全文获取类型
收费全文 | 43666篇 |
免费 | 489篇 |
国内免费 | 313篇 |
专业分类
安全科学 | 1238篇 |
废物处理 | 1706篇 |
环保管理 | 5944篇 |
综合类 | 7180篇 |
基础理论 | 12484篇 |
环境理论 | 30篇 |
污染及防治 | 11103篇 |
评价与监测 | 2659篇 |
社会与环境 | 1818篇 |
灾害及防治 | 306篇 |
出版年
2022年 | 268篇 |
2021年 | 291篇 |
2019年 | 310篇 |
2018年 | 561篇 |
2017年 | 567篇 |
2016年 | 858篇 |
2015年 | 698篇 |
2014年 | 997篇 |
2013年 | 3273篇 |
2012年 | 1248篇 |
2011年 | 1812篇 |
2010年 | 1484篇 |
2009年 | 1494篇 |
2008年 | 1813篇 |
2007年 | 1903篇 |
2006年 | 1684篇 |
2005年 | 1443篇 |
2004年 | 1390篇 |
2003年 | 1367篇 |
2002年 | 1336篇 |
2001年 | 1702篇 |
2000年 | 1224篇 |
1999年 | 768篇 |
1998年 | 588篇 |
1997年 | 614篇 |
1996年 | 624篇 |
1995年 | 690篇 |
1994年 | 640篇 |
1993年 | 583篇 |
1992年 | 591篇 |
1991年 | 555篇 |
1990年 | 573篇 |
1989年 | 594篇 |
1988年 | 507篇 |
1987年 | 459篇 |
1986年 | 428篇 |
1985年 | 439篇 |
1984年 | 477篇 |
1983年 | 479篇 |
1982年 | 513篇 |
1981年 | 440篇 |
1980年 | 377篇 |
1979年 | 415篇 |
1978年 | 360篇 |
1977年 | 302篇 |
1976年 | 296篇 |
1975年 | 285篇 |
1974年 | 283篇 |
1973年 | 291篇 |
1972年 | 298篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
972.
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
973.
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
974.
Jon R Miller 《Journal of Environmental Economics and Management》1978,5(3):292-300
Concern for the acceleration in threats to species diversity in the United States led to the passage of the Endangered Species Act of 1973. In this paper, this legislation is examined in an economic context. A simple model is developed where management and constraints on economic activity are substitutes in the production of species stocks. Whether economic growth constraints (the primary policy tool of the 1973 Act) are justified for preservation purposes depends on technical substitution possibilities, relative cost ratios, and the existence of budget constraints for species management. Since the same combination of these factors will not occur for all species, it is argued that more flexibility in endangered species policy may preserve the same levels of species stocks at lower costs to society. 相似文献
975.
Phase relations between a circadian rhythm and its zeitgeber within the range of entrainment 总被引:1,自引:0,他引:1
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
976.
The exploration of offshore areas for hydrocarbons has involved new technical and economic considerations and has posed new problems, not the least of which has been the changing relationship between companies and governments. In this article, the authors present an analysis of the different perspectives and policies which emanate from national governments on the one hand and from transnational oil companies on the other. The issues examined include the considerations involved in establishing exploration legislation, post-discovery problems, the impact on revenues of increased production, the interests of companies in developing fields and the overall economic environment within which decisions have to be agreed. 相似文献
977.
Duffy JC 《Disasters》1978,2(2-3):159-162
978.
979.
Epidemiological procedures can be organised under disaster conditions by means of a simple surveillance system and with few personnel.
In the aftermath of the 4 February 1976 earthquake in Guatemala, an information system was organized by which the requisite information for decision-making was obtained with adequate speed and promptness.
The initial epidemiologic informution was based on reports collected during the early days on symptoms observed at hospitals and health centers and in localities and villages in the stricken area.
At a second, post-emergency stage a more elaborate surveillance system was instituted to provide guidance in the investigntwn of outbreaks, evaluate the health activities and establish basic criteria for preventive and control measures. 相似文献
In the aftermath of the 4 February 1976 earthquake in Guatemala, an information system was organized by which the requisite information for decision-making was obtained with adequate speed and promptness.
The initial epidemiologic informution was based on reports collected during the early days on symptoms observed at hospitals and health centers and in localities and villages in the stricken area.
At a second, post-emergency stage a more elaborate surveillance system was instituted to provide guidance in the investigntwn of outbreaks, evaluate the health activities and establish basic criteria for preventive and control measures. 相似文献
980.