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   21582篇
  免费   152篇
  国内免费   152篇
安全科学   481篇
废物处理   858篇
环保管理   2301篇
综合类   6103篇
基础理论   4969篇
环境理论   3篇
污染及防治   5072篇
评价与监测   1164篇
社会与环境   863篇
灾害及防治   72篇
  2018年   325篇
  2017年   333篇
  2016年   489篇
  2015年   292篇
  2014年   359篇
  2013年   1254篇
  2012年   800篇
  2011年   782篇
  2010年   561篇
  2009年   634篇
  2008年   688篇
  2007年   725篇
  2006年   645篇
  2005年   897篇
  2004年   1042篇
  2003年   880篇
  2002年   530篇
  2001年   700篇
  2000年   480篇
  1999年   341篇
  1998年   226篇
  1997年   234篇
  1996年   220篇
  1995年   265篇
  1994年   272篇
  1993年   231篇
  1992年   245篇
  1991年   267篇
  1990年   296篇
  1989年   250篇
  1988年   203篇
  1987年   197篇
  1986年   190篇
  1985年   201篇
  1984年   215篇
  1983年   200篇
  1982年   221篇
  1981年   216篇
  1980年   180篇
  1979年   198篇
  1978年   159篇
  1977年   153篇
  1976年   160篇
  1974年   155篇
  1973年   153篇
  1968年   162篇
  1967年   197篇
  1966年   170篇
  1965年   157篇
  1964年   158篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
This article postulates strong endogenous relationships in lower income countries between institutional quality, financial development and sustained economic growth. These associations were investigated using the vector-error correction model (VECM) and Granger causality method for a sample of 79 countries from 2005 to 2022. The findings show that (1) these variables reinforce each other in the short run. (2) In the long run, both institutional quality and financial development can fuel economic growth. (3) The positive effect of institutional quality on economic growth is greater than that of financial development. Policy implications of these findings are that careful attention should be paid to co-development policies to enhance the institutional quality and the financial system in these economies. Policies should also consider economic growth strategies to enable sustainable economic growth rates.  相似文献   
2.
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   
3.
4.
5.
6.
7.
8.
9.
10.
The genetic polymorphism of natural populations of Lepilemur mustelinus ruficaudatus was studied by protein electrophoresis. We sampled blood from 72 individuals from four populations separated by geographic or anthropogenic barriers from southwestern Madagascar. Six out of 22 enzyme loci showed genetic variation with a degree of polymorphism of 0.273. The expected and observed degree of genetic heterozygosity over all loci is similar to that of other primates (He = 0.058, Ho = 0.036). The F-statistics revealed that the four subpopulations were similar with respect to gene structure (FST = 0.065, p = 0.016), but the genotypic structures within subpopulations were inconsistent with random mating. For the total of the four subpopulations the proportion of heterozygous individuals was significantly smaller than expected under random mating (FIS = 0.373, FIT = 0.414, p < 0.01). These results correspond closely to what is expected considering the low migration ability of individuals of L. m ruficaudatus leading to small and rather isolated inbred populations.  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