全文获取类型
收费全文 | 3142篇 |
免费 | 169篇 |
国内免费 | 165篇 |
专业分类
安全科学 | 2098篇 |
废物处理 | 33篇 |
环保管理 | 220篇 |
综合类 | 638篇 |
基础理论 | 132篇 |
环境理论 | 5篇 |
污染及防治 | 106篇 |
评价与监测 | 24篇 |
社会与环境 | 76篇 |
灾害及防治 | 144篇 |
出版年
2024年 | 8篇 |
2023年 | 19篇 |
2022年 | 43篇 |
2021年 | 100篇 |
2020年 | 85篇 |
2019年 | 114篇 |
2018年 | 33篇 |
2017年 | 315篇 |
2016年 | 135篇 |
2015年 | 386篇 |
2014年 | 48篇 |
2013年 | 77篇 |
2012年 | 213篇 |
2011年 | 118篇 |
2010年 | 125篇 |
2009年 | 124篇 |
2008年 | 106篇 |
2007年 | 188篇 |
2006年 | 266篇 |
2005年 | 239篇 |
2004年 | 183篇 |
2003年 | 142篇 |
2002年 | 53篇 |
2001年 | 43篇 |
2000年 | 58篇 |
1999年 | 36篇 |
1998年 | 30篇 |
1997年 | 30篇 |
1996年 | 24篇 |
1995年 | 39篇 |
1994年 | 15篇 |
1993年 | 11篇 |
1992年 | 12篇 |
1991年 | 7篇 |
1990年 | 10篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1980年 | 2篇 |
1979年 | 5篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1970年 | 2篇 |
排序方式: 共有3476条查询结果,搜索用时 31 毫秒
951.
防灾减灾系统工程的国际对比分析及建议 总被引:11,自引:2,他引:9
针对我国现存的灾害状况,本文通过国际对比的方法,对其他国家已有的减灾系统工程作了简单介绍,并结合我国实际,对未来建立减灾系统工程中应着重加强的薄弱环节作了分析,提出了加强立法工作,增加减灾投入,建立全国统一的减灾通讯系统的建议。 相似文献
952.
不稳定边坡治理方案的多层次模糊综合群决策 总被引:11,自引:1,他引:10
不稳定边坡治理方案的选择经常涉及到的是可行域为有限集的多层次模糊综合群决策问题。本文基于边坡工程知识,构造了不稳定边坡治理方案的评判指标层次结构,应用系统工程、模糊数学等知识,建立了不稳定边坡治理方案的多层次模糊综合群决策模型,从而使不稳定边坡治理方案选择更趋合理、科学。 相似文献
953.
J.C. Doornkamp 《Journal of environmental management》1998,52(4):327-333
A review of the difficulties associated with the definition of coastal flood frequencies and magnitudes leads to a recognition that there is considerable doubt in many parts of the world as to the precise nature of this particular hazard. Similarly, a review of the sea-level measurements that have been used to indicate a response to global warming shows that there is uncertainty about the amount of other controlling influences. What is clear, however, are that past management decisions about human endeavours in the coastal zone (including flood defences, occupance of flood-prone lands, extraction of ground water and natural gas) have had an impact on relative land and sea levels and have done more to increase the risk of coastal flooding than can be assigned so far to global warming. In addition, these changes induced by human activity may render inappropriate calculations of coastal-flood frequencies based on historical records since the latter relate to a period of time when the controls on flooding may have been very different. 相似文献
954.
955.
阐述了计算机实时仿真在危险气体泄漏扩散预警系统中的应用。文中首次提出了通过求解气体扩散方程一类反问题来确定源强,即根据传感器实时检测的浓度值,代入反问题算法的仿真程序求得近似泄漏强度,再将实时采集的气象参数一并代入扩散方程,在显示屏上给出有害气体云团在区域电子地图上的扩散态势。 相似文献
956.
J. G. Elliott R. S. Parker 《Journal of the American Water Resources Association》1997,33(5):1041-1054
ABSTRACT: The Gunnison River in the Gunnison Gorge is a canyon river where upstream dams regulate mainstem discharge but do not affect debris-flow sediment supply from tributaries entering below the reservoirs. Regulation since 1966 has altered flood frequency, streambed mobility, and fluvial geomorphology creating potential resource-management issues. The duration of moderate streamflows between 32.3 and 85.0 m3/s has increased threefold since 1966. This, along with flood-peak attenuation, has facilitated fine-sediment deposition and vegetation encroachment on stream banks. The Shields equation and on-site channel geometry and bed-material measurements were used to assess changes in sediment entrainment in four alluvial reaches. Sand and fine gravel are transported through riffle/pool reaches at most discharges, but the cobbles and boulders composing the streambed in many reaches now are infrequently entrained. Periodic debris flows add coarse sediment to rapids and can increase pool elevation and the streambed area affected by backwater and fine-sediment accumulation. Debris-flow supplied boulders accumulate on fans and in rapids and constrict the channel until reworked by larger floods. The response to streamflow-régime changes in the Gunnison Gorge could serve as an analog for alluvial reaches in other regulated canyon rivers. 相似文献
957.
铁路安全管理与安全工程、安全文化 总被引:1,自引:0,他引:1
论述了铁路安全工作中的工程问题和文化问题,提出铁路安全基础建设工程应是加强铁路安全综合性研究与综合管理,建设铁路安全文化。 相似文献
958.
本文提出了防灾工程中计算机仿真的作用、思路及主要技术关键,并通过若干例子,包括混凝土构件破坏,岩石块体崩塌,地震作用下房屋碎片分布,房屋在爆炸作用下倒塌等说明仿真技术的应用。 相似文献
959.
Richard M. Vogel Neil M. Fennessey 《Journal of the American Water Resources Association》1995,31(6):1029-1039
ABSTRACT: A streamflow duration curve illustrates the relationship between the frequency and magnitude of streamflow. Flow duration curves have a long history in the field of water-resource engineering and have been used to solve problems in water-quality management, hydropower, instream flow methodologies, water-use planning, flood control, and river and reservoir sedimentation, and for scientific comparisons of streamflow characteristics across watersheds. This paper reviews traditional applications and provides extensions to some new applications, including water allocation, wasteload allocation, river and wetland inundation mapping, and the economic selection of a water-resource project. 相似文献
960.
Jacek K. Leznicki George P. Korfiatis 《Journal of the American Water Resources Association》1987,23(6):1085-1089
ABSTRACT: Two models based on variations of the one dimensional Boussinesq equation are presented. The models are formulated by treating each of the two nonlinearities appearing in the equation separately, and the resulting equations are solved by implicit finite difference techniques. The models have been used to predict drawdowns created from large scale pumping at an open coal mine pit dewatering project in Poland. The predictions were found to be in good agreement with data collected over a period of seven years. 相似文献