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   1564篇
  免费   65篇
  国内免费   492篇
安全科学   125篇
废物处理   96篇
环保管理   112篇
综合类   774篇
基础理论   316篇
污染及防治   540篇
评价与监测   50篇
社会与环境   41篇
灾害及防治   67篇
  2023年   29篇
  2022年   95篇
  2021年   80篇
  2020年   47篇
  2019年   44篇
  2018年   65篇
  2017年   59篇
  2016年   65篇
  2015年   75篇
  2014年   128篇
  2013年   147篇
  2012年   121篇
  2011年   119篇
  2010年   103篇
  2009年   105篇
  2008年   111篇
  2007年   68篇
  2006年   74篇
  2005年   45篇
  2004年   54篇
  2003年   69篇
  2002年   44篇
  2001年   37篇
  2000年   48篇
  1999年   31篇
  1998年   62篇
  1997年   44篇
  1996年   26篇
  1995年   27篇
  1994年   26篇
  1993年   27篇
  1992年   18篇
  1991年   11篇
  1990年   5篇
  1989年   6篇
  1988年   2篇
  1987年   2篇
  1984年   2篇
排序方式: 共有2121条查询结果,搜索用时 328 毫秒
491.
四川某生物防治公司在利用磷化氢与二氧化碳混合气体熏蒸处理烟草和粮食杀菌生产过程中产生少量废水。废水主要含氢氧化铝等固体废物,具有产生量小、SS浓度大、颗粒物粒径极小、色度大、溢出气含腐蚀性等特点,对客户感官产生不适。结合该公司实例介绍了以"沉淀+一体化负压两级过滤"为主体的处理工艺的熏蒸废水处理过程。经过处理,该公司生产废水中SS和色度去除率可达到99.3%与98.1%,出水可满足相关标准与相应感官要求。  相似文献   
492.
经过近10年的生态示范建设,西青区逐步改善了经济发展与资源环境的协调关系,并迈入生态文明建设的新阶段。本文对西青区2005年至2012年经济增长、资源消耗及环境污染的相关数据进行分析,找出三者间关系的变化趋势。分析得出,西青区水资源、能源消耗及主要污染物排放强度随经济增长开始出现下降趋势,这表明经济增长对资源及环境的依赖程度正逐步降低;同时也指出随着社会经济的高速发展,未来该区的资源环境仍可能面临巨大压力,并为其开展生态文明建设提出建议。  相似文献   
493.
《重点区域大气污染防治"十二五"规划》是中国第一部综合性大气污染防治的规划,涉及14个城市,四川省属于《重点区域大气污染防治"十二五"规划》中面积最大的成渝城市群,约占该规划区的面积达10.7%。为更好地促进该规划的实施,四川省编制了《重点区域大气污染防治"十二五"规划四川省实施方案》。环境监测是环境保护及管理工作的基础,论文简要分析了在四川省规划实施过程中,环境监测的工作重点、工作方向以及应如何发挥作用。  相似文献   
494.
在对环境水进行检测时,一个非常重要的项目就是对锡含量进行检测,所以,运用准确、灵敏的测定方法对环境水体中痕量锡进行检测具有非常重要的意义。文章将结合实验,在对环境水体中的痕量锡进行测定时,运用原子荧光光谱法,对测定环境水体中痕量锡的方法进行了一定的研究。采用原子荧光光谱法测定环境水体中的痕量锡,方法检出限是0.10μg/L,相对标准偏差0.20%~0.90%,实际样品加标回收率为98%~102%,满足环境监测实验室分析测定要求,值得推广。  相似文献   
495.
496.
