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   39967篇
  免费   366篇
  国内免费   464篇
安全科学   992篇
废物处理   2171篇
环保管理   5020篇
综合类   5990篇
基础理论   10982篇
环境理论   18篇
污染及防治   9736篇
评价与监测   3068篇
社会与环境   2627篇
灾害及防治   193篇
  2023年   139篇
  2022年   323篇
  2021年   332篇
  2020年   249篇
  2019年   297篇
  2018年   1818篇
  2017年   1761篇
  2016年   1856篇
  2015年   702篇
  2014年   922篇
  2013年   2484篇
  2012年   1526篇
  2011年   2684篇
  2010年   1836篇
  2009年   1731篇
  2008年   2260篇
  2007年   2604篇
  2006年   1327篇
  2005年   1154篇
  2004年   1055篇
  2003年   1174篇
  2002年   1066篇
  2001年   1267篇
  2000年   890篇
  1999年   537篇
  1998年   371篇
  1997年   379篇
  1996年   377篇
  1995年   438篇
  1994年   458篇
  1993年   365篇
  1992年   387篇
  1991年   359篇
  1990年   397篇
  1989年   349篇
  1988年   305篇
  1987年   286篇
  1986年   234篇
  1985年   253篇
  1984年   286篇
  1983年   272篇
  1982年   252篇
  1981年   237篇
  1980年   181篇
  1979年   204篇
  1978年   182篇
  1977年   121篇
  1975年   142篇
  1972年   130篇
  1971年   131篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
Collaborative monitoring over broad scales and levels of ecological organization can inform conservation efforts necessary to address the contemporary biodiversity crisis. An important challenge to collaborative monitoring is motivating local engagement with enough buy-in from stakeholders while providing adequate top-down direction for scientific rigor, quality control, and coordination. Collaborative monitoring must reconcile this inherent tension between top-down control and bottom-up engagement. Highly mobile and cryptic taxa, such as bats, present a particularly acute challenge. Given their scale of movement, complex life histories, and rapidly expanding threats, understanding population trends of bats requires coordinated broad-scale collaborative monitoring. The North American Bat Monitoring Program (NABat) reconciles top-down, bottom-up tension with a hierarchical master sample survey design, integrated data analysis, dynamic data curation, regional monitoring hubs, and knowledge delivery through web-based infrastructure. NABat supports collaborative monitoring across spatial and organizational scales and the full annual lifecycle of bats.  相似文献   
992.
The provision of ecosystem services is a prominent rationale for urban greening, and there is a prevailing mantra that ‘trees are good’. However, understanding how urban trees contribute to sustainability must also consider disservices. In this perspective article, we discuss recent research on ecosystem disservices of urban trees, including infrastructure conflicts, health and safety impacts, aesthetic issues, and environmentally detrimental consequences, as well as management costs related to ecological disturbances and risk management. We also discuss tradeoffs regarding species selection and local conservation concerns, as well as the central role of human perception in the interpretation of ecosystem services and disservices, particularly the uncritical assertion that ‘everybody loves trees’. Urban forestry decision-making that fails to account for disservices can have unintended negative consequences for communities. Further research is needed regarding life cycle assessments, stakeholder decision-making, return-on-investment, and framings of services and disservices in urban forestry.  相似文献   
993.
Environmental Science and Pollution Research - Marine and freshwater pollution caused by transport of invasive species in shipping ballast water is a major global problem and will increase in...  相似文献   
994.
Environmental Science and Pollution Research - Biochar has strong potential to improve nitrogen (N) use efficiency in both agricultural and horticultural systems. Biochar is usually co-applied with...  相似文献   
995.
996.
Environmental Science and Pollution Research - On-site small-scale sanitation is common in rural areas and areas without infrastructure, but the treatment of the collected fecal matter can be...  相似文献   
997.
Environmental Science and Pollution Research - The discovery of microRNAs (miRNAs) 20 years ago has advocated a new era of “small molecular genetics.” About 2000 miRNAs are present that...  相似文献   
998.
Environmental Science and Pollution Research - COVID-19 was first discovered in Wuhan, China in December 2019. It is one of the worst pandemics in human history. Recent studies reported that...  相似文献   
999.

Natural products may be applied in a wide range of domains, from agriculture to food and pharmaceutical industries. In this study, the antioxidant properties and the capacity to inhibit some enzymatic activities of Euphorbia resinifera and Euphorbia officinarum aqueous extracts and honeys were assessed. The physicochemical characteristics were also evaluated. Higher amounts of iron, copper and aluminium were detected in E. officinarum honey, which may indicate environmental pollution around the beehives or inadequate storage of honey samples. This honey sample showed higher amounts of total phenols and better capacity for scavenging superoxide anion free radicals and DPPH free radicals as compared with E. resinifera honey, but poorer capacity for inhibiting lipoxygenase, acetylcholinesterase, tyrosinase and xanthine oxidase. The ratio plant mass:solvent volume (1:100) and extraction time (1 - 2 h) were associated with higher total phenols and better antioxidant activities and lipoxygenase, acetylcholinesterase and tyrosinase inhibitory activities, regardless of the plant species. The aqueous extracts had systematically higher in vitro activities than the respective honey samples.

  相似文献   
1000.
Environmental Science and Pollution Research - The quest for improved environmental quality through low-carbon emission has been explored in this study in the wake of the growing call for a...  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