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   770篇
  免费   132篇
  国内免费   208篇
安全科学   136篇
废物处理   4篇
环保管理   89篇
综合类   339篇
基础理论   204篇
污染及防治   37篇
评价与监测   14篇
社会与环境   18篇
灾害及防治   269篇
  2024年   7篇
  2023年   11篇
  2022年   27篇
  2021年   35篇
  2020年   29篇
  2019年   26篇
  2018年   35篇
  2017年   41篇
  2016年   56篇
  2015年   43篇
  2014年   34篇
  2013年   66篇
  2012年   68篇
  2011年   69篇
  2010年   70篇
  2009年   41篇
  2008年   31篇
  2007年   64篇
  2006年   60篇
  2005年   42篇
  2004年   42篇
  2003年   37篇
  2002年   18篇
  2001年   28篇
  2000年   15篇
  1999年   11篇
  1998年   12篇
  1997年   7篇
  1996年   14篇
  1995年   11篇
  1994年   16篇
  1993年   7篇
  1992年   5篇
  1991年   3篇
  1990年   7篇
  1988年   4篇
  1987年   2篇
  1986年   1篇
  1985年   1篇
  1984年   1篇
  1983年   2篇
  1982年   1篇
  1981年   1篇
  1980年   1篇
  1978年   1篇
  1977年   2篇
  1976年   1篇
  1975年   1篇
  1974年   1篇
  1970年   1篇
排序方式: 共有1110条查询结果,搜索用时 296 毫秒
721.
Masanori Izumi 《Disasters》1983,7(4):244-250
A summary review of the Japan Sea (Nipponkai-chubu) earthquake of 1983 is presented. Damage to civil and building structures is explained in brief. Owing to the spread of earthquake-proof design, damage sustained was very slight for a M = 7.7 earthquake, except to those built on liquefied ground. Our next target in earthquake engineering may be to protect and maintain the functions of city-facilities against strong shaking so that citizens might not experience much disruption in their daily lives after big earthquakes.  相似文献   
722.
中国农业雹灾灾情及其季节分区   总被引:9,自引:3,他引:9  
根据中国雹灾灾情数据库资料,中国雹灾受灾、成灾面积均呈下降趋势,但成灾率仍呈上升趋势。雹灾季节变化明显,春夏为全国降雹的主要时段,4~9月出现的冰雹次数约占全年总次数的92.3%。降雹与成灾在空间分布上有明显的差异,成灾中心集中在黄淮海平原及江南丘陵地区。本文基于县级雹灾季节类型图和农业综合区划图,采用"自上而下"和"自下而上"相结合的方法对雹灾进行了季节分区,将全国分为5个雹灾类型大区:夏季型(I)、春末夏初-夏季型(II)、春末夏初-双峰型(III)、春季型(IV)、夏季-双峰型(V),以及16个二级雹灾亚区,28个三级雹灾区。  相似文献   
723.
振动与冲击试验中单自由度线性系统损坏可能性的比较   总被引:1,自引:0,他引:1  
比较了单自由度线性机械系统在稳态振动,随机振,运输试验以及冲击试验中响应的大小。  相似文献   
724.
一种简易的城市地震小区划方法—场地指数法   总被引:1,自引:0,他引:1  
本文提出了以模糊推论的综合评判方法导出的场地指数作为地震小区划的尺度进行地震小区划的方法。文中介绍了场地指数的定义和计算方法;场地指数与震害和地震动参数的关系。最后以唐山地震时该地区实际震害的分布与小区划结果的对比,验证了场地指数小区划方法的可靠性。  相似文献   
725.
陕西省自然灾害损失评估的初步研究   总被引:2,自引:0,他引:2  
本文首先以陕西省1960~1990年10个代表气象台(站)的降水距平率和分布面积为指标将旱涝程度划分为5级,然后分析了各级旱涝程度下的暴雨、冰雹、洪水等自然灾害频度及相应的农田成灾、倒塌房屋、死亡人口、减产粮食等损失,从而建立起了自然因子-灾害-损失之间的平均定量关系,为进行自然灾害评估奠定了基础,最后对研究期间做了检验和预测试验。  相似文献   
726.
干旱、洪涝、霜冻、冰雹是山东省最主要的气象灾害,具有频率高、范围广、灾情重等特征。通过对历史资料的整理、编码和输入,建立了山东省近600年旱涝霜雹数据库、近40年降水数据库和预报因子数据库,并编制了数据管理和分析软件包,在国际著名的SAS统计分析系统基础上,建立了山东省旱涝霜雹超长期预报系统。本文简要论述灾害数据库和预报系统建立的技术方法及系统应用的初步结果。  相似文献   
727.
