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   700篇
  免费   19篇
  国内免费   40篇
安全科学   36篇
废物处理   5篇
环保管理   95篇
综合类   383篇
基础理论   77篇
污染及防治   104篇
评价与监测   40篇
社会与环境   10篇
灾害及防治   9篇
  2023年   8篇
  2022年   14篇
  2021年   18篇
  2020年   17篇
  2019年   10篇
  2018年   13篇
  2017年   8篇
  2016年   15篇
  2015年   13篇
  2014年   21篇
  2013年   21篇
  2012年   19篇
  2011年   46篇
  2010年   19篇
  2009年   43篇
  2008年   30篇
  2007年   51篇
  2006年   36篇
  2005年   31篇
  2004年   24篇
  2003年   33篇
  2002年   35篇
  2001年   28篇
  2000年   35篇
  1999年   40篇
  1998年   35篇
  1997年   21篇
  1996年   13篇
  1995年   8篇
  1994年   14篇
  1993年   11篇
  1992年   15篇
  1991年   4篇
  1990年   4篇
  1989年   1篇
  1988年   1篇
  1987年   1篇
  1984年   1篇
  1983年   2篇
排序方式: 共有759条查询结果,搜索用时 546 毫秒
201.
/ We identified and ranked 108 resident and migratory wildlife taxa on John F. Kennedy Space Center (KSC) that were vulnerable to local, regional, or global extinction. We ranked taxa based on their vulnerability to extinction, their potential role for maintaining faunal integrity, and the relevance of KSC for maintaining their populations in the United States and Florida. Several taxa, not listed by agencies, were vulnerable to regional or global extinction. Many taxa not vulnerable to global extinction were vulnerable to local and regional extinction. Top predators were vulnerable to extinction because of small population size, isolation from other populations, and road mortality. Many taxa were dependent on habitat conditions at different geographic locations so that conservation required greater collaboration among land owners, managers, and researchers at local, regional, and global scales.KEY WORDS: Biological diversity; Endangered species; Conservation  相似文献   
202.
Oily wastewater poses significant threats to the soil, water, air and human beings because of the hazardous nature of its oil contents. The objective of this review paper is to highlight the current and recently developed methods for oily wastewater treatment through which contaminants such as oil, fats, grease, and inorganics can be removed for safe applications. These include electrochemical treatment, membrane filtration, biological treatment, hybrid technologies, use of biosurfactants, treatment via vacuum ultraviolet radiation, and destabilization of emulsions through the use of zeolites and other natural minerals. This review encompasses innovative and novel approaches to oily wastewater treatment and provides scientific background for future work that will be aimed at reducing the adverse impact of the discharge of oily wastewater into the environment. The current challenges affecting the optimal performance of oily wastewater treatment methods and opportunities for future research development in this field are also discussed.  相似文献   
203.
溶藻细菌L7代谢物对水华鱼腥藻的溶藻效应   总被引:2,自引:1,他引:1  
从等体积不同密度的溶藻细菌L7菌液中提取胞内、胞外代谢物,分别加入等体积等密度的水华鱼腥藻中连续培养7d,研究L7代谢物对水华鱼腥藻的溶藻效应。2.78×105~2.78×10 7cfu/mL的L7胞内代谢物能显著促进藻生长和异形胞分化,到培养结束藻密度为对照组的1.7~1.98倍;异形胞数最大可为对照组的2.31倍。2.78×10 8、2.78×10 9cfu/mL的L7胞内代谢物能抑制藻生长,藻密度最低为对照组的58%;能极显著抑制异形胞分化,可不形成异形胞。2.78×10 5~2.78×109 cfu/mL的L7胞外代谢物能极显著抑制藻生长和异形胞分化,藻密度最低为对照组的0.63%,不形成异形胞;藻丝的藻细胞间隔变模糊,藻细胞变大变形,并有大量的单个球形藻体散落。L7主要通过分泌胞外代谢物溶藻,菌胞内代谢物对藻生长有"低促高抑"的作用。  相似文献   
204.
生物脱氮组合工艺的研究及应用   总被引:2,自引:1,他引:1  
为处理高浓度含氮废水,提出生物脱氮组合工艺,首先介绍3种生物脱氮技术原理,同时对其进行比较分析,找出现有技术在实际应用中存在的不足,从而归纳出生物脱氮组合工艺,即"短程硝化+厌氧氨氧化+反硝化"。该组合工艺可去除废水中各种形式的氮,且去除1 mol氨态氮消耗0.75 mol氧气。实际应用中总氮去除率最高可达87.5%,氨氮去除率最高可达91.8%。  相似文献   
205.
生物活性炭吸附石化二级废水有机污染物实验主要包括生物活性炭挂膜实验和生物活性碳影响因素实验。在实验中考察了水力负荷和活性炭滤层厚度两因素对有机污染物吸附作用。结果表明:在45 d左右挂膜基本成功,最佳水力负荷为0.25~0.75m3/(m2·h),活性炭滤层最佳厚度为90cm。  相似文献   
206.
Radionuclide transfer parameters and dose-rates for an adult ringed seal from Svalbard have been determined based on empirical and estimated tissue activity concentrations and detailed dietary and habitat information. Whole-body equivalent concentration factors determined for anthropogenic radionuclides ranged from 10(1) ((90)Sr) to 10(2) ((137)Cs, (238)Pu and (239,240)Pu), while natural radionuclides ranged from 10(2) ((210)Pb) to 10(4) ((210)Po). Employing a dietary composition of 40% fish, 40% zooplankton and 20% benthic invertebrates, a whole-body biological half-life of 29 days was derived for (137)Cs. A total dose-rate of approximately 0.19microGyh(-1) (1.7mGya(-1)) was derived for an adult ringed seal; this dose-rate is virtually entirely attributable to the internal components of (210)Po and (40)K. The dose-rates associated with the presence of anthropogenically derived radionuclides in the present assessment fall many orders of magnitude below the dose-rates at which any biological effects would be expected.  相似文献   
207.
第一届亚太区安全健成海报、录像带创作比赛即将在港举行我国有关职业安全卫生单位积极报名参赛第十三届亚太区职业安全健康组织大会及展览会将于1997年4月21日至4月26日在香港举行,这是香港职业安全健康局首次主办的大型国际性会议,预计将有二千多人参加,此...  相似文献   
208.
生物资源在农业减灾中的开发利用前景   总被引:1,自引:1,他引:0  
论述了以水、旱为主的气象灾害和农作物病、虫、草、鼠所致的生物灾害对农业生产的灾害性影响, 同时阐述了有效开发利用生物资源是防止和减轻农业灾害的有效途径, 提出了加强生物资源的开发利用研究内容  相似文献   
209.
210.
Experiments were carried out to determine the feasibility of treating tannery wastewater containing chromium, an inhibiting compound, with sequencing batch reactors (SBR). The maximum chromium concentration tolerated by microorganisms was determined through aerobic and anoxic batch experiments, and the biomass inhibition process was analyzed in a lab scale reactor at increasing chromium concentrations. The results obtained, in batch experiments and in the SBR reactor, have demonstrated that chromium addition had less influence on the denitrification bacteria than on the nitrification bacteria. In addition, it was observed that nitrification and denitrification rates, at the same chromium concentration, were higher in the SBR reactor than in batch experiments with unacclimated biomass. Experimental results confirm that sequencing batch reactors are able to produce a more resistant biomass, which acclimates quickly to inhibiting conditions. A large amount of chromium was found in the sludge from the reactor, while the effluent was devoid of the inhibiting metal.  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