆炸的条件及爆炸的主要地点。提出了从设计、管理等方面采取的主要安全措施。  相似文献   
759.
This study presents detailed and comprehensive inventories on the horticultural production of tomato using compost (CM) or mineral fertilizers (M), in both open-fields (OF) and greenhouses (GH), providing information on the environmental impacts and assessing the agronomic viability of the four cultivation options. Life cycle assessment (LCA) was used to calculate the potential environmental impacts of the tomato production cycle per ton of product. The stages in the assessment included: mineral and organic fertilizers production, fertilizers transport, cultivation stage and greenhouse stage. The data were obtained experimentally in pilot fields and in an industrial composting facility using municipal organic waste, both located in the Mediterranean area. The results indicate that replacing a fraction of the mineral fertilizers dosage with compost is a good option, as this did not alter yield or fruit size parameters. Greenhouse protection increased infrastructure materials requirements but enhanced harvest by almost 50% and reduced the water and pesticides requirement. Compost production and greenhouse stages were the most impacting stages. Without subtracting the avoided burdens by composting and not dumping organic waste, the cultivation option OF_M had the lowest and OF_CM the highest impact. When avoided burdens were taken into consideration, the environmental impacts of the four cultivation options varied, depending on the impact category, with bigger differences due to fertilization as a variable rather than the production system.  相似文献   
760.
Summary.  The differing antagonist activity of (Z)-13-hexadecen-2-one (Z11 – 14 :MK, 1) and its 1,1,1-trifluoro derivative (Z11 –14 :TFMK, 2), two closely related analogues of the European corn borer pheromone Ostrinia nubilalis (Z strain), and their rationale is reported. Both chemicals exhibited some electrophysiological activity, and topical application of 10 pg of pheromone analogue on male antennae was sufficient to induce significantly lower depolarization responses to the pheromone versus untreated insects. In a wind tunnel, the number of European corn borer males attracted to sources containing mixtures of 1 + pheromone in ratios ≥ 1 :1 was significantly lower than the number attracted to a source containing pheromone alone. Source contact behaviour was dramatically impaired when the 1 + pheromone blend reached a ratio of 10 :1, in which only 2% of males displayed source contact in the presence of antagonist. When compound 1 was present at the source, males usually flew upwind with occasional downwind reversals; when compound 2 was present at the lure, males performed wider crosswind reversals, with little progress toward the source. In the field, traps baited with mixtures of both compounds with the pheromone in ratios of 5 :1 and 10 :1 elicited a significantly decreased number of male catches. In esterase inhibition assays, compound 2 was a potent inhibitor (IC50 = 70 nM), whereas the non-fluorinated compound 1 was not. The different activity of both compounds is presumed to be due to different mechanisms of action; considerations for using methyl ketone analogues as new behavioural antagonists of the pheromone are outlined.  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