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   1934篇
  免费   88篇
  国内免费   44篇
安全科学   539篇
废物处理   7篇
环保管理   308篇
综合类   342篇
基础理论   57篇
环境理论   1篇
污染及防治   22篇
评价与监测   19篇
社会与环境   119篇
灾害及防治   652篇
  2023年   18篇
  2022年   23篇
  2021年   38篇
  2020年   33篇
  2019年   43篇
  2018年   38篇
  2017年   35篇
  2016年   38篇
  2015年   70篇
  2014年   41篇
  2013年   85篇
  2012年   131篇
  2011年   157篇
  2010年   100篇
  2009年   114篇
  2008年   46篇
  2007年   106篇
  2006年   111篇
  2005年   129篇
  2004年   92篇
  2003年   65篇
  2002年   73篇
  2001年   47篇
  2000年   61篇
  1999年   47篇
  1998年   33篇
  1997年   19篇
  1996年   21篇
  1995年   32篇
  1994年   32篇
  1993年   20篇
  1992年   16篇
  1991年   14篇
  1990年   9篇
  1989年   10篇
  1988年   7篇
  1987年   7篇
  1986年   5篇
  1985年   8篇
  1984年   9篇
  1983年   4篇
  1982年   10篇
  1981年   12篇
  1980年   11篇
  1979年   12篇
  1978年   8篇
  1977年   5篇
  1975年   4篇
  1974年   3篇
  1972年   6篇
排序方式: 共有2066条查询结果,搜索用时 593 毫秒
141.
简述了我国重大工业事故发生的主要原因,提出了建立重大事故预防控制体系的建议,制定《重大事故预防和控制法》,实行重大危险源上报、登记、评价、分级监察管理,建立国家、省、市三级重大事故应急反应系统和重大危险源动态监控网络系统。  相似文献   
142.
五氯酚对环境污染及居民健康影响研究   总被引:2,自引:0,他引:2  
中国长期以来使用五氯酚纳盐杀灭亡血吸虫的中间宿主──—钉螺.为评价它对环境的污染及居民健康危害,1990-1993年在我省开展了五氯酚环境污染及对居民健康影响研究.在研究区采集环境样品(空气、水体、土壤及底泥、蔬菜、肉、蛋、鱼等)共173份;生物材料(人血、尿)共457份,分析五氯酚浓度.结果在明,在五氯酚使用区,环境中PCP浓度稍高于对照区,而生物材料尿、血中PCP浓度明显高于对照区.全血胆碱脂酶活性用药区明显低于对照区,统计学分析有显著差异(P<0.001),证实了长期低剂量使用可造成环境及生物蓄积.  相似文献   
143.
ABSTRACT: Both catchment experiments and a review of hydrologic processes suggest a varying effect of forest harvest on the magnitude of peak flows according to the cause of those peak flows. In northwestern Montana and Northeastern Idaho, annual maximum flows can result from spring snowmelt, rain, mid-winter rain-on-snow, or rain-on-spring-snowmelt. Meteorologic and physical data were used to determine the cause of annual maximum flows in six basins which had the necessary data and were smaller than 150 mi2. Rain-on-spring-snowmelt was the most frequent cause of annual maximum flows in all six basins, although there was a strong gradient in the magnitude and cause of peak flows from southwest to northeast. Less frequent mid-winter rain-on-snow events caused the largest flows on record in four basins. Mid-winter rain-on-snow should be distinguished from rain-on-spring-snowmelt because of differences in seasonal timing, the relative contributions of rain vs. snowmelt, and the projected effects of forest harvest. The effects of mixed flood populations on the flood-frequency curve varied from basin to basin. Annual maximum daily flows could not be reliably predicted from rainfall and snowmelt data.  相似文献   
144.
在研究汕头市地震、风、洪潮、火等多种灾害的危险性、成灾模式和损失估计的基础上,应用地理信息系统(GIS)技术建立可视化的计算机综合防灾系统,可以提高城市的防灾能力。本文针对基于GIS的城市综合防灾系统的建立,提出了较为具体的研究方案和实施框架,便于课题组各项研究工作的开展和统一。  相似文献   
145.
城市防洪工程风险决策方法   总被引:2,自引:2,他引:2  
李清富  江见鲸 《灾害学》1995,10(1):13-17
本文着重讨论了与城市防洪工程决策制定密切相关的几个问题:①城市防洪工程设计标准的确定;②现有防洪工程的性能评估,③最优防洪工程对策的确定等,并在风险分析的基础上,给出了解决上述问题的方法。所得结论可为城市防洪工程决策的制定提供较为科学的理论依据。  相似文献   
146.
ABSTRACT: Twenty-two gaging stations were selected for developing a regional flood frequency curve for small (area less than 2 square miles) watersheds in southern Illinois. Five probability functions were compared, and the extreme value type I function was selected to develop the regional flood curve. The curve was generated with the index flood method and also another empirical method that related the function parameters to the watershed area. Estimated peak discharges with various return periods were compared with the results obtained from multiple regression analysis.  相似文献   
147.
ABSTRACT: The routing of flood waves through the Central Basin of the Passaic River in New Jersey is complex because of flat gradients and flow reversals. The one-dimensional unsteady flow program DWOPER, developed by the National Weather Service, was used to simulate flood wave movement through the Basin. A historical event was used for calibration and two synthetic events were simulated. Boundary conditions consisted of discharge hydrographs at inflow points to the study area, local flow hydrographs at interior points, and a stage discharge relation for flow over the crest of a diversion dam at the basin outlet. Manning's n values were adjusted based on stage and discharge data for the historical event; however, verification data were not available for events comparable in magnitude to the synthetic events. Aspects of the investigation reported include techniques for characterizing the flow system, model calibration, techniques for representing a tunnel diversion, and simulation results.  相似文献   
148.
The Keelung River Basin in northern Taiwan lies immediately upstream of the Taipei metropolitan area. The Shijr area is in the lower basin and is subject to frequent flooding. This work applies micromanagement and source control, including widely distributed infiltration and detention/ retention runoff retarding measures, in the Wudu watershed above Shijr. A method is also developed that combines a genetic algorithm and a rainfall runoff model to optimize the spatial distribution of runoff retarding facilities. Downstream of Wudu in the Shijr area, five dredging schemes are considered. If 10‐year flood flows cannot be confined in the channel, then a levee embankment that corresponds to the respective runoff retarding scheme will be required. The minimum total cost is considered in the rule to select from the regional flood mitigation alternatives. The results of this study reveal that runoff retarding facilities installed in the upper and middle parts of the watershed are most effective in reducing the flood peak. Moreover, as the cost of acquiring land for the levee embankment increases, installing runoff retarding measures in the upper portion of the watershed becomes more economical.  相似文献   
149.
讨论了美国等国家在防洪减灾中非工程措施方面的一些做法 ,给出了其中一些实例 ,阐述了防洪减灾工程措施与非工程措施的发展趋势。  相似文献   
150.
粮食烘干过程的噪声危害必须引起人们的重视,通过对噪声产生的根源及给作业人员健康带来的损害进行分析,结合生产实际,提出了防治措施。  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