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   85240篇
  免费   1272篇
  国内免费   1185篇
安全科学   3628篇
废物处理   3053篇
环保管理   13306篇
综合类   21119篇
基础理论   25591篇
环境理论   71篇
污染及防治   12086篇
评价与监测   5130篇
社会与环境   3208篇
灾害及防治   505篇
  2022年   757篇
  2021年   804篇
  2020年   675篇
  2019年   885篇
  2018年   1059篇
  2017年   1104篇
  2016年   2140篇
  2015年   1845篇
  2014年   2616篇
  2013年   9264篇
  2012年   1975篇
  2011年   2045篇
  2010年   3167篇
  2009年   3295篇
  2008年   1523篇
  2007年   1336篇
  2006年   1872篇
  2005年   1952篇
  2004年   2290篇
  2003年   2096篇
  2002年   1650篇
  2001年   1874篇
  2000年   1775篇
  1999年   1400篇
  1998年   1344篇
  1997年   1327篇
  1996年   1419篇
  1995年   1536篇
  1994年   1443篇
  1993年   1286篇
  1992年   1275篇
  1991年   1249篇
  1990年   1194篇
  1989年   1167篇
  1988年   1007篇
  1987年   947篇
  1986年   981篇
  1985年   1049篇
  1984年   1140篇
  1983年   1156篇
  1982年   1168篇
  1981年   1089篇
  1980年   932篇
  1979年   903篇
  1978年   813篇
  1977年   705篇
  1976年   629篇
  1975年   589篇
  1973年   611篇
  1972年   615篇
排序方式: 共有10000条查询结果,搜索用时 421 毫秒
71.
72.
采用2013年环境空气自动监测数据,分析杭州市空气中黑碳质量浓度的变化规律,并对变化特征的产生原因进行探讨。结果表明:黑碳测定年均值为4.10μg/m3,日变化有明显双峰结构,峰值出现在早7时和晚8时左右;从季节看,黑碳质量浓度冬季高(5.20μg/m3)、夏季低(3.00μg/m3);黑碳质量浓度与NO2、CO、PM10、PM2.5显著相关,与O3、风速、气温呈负相关,降水对黑碳的清除作用明显。  相似文献   
73.
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   
74.
75.
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   

76.
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   
77.
78.
Journal of Material Cycles and Waste Management - The present research work focused on fabricating Biodegradable Plate (BD plate) composed of rice husk ash, bagasse and corn starch which is...  相似文献   
79.
The objective of this paper is to discuss the main barriers for modelling and integrating the environmental performances in the automotive concept design. Incorporating environmental assessment in the early design phase of a vehicle component is known as an important challenge that car makers need to face in order to develop more sustainable design solutions; in this regard, the Life Cycle Assessment is the most widespread methodology for the environmental assessment and comparison of alternatives. The present work illustrates the combination of such methodology with the traditional design procedure at two different levels of the component design phase, material choice and concept design. In particular, the potential benefits originated by a lightweight solution for the automotive component Throttle Body are evaluated by considering environmental and technical implications at the same level. The case study shows that a multi-disciplinary approach for design effectively allows the integration of the environmental issue in the company’s established procedures. However, interpretation of results is still a challenging aspect due to the inevitable contradicting elements which should not discourage to develop comprehensive sustainability assessment within the early design stage.  相似文献   
80.
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