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   103601篇
  免费   1794篇
  国内免费   6532篇
安全科学   4511篇
废物处理   4221篇
环保管理   14836篇
综合类   29154篇
基础理论   28439篇
环境理论   75篇
污染及防治   19637篇
评价与监测   5905篇
社会与环境   4019篇
灾害及防治   1130篇
  2023年   642篇
  2022年   1384篇
  2021年   1330篇
  2020年   1038篇
  2019年   1273篇
  2018年   1585篇
  2017年   1790篇
  2016年   2807篇
  2015年   2644篇
  2014年   3703篇
  2013年   10749篇
  2012年   3351篇
  2011年   3640篇
  2010年   4162篇
  2009年   4295篇
  2008年   2886篇
  2007年   2668篇
  2006年   2992篇
  2005年   2787篇
  2004年   2925篇
  2003年   2870篇
  2002年   2376篇
  2001年   2698篇
  2000年   2448篇
  1999年   1987篇
  1998年   1777篇
  1997年   1689篇
  1996年   1760篇
  1995年   1843篇
  1994年   1712篇
  1993年   1494篇
  1992年   1453篇
  1991年   1377篇
  1990年   1311篇
  1989年   1241篇
  1988年   1080篇
  1987年   1001篇
  1986年   1014篇
  1985年   1073篇
  1984年   1166篇
  1983年   1182篇
  1982年   1184篇
  1981年   1105篇
  1980年   939篇
  1979年   927篇
  1978年   820篇
  1977年   712篇
  1976年   639篇
  1973年   636篇
  1972年   640篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
Environmental Science and Pollution Research - Anaerobic batch experiments were conducted to study the regulatory role of endogenous iron in greenhouse gas emissions under intensive nitrogen...  相似文献   
83.
To explore the relationships between human factors and accident proneness of coal mine workers, the depth perception, dark adaptation and vigilance abilities of 239 Chinese coal mine workers were tested and their accident proneness was surveyed with an accident proneness questionnaire. The results indicated that dark adaptation and vigilance abilities of the mine workers declined with increasing age. Vigilance had a significant negative relationship with accident proneness. There were significant differences in vigilance between coal mine workers doing different types of work. Individual difference in vigilance was relevant to the type of work that an individual did in a coal mine. The dark adaptation index had a significant positive relationship with accident proneness. Coal mine workers with weaker dark adaptation ability were also more accident prone. Some ergonomics recommendations concerning coal mine safety management in China are proposed.  相似文献   
84.
85.
Objective: The objective of this article is to provide empirical evidence for safe speed limits that will meet the objectives of the Safe System by examining the relationship between speed limit and injury severity for different crash types, using police-reported crash data.

Method: Police-reported crashes from 2 Australian jurisdictions were used to calculate a fatal crash rate by speed limit and crash type. Example safe speed limits were defined using threshold risk levels.

Results: A positive exponential relationship between speed limit and fatality rate was found. For an example fatality rate threshold of 1 in 100 crashes it was found that safe speed limits are 40 km/h for pedestrian crashes; 50 km/h for head-on crashes; 60 km/h for hit fixed object crashes; 80 km/h for right angle, right turn, and left road/rollover crashes; and 110 km/h or more for rear-end crashes.

Conclusions: The positive exponential relationship between speed limit and fatal crash rate is consistent with prior research into speed and crash risk. The results indicate that speed zones of 100 km/h or more only meet the objectives of the Safe System, with regard to fatal crashes, where all crash types except rear-end crashes are exceedingly rare, such as on a high standard restricted access highway with a safe roadside design.  相似文献   

86.
Journal of Material Cycles and Waste Management - The traditional Chinese medicinal plant Magnolia officinalis has a wide range of applications; including more than 200 kinds of patented Chinese...  相似文献   
87.
This study investigated the application of bamboo as a natural composite, in which its potential as a composite material had been examined for 2–6 layers. In precise, the woven bamboo (BW) formed the culm fiber composite with an average of 0.5 mm thickness and 5.0 mm width strip. In addition, this study looked into a specific type of bamboo species known as Gigantochloa Scortechinii (Buluh Semantan), which can be found in Malaysia. This laminated plain BW, which had been reinforced with epoxy (EP), was developed by applying the hand lay-up technique. After that, the specimens were characterized via mechanical analyses, for instance, tensile, flexural, hardness, and impact tests. As a result, the 2-layer BW had displayed rather excellent results chiefly due to the incorporation of epoxy composite, although this is exceptional hardness value.  相似文献   
88.
Catastrophic disasters like earthquake and flood cause widespread destruction and financial devastation. This has brought disaster management into limelight making it a burgeoning academic research field. The remarkable rise of ICT (Information and Communication Technology) has instigated the scientific world to incorporate these technologies in disaster management. This study presents scientometric analysis to identify the status quo of research on the management of various disasters and role of ICT in it. This paper uses bibliographic data retrieved from Scopus for the observation period from 2011 to 2018. We provide extensive insights into growth of publications, citation pattern and their connectedness with other subject disciplines. Furthermore, we identify most productive and influential countries, institutes and journals. Our study analyses co-occurrence of keywords using Visualization of Similarities (VOS) Viewer. This structured overview will enhance the understanding of this field leading to more focussed and purposeful research.  相似文献   
89.
以丝瓜络为原料,采用醚化-接枝技术制备出季胺基阴离子交换吸附剂。采用电镜扫描、傅里叶红外光谱、比表面积孔径分布测定仪和元素分析仪等仪器对其进行分析和结构表征,并考察了温度、p H和硝酸盐初始浓度等因素对NO-3去除率的影响。实验结果表明,在20℃,p H值为3~10时,NO-3的吸附率可达90%左右;在不同温度下该吸附过程用Langmuir等温线模型和Freundich等温线模型描述均可;与伪一级动力学方程相比,伪二级动力学方程能更好地描述其吸附动力学方程。  相似文献   
90.
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