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   443篇
  免费   69篇
  国内免费   139篇
安全科学   67篇
废物处理   4篇
环保管理   60篇
综合类   307篇
基础理论   87篇
污染及防治   29篇
评价与监测   23篇
社会与环境   46篇
灾害及防治   28篇
  2024年   4篇
  2023年   21篇
  2022年   17篇
  2021年   36篇
  2020年   18篇
  2019年   19篇
  2018年   29篇
  2017年   16篇
  2016年   25篇
  2015年   26篇
  2014年   21篇
  2013年   51篇
  2012年   38篇
  2011年   42篇
  2010年   34篇
  2009年   28篇
  2008年   27篇
  2007年   30篇
  2006年   33篇
  2005年   22篇
  2004年   18篇
  2003年   17篇
  2002年   6篇
  2001年   11篇
  2000年   7篇
  1999年   8篇
  1998年   7篇
  1997年   6篇
  1996年   2篇
  1995年   5篇
  1994年   3篇
  1993年   3篇
  1992年   4篇
  1991年   2篇
  1990年   3篇
  1989年   1篇
  1988年   1篇
  1984年   2篇
  1981年   2篇
  1980年   2篇
  1979年   2篇
  1974年   1篇
  1973年   1篇
排序方式: 共有651条查询结果,搜索用时 31 毫秒
51.
Release of domestic sewage leads to accumulation of xenoestrogens in holding waters, especially in closed or semi-enclosed waters such as lakes. In the study, the occurrence, distribution, estrogenic activity and risk of eight xenoestreogens were evaluated in Lake Donghu, China. Nonylphenol (NP), octylphenol (OP), and bisphenol A (BPA) were identified as the main xenoestrogens ranging from tens of ng L−1 (in the surface water) or ng g−1 dw (in the suspended particles and sediment) to tens of μg L−1 or μg g−1 dw. The sum of 17β-estradiol equivalents (∑EEQs) ranged from 0.32 to 45.02 ng L−1 in the surface water, 0.53 to 71.86 ng g−1 dw in the suspended particles, and 0.09 to 24.73 ng g−1 dw in the sediment. Diethylstilbestrol (DES) was determined as the main contributor to ∑EEQs followed by NP. The risk assessment showed a higher risk in the surface water than in the suspended particles and sediment in such domestic sewage-holding lake.  相似文献   
52.
Bankside groundwater is widely used as drinking water resource and, therefore, contamination has to be avoided. In the European Union groundwater protection is explicit subject to Water Framework Directive. While groundwater pollution may originate from different sources, this study investigated on impacts via flood events.Groundwater was sampled with increasing distance to the river Rhine near Karlsruhe, Germany. Samples were HPLC-MS-MS analyzed for the river contaminant carbamazepine to indicate river water infiltration, giving permanent presence in 250 m distance to the river (14-47 μg L−1). Following a flood event, concentrations of about 16-20 μg L−1 could also be detected in a distance of 750 m to the river. Furthermore, estrogenic activity as determined with the Yeast Estrogen Screen assay was determined to increase up to a 17β-ethinylestradiol equivalent concentration (E-EQ) = 2.9 ng L−1 near the river, while activity was initially measured following the flood with up to E-EQ = 2.6 ng L−1 in 750 m distance. Detections were delayed with increasing distance to the river indicating river water expansion into the aquifer.Flood suspended matter and floodplain soil were fractionated and analyzed for estrogenic activity in parallel giving up to 1.4 ng g−1 and up to 0.7 ng g−1, respectively. Target analysis focusing on known estrogenic active substances only explained <1% of measured activities.Nevertheless, river water infiltration was shown deep into bankside groundwater, thus, impacting groundwater quality. Therefore, flood events have to be in the focus when aiming for groundwater and drinking water protection as well as for implementation of Water Framework Directive.  相似文献   
53.
An environmental assessment of six scenarios for handling of garden waste in the Municipality of Aarhus (Denmark) was performed from a life cycle perspective by means of the LCA-model EASEWASTE. In the first (baseline) scenario, the current garden waste management system based on windrow composting was assessed, while in the other five scenarios alternative solutions including incineration and home composting of fractions of the garden waste were evaluated. The environmental profile (normalised to Person Equivalent, PE) of the current garden waste management in Aarhus is in the order of −6 to 8 mPE Mg−1 ww for the non-toxic categories and up to 100 mPE Mg−1 ww for the toxic categories. The potential impacts on non-toxic categories are much smaller than what is found for other fractions of municipal solid waste. Incineration (up to 35% of the garden waste) and home composting (up to 18% of the garden waste) seem from an environmental point of view suitable for diverting waste away from the composting facility in order to increase its capacity. In particular the incineration of woody parts of the garden waste improved the environmental profile of the garden waste management significantly.  相似文献   
54.
