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   1146篇
  免费   76篇
  国内免费   139篇
安全科学   179篇
废物处理   19篇
环保管理   227篇
综合类   450篇
基础理论   190篇
环境理论   2篇
污染及防治   71篇
评价与监测   49篇
社会与环境   122篇
灾害及防治   52篇
  2024年   1篇
  2023年   16篇
  2022年   31篇
  2021年   30篇
  2020年   54篇
  2019年   37篇
  2018年   25篇
  2017年   53篇
  2016年   62篇
  2015年   57篇
  2014年   45篇
  2013年   82篇
  2012年   86篇
  2011年   88篇
  2010年   56篇
  2009年   75篇
  2008年   42篇
  2007年   77篇
  2006年   47篇
  2005年   47篇
  2004年   54篇
  2003年   34篇
  2002年   38篇
  2001年   29篇
  2000年   14篇
  1999年   18篇
  1998年   26篇
  1997年   11篇
  1996年   9篇
  1995年   10篇
  1994年   7篇
  1993年   6篇
  1992年   5篇
  1991年   2篇
  1990年   8篇
  1989年   2篇
  1988年   2篇
  1987年   2篇
  1986年   1篇
  1985年   31篇
  1984年   14篇
  1983年   11篇
  1982年   5篇
  1981年   2篇
  1980年   3篇
  1979年   1篇
  1978年   2篇
  1977年   1篇
  1971年   2篇
排序方式: 共有1361条查询结果,搜索用时 812 毫秒
921.
调查了水泥厂机立窑各类除尘设备的现状 ,结果表明 ,干法静电除尘器是目前机立窑烟尘治理的首选除尘器  相似文献   
922.
在处理了部分有关资料的基础上 ,从发震断层旋性、历史地震类比、地震活动图像变化和地震序列特征等多方面对昆仑山口西 8.1级地震的余震活动趋势进行了讨论 ,结果表明 :本次 8.1级地震的最大余震震级可能为 6级左右  相似文献   
923.
从供给角度对地震灾害国民经济体系易损性的分析   总被引:1,自引:0,他引:1  
王海滋  黄渝祥 《灾害学》1997,12(3):18-22
以投入产出分析为基础,从供给的角度提出了对地震灾害国民经济体系易损性分析方法,为经济体系生命线工程的确定和防灾、抗灾投入的有效实施提供了基础。  相似文献   
924.
阮小明 《灾害学》1993,8(4):37-40
本文在分析湖北省局部地区自然疫源变化及疾病趋势的基础上,指出了南水北调中线工程可能对地氟病、血吸虫、疟疫、乙脑及其它水源性疾病所带来的影响,并提出了建设性的建议和对策。  相似文献   
925.
论大气灾害链   总被引:15,自引:2,他引:15  
文传甲 《灾害学》1994,9(3):1-6
本文从功能、结构和本质三个角度给出了灾害链的定义,提出了灾害环、致灾体和可能受灾体(移动或静止)的概念,对现实中的大气灾害链进行了分类;分析了它们的共性与个性。对其引起破坏作用和造成损失的因素,从致灾体、可能受灾体和灾体环境及其相互关系进行了探讨;对由此而引出的减防救灾的四种途径与“除、抑、避、抗、保、跑、救、治”八项指导原则,和与其有关的战略、策略及组织问题进行了简略讨论。  相似文献   
926.
Competence in understanding and resolving environmental problems requires a curriculum that integrates traditional disciplines with applied problem-solving skills and/or methods. Building upon the work of scholars who are calling for curriculum reform so that students may understand better the ethical dimensions of environmental problems, we analyze the theory of using dialogic writing to think and learn about the environment, and we provide examples of application of this technique.  相似文献   
927.
