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   1547篇
  免费   88篇
  国内免费   724篇
安全科学   92篇
废物处理   98篇
环保管理   92篇
综合类   955篇
基础理论   292篇
污染及防治   639篇
评价与监测   70篇
社会与环境   59篇
灾害及防治   62篇
  2024年   2篇
  2023年   25篇
  2022年   89篇
  2021年   75篇
  2020年   56篇
  2019年   54篇
  2018年   66篇
  2017年   65篇
  2016年   89篇
  2015年   100篇
  2014年   118篇
  2013年   139篇
  2012年   143篇
  2011年   140篇
  2010年   102篇
  2009年   88篇
  2008年   87篇
  2007年   91篇
  2006年   96篇
  2005年   63篇
  2004年   61篇
  2003年   63篇
  2002年   48篇
  2001年   58篇
  2000年   65篇
  1999年   55篇
  1998年   59篇
  1997年   48篇
  1996年   48篇
  1995年   41篇
  1994年   26篇
  1993年   21篇
  1992年   17篇
  1991年   7篇
  1990年   12篇
  1989年   6篇
  1988年   5篇
  1987年   4篇
  1986年   5篇
  1985年   2篇
  1984年   4篇
  1983年   7篇
  1982年   4篇
  1981年   2篇
  1980年   1篇
  1978年   2篇
排序方式: 共有2359条查询结果,搜索用时 15 毫秒
191.
慎义勇  米永红  韦朝海 《环境工程》2007,25(2):30-32,38
利用筛选的3种微生物,在初步研究其对某些化合物降解能力的基础上,考察其降解油制气废水过程中一般因素如温度、pH值、供氧条件、废水浓度以及营养因素如磷源、碳源对微生物降解能力的影响。研究表明,各菌种可在自然环境条件范围内,保持对废水CODCr降解效果的稳定性。葡萄糖、乙醇的加入,可将各菌种对CODCr的去除率分别提高16.9%~26.5%、17.6%~25.6%。  相似文献   
192.
本文系统分析现代灾害的特点;评述灾害研究及灾害学的历史与现状,预测其发展趋势;探讨灾害学的基本范畴,界定其学科体系的总体框架,对灾害研究及灾害学发展中的几个重要问题提出认识与建议。  相似文献   
193.
灾害基本成因研究   总被引:4,自引:2,他引:4  
本文依据灾害的生态经济性质,在对各类灾害的具体成因进行概括与抽象的基础上,从地球系统、自然生态系统、社会经济系统、城市系统的运动与发展及灾害与这些系统的相互联系和相互作用等方面研究各类灾害的共同成因,即灾害的基本成因,并对其进行系统分析。  相似文献   
194.
Summary The author was a consultant, assigned from the United Nations Development Programme (UNDP), to provide technical assistance to China's environmental pollution research and control. His assignment in China from September 1 through October 8, 1983 was filled with visits and meetings at key research institutes, universities, and regulatory agencies in the cities of Beijing (Peiking), Shanghai, Hangchow, Zhuji and Zhiaxing (Fig. 1). Trips to famous historical sites and scenic points in and around those cities were squeezed in between the heavily scheduled meetings. Dr Shen was born and educated in China through college. This is a report of his first trip back to his homeland since he left 35 years ago. His ability to communicate with the Chinese professionals and social strata in their native tongue provided him with a greater advantage in understanding the current status of China's environmental sciences and technology in preventing air, water, and land pollution. His contribution lies not only in the technical transfer of environmental sciences and engineering, but also in strengthening the ties of cooperation and communication between American and Chinese professionals. Dr Shen is a senior research scientist with the New York State Department of Environmental Conservation and an adjunct faculty member of the Division of Environmental Sciences, Columbia University.  相似文献   
195.
