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   41922篇
  免费   397篇
  国内免费   313篇
安全科学   1177篇
废物处理   2266篇
环保管理   6022篇
综合类   5628篇
基础理论   11225篇
环境理论   12篇
污染及防治   9789篇
评价与监测   3287篇
社会与环境   3000篇
灾害及防治   226篇
  2023年   149篇
  2022年   275篇
  2021年   356篇
  2020年   221篇
  2019年   293篇
  2018年   1824篇
  2017年   1765篇
  2016年   1878篇
  2015年   711篇
  2014年   944篇
  2013年   2892篇
  2012年   1568篇
  2011年   2702篇
  2010年   1862篇
  2009年   1786篇
  2008年   2349篇
  2007年   2584篇
  2006年   1383篇
  2005年   1217篇
  2004年   1204篇
  2003年   1187篇
  2002年   1153篇
  2001年   1164篇
  2000年   867篇
  1999年   565篇
  1998年   432篇
  1997年   436篇
  1996年   450篇
  1995年   521篇
  1994年   444篇
  1993年   397篇
  1992年   434篇
  1991年   391篇
  1990年   364篇
  1989年   359篇
  1988年   318篇
  1987年   270篇
  1986年   284篇
  1985年   282篇
  1984年   313篇
  1983年   302篇
  1982年   300篇
  1981年   272篇
  1980年   207篇
  1979年   200篇
  1978年   183篇
  1977年   146篇
  1975年   149篇
  1973年   174篇
  1972年   146篇
排序方式: 共有10000条查询结果,搜索用时 222 毫秒
71.
20世纪70和80年代,"酸雨"成为一个主要公共政策问题.在加拿大和北欧的斯堪的纳维亚半岛的酸化水体中,生物群落及生境遭到频繁破坏,诸如土著鲑鱼和鳟鱼种群受损乃至灭绝的现象屡见不鲜.  相似文献   
72.
The effect of mountain relief and industrial air pollution on biometric parameters of pine stands was studied. The empirical–statistical models of the dependence of biometric characteristics on the parameters of forest sites were developed using raster modeling and multivariate analysis. The possibility of predicting changes in the biometric parameters at any site on the basis of these models is shown.  相似文献   
73.
In recent years flows of foreign direct investment (FDI) to developing countries have rapidly been increasing. It is now an important contributor to the national economy and urban growth in scores of developing countries. Rapid urbanization in these countries is leading to many problems in the cities. Existing urban infrastructure and municipal services have been unable to cope with the increased demand arising from growing population and rapid economic growth. Consequently, the environment in these cities has deteriorated alarmingly. This paper assesses the role of FDI in urban environmental management (UEM) by analyzing the linkages between them for Hanoi City in Vietnam. The paper's analysis and findings are presented under three main themes: one, FDI, employment and income; two, FDI and environmental degradation; and three, potential of utilizing FDI for the provision of urban environmental infrastructure and services (UEI&S) in order to improve the urban environment. Both primary and secondary source data have been used. Policy implications of the research findings are drawn from the perspective of sustainable development.  相似文献   
74.
75.
We present a case of ultrasonographic prenatal diagnosis at 24 weeks of femur—fibula—ulna (FFU) complex. To our knowledge, this is the first report of an early prenatal diagnosis of FFU.  相似文献   
76.
77.
Observations of air temperature changes in a steppe marmot burrow were performed from late July to mid-October. Until early September, temperature in the burrow remained relatively constant, but then it began to decrease rapidly. This occurred after air temperature above the ground became equal to the temperature in the burrow. Supposedly, it is in this particular period that marmots begin to plug the entrance to the burrow with earth, thus reducing heat exchange between the increasingly cold aboveground air and the air in the burrow.  相似文献   
78.
In the periods of summer and autumn bloom of the Stephanodiscus hantzschii Crun. in recreational water bodies, studies on the vertical distribution of chlorophyll a, its contents per unit biomass, efficiency in using photosynthetically active radiation (EPhAR), and assimilative activity of microalgae were performed. The results confirmed the existence of two ecophysiological forms of St. hantzschii and provided evidence that both forms are typically autotrophic and can efficiently use low-intensity PhAR for photosynthesis.  相似文献   
79.
80.
Whereas past research has treated co-management of common pool resources as if villagers and project implementing authorities were the only relevant actors, numerous external factors beyond the control of these two partners create barriers to successful co-management. This paper draws on discussions with Forest Department officials to examine the influence of these forces on the outcomes of Joint Forest Management (JFM) in Tamil Nadu, India. An empirical inquiry into the operational aspects of JFM indicates the important roles of political parties, powerful people, and other state institutions and functionaries as well as the flow of foreign funding. Further, the strong demand by local people for socio-economic development interventions as opposed to improvement of degraded forests belittles the role of the Forest Department relative to other departments. Numerous other conditioning factors and relationships are explored. The authors call for reforms in public governance to allow better participation of all the actors involved for this participatory management approach to succeed and sustain.  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