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   37003篇
  免费   350篇
  国内免费   267篇
安全科学   1085篇
废物处理   1814篇
环保管理   4801篇
综合类   5421篇
基础理论   10048篇
环境理论   9篇
污染及防治   8701篇
评价与监测   2649篇
社会与环境   2888篇
灾害及防治   204篇
  2023年   168篇
  2022年   307篇
  2021年   351篇
  2020年   207篇
  2019年   263篇
  2018年   870篇
  2017年   876篇
  2016年   1121篇
  2015年   598篇
  2014年   937篇
  2013年   2730篇
  2012年   1283篇
  2011年   2044篇
  2010年   1521篇
  2009年   1607篇
  2008年   1991篇
  2007年   2070篇
  2006年   1375篇
  2005年   1234篇
  2004年   1170篇
  2003年   1196篇
  2002年   1142篇
  2001年   1261篇
  2000年   881篇
  1999年   547篇
  1998年   412篇
  1997年   419篇
  1996年   427篇
  1995年   507篇
  1994年   431篇
  1993年   379篇
  1992年   417篇
  1991年   397篇
  1990年   373篇
  1989年   363篇
  1988年   336篇
  1987年   283篇
  1986年   290篇
  1985年   276篇
  1984年   313篇
  1983年   290篇
  1982年   298篇
  1981年   239篇
  1980年   189篇
  1979年   207篇
  1978年   177篇
  1977年   158篇
  1974年   153篇
  1973年   191篇
  1972年   162篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Russian Journal of Ecology - The dynamics of the species richness, breeding density, and structure of the community of birds occupying nest-boxes upon a 50-fold reduction of atmospheric emissions...  相似文献   
2.
Russian Journal of Ecology - A new method for assessing the response of biota to climatic changes in the ecosystem has been tested. In the Central Forest Natural Biosphere Reserve, the average...  相似文献   
3.
Brazil hosts the largest expanse of tropical ecosystems within protected areas (PAs), which shelter biodiversity and support traditional human populations. We assessed the vulnerability to climate change of 993 terrestrial and coastal-marine Brazilian PAs by combining indicators of climatic-change hazard with indicators of PA resilience (size, native vegetation cover, and probability of climate-driven vegetation transition). This combination of indicators allows the identification of broad climate-change adaptation pathways. Seventeen PAs (20,611 km2) were highly vulnerable and located mainly in the Atlantic Forest (7 PAs), Cerrado (6), and the Amazon (4). Two hundred fifty-eight PAs (756,569 km2), located primarily in Amazonia, had a medium vulnerability. In the Amazon and western Cerrado, the projected severe climatic change and probability of climate-driven vegetation transition drove vulnerability up, despite the generally good conservation status of PAs. Over 80% of PAs of high or moderate vulnerability are managed by indigenous populations. Hence, besides the potential risks to biodiversity, the traditional knowledge and livelihoods of the people inhabiting these PAs may be threatened. In at least 870 PAs, primarily in the Atlantic Forest and Amazon, adaptation could happen with little or no intervention due to low climate-change hazard, high resilience status, or both. At least 20 PAs in the Atlantic Forest, Cerrado, and Amazonia should be targeted for stronger interventions (e.g., improvement of ecological connectivity), given their low resilience status. Despite being a first attempt to link vulnerability and adaptation in Brazilian PAs, we suggest that some of the PAs identified as highly or moderately vulnerable should be prioritized for testing potential adaptation strategies in the near future.  相似文献   
4.
Environmental Science and Pollution Research - Seasonal distribution of phytoplankton community and size structure was assessed in three different tropical ecosystems of the western Bay of Bengal...  相似文献   
5.
6.
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   
7.
8.
9.
Pentachlorotoluene (PCT) and pentabromotoluene (PBT) are environmental contaminants detected in the Great Lakes ecosystem. In view of the paucity of toxicity data and the potential for human exposure, a subacute (28 day) and a subchronic (91 day) study were conducted in the rat. In the subacute study, groups of 10 male and 10 female rats were fed the diet containing PCT or PBT at 0, 0.5, 5.0, 50 or 500 ppm for 28-days. In the subchronic study, the group size was increased to 15, the dose levels were 0, 0.05, 0.5, 5.0, 50 and 500 ppm in the diet and the exposure period was 91 days. Growth rate and food consumption were not affected by exposure to either chemical in the subacute and subchronic study. Clinical observations revealed no abnormalities. Decreased hemoglobin was observed in female rats fed 5.0 ppm PCT and higher levels in the subacute (28 day) study. In the same study the hematocrit value and erythrocyte numbers of females fed 5.0 or 500 ppm PCT diets were significantly lower than the control. In both subacute and subchronic studies mild dose-dependent histopathological changes were observed in the thyroid, liver and kidney of rats fed PCT and PBT diets. In general male rats were more susceptible than females to the treatment of PCT and PBT. Based on these data, it was concluded that the no observable adverse effect level for PCT was 50 ppm in the diet (3.5 mg/kg b.w./day) and that of PBT was 5.0 ppm (0.35 mg/kg b.w./day).  相似文献   
10.
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