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   98228篇
  免费   1610篇
  国内免费   4263篇
安全科学   4271篇
废物处理   3738篇
环保管理   14553篇
综合类   25564篇
基础理论   27490篇
环境理论   72篇
污染及防治   17826篇
评价与监测   5716篇
社会与环境   3980篇
灾害及防治   891篇
  2022年   1227篇
  2021年   1170篇
  2020年   929篇
  2019年   1155篇
  2018年   1405篇
  2017年   1535篇
  2016年   2606篇
  2015年   2302篇
  2014年   3206篇
  2013年   10050篇
  2012年   2846篇
  2011年   3093篇
  2010年   3791篇
  2009年   3851篇
  2008年   2565篇
  2007年   2285篇
  2006年   2710篇
  2005年   2519篇
  2004年   2833篇
  2003年   2653篇
  2002年   2197篇
  2001年   2505篇
  2000年   2252篇
  1999年   1755篇
  1998年   1574篇
  1997年   1569篇
  1996年   1648篇
  1995年   1724篇
  1994年   1581篇
  1993年   1441篇
  1992年   1426篇
  1991年   1370篇
  1990年   1275篇
  1989年   1225篇
  1988年   1070篇
  1987年   999篇
  1986年   1004篇
  1985年   1072篇
  1984年   1160篇
  1983年   1173篇
  1982年   1184篇
  1981年   1102篇
  1980年   941篇
  1979年   922篇
  1978年   825篇
  1977年   718篇
  1976年   639篇
  1975年   611篇
  1973年   642篇
  1972年   646篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
361.
As a consequence of decreases in the emission rate of sulphur in eastern North America in the late 1970s and early 1980s, sulphate deposition in central Ontario declined by about 40%, but has remained constant for about six years. Plastic Lake, a small, dilute lake on the Precambrian shield that the authors have studied since 1979, acidified between the start of the study and about 1986, but since then has not changed. The authors also monitored the chemistry of streamwater draining the Plastic Lake catchment. Water quality of runoff from an upland site improved rapidly (pH and alkalinity increased, SO4(2-) and Al decreased), but two factors offset these improvements. A small wetland area downstream reversed most of these changes, resulting in a constant output of strong acid from the catchment. In addition, in extremely dry years (1983, 1987, 1989) there were very high concentrations of SO4(2-) in the streamwater, suggesting substantial re-oxidation of reduced S in the catchment.  相似文献   
362.
Death and injury in earthquakes   总被引:1,自引:0,他引:1  
Alexander D 《Disasters》1985,9(1):57-60
The assumption that the ratio of mortality to morbidity will approximate 1:3 in earthquake disasters is investigated. When it occurs, a 1:3 ratio is most likely to coincide with a Richter magnitude in the range 6.5–7.4, but many other ratios of death to injuries may instead be probable. For each individual disaster the pattern of casualties is likely to be very heterogeneous, but it would be easier to discover regularities if a more standardized definition of 'injury' could be found.  相似文献   
363.
364.
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   
365.
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   
366.
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   
367.
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   
368.
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   
369.
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   
370.
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