全文获取类型
收费全文 | 34825篇 |
免费 | 368篇 |
国内免费 | 278篇 |
专业分类
安全科学 | 977篇 |
废物处理 | 1452篇 |
环保管理 | 4813篇 |
综合类 | 5358篇 |
基础理论 | 9564篇 |
环境理论 | 14篇 |
污染及防治 | 9353篇 |
评价与监测 | 2177篇 |
社会与环境 | 1517篇 |
灾害及防治 | 246篇 |
出版年
2022年 | 227篇 |
2021年 | 267篇 |
2019年 | 250篇 |
2018年 | 425篇 |
2017年 | 452篇 |
2016年 | 740篇 |
2015年 | 576篇 |
2014年 | 866篇 |
2013年 | 2836篇 |
2012年 | 1048篇 |
2011年 | 1433篇 |
2010年 | 1151篇 |
2009年 | 1235篇 |
2008年 | 1472篇 |
2007年 | 1578篇 |
2006年 | 1387篇 |
2005年 | 1157篇 |
2004年 | 1168篇 |
2003年 | 1108篇 |
2002年 | 1074篇 |
2001年 | 1347篇 |
2000年 | 1006篇 |
1999年 | 568篇 |
1998年 | 444篇 |
1997年 | 448篇 |
1996年 | 492篇 |
1995年 | 523篇 |
1994年 | 501篇 |
1993年 | 461篇 |
1992年 | 433篇 |
1991年 | 419篇 |
1990年 | 447篇 |
1989年 | 418篇 |
1988年 | 390篇 |
1987年 | 371篇 |
1986年 | 330篇 |
1985年 | 315篇 |
1984年 | 384篇 |
1983年 | 344篇 |
1982年 | 391篇 |
1981年 | 359篇 |
1980年 | 297篇 |
1979年 | 321篇 |
1978年 | 264篇 |
1977年 | 231篇 |
1976年 | 209篇 |
1975年 | 213篇 |
1974年 | 210篇 |
1973年 | 224篇 |
1972年 | 230篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
Duffy JC 《Disasters》1978,2(2-3):159-162
102.
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
103.
A dynamic programming code was formulated for the purpose of assigning sampling frequencies throughout a regulatory water quality monitoring network in order to optimize the statistical performance of the network while operating within a fixed budgetary constraint. The statistical objective is to achieve the greatest possible station to station uniformity in confidence interval widths about annual geometric means of the measured water quality variables and to keep the average confidence width reasonably small. The objective function is the sum (over several selected variables and all stations) of the normalized positive deviations of the predicted confidence interval widths from preselected design confidence interval widths. The code was designed to account for the effects of deterministic seasonal variation and serial correlation of the water quality observations by incorporating the results of the time series analysis of historical quality data. The economic constraint ensures that the annual operating cost of the system, including direct costs of travel and laboratory analysis, will not exceed the allowable budget. As an example situation, the dynamic programming code was used to assign sampling frequencies to the nine stations in Illinois from which historical quality data had been obtained and analyzed. Using five design quality constituents and representative travel and laboratory costs, an “optimal” design was produced. The optimal design achieved a 10% improvement in uniformity (standard deviation) of confidence interval widths when compared to a more traditional design based on the same budget and using identical sampling frequencies at every station. 相似文献
104.
The results of recent IAEA intercomparison programs are reviewed. 相似文献
105.
J.M.R. Hutchinson 《Environment international》1980,3(5):363-364
The development of traceability in low-level radioactivity measurements is discussed. The role that the development of large quantities of natural matrix standards can play is also discussed. 相似文献
106.
Although oil spill cleanup requirements have existed in the United States for years, recent increases in oil imports and marine transportation of petroleum products as well as growing environmental concern have exposed a new industry, the Oil Spill Cleanup Industry. This paper explores some of the microeconomic aspects of this industry which has come under increased scrutiny by the general public, big business, and the federal government.In addition to a brief history and definition, several basic questions about the economic viability of the oil spill cleanup industry are raised and explored, and the impact on the industry of cleanup from government sources is examined, both from the perspective of present operations and from apparent future increases in federal participation. The primary dilemma facing the industry, that of providing continued and immediate supply while confronted with stochastic demand, is discussed. The effects of the large spill on the industry both in terms of revenue and ability to meet cleanup requirements is also considered.Information for the paper is drawn from past and continuing involvement in the U.S. Coast Guard's Marine Environmental Protection Program by both authors. The statistical evidence presented here was compiled through personal interviews and from two computerized Coast Guard information systems; PIRS (the Pollution Incident Reporting System), and SKIM (the Spill Cleanup Equipment Inventory System). 相似文献
107.
108.
109.
110.
Darwin C Hall 《Journal of Environmental Economics and Management》1977,4(3):258-264
Two techniques are presented for estimation of natural animal populations, both of which may incorporate the effect of pollutants on populations. Both techniques assume specific underlying population dynamics which may not be applicable to certain species or ecosystems. However, both techniques allow for testing the hypothesis that the population dynamics specified is applicable. The techniques are used to criticize two recent empirical investigations of fisheries. 相似文献