全文获取类型
收费全文 | 2016篇 |
免费 | 9篇 |
国内免费 | 5篇 |
专业分类
安全科学 | 38篇 |
废物处理 | 70篇 |
环保管理 | 132篇 |
综合类 | 672篇 |
基础理论 | 354篇 |
环境理论 | 7篇 |
污染及防治 | 588篇 |
评价与监测 | 90篇 |
社会与环境 | 73篇 |
灾害及防治 | 6篇 |
出版年
2021年 | 21篇 |
2020年 | 21篇 |
2019年 | 21篇 |
2018年 | 34篇 |
2017年 | 43篇 |
2016年 | 46篇 |
2015年 | 35篇 |
2014年 | 55篇 |
2013年 | 108篇 |
2012年 | 44篇 |
2011年 | 81篇 |
2010年 | 56篇 |
2009年 | 65篇 |
2008年 | 94篇 |
2007年 | 87篇 |
2006年 | 77篇 |
2005年 | 72篇 |
2004年 | 47篇 |
2003年 | 48篇 |
2002年 | 47篇 |
2001年 | 58篇 |
2000年 | 39篇 |
1999年 | 29篇 |
1998年 | 18篇 |
1997年 | 21篇 |
1996年 | 18篇 |
1995年 | 20篇 |
1994年 | 31篇 |
1993年 | 15篇 |
1991年 | 15篇 |
1989年 | 14篇 |
1984年 | 14篇 |
1981年 | 16篇 |
1975年 | 13篇 |
1974年 | 14篇 |
1969年 | 14篇 |
1968年 | 13篇 |
1967年 | 15篇 |
1966年 | 23篇 |
1965年 | 29篇 |
1964年 | 17篇 |
1963年 | 26篇 |
1962年 | 22篇 |
1961年 | 31篇 |
1960年 | 20篇 |
1959年 | 22篇 |
1958年 | 13篇 |
1957年 | 24篇 |
1956年 | 16篇 |
1955年 | 16篇 |
排序方式: 共有2030条查询结果,搜索用时 0 毫秒
81.
We present a case report on a fetus with multiple malformations, diagnosed by ultrasound at 20 weeks' gestation. From the combination of intrauterine growth retardation and limb abnormalities that were observed, the most likely diagnosis was considered to be Cornelia de Lange Syndrome (CdLS). Following counselling, the mother opted to terminate the pregnancy. Chromosome analysis of cultured amniotic fluid cells showed a karyotype of 46,XX,t(3;5)(q21;p13). Postmortem examination of the baby confirmed the presence of features consistent with a diagnosis of CdLS. This case provides a report of a definitive diagnosis of Cornelia de Lange Syndrome, suspected on the basis of ultrasound imaging and confirmed by amniocentesis findings. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
82.
83.
84.
85.
86.
Comparing the impacts of hiking, skiing and horse riding on trail and vegetation in different types of forest 总被引:1,自引:0,他引:1
Törn A Tolvanen A Norokorpi Y Tervo R Siikamäki P 《Journal of environmental management》2009,90(3):1427-1434
Nature-based tourism in protected areas has increased and diversified dramatically during the last decades. Different recreational activities have a range of impacts on natural environments. This paper reports results from a comparison of the impacts of hiking, cross-country skiing and horse riding on trail characteristics and vegetation in northern Finland. Widths and depths of existing trails, and vegetation on trails and in the neighbouring forests were monitored in two research sites during 2001 and 2002. Trail characteristics and vegetation were clearly related to the recreational activity, research site and forest type. Horse trails were as deep as hiking trails, even though the annual number of users was 150-fold higher on the hiking trails. Simultaneously, cross-country skiing had the least effect on trails due to the protective snow cover during winter. Hiking trail plots had little or no vegetation cover, horse riding trail plots had lower vegetation cover than forest plots, while skiing had no impact on total vegetation cover. On the other hand, on horse riding trails there were more forbs and grasses, many of which did not grow naturally in the forest. These species that were limited to riding trails may change the structure of adjacent plant communities in the long run. Therefore, the type of activities undertaken and the sensitivity of habitats to these activities should be a major consideration in the planning and management of nature-based tourism. Establishment of artificial structures, such as stairs, duckboards and trail cover, or complete closure of the site, may be the only way to protect the most sensitive or deteriorated sites. 相似文献
87.
88.
89.
Annika Varnäs Berit Balfors Charlotta Faith-Ell 《Journal of Cleaner Production》2009,17(13):1214-1222
Research and initiatives concerning green procurement have to a great extent focused on products. This article, however, explores the current practice, problems and opportunities of green procurement of construction contracts. In particular, the application of environmental criteria for contract awarding is targeted. The findings of the study indicate that both public and private clients in the Swedish construction industry take environmental issues into consideration in their procurements. The environmental preferences are often formulated as environmental requirements. However, environmental criteria in tender evaluation are less common and seldom affect the award decisions. The environmental evaluation criteria that do occur often relate to the contractors' capabilities of managing the environmental work in the project. 相似文献
90.