全文获取类型
收费全文 | 2674篇 |
免费 | 17篇 |
国内免费 | 33篇 |
专业分类
安全科学 | 75篇 |
废物处理 | 137篇 |
环保管理 | 262篇 |
综合类 | 481篇 |
基础理论 | 544篇 |
环境理论 | 2篇 |
污染及防治 | 784篇 |
评价与监测 | 239篇 |
社会与环境 | 179篇 |
灾害及防治 | 21篇 |
出版年
2023年 | 30篇 |
2022年 | 85篇 |
2021年 | 103篇 |
2020年 | 51篇 |
2019年 | 41篇 |
2018年 | 97篇 |
2017年 | 101篇 |
2016年 | 120篇 |
2015年 | 70篇 |
2014年 | 112篇 |
2013年 | 164篇 |
2012年 | 124篇 |
2011年 | 162篇 |
2010年 | 114篇 |
2009年 | 104篇 |
2008年 | 116篇 |
2007年 | 109篇 |
2006年 | 74篇 |
2005年 | 115篇 |
2004年 | 155篇 |
2003年 | 149篇 |
2002年 | 96篇 |
2001年 | 74篇 |
2000年 | 33篇 |
1999年 | 34篇 |
1998年 | 14篇 |
1997年 | 26篇 |
1996年 | 16篇 |
1995年 | 23篇 |
1994年 | 17篇 |
1993年 | 8篇 |
1992年 | 11篇 |
1991年 | 17篇 |
1990年 | 10篇 |
1989年 | 12篇 |
1988年 | 5篇 |
1987年 | 10篇 |
1986年 | 8篇 |
1985年 | 10篇 |
1984年 | 10篇 |
1983年 | 11篇 |
1982年 | 5篇 |
1981年 | 7篇 |
1979年 | 8篇 |
1977年 | 3篇 |
1975年 | 3篇 |
1970年 | 3篇 |
1966年 | 3篇 |
1964年 | 4篇 |
1961年 | 3篇 |
排序方式: 共有2724条查询结果,搜索用时 296 毫秒
31.
32.
33.
Caching or storing surplus prey may reduce the risk of starvation during periods of food deprivation. While this behaviour occurs in a variety of birds and mammals, it is infrequent among invertebrates. However, golden orb-web spiders, Nephila edulis, incorporate a prey cache in their relatively permanent web, which they feed on during periods of food shortage. Heavier spiders significantly reduced weight loss if they were able to access a cache, but lost weight if the cache was removed. The presence or absence of stored prey had no effect on the weight loss of lighter spiders. Furthermore, N. edulis always attacked new prey, irrespective of the number of unprocessed prey in the web. In contrast, females of Argiope keyserlingi, who build a new web every day and do not cache prey, attacked fewer new prey items if some had already been caught. Thus, a necessary preadaptation to the evolution of prey caching in orb-web spiders may be a durable or permanent web, such as that constructed by Nephila. 相似文献
34.
35.
Goyet Cde V 《Disasters》1993,17(2):169-176
36.
37.
38.
39.
Tamim Younos Raymond de Leon Christine Lewicki 《Journal of the American Water Resources Association》2003,39(1):1-5
ABSTRACT: The objective of this article is to open a dialogue on integrating service‐learning into community based watershed management programs and to discuss opportunities and challenges that a service‐learning program presents to universities and communities. The article presents the concept and definition of service‐learning, and arguments concerning why institutions of higher education and university faculty and students should be involved with community based watershed management programs. The article describes a case study for developing a service‐learning program for watershed management at Virginia Tech and discusses lessons learned from the case study. The paper concluded that to make a service‐learning program sustainable, there should be a long term plan, regular and effective communication with the stakeholders, and some incentives for faculty and students for long term commitment to the community based watershed management programs. 相似文献
40.
The article focuses on fossil energy resources in the Andean Group and Mexico, and argues for a dynamic approach to calculating reserves to production ratios. Individual countries are surveyed in terms of estimated reserves of fossil energy resources, current production rates and future prospects; energy policy options for individual countries are analysed. As a primary objective of energy policy is to ensure security of supply, it is important that calculations of reserves to production ratios accurately estimate the desired level of investment in exploration. The calculations need to take into account a variety of parameters, including different energy sources, availability and risk; geographic considerations including proximity, transport, storage capacity and commercial aspects; the competitive and environmental implications of developing indigenous resources; and the use of instruments to establish contingency plans for emergencies.
The opinions expressed in this article are those of the authors, and do not necessarily reflect the views of OLADE, ECLAC or GTZ. The authors apologize for any inaccuracies or omissions in the article. 相似文献
The opinions expressed in this article are those of the authors, and do not necessarily reflect the views of OLADE, ECLAC or GTZ. The authors apologize for any inaccuracies or omissions in the article. 相似文献