ABSTRACT: Rapidly increasing demand for recreational use of Texas' public waters is resulting in growing conflict between riparian landowners and the public. This paper examines the public access question, certainly one of the most poorly defined and understood areas of Texas water and property law. Since the appropriation acts of the late 1800's, most surface waters are owned by the state, and are held in trust for the benefit of the people. While there is no express statutory authority giving the general public the right to use these waters, there is extensive, if often conflicting, case law recognizing such rights on navigable streams. It is equally well established that the public may not gain access by crossing private property. Definition of public and private rights is complicated by the fact that Texas land grants (with their attendant property rights) have emanated from Spain, Mexico, the Republic of Texas, and the state. Obstacles imposed by riparian landowners to public entry, use and passage, as well as spatial aspects of access, are also considered. Because public access rights are based on the peculiar circumstances of each case, it is difficult to establish general legal principles, and there is almost no reliable information to aid the recreation-seeking public. A clear legislative enunciation of public rights appears politically infeasible at present, the most immediately attainable goal lying in the area of better public education.  相似文献   
928.
ABSTRACT. Evaluation of lakes as they are related to groundwater flow systems is of special concern prior to efficient development and planning operations. Both naturally occurring and artificially created lakes are being developed rapidly as recreational and residential areas. Simultaneously, field verification of theoretical groundwater flow system behavior has progressed to the point where hydrogeologists trained to understand basic concepts of flow-system analysis can begin to broaden their research and service base, and to work closer with planners, developers, and engineers. It is suggested that particular efforts be directed toward a greater evaluation of physical, chemical, and biological aspects of potentially developable lake sites to aid in selecting use patterns in accord with these factors. Many lake developments are not in harmony with the physical environment. The resulting misuse of resources is often expressed as accelerated eutrophication of lakes, or by quality degradation of shallow groundwater flow systems contiguous to them. Lakes can no longer be considered as separate entities. Methodology for investigating the interchange of surface and near-surface water is adequate however, the application of known interchange relationships is inadequate. .  相似文献   
929.
ABSTRACT A critical examination of single gage site, monthly streamflow statistical characteristics for two southern Illinois rivers, an Oklahoma river and a Texas river was made using a digital computer at Northwestern University. High flow variability for the rivers was evident in that, for the rivers tested, 8 to 11 months had coefficients of variation in excess of unity. The gamma distribution was not as efficient as the normal distribution for fitting power or logarithmic transforms of the historical monthly flow data (i.e., F1-0, F0-5, F0-25, Fa125, F0.085, and log F). No single transform to a normal distribution was adequate for all twelve monthly flows, since definite seasonal grouping patterns were found for the four rivers examined. The highly variable flow in the low-flow season(s) indicated much more skewness than was typical of the remainder of the year. For the low-flow seasons, the higher-root (smaller exponent) transforms were particularly useful. Flows were generated from a linear regression model of lag one utilizing two or more transforms for the twelve periods. The definite seasonal patterns found historically were reproduced quite well in the generated streamflows. The effect of a change in data transform from one season to the next was insignificant after one month. Thus the use of different transforms within the year did not bias the results from the linear regression model appreciably, but did help in reproducing the seasonal distribution pattern. The technique seems especially well suited for rivers with highly variable flows.  相似文献   
930.
ABSTRACT: A pilot study was conducted to test the potential of the Contingent Valuation Methodology (CVM) to reveal the value of non-market goods in a partially monetized subsistence economy. CVM was used to estimate the willingness to pay, in the form of labor, for potable drinking water in a rural river-based community located in the Esmeraldas state of northwest Ecuador. Surveys were administered by personal interviews with families living along the waterways of the Santiago river system who used river water for cooking, drinking, washing, and waste disposal. The mean willingness to pay represented over 23 percent of real income, or 1.4 days per week for a period of one year. Results of multiple regression analysis identified the history of water-related health problems and the number of working adults in a household as significant determinants of willingness to pay. Using a non-monetary, rather than a monetary measure of willingness to pay may provide a more accurate representation of value in a subsistence economy where the use of money is limited. The potential for CVM to measure the benefits of non-market goods in rural developing regions whose economies are only partially monetized is demonstrated.  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