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   101668篇
  免费   2164篇
  国内免费   7172篇
安全科学   4969篇
废物处理   4084篇
环保管理   14587篇
综合类   31326篇
基础理论   27976篇
环境理论   71篇
污染及防治   17073篇
评价与监测   5861篇
社会与环境   3802篇
灾害及防治   1255篇
  2023年   680篇
  2022年   1596篇
  2021年   1545篇
  2020年   1246篇
  2019年   1375篇
  2018年   1654篇
  2017年   1849篇
  2016年   2791篇
  2015年   2742篇
  2014年   3947篇
  2013年   10924篇
  2012年   3419篇
  2011年   3476篇
  2010年   4394篇
  2009年   4489篇
  2008年   2802篇
  2007年   2427篇
  2006年   2954篇
  2005年   2642篇
  2004年   2771篇
  2003年   2650篇
  2002年   2144篇
  2001年   2252篇
  2000年   2260篇
  1999年   1834篇
  1998年   1694篇
  1997年   1709篇
  1996年   1784篇
  1995年   1804篇
  1994年   1653篇
  1993年   1468篇
  1992年   1430篇
  1991年   1326篇
  1990年   1278篇
  1989年   1202篇
  1988年   1039篇
  1987年   971篇
  1986年   1000篇
  1985年   1058篇
  1984年   1149篇
  1983年   1165篇
  1982年   1181篇
  1981年   1096篇
  1980年   932篇
  1979年   902篇
  1978年   812篇
  1977年   705篇
  1976年   630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 328 毫秒
371.
Historical records from Ontario's Provincial Water Quality Monitoring Network (PWQMN) for rivers and streams were analyzed to assess the feasibility of mapping regional water quality patterns in southeastern Ontario which spans two major geologic zones, the Precambrian Shield and the St. Lawrence Lowlands, thus serving as a paradigm for much of Ontario. Despite biases toward the populated Lowlands and associated pollution problems, general spatial trends are evident via the analysis of intervariable relations, individual parameter maps and multivariate analysis. Using a robust algorithm designed to identify outliers and abstract underlying bivariate relations, a linear regional hardness-alkalinity relation was derived, where most anomalies proved to be mine drainage impacted sites. Regionally, multivariate ordination reveals that central tendencies of common indicators of ionic strength and nutrient richness correlate positively and that site clusters broadly reflect the transition from oligotrophic Shield waters to eutrophic conditions of heavily agricultural Lowland streams. Results suggest that on the Shield more precisely delineated aquatic regions may be realized by applying GIS to integrate river and synoptic lake survey data. Further synthesis with bedrock and surficial geology, physiography, pedology and other temporally invariant spatial attributes should yield regional patterns of background quality from which locally attainable water objectives might be defined. Additional synoptic surveys of sedimentary Lowland streams may be required as most available sites relflect anthropogenic pollution.  相似文献   
372.
Environment, Development and Sustainability - Environmental deterioration and global warming has created a substantial impact on international companies to incorporate eco-friendly, green supply...  相似文献   
373.
Environment, Development and Sustainability - In order to reveal the distribution and migration law of downwind and upwind coal cutting, total dust (TD) and respirable dust (RD) concentration...  相似文献   
374.
Environment, Development and Sustainability - Renewable energy (RE) plays an increasingly important role in the economy of almost every country in the world. In order to examine the state of...  相似文献   
375.
Environment, Development and Sustainability - This study describes the results of groundwater table variation in Thanjavur District before and after the monsoon seasons. Groundwater-level data...  相似文献   
376.
Jiao  Youzhou  Xue  Huizan  He  Chao  Wang  Zigang  Ma  Xiaoran  Liu  Xinxin  Liu  Liang  Chang  Chun  Petracchini  Francesco  Li  Panpan 《Environment, Development and Sustainability》2022,24(4):4709-4726
Environment, Development and Sustainability - Anaerobic digestion (AD) is an attractive straw resource treatment technology as it can improve the utilization efficiency of straw resource. Raw straw...  相似文献   
377.
Russian Journal of Ecology - Populations at the border of ranges are considered more vulnerable than those in the center. However, some recent reviews contradict this hypothesis. We have studied...  相似文献   
378.
Russian Journal of Ecology - Abstract—We tested a hypothesis about the different abilities of alien and native plants to form arbuscular mycorrhizae. The studies were carried out in the...  相似文献   
379.
Rate-temperature responses in scyphozoan medusae and polyps   总被引:1,自引:0,他引:1  
The effects of temperature on oxygen consumption and spontaneous rhythmic activity have been investigated in various stages of the life histories of 3 species of jellyfish from the Chesapeake Bay, USA. All 3 species clearly show the ability to acclimate positively to temperature change. Thermal sensitivity of metabolism in the winter medusa Cyanea capillata fulva is fairly low at temperature intervals which are experienced in nature. Polyps of the two summer medusae, Chrysaora quinquecirrha and Aurelia aurita, show reduced metabolic sensitivity at temperatures normally accompanying high developmental activity and the onset of strobilation.  相似文献   
380.
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