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   859篇
  免费   106篇
  国内免费   296篇
安全科学   119篇
废物处理   30篇
环保管理   64篇
综合类   562篇
基础理论   148篇
污染及防治   184篇
评价与监测   47篇
社会与环境   79篇
灾害及防治   28篇
  2024年   2篇
  2023年   24篇
  2022年   92篇
  2021年   52篇
  2020年   83篇
  2019年   58篇
  2018年   47篇
  2017年   40篇
  2016年   42篇
  2015年   47篇
  2014年   59篇
  2013年   65篇
  2012年   77篇
  2011年   82篇
  2010年   60篇
  2009年   72篇
  2008年   54篇
  2007年   58篇
  2006年   42篇
  2005年   26篇
  2004年   28篇
  2003年   24篇
  2002年   16篇
  2001年   18篇
  2000年   21篇
  1999年   16篇
  1998年   9篇
  1997年   7篇
  1996年   6篇
  1995年   11篇
  1993年   5篇
  1992年   4篇
  1991年   2篇
  1990年   3篇
  1989年   1篇
  1984年   1篇
  1982年   3篇
  1972年   1篇
  1971年   1篇
  1967年   1篇
  1964年   1篇
排序方式: 共有1261条查询结果,搜索用时 31 毫秒
981.
不同来源的海州香薷和野胡萝卜的铜抗性及铜积累差异   总被引:2,自引:0,他引:2  
以来自矿区(铜绿山和赤马山铜矿)和非矿区(红安、武汉严西湖)的海州香薷和野胡萝卜种群为对象,通过土培实验,研究了2种植物的铜抗性及铜吸收积累差异.结果显示,来自矿区的海州香薷和野胡萝卜种群的铜抗性都明显高于非矿区种群,但2种植物种群的铜吸收积累特征明显不同:海州香薷植物吸收的Cu主要集中在根中,但矿区种群吸收积累的铜量明显低于非矿区种群;而野胡萝卜吸收的Cu主要集中在地上部分(地上部分的Cu富集量是根的1.5倍),但积累的铜量在矿区和非矿区种群间没有明显的差异.因此,来自矿区的海州香薷可能进化为铜避性对策,而野胡萝卜的铜抗性与其吸收积累的总量没有明显的关系,但有很好的向地上运输能力.  相似文献   
982.
Background, aim, and scope  It has been known that the pollutants of electronic wastes (E-wastes) can lead to severe pollution to the environment. It has been reported that about 50% to 80% of E-wastes from developed countries are exported to Asia and Africa. It has become a major global environmental problem to deal with ‘E-wastes’. E-waste recycling has remained primitive in Jinghai, China. This not only produces enormous environmental pollution but also can bring about toxic or genotoxic effects on the human body, threatening the health of both current residents and future generations living in the local environment. The concentration of lead in the blood of children in the E-waste polluted area in China is higher than that of the control area. But little is known about the cytogenetic effect to human beings caused by the pollution of E-wastes. In the present study, experiments have been performed to investigate the genetics of permanent residents of three villages with numerous E-waste disposal sites and to analyze the harmful effects of exposure to E-wastes. Materials and methods  In total, 171 villagers (exposed group) were randomly selected from permanent residents of three villages located in Jinghai County of Tianjin, China, where there has been massive disposal of E-wastes. Thirty villagers were selected from the neighboring towns without E-waste disposal sites to serve as controls. Chromosomal aberrations and cytokinesis blocking micronucleus were performed to detect the cytogenetic effect, dic + r (dicentric and ring chromosome), monomer, fragments (acentric fragments, minute chromosomes, and acentric rings), translocation, satellite, quadriradial, total aberrations, and micronuclear rate were scored for each subject. DNA damage was detected using comet assay; the DNA percentage in the comet tail (TDNA%), tail moment (TM), and Olive tail moment (OTM) were recorded to describe DNA damage to lymphocytes. Results  The total chromosome aberration rates (5.50%) and micronuclear rates (16.99%) of the exposure group were significantly higher than in the control group (P = 0.000). The percentage of DNA in the comet tail, tail moment, and Olive tail moment detected by comet assay showed that there was a significant difference in DNA damage in the exposure group (P = 0.000). The chromosome aberration, micronucleus rate, and DNA damage observed in women were significantly higher than those in men. Chromosome aberration and micronuclear rates of both smokers and non-smokers in the exposure group are obviously higher than that in the control group (P = 0.000). Discussion  The use of outdated (and unsafe) ways to deal with E-wastes can lead to exposure to a variety of substances harmful to human health. The components of pollution may enter the human body through the air, drinking water, and food chain to damage human genetic material, resulting in genomic instability. The rates of chromosomal aberration, micronucleus formation, and the degree of DNA damage in women in the group exposed to electronic waste were significantly higher than in men. The reason for this may be concerned with the traditional lifestyle of the local residents or the difference of sensitivity to the exposure to E-wastes or any others. Further investigations are needed to provide evidence to demonstrate this. Conclusions  Here, we report the obviously cytogenetic toxicity to the exposure population by the E-waste pollution for the first time. E-waste pollution may be a potential agent of genetic mutation, and may induce cytogenetic damage within the general population exposed to the pollution. These findings need to be considered, and steps should be taken to protect the current population and future generations from the effects of pollution with E-wastes. Recommendations and perspectives  The above results remind us that the impact of E-waste recycling on environmental quality of Jinghai should be evaluated soon. Moreover, it is urgent for the government to prohibit E-waste import and its processing by outdated ways. The future studies such as pollutant details of drinking water, air, and soil in the area as well as epidemiological investigations on the harmful effect to children must be performed eagerly. All the data available do provide a compelling case for immediate action in both countries to address workplace health and safety and waste management. Qiang Liu and Jia Cao contributed equally to this study and share the first authorship.  相似文献   
983.