Adequate radioprotection of the environment requires the identification of biomonitors sensitive to the variation of its radionuclide content. Due to the chemical similarities between calcium and strontium, calcified tissues of mammals are considered to be good 90Sr biomonitors. This work considered Cervus elaphus antlers which, being shed annually, can give information about the importance of radiostrontium contamination in an ecosystem in the time period required for the growth of the antler. The samples were collected at various points of W and SW Spain. The mean value of their 90Sr content was (70 ± 43 (S.D.)) Bq/kg d.w., range (16-218) Bq/kg d.w., and the radionuclide was evenly distributed in the different parts of the antler. There was a good correlation between the antlers’ 90Sr content and the 90Sr deposited in the soil. The antlers’ content of 226Ra (from the natural uranium series) and the contents of some stable elements (Ca, Mg, Sr, and K) were also determined. The values for these stable elements were practically constant in the analyzed samples, and the concentrations measured decreased in the following order:Ca » Mg > K > Sr » 90Sr > 226Ra  相似文献   
55.
张大任 《四川环境》1993,12(3):66-70
作者将自然运动与人类活动、生态环境与气候结合起来研究,求索洪旱灾害之谜,着重探讨了其中多种生态环境因素。由大灾后的反思,找出灾害加剧的人为原因是:人中激增、生态危机、水利失修等,提出必须加强防灾减灾的对策研究。  相似文献   
56.
The study contains the methodology of finding the optimal time to start the operation of a desalting plant or any other non conventional source of water for agricultural use in Israel. The essence of the methodology is the moving equilibrium price and quantity of agricultural products. The market of agricultural products is represented by a single demand curve and a supply curve which is derived from the agricultural sector production function. Both the demand for and the supply of agricultural products functions are shifting over time. The marginal value product of water is the critical value that determines the optimal time of a desalting plant. The study is static in the sense that dynamic aspects per se are not dealt with-e.g. learning by doing of building and operating desalting plants. The empirical results although used for illustrative purposes can be used as reference points for other detailed and more ‘exact’ studies on water desalination.  相似文献   
57.
居室放射性   总被引:3,自引:0,他引:3  
本文介绍了放射性的来源,讨论了室内γ射线和氡及其子体,计算了相关的年剂量当量  相似文献   
58.
泥石流与人类经济活动   总被引:10,自引:1,他引:9  
山地是泥石流与人类共存的环境,泥石流作用于山地环境,强烈地影响人类经济活动:人类经济活动也作用于山地环境,强烈地影响泥石流。泥石流对山地环境的危害,主要为破坏地表、破坏生态系统和淤堵江河;泥石流对人类及其经济活动的危害,主要为破坏城镇,村庄,工矿,交通水利水电工程,农田和人类自身的安全。泥石流危害的结果,能导致山地坡面破碎化、沟口沙石化、河床宽浅化和植被逆向演替化,以及耕地贫瘠化、经济发展滞后化和  相似文献   
59.
迄今为止,国内外有关计算构件耐火极限的方法,是钢筋混凝土构件与防火研究的主要内容。而在结构设计中,由于直接考虑的是荷载作用,为此提出了一个新概念——等效火灾荷载,将火灾对结构的影响直接考虑成荷载作用。在确定了混凝土柱的截面温度场后,利用一种简化计算方法计算出钢筋混凝土柱的等效火灾荷载,进而计算出钢筋混凝土柱的耐火极限。在火灾中,作为结构最基本的构件柱可能受到单面或多面的火作用,这里仅介绍轴心受压钢筋混凝土柱等效火灾荷载的计算。  相似文献   
60.
ABSTRACT: Participation in water-based recreation activities does not arise in random fashion nor simply as a result of having a water resource immediately available. Neither do individuals and groups engage in the same activities or a specific activity in the same way. The purpose of the present paper is to describe an alternative framework whereby differences among recreation users can be identified. Prior to this time, research directed toward understanding participation patterns at a recreational site have emphasized the activities while ignoring the human behavior factors which determine how participation arises. People consider recreation sites to be leisure settings in which the definition of such places has a broader socio-cultural meaning than that the site was designed. These definitions are reflected within the context of the social group and can be observed in the subsequent orientation to leisure and play. When activities are considered in the context of a human group, differences in participation patterns can be discovered.  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