全文获取类型
收费全文 | 1947篇 |
免费 | 81篇 |
国内免费 | 657篇 |
专业分类
安全科学 | 148篇 |
废物处理 | 105篇 |
环保管理 | 142篇 |
综合类 | 1084篇 |
基础理论 | 315篇 |
污染及防治 | 580篇 |
评价与监测 | 78篇 |
社会与环境 | 107篇 |
灾害及防治 | 126篇 |
出版年
2024年 | 1篇 |
2023年 | 22篇 |
2022年 | 83篇 |
2021年 | 73篇 |
2020年 | 70篇 |
2019年 | 67篇 |
2018年 | 83篇 |
2017年 | 89篇 |
2016年 | 91篇 |
2015年 | 114篇 |
2014年 | 146篇 |
2013年 | 182篇 |
2012年 | 115篇 |
2011年 | 144篇 |
2010年 | 111篇 |
2009年 | 103篇 |
2008年 | 126篇 |
2007年 | 130篇 |
2006年 | 86篇 |
2005年 | 86篇 |
2004年 | 66篇 |
2003年 | 104篇 |
2002年 | 103篇 |
2001年 | 82篇 |
2000年 | 85篇 |
1999年 | 58篇 |
1998年 | 47篇 |
1997年 | 61篇 |
1996年 | 31篇 |
1995年 | 29篇 |
1994年 | 28篇 |
1993年 | 21篇 |
1992年 | 16篇 |
1991年 | 9篇 |
1990年 | 8篇 |
1989年 | 4篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1983年 | 1篇 |
1981年 | 1篇 |
排序方式: 共有2685条查询结果,搜索用时 78 毫秒
781.
本文从水利生态学的角度出发,研究分析了与水利有关的生态问题和与生态有关的水利问题。首次提出了生态灌溉制度的概念,为水利生态学的建立、水资源的高效利用打下了基础。建立了三级数学模型,用系统工程的方法,通过计算机求解,能够得到高效低耗的生态灌溉制度,为发展节水型的高效生态农业提供可靠的科学依据。 相似文献
782.
Ji-Quan Shi Ziqiu Xue Sevket Durucan 《International Journal of Greenhouse Gas Control》2007,1(4):473-480
This paper reports on an integrated laboratory and numerical simulation study of ultrasonic P-wave velocity response to supercritical CO2 displacement of pore water in Tako sandstone. The analysis of dynamic velocity data recorded using an array of piezoelectric transducers mounted on a core sample showed that the P-wave velocities at different positions displayed a similar trend in time, i.e., an initial sharp fall followed by a more gradual decline. Considerable variations observed in the measured P-wave velocity reductions across the sandstone core could largely be attributed to the final state of saturation (e.g. uniform, patchy or in-between) attained by the two-phase fluids. Numerical simulation of the injection test using a simple 1D model was carried out to provide an estimation of the phase saturation changes underlying the measured P-wave velocity reductions. A second order polynomial correlation between the measured ultrasonic P-wave velocity reductions and the estimated CO2 saturation was established. Comparison with the Gassmann velocities showed that the empirically established relationship marks a clear deviation from both the patchy and uniform saturation velocity curves. 相似文献
783.
Hua Shi Ashbindu Singh 《Ambio-人类环境杂志》2003,32(2):145-152
引言 "亮点"是由城镇发射出来的光经过聚集而形成,在地球卫星的夜间景象上可以观察到.它们主要位于海岸带中,是反映地球上人口分布的良好标志[1].海岸带拥有各种不同的生物生境、重要居民点以及宝贵资源的产地. 相似文献
784.
Tsunami represents one of the most potentially serious forms of coastal flood risk. Although much is known on the recorded history of tsunamis for given areas of the world, very little information is available on the occurrence of palaeotsunamis during prehistory. This is of fundamental importance in calculating tsunami flood risk for any given coastal area. Given sufficient information on past tsunami activity for a particular coastal area, the numerical calculation of aggregate coastal flood risk (including tsunami) for a coastal area is very difficult to estimate since one needs also to take into account the risk of a tsunami and a storm surge taking place simultaneously during a high tide. Estimates of coastal flood risk also need to consider future changes in relative sea level caused by the combined effects of global climate change and vertical movements of the lithosphere. 相似文献
785.
Speciation of heavy metals in marine sediments from the East China Sea by ICP-MS with sequential extraction 总被引:22,自引:0,他引:22
Twelve elements (V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Sn, Cd and Pb) in 24 sediment samples at eight sites (S1-S8) from the East China Sea were analyzed with the BCR sequential extraction (SE) protocol to obtain the metal distribution patterns in this region. The results showed that the heavy metal pollutions in S4 and S8 were more severe than in other sampling sites, especially Cd and Pb pollution. In the top sediments at S4 and S8, both the total contents and the most dangerous non-residual fractions of Cd and Pb were extremely high. More than 90% of the total concentrations of V, Cr, Mo and Sn existed in the residual fraction. Fe, Co, Ni, Cu and Zn mainly (more than 60%) occurred in the residual fraction. While Mn, Pb and Cd dominantly presented in the non-residual fractions in the top sediments. The metal distribution patterns with depth and the correlations between total organic carbon (TOC) and the total Fe-Mn content were also investigated. The results showed that, for most of the elements except Fe, the concentration of elements in fraction A in the top sediments was higher than that in other depth. The similar rule was also found in fraction B but not in fraction C. Besides, the distributions of V, Cd in fraction B and Pb, Cd, Cu in fraction C might be affected by TOC. 相似文献
786.
石油短缺与中国经济安全 总被引:6,自引:0,他引:6
石油短缺已经成为引起中国能源危机最核心的问题,本文分析了中国石油短缺的背景及其影响因素,在实证分析的基础上,提出了“对石油依赖程度”这一概念。本文还把石油短缺与经济安全问题联系了起来,并提出了确保我国经济安全的具体对策。 相似文献
787.
日本安全监督管理启示录 总被引:2,自引:2,他引:0
施卫祖 《中国安全科学学报》2000,10(2):47-51
通过对日本安全监督管理机构、研究机构、社团组织和企业的亲身考察 ,对日本安全生产法规建设、监督管理体系、工作机制、主要措施进行了分析、思考和总结 ,认为对如何加强我国安全生产监督管理、改进工作有很大的启示和有益的借鉴。希望文中介绍的内容和观点能在安全生产专家、学者中 ,引起广泛讨论 ,从而建立适合我国国情的安全生产法规体系、安全生产监督管理体系和符合时代发展的创新的安全生产工作思路。 相似文献
788.
湛江具有较强的港口、地缘和腹地优势。要充分利用这些优势,开辟海洋型经济产业开发带,开发利用好海洋资源,促进湛江经济的腾飞。 相似文献
789.
生态旅游项目的可持续设计 总被引:14,自引:1,他引:13
本文基于我国目前生态旅游项目开发存在的普遍问题,从可持续旅游的观点提出了生态旅游项目开发的四个基本准则,同时讨论分析了生态旅游项目可持续设计应遵循的方法和主要内容。 相似文献
790.