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   1041篇
  免费   76篇
  国内免费   93篇
安全科学   235篇
废物处理   29篇
环保管理   171篇
综合类   514篇
基础理论   79篇
污染及防治   74篇
评价与监测   31篇
社会与环境   38篇
灾害及防治   39篇
  2024年   3篇
  2023年   9篇
  2022年   11篇
  2021年   22篇
  2020年   33篇
  2019年   28篇
  2018年   13篇
  2017年   20篇
  2016年   42篇
  2015年   42篇
  2014年   37篇
  2013年   41篇
  2012年   71篇
  2011年   83篇
  2010年   39篇
  2009年   44篇
  2008年   57篇
  2007年   62篇
  2006年   56篇
  2005年   56篇
  2004年   43篇
  2003年   43篇
  2002年   36篇
  2001年   41篇
  2000年   30篇
  1999年   17篇
  1998年   25篇
  1997年   23篇
  1996年   13篇
  1995年   16篇
  1994年   17篇
  1993年   12篇
  1992年   14篇
  1991年   9篇
  1990年   8篇
  1989年   10篇
  1988年   13篇
  1987年   7篇
  1986年   9篇
  1985年   3篇
  1984年   16篇
  1983年   11篇
  1982年   13篇
  1981年   10篇
  1974年   1篇
  1971年   1篇
排序方式: 共有1210条查询结果,搜索用时 281 毫秒
991.
废钻井液固化处理实验研究   总被引:2,自引:0,他引:2  
固化处理技术是实现废钻井液无害化处理主要方法之一,论文以水泥基为主,针对钻井现场的泥浆进行了废钻井液的固化处理研究,探讨了水泥、石灰、固化助剂、工艺条件对固化作用效果的影响,获得优化的处理工艺条件为:水泥加量为废钻井液重量的10%左右,固化块用10倍去离子水浸泡48h后,测得COD含量显著下降.经大量实验证明,固化物浸出液的分析结果符合国家危险废物鉴别标准(GB5085.3-1996)和国家污水综合排放标准(GB8978-1996).  相似文献   
992.
Deficiency of amylo-1,6–glucosidase activity was expressed in parallel in liver and skin fibroblasts from a patient with type III glycogenosis. In crude extracts of control liver and muscle, amylo-1, 6–glucosidase (M.W. 164000) was identified by immunoprecipitation; no cross-reacting material was found in the patient's liver. Assay of amylo-1,6–glucosidase activity in cultured skin fibroblasts from the affected family revealed less than 10 per cent of control value in mutant homozygous cells whereas in cells from the parents, activity was reduced to 40–60 per cent of the control value. Activity in cultured amniotic fluid cells was similar to that of control fibroblasts. In cultured amniotic fluid cells obtained during the mother's subsequent pregnancy, the normal amylo–1,6–glucosidase activity measured, predicted correctly the outcome of this pregnancy prior to the 20th week of gestation.  相似文献   
993.
排污权交易的经济优化机制研究   总被引:6,自引:0,他引:6  
利用经济学原理,分析了环境污染产生的原因和经济学对策,对排污权交易理论和市场优化机制进行了研究,并说明我国建立排污权交易市场的可行性。  相似文献   
994.
静电除尘声波清灰原理及设计要点   总被引:2,自引:0,他引:2  
张殿印 《云南环境科学》2000,19(Z1):230-232
本文介绍了静电除尘器声波清灰的特点 ,声波清灰原理、声波发生器性能以及静电除尘器声波清灰设计要点。  相似文献   
995.
铁屑—粉煤灰处理含铬电镀废水的探讨   总被引:9,自引:0,他引:9  
根据腐蚀电池原理,用铁屑-铁煤灰处理电镀含铬废水,结果表明,Cr(Ⅵ)去除率达到98%处理后出水水质良好,水质符合排放标准要求。  相似文献   
996.
IntroductionTiO2 iswidelyusedinmultiphasephoto catalyticreactions ,andisalsooneofthemosteffectivecatalystsinthedegradationofenvironmentalcontaminants (Hoffmann ,1995 ;Fujishima ,2 0 0 0 ) .However,asasemiconductorofwidebandgap ,itcouldonlybeactivatedbyult…  相似文献   
997.
A child was tentatively diagnosed as having cystic fibrosis, based on neonatal presentation with severe gastrointestinal complications; the diagnosis was not confirmed biochemically and no tissues were available for DNA analysis. The mother presented in her subsequent pregnancy, and microvillar enzyme analysis of cell-free amniotic fluid at both 18 and 20 weeks gestation gave equivocal results. The pregnancy was terminated voluntarily because of a trend towards abnormal enzyme assay results on the second amniocentesis. Retrospectively, fetal tissues were found to be homozygous for the most common mutation of the cystic fibrosis gene (AF508), which confirmed the prenatal assessment and suggested that the first infant of the couple was probably also affected by the disease.  相似文献   
998.
Maternal serum and amniotic fluid alpha-fetoprotein levels were studied retrospectively in a total of 58 pregnancies with trisomy 18. In those pregnancies uncomplicated by either fetal exomphalos or neural tube defect the midtrimester maternal serum alpha-fetoprotein (MSAFP) levels were markedly reduced, the median value for 38 such pregnancies being 0.6 multiples of the median (MoM). Trisomy 18 with exomphalos was associated with a higher median MSAFP, but still within the normal range: 1.1 MoM, (nine pregnancies); trisomy 18 with exomphalos and neural tube defect (NTD) was associated with grossly raised levels: median MSAFP was 4-5 MoM (three pregnancies). Amniotic fluid alpha-fetoprotein (AFAFP) levels were normal in uncomplicated trisomy 18 pregnancies: median AFAFP, for 19 pregnancies, was 1.1 MoM. Exomphalos alone, or together with neural tube defect, was associated with greatly elevated levels of AFAFP; for exomphalos alone median AFAFP was 9.59 MoM (four pregnancies), and for exomphalos with neural tube defect the median AFAFP was 23.95 Mom (three pregnancies). Screening with low and high MSAFP, routine ultrasound, and amniocentesis on all women aged 35 years or over, together might identify over 50 per cent of pregnancies with trisomy 18.  相似文献   
999.
磁流体处理印染废水初探   总被引:3,自引:0,他引:3  
探讨了Fe3O4磁流体在不同条件下对降低印染废水的COD和色度两个方面的影响,实验表明,当pH=11,十二烷基叔胺的量是亚铁量的0.16倍时,COD降低最多,脱色效果最好,且磁场强度在160mT左右时,磁流体沉降最快。  相似文献   
1000.
Most of the large surface reservoirs are stably stratified throughout most or all of the year. One means of assisting in the management is to allow for the selective withdrawal from the reservoir. The value of the intake’s submergence when the upper layer fluids begin to be drawn into the intake is known as “critical submergence”. In this study, the critical submergence for a circular intake pipe in a stratified body is investigated. Experiments were conducted on a vertically flowing downward intake pipe in a still-water reservoir. Experimental results are compared with that of the neuro-fuzzy models.  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