全文获取类型
收费全文 | 720篇 |
免费 | 1篇 |
国内免费 | 3篇 |
专业分类
综合类 | 722篇 |
基础理论 | 2篇 |
出版年
2021年 | 7篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2012年 | 15篇 |
2011年 | 99篇 |
2010年 | 73篇 |
2009年 | 52篇 |
2008年 | 41篇 |
2007年 | 52篇 |
2006年 | 52篇 |
2005年 | 56篇 |
2004年 | 54篇 |
2003年 | 52篇 |
2002年 | 51篇 |
2001年 | 36篇 |
1995年 | 36篇 |
1994年 | 27篇 |
1991年 | 1篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 4篇 |
1983年 | 3篇 |
排序方式: 共有724条查询结果,搜索用时 421 毫秒
41.
42.
43.
44.
45.
46.
Laird Jackson 《黑龙江环境通报》2003,23(10):837-846
Although fetal cells have been known to escape to the maternal circulation for a number of years, research attempts to use them for prenatal diagnosis have not had any consistent success. This review attempts to trace the history of such attempts and to document their progress and reasons for success or failure. The opinions of recent conferences including that of the US National Institute of Child Health and Human Development, a sponsor of major US research in the field, are reported and discussed. It is concluded that although basic work has demonstrated the biologic availability of both fetal cells and their free DNA representatives in the maternal circulation at gestational ages relevant to prenatal diagnosis, much work remains to develop practical technology for their consistent recovery and assay. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
47.
48.
49.
50.
Prenatal diagnosis of congenital and acquired cerebellar disorders is possible by the use of ultrasound (US) and magnetic resonance imaging (MRI). Although numerous studies have been conducted in this field, diagnostic uncertainties are still common in daily clinical practice. This review outlines five possible pitfalls in the diagnosis of fetal cerebellar disorders: confusion between different entities describing vermian pathologies (Dandy–Walker variant, vermian hypoplasia and vermian agenesis); premature diagnosis of abnormal vermian formation; difficulties in the ultrasonographic differentiation between the cerebellar hemispheres and the vermis; late development of cerebellar hypoplasia/atrophy and differential diagnosis of unilateral cerebellar findings. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献