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   20542篇
  免费   1525篇
  国内免费   3210篇
安全科学   3697篇
废物处理   624篇
环保管理   2807篇
综合类   10694篇
基础理论   1939篇
环境理论   15篇
污染及防治   1744篇
评价与监测   1184篇
社会与环境   1515篇
灾害及防治   1058篇
  2024年   61篇
  2023年   300篇
  2022年   505篇
  2021年   647篇
  2020年   633篇
  2019年   557篇
  2018年   497篇
  2017年   730篇
  2016年   843篇
  2015年   900篇
  2014年   908篇
  2013年   1170篇
  2012年   1446篇
  2011年   1553篇
  2010年   1123篇
  2009年   1156篇
  2008年   875篇
  2007年   1368篇
  2006年   1399篇
  2005年   1100篇
  2004年   915篇
  2003年   1044篇
  2002年   848篇
  2001年   725篇
  2000年   678篇
  1999年   634篇
  1998年   472篇
  1997年   403篇
  1996年   334篇
  1995年   284篇
  1994年   273篇
  1993年   222篇
  1992年   173篇
  1991年   128篇
  1990年   91篇
  1989年   49篇
  1988年   44篇
  1987年   21篇
  1986年   20篇
  1985年   29篇
  1984年   14篇
  1983年   17篇
  1982年   12篇
  1981年   11篇
  1980年   8篇
  1979年   11篇
  1977年   11篇
  1974年   5篇
  1973年   9篇
  1971年   6篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
本系统基于气体浓度光学分析方法理论朗伯-比尔(Lambert-Beer)定律、光谱气体检测技术开发,实现了对煤矿火灾与瓦斯灾害超前预警、灾害产生的有毒有害气体实时监测和煤矿环境气体爆炸危险性辨识,对于煤矿灾害防治、救灾过程中杜绝次生灾害,保障煤矿工人及救护队员的生命安全,促进煤矿安全生产具有重要意义。  相似文献   
2.
In order to study a new leak detection and location method for oil and natural gas pipelines based on acoustic waves, the propagation model is established and modified. Firstly, the propagation law in theory is obtained by analyzing the damping impact factors which cause the attenuation. Then, the dominant-energy frequency bands of leakage acoustic waves are obtained through experiments by wavelet transform analysis. Thirdly, the actual propagation model is modified by the correction factor based on the dominant-energy frequency bands. Then a new leak detection and location method is proposed based on the propagation law which is validated by the experiments for oil pipelines. Finally, the conclusions and the method are applied to the gas pipelines in experiments. The results indicate: the modified propagation model can be established by the experimental method; the new leak location method is effective and can be applied to both oil and gas pipelines and it has advantages over the traditional location method based on the velocity and the time difference. Conclusions can be drawn that the new leak detection and location method can effectively and accurately detect and locate the leakages in oil and natural gas pipelines.  相似文献   
3.
用StrandenE.推荐的测量方法对哈密地区环境空气中220Rn子体α潜能浓度测量结果表明,室内、外平均值分别为56.1和10.2(×10-7J·m-3)。室内外220Rn/222Rn子体α潜能浓度比值分别为0.84和032。220Rn子体所致居民有效剂量当量为228μSv·a-1(集体有效剂量当量为0.9×02man·Sv)。  相似文献   
4.
Sequential extraction of metals from solid media is a common analytical tool used in environmental and exploration geochemistry. A number of procedures exist, but without harmonization and standardization, meaningful comparisons are tenuous without baseline data. A newly developed, standardized sequential extraction procedure (optimized BCR) was applied to two contaminated certified reference soils from Montana, US (SRM 2710 and SRM 2711) for Cu, Pb and Zn. Four operationally defined fractions were isolated, acid extractable, reducible, oxidizable, and residual (by aqua regia). Fraction-specific concentrations, percentages and recoveries for Cu, Pb and Zn were used to explore differences between the optimized BCR procedure and three other sequential extraction schemes with published data for SRM 2710 and 2711 (i.e. Tessier scheme, Geological Survey of Canada scheme and the original BCR scheme). Results indicate significant differences between the four schemes, even for schemes that are closely associated (i.e. the original and optimized BCR schemes). Order-of-magnitude fraction-specific concentration differences were observed, especially for Pb in the reducible fraction. Differences between schemes are worrisome because trends varied between metals, between fractions and between reference soils. These data reinforce the need for increased adoption of standardized sequential extraction procedures and further examination of different solid media.  相似文献   
5.
长白山西坡风灾干扰区的恢复和保护   总被引:3,自引:0,他引:3  
长白山西坡发生的灾害性风灾干扰,一方面给长白山自然保护区的森林资源造成巨大损失,同时也提出了如何加强保护和加速恢复的新课题。文中分析了风灾干扰区的更新格局和过程以及干扰后处理的有关问题,提出了从立地和景观水平促进更新恢复的保护措施  相似文献   
6.
安徽月山地区是长江中下游地区的重要成岩-成矿区段。本文通过岩石学、岩石化学和同位素地球化学等方面的研究,探讨和阐明了月山地区闪长岩类的形成环境、物质来源、源区特征、岩浆形成与演化机理等。  相似文献   
7.
Mitigation and adaptation synergy in forest sector   总被引:1,自引:1,他引:1  
Mitigation and adaptation are the two main strategies to address climate change. Mitigation and adaptation have been considered separately in the global negotiations as well as literature. There is a realization on the need to explore and promote synergy between mitigation and adaptation while addressing climate change. In this paper, an attempt is made to explore the synergy between mitigation and adaptation by considering forest sector, which on the one hand is projected to be adversely impacted under the projected climate change scenarios and on the other provide opportunities to mitigate climate change. Thus, the potential and need for incorporating adaptation strategies and practices in mitigation projects is presented with a few examples. Firstly, there is a need to ensure that mitigation programs or projects do not increase the vulnerability of forest ecosystems and plantations. Secondly, several adaptation practices could be incorporated into mitigation projects to reduce vulnerability. Further, many of the mitigation projects indeed reduce vulnerability and promote adaptation, for example; forest and biodiversity conservation, protected area management and sustainable forestry. Also, many adaptation options such as urban forestry, soil and water conservation and drought resistant varieties also contribute to mitigation of climate change. Thus, there is need for research and field demonstration of synergy between mitigation and adaptation, so that the cost of addressing climate change impacts can be reduced and co-benefits increased.  相似文献   
8.
运用人类工效学的基本原理与方法。指出一些企业任意延长劳动工时,无视劳动保护和劳动保障。事故发生后对事故的分析不全面、不科学。是导致我国目前伤亡事故频频发生的致因。  相似文献   
9.
揭示了农业污染纠纷的内涵,提出了处理农业污染纠纷的4个“支撑点”,即运用农业技术先行界定,运用监测数据科学鉴证;运用因果关系逻辑推定,强化环境管理,疏通综合处理渠道等。  相似文献   
10.
关于促进我国循环经济法制建设的思考   总被引:1,自引:0,他引:1  
循环经济作为一种有效平衡经济增长,社会发展和环境保护三者关系的全新经济模式,在我国的发展已是大势所趋.而这一系统工程建立的基础是相关法律法规的建立.目前,许多发达国家已经以立法的方法来保障循环型社会的建立和发展.加快我国循环经济法制建设需要对循环经济的内涵,发达国家的循环经济立法,我国循环经济法制建设的实践及其存在的问题进行系统研究,根据我国的实际情况,得出对中国的循环经济立法具有针对性的建议,在依法治国的当今中国,以法律形式对循环经济加以肯定和规范具有重要意义.  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