Administrative machinery has been set up to regulate and control most of the emissions that are known to have severe local consequences, such as the discharge of raw sewage into rivers and lakes and the smokestack emission of air pollutants. Now, the nature of environmental degradation is usually different. We are faced with pollutants and effects with more subtle cause-effect relationships, often characterized by larger geographic areas of interest and longer term potential damage; the potential risk is now more chronic than acute. Acid rain and climate change are good examples, in that they are associated with a variety of pollutants from a number of sources and damage to ecosystems occurs over many years. It is argued that monitoring programs should evolve to reflect the changing nature of the environmental problems they are addressing. It is now necessary to consider interactions among many pollutants, mixing among the various media, and potentially affecting many components of the ecosystem in both indirect and direct ways. Here, integrated monitoring and analysis is presented as a unifying strategy to bring together different measurement methodologies in different disciplines, addressing environmental questions of complexity beyond the scope of many existing activites that have a classical narrower focus. The underlying concept is of nested networks, each tier being composed of sites selected for specific purposes but arranged to maximize the number of common sites where more multidisciplinary questions can be addressed.  相似文献   
728.
ABSTRACT: The hypothesis of this paper is that regulatory systems for the control of effluent released to the environment can be, if improperly designed, inadequate for both the establishment of effective pollution control policy and the assessment of the biological significance of violations. This inadequacy may stem from several factors: first, the use of single point standards which delineate the boundary between legally acceptable and unacceptable pollutant discharges; and second, the existence of significant weaknesses in the frequency and design of monitoring programs. In order to be effective, pollution standards must reflect the impact of pollutants on the ecosystem. To achieve this goal, three critical pieces of information are required: measurement of ambient levels of released pollutants, frequency distributions derived from these data, and estimates of biological damage functions. Illustrating the above three requirements with data drawn from research in British Columbia, the authors recommended a restructuring of environmental policy to provide regulatory agencies with an effective mechanism for the analysis and control of environmental degradation.  相似文献   
729.
ABSTRACT: An evaluation of the Leadville, Colorado, precipitation records that include a reported record-breaking storm (and flood) at higher elevations in the Rocky Mountains has indicated that the use of an experimental Marvin windshield (designed to decrease the effects of wind on precipitation-gage catchment of snow during winter) resulted in substantially overregistered summer precipitation for 1919 to 1938. The July monthly precipitation for these years was over-registered by an average of 157 percent of the long-term July monthly precipitation at Leadville. The cause of the overregistration of precipitation was the almost 4-foot-top-diameter cone-shaped windshield that had the effect of “funneling” hail and rain splash into the rain gage. Other nearby precipitation gages, which did not use this Marvin windshield, did not have this trend of increased precipitation for the same period. Streamflow records from the Leadville area also do not indicate an increase in streamfiow from 1919 to 1938. The storm of July 27, 1937, considered one of the few, large, intense rainstorms at higher elevations, had a recorded precipitation of total 4.34 inches (4.26 inches in 1 hour). Streamflow-gaging-station records indicate that only 0.09 inch of storm runoff occurred. Paleoflood investigations of channels in the Leadville area and old newspaper accounts also indicate no substantial flood from this storm. This study indicates that the 1937 storm probably totaled about 1.7 inches of precipitation, much of which occurred as hail.  相似文献   
730.
ABSTRACT: This paper presents a new methodology to calculate economic losses from hypothetical, extreme flood events, such as the Probable Maximum Flood. The methodology uses economic data compiled from already-available secondary sources, such as U.S. Census data on magnetic tapes, utilizing microcomputer and other electronic media. Estimates of land elevations are obtained from topographic maps, and flood elevations axe estimated using, for example, a dam breach and flood routing (DAMBRK) model (Fread, 1984). The calculations are performed at a disaggregate spatial scale, by various land use and industrial classification categories. The basic areal units are city blocks (for urbanized areas), enumeration districts, and Census tracts. Depth-damage functions, which provide an estimate of damages as a proportion of the existing value of the structure, are estimated statistically. Computer software (called DAMAGE) is used to combine the economic, flood elevation, and depth-damage information to compute economic losses for different possible flood stages and for different inflow events. Two case studies are presented as illustrations of the method.  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