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   40799篇
  免费   441篇
  国内免费   325篇
安全科学   1120篇
废物处理   1548篇
环保管理   5461篇
综合类   6493篇
基础理论   11590篇
环境理论   25篇
污染及防治   10538篇
评价与监测   2535篇
社会与环境   1983篇
灾害及防治   272篇
  2022年   283篇
  2021年   265篇
  2019年   301篇
  2018年   543篇
  2017年   563篇
  2016年   825篇
  2015年   683篇
  2014年   999篇
  2013年   3120篇
  2012年   1202篇
  2011年   1774篇
  2010年   1470篇
  2009年   1469篇
  2008年   1721篇
  2007年   1848篇
  2006年   1624篇
  2005年   1365篇
  2004年   1353篇
  2003年   1299篇
  2002年   1260篇
  2001年   1647篇
  2000年   1175篇
  1999年   734篇
  1998年   548篇
  1997年   566篇
  1996年   582篇
  1995年   652篇
  1994年   585篇
  1993年   520篇
  1992年   543篇
  1991年   504篇
  1990年   511篇
  1989年   536篇
  1988年   450篇
  1987年   412篇
  1986年   382篇
  1985年   406篇
  1984年   410篇
  1983年   429篇
  1982年   416篇
  1981年   352篇
  1980年   323篇
  1979年   357篇
  1978年   305篇
  1977年   272篇
  1976年   249篇
  1975年   250篇
  1974年   237篇
  1973年   247篇
  1972年   264篇
排序方式: 共有10000条查询结果,搜索用时 156 毫秒
901.
Cutler P 《Disasters》1984,8(1):48-56
This paper, completed in January 1984, begins by briefly outlining the contrasting views of price behaviour during the last Ethiopian famine (1972–1974) put forward by Seaman and Holt (1980) and Sen (1981). A hypothesis is developed to account for peasant behaviour and price responses under developing famine conditions. This is then tested with data recently made available. The paper concludes by summarizing the findings and their implications for famine forecasting, and argues that famine conditions in Northern Ethiopia are likely to worsen during 1984.  相似文献   
902.
Turton D  Turton P 《Disasters》1984,8(3):178-189
Based upon two recent periods of fieldwork among a spontaneously resettled population of cattle herders in southwestern Ethiopia, this paper is an attempt to illustrate, by a particular case, the general proposition that external aid, if it is not to be counter-productive, must meet people's needs as they themselves define them. The people in question, the Mursi, have experienced, since 1970, their worst period of drought and hunger in living memory. They have responded to this experience with resilience and inventiveness and largely without external assistance. The paper concentrates on a recent, drought induced, migration of Mursi to higher land, outside their traditional territory, and shows how the migrants are adapting to a new way of life which brings them into direct conflict with some of their most cherished cultural traditions.  相似文献   
903.
904.
905.
Community response to hazard information   总被引:1,自引:0,他引:1  
McKay JM 《Disasters》1984,8(2):118-123
The impact of flood hazard information on public acceptance of a selected flood mitigation strategy was assessed by an analysis of the content of newspaper reports of community reaction and letters to the editor. The impact of personal delivery of a flood hazard map on individual perception of risk and attitude to such information was assessed using personal interviews. The results indicated that media coverage of the flood hazard information reduced public criticism of the works. This result must be partially attributable to the dramatic style of media coverage and the fact that the media only emphasized the positive value of the works. The interview demonstrated that personal delivery of the information raised perception of risk, improved comprehension of flood risk, had no impact on acceptability of risk but discouraged some respondents from seeking such information in the future. Factors to explain the last negative change were identified to be the format of the map sheet and low salience of flood hazard. On the basis of all results, methods to improve community response to hazard information are provided.  相似文献   
906.
907.
Davey  J. T.  Gee  J. M.  Moore  S. L. 《Marine Biology》1978,45(4):319-327
The population dynamics of Mytilicola intestinalis Steuer in mussels (Mytilus edulis L.) from the River Lynher, Cornwall, England, have been studied over 3 years. By transplanting uninfested mussels from the River Erme, South Devon, into the Lynher mussel bed, the study was extended to the growth and development of new infestations under natural conditions. Female Mytilicola intestinalis are shown to breed twice, and two generations of parasites coexist for most of the year, with recruitment taking place in summer and autumn. One generation contributes its first brood to the autumn recruits before overwintering and contributing its second brood to the following summer's recruits. The other generation overwinters as juvenile and immature stages to contribute its two broods successively to the summer and autumn recruits. Environmental temperatures are believed to control the rates of development at all stages rather than acting as triggers in the onset or cessation of breeding at specific times. There is no evidence to support the contention that heavily infested mussels are killed, and parasite mortality is shown to be density-independent.  相似文献   
908.
This paper examines the effects of congestion on recreational behavior within a household production model of consumer behavior. We assume that congestion affects the household's ability to produce constant quality recreational service flows and derive a reduced-form model for participation decisions in remote and developed camping. Empirical estimates of the effects of a congestion measure on the conditional probability of participation as well as on the level of participation are estimated for each activity by the type of trip using information from the 1972 National Recreation Survey. The findings suggest that congestion was most likely to affect the decision to participate and not the level once that decision had been made. While differences in these effects were observed across the activities studied, it is not clear how they should be interpreted since our congestion measure was a proxy variable likely to perform better for remote camping than developed camping.  相似文献   
909.
The regular day-night changes in tissues, physiologic functions, and behavior of organisms are based on endogenous rhythmic processes which under constant conditions continue with periods slightly deviating from 24h. These ‘arcadian’ rhythms have properties of self-sustained oscillators. Under natural conditions, circadian rhythms are synchronized (entrained) to 24 h by periodic factors in the environment, the so-called ‘Zeitgebers’. In the laboratory, circadian rhythms can also be entrained to periods other than 24 h within certain limits. Data on the phase relationship between the circadian rhythm and an entraining light-dark cycle for vertebrates, insects, plants, and unicellular organisms are reviewed.  相似文献   
910.
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