Fossil record of Phanerozoic non-spicular sponges, beside of being important with respect to the lineage evolution per se, could provide valuable references for the investigation of Precambrian ancestral animal fossils. However, although modern phylogenomic studies resolve non-spicular demosponges as the sister group of the remaining spiculate demosponges, the fossil record of the former is extremely sparse or unexplored compared to that of the latter; the Middle Cambrian Vauxiidae Walcott 1920, is the only confirmed fossil taxon of non-spicular demosponges. Here, we describe carbonate materials from Devonian (Upper Givetian to Lower Frasnian) bioherms of northern France and Triassic (Anisian) microbialites of Poland that most likely represent fossil remnants of keratose demosponges. These putative fossils of keratose demosponges are preserved as automicritic clumps. They are morphologically distinguishable from microbial fabrics but similar to other spiculate sponge fossils, except that the skeletal elements consist of fibrous networks instead of assembled spicules. Consistent with the immunological behavior of sponges, these fibrous skeletons often form a rim at the edge of the automicritic aggregate, separating the inner part of the aggregate from foreign objects. To confirm the architecture of these fibrous networks, two fossil specimens and a modern thorectid sponge for comparison were processed for three-dimensional (3-D) reconstruction using serial grinding tomography. The resulting fossil reconstructions are three-dimensionally anastomosing, like modern keratose demosponges, but their irregular and nonhierarchical meshes indicate a likely verongid affinity, although a precise taxonomic conclusion cannot be made based on the skeletal architecture alone. This study is a preliminary effort, but an important start to identify fossil non-spicular demosponges in carbonates and to re-evaluate their fossilization potential.  相似文献   
497.
This paper presents a methodology for quantifying the effectiveness of water-trading under uncertainty, by developing an optimization model based on the interval-parameter two-stage stochastic program (TSP) technique. In the study, the effectiveness of a water-trading program is measured by the water volume that can be released through trading from a statistical point of view. The methodology can also deal with recourse water allocation problems generated by randomness in water availability and, at the same time, tackle uncertainties expressed as intervals in the trading system. The developed methodology was tested with a hypothetical water-trading program in an agricultural system in the Swift Current Creek watershed, Canada. Study results indicate that the methodology can effectively measure the effectiveness of a trading program through estimating the water volume being released through trading in a long-term view. A sensitivity analysis was also conducted to analyze the effects of different trading costs on the trading program. It shows that the trading efforts would become ineffective when the trading costs are too high. The case study also demonstrates that the trading program is more effective in a dry season when total water availability is in shortage.  相似文献   
498.
Residues of organochlorine pesticides in Hong Kong soils   总被引:22,自引:0,他引:22  
Zhang HB  Luo YM  Zhao QG  Wong MH  Zhang GL 《Chemosphere》2006,63(4):633-641
It was short of research on the organochlorine pesticides (OCPs) residues in the soils of Hong Kong. Sixty-six representative soil samples were collected from the 46 sites covering five types of land uses in Hong Kong. Hexachlorohexanes (HCH) and 7 Stockholm Convention OCPs were analyzed by gas chromatograph (GC) equipped with a Nickel 63 electronic capture detector (muECD). The results presented that HCH and 5 Stockholm Convention pesticides were detected in Hong Kong soils although the detectable ratio varies to a great extent. The concentration sequence of the five detectable OCPs was HCH > dichlorodiphenyltrichloroethane (DDT) > hexachlorobenzene (HCB) approximately = Endrin > alpha-endosulfan. Among the OCPs and their homologues or isomers, beta-HCH and p,p'-DDE were the two predominant substances according to the concentrations and detectable ratios, concentrations of which in soils were averagely 6.12 microg kg(-1) and 0.41 microg kg(-1) respectively. Soil horizon samples of 0-10 cm, 10-30 cm and >30 cm depth were selected from nine soil profiles to demonstrate the depth distributions of DDT and HCH in soil profiles. Concentrations of HCH tended to increase gradually from the topsoil to bottom layer while the lowest concentration of DDT is usually found in the subsoil (10-30 cm) in most sampling sites. In addition, close correlations of pH(KCl) and total organic carbon (TOC) with HCH indicated an effect on the residues of HCH caused by these two soils properties, but such relationships were not found with DDT or other OCPs.  相似文献   
499.
500.
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