水利水电工程环境影响评价分析   总被引:1,自引:0,他引:1  
主要介绍了中国水利水电工程与环境的关系,综述了中国水电工程兴建对环境与生态方面的有利与不利影响,以及进行环境影响评价的目的、影响识别、预测评价方法和步骤、评价结论与对策措施,指出了在环境评价的实际工作中的不足,并提出了相应的措施.  相似文献   
984.
从资源环境因子、生态环境压力因子、社会经济因子3个方面入手,对郑州市的生态环境质量与生态安全进行综合评价,确定了郑州市生态安全综合指数,并对郑州市的生态安全建设提出了可行的对策与建议.  相似文献   
985.
在综合已有研究的基础上,以广州市为案例,对其近年来的土地利用生态服务价值进行了评价.研究表明:①2000-2007年广州市土地利用的生态服务价值不断上涨,但与GDP的比值远小于全国平均水平,且处于下降态势;②这7年间不同土地类型生态服务价值增长量最大的是城市绿地,耕地、城镇居住用地、工业用地则呈现出负增长状态.  相似文献   
986.
采用等体积浸渍法制备了MnOx/CNTs催化剂,用于低温NH3选择性催化还原(SCR)NO的实验。使用BET,FT-IR,TEM和XRD对催化剂进行表征,结果表明:碳纳米管经混酸超声分散,增加了羧基活性基团,锰氧化物颗粒分布较均匀。在模拟烟气条件下,考察了催化剂的MnOx负载量、煅烧温度及质量和烟气流速比(W/F)对NO脱除率的影响。煅烧温度为773 K,MnOx负载量为10%时,NO脱除率达到98.56%;W/F为2-3 mg/(mL·min^-1)时NO的脱除率更高。  相似文献   
987.
Du Y  Shi X  Liu C  Yu K  Zhou B 《Chemosphere》2009,74(5):723-729
Perfluorooctane sulfonate (PFOS) is widely distributed and persistent in the environment and wildlife. The main aim of this study was to investigate the impact of long-term exposure to low concentrations of PFOS in zebrafish. Zebrafish fry (F(0), 14 d post-fertilization, dpf) were exposed via the water for 70 d to 0 (control), 10, 50 and 250 microg L(-1) PFOS, followed by a further 30 d to assess recovery in clean water. The effects on survival and growth parameters and liver histopathology were assessed. Although growth suppression (weight and length) was observed in fish treated with high concentrations PFOS during the exposure period, no mortality was observed throughout the 70 d experiment. Embryos and larvae (F(1)) derived from maternal exposure suffered malformation and mortality. Exposure to 50 and 250 microg L(-1) PFOS could inhibit the growth of the gonads (GSI) in the female zebrafish. Histopathological alterations, primary with lipid droplets accumulation, were most prominently seen in the liver of males and the changes were not reversible, even after the fish were allowed to recover for 30 d in clean water. The triiodothyronine (T(3)) levels were not significantly changed in any of the exposure groups. Hepatic vitellogenin (VTG) gene expression was significantly up-regulated in both male and female zebrafish, but the sex ratio was not altered. The overall results suggested that lower concentrations of PFOS in maternal exposure could result in offspring deformation and mortality.  相似文献   
988.
活性红BF-3BN脱色菌群的构建及特性研究   总被引:1,自引:0,他引:1  
采用梯度压力式驯化法,从河南某印染厂的活性污泥中富集筛选一组活性红BF-3BN高效脱色菌群AR1。经菌株分离和16S rDNA测序分析,确定菌群内微生物分别归属Clostridium sp.、Pseudomonas sp.和Shewtnella sp.等3个属。染料脱色实验结果表明,在活性红BF-3BN起始浓度为200...  相似文献   
989.
广玉兰提取物对铜绿微囊藻抑制作用的机制研究   总被引:2,自引:0,他引:2  
采用前期研究发现的可显著抑制铜绿微囊藻的广玉兰正己烷和正丁醇提取物,对其抑藻机制进行初步研究.研究发现,经广玉兰提取物处理后,藻细胞的叶绿素a含量显著减少;超氧化物歧化酶(SOD)活性先升后降;细胞膜透性显著增强,最高值达到对照组的7~8倍.同时,藻细胞的超微结构也相应地发生改变,具体表现为:细胞变形,质膜皱缩甚至断裂...  相似文献   
990.
Cheng H  Ma L  Zhao C  Li X  Wang X  Liu Y  Yang K 《Chemosphere》2011,85(3):406-411
The concentrations, spatial distribution and compositional patterns of extensively used hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) in urban dustfall in a metropolis-Beijing are presented in this paper. The potential sources are discussed and soil burdens are predicted based on the fluxes. The hotspots in commercial areas are identified by spatial distribution maps and the fractional value isomers indicates that dustfall in urban Beijing are affected by both current and historical usage of DDTs. It is worth noticing that there is possible application "dicofol-type of DDTs" in Beijing. The measured atmospheric deposition flux is 1.14×10(5) ng h(-1) m(-2) for HCHs and 1.47×10(5) ng h(-1) m(-2) for DDTs, respectively. However, when compared with atmospheric deposition flux, the volatilization flux estimated from concentrations in soils by fugacity model is significantly lower for HCHs (2.41 ng h(-1) m(-2)) and DDTs (0.07 ng h(-1) m(-2)). The net atmospheric flux to the soil suggests that the levels of HCHs and DDTs in soil are dominated by atmospheric deposition and the urban soil in Beijing would be a sink for HCHs and DDTs in the long term.  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