This paper presents results from a study conducted in two urban areas of southern California, Downey and Riverside, to examine the effect of different sources and formation mechanisms on the size distribution and temporal trends of ultrafine particles. Near-continuous data were collected for 5 months at each location. Our data clearly identified Downey as a source site, primarily affected by vehicular emissions from nearby freeways, and Riverside as a receptor site, where photochemical secondary reactions form a substantial fraction of particles, along with local vehicular emissions. In Downey, the diurnal trends of total particle number concentration and elemental carbon (EC) appear to be almost identical throughout the day and irrespective of season, thereby corroborating the role of primary emissions in the formation of these particles. This agreement between EC and particle number was not observed in Riverside during the warmer months of the year, while very similar trends to Downey were observed during the winter months in that area. Similarly, the size distribution of ultrafine particles in Downey was generally unimodal with a mode diameter of 30-40 nm and without significant monthly variations. The number-based particle size distributions obtained in Riverside were bimodal, with a significant increase in accumulation mode as the season progressed from winter to summer. During the warmer months, there was also an increase in sub-100-nm particles in the afternoon hours, between 2:00 p.m. and 4:00 p.m., that also increased with the temperature. The differences observed in the ultrafine particle distribution and temporal trends clearly demonstrated that mechanisms other than direct emissions play an important role in the formation of ultrafine particles in receptor sites of the Los Angeles Basin.  相似文献   
196.
关于重大隐患监控GIS模式的研究   总被引:3,自引:3,他引:3  
系统地分析了重大危险源、事故隐患的地域监管体系以及隐患监控的新技术应用基础 ;提出了职业安全卫生监管体系中的危险源和隐患监控 ,应该分为过程安全监控和安全目标监控两个层次。隐患监管功能的有效实现 :隐患监控的技术载体则越来越依托信息网络的发展 ;重大隐患监管体系特别适合采用地理信息系统  相似文献   
197.
关于城市应急供水系统建设的思考   总被引:5,自引:3,他引:5  
沈晓娟  徐向阳  崔韩 《灾害学》2007,22(1):134-137
从城市应急供水系统建设的紧迫性和重要性出发,分析了目前我国城市应急供水系统存在的问题和造成城市非常供水的原因。构建了城市应急供水系统的框架,将其分成工程措施和非工程措施两部分,并阐述了工程措施的类型和实施方法,以及非工程措施的各项应急机制,对建立、健全城市应急供水系统进行了探讨。  相似文献   
198.
This paper's survey of the pollution of the Wujin'gang River is important because it is one of the main rivers flowing into Meiliang Bay of Lake Taihu in eastern China. Trace metals (TMs) in this paper are described according to their pollution index (P i). Cluster analysis and correlation analysis are utilized for group sites and to assess co-contamination. Toxicity effect analysis was conducted using individual sediment quality guideline quotients (SQGQs) and mean SQGQs. The results showed that sediment from the Wujin'gang River basin was affected by nutrients, heavy metals, and polycyclic aromatic hydrocarbons (PAHs), which are an essential contamination source for both Meiliang Bay and Zhushan Bay of Lake Taihu. The discharge of TMs has significant correlations to total nitrogen (TN) and total phosphorus (TP); however, no significant correlations were observed between the content of PAHs and TMs. Toxicity effect results show that sediment in the Wujin'gang River basin threatens sediment-dwelling organisms. The harmful effect was mainly caused by heavy metals especially Cd, Cr, Ni, and Cu. Sediment dredging is an effective way to control pollution from internal rivers especially for the pollution of TN and heavy metals in the Wujin'gang River basin.  相似文献   
199.
王伟  沈凯  黄亚继 《环境工程》2012,30(1):135-138
针对费用最小化理论在可靠性分配中的局限性,建立更切合实际的固定费用下可靠度极大化思想。将该思想运用到尿素热解脱硝系统中,针对系统结构功能特征及运行特点,深入分析各系统间逻辑功能关系,提出了完整的尿素热解脱硝系统可靠性分配模型。并引入可靠性成本预估函数,以固定费用为约束,建立数学模型,实现了系统可靠性指标的最优化分配。最后以脱硝系统为例,获得具有实际意义的数值解,证明了该方法的可用性及正确性。  相似文献   
200.
目前企业化经营已被越来越多地运用于农业开发的生产管理中。本文阐述了农业开发中企业化经营形式及其重要性,分析了当前企业化经营优势尚未充分发挥的原因,提出了加强农业开发企业化管理的对策。  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