全文获取类型
收费全文 | 1014450篇 |
免费 | 118089篇 |
国内免费 | 556篇 |
出版年
2016年 | 11369篇 |
2015年 | 16753篇 |
2014年 | 19408篇 |
2013年 | 27249篇 |
2012年 | 30953篇 |
2011年 | 31034篇 |
2010年 | 21041篇 |
2009年 | 19720篇 |
2008年 | 28070篇 |
2007年 | 29073篇 |
2006年 | 27189篇 |
2005年 | 26175篇 |
2004年 | 25742篇 |
2003年 | 24906篇 |
2002年 | 24381篇 |
2001年 | 45445篇 |
2000年 | 45908篇 |
1999年 | 36574篇 |
1998年 | 13195篇 |
1997年 | 13843篇 |
1996年 | 13191篇 |
1995年 | 12850篇 |
1994年 | 12721篇 |
1993年 | 12498篇 |
1992年 | 31212篇 |
1991年 | 30349篇 |
1990年 | 29650篇 |
1989年 | 28733篇 |
1988年 | 26578篇 |
1987年 | 25750篇 |
1986年 | 23751篇 |
1985年 | 23751篇 |
1984年 | 19691篇 |
1983年 | 17143篇 |
1982年 | 13465篇 |
1981年 | 11978篇 |
1980年 | 11359篇 |
1979年 | 19006篇 |
1978年 | 15057篇 |
1977年 | 13677篇 |
1976年 | 12716篇 |
1975年 | 14057篇 |
1974年 | 15013篇 |
1973年 | 14781篇 |
1972年 | 13367篇 |
1971年 | 12167篇 |
1970年 | 10616篇 |
1969年 | 10011篇 |
1968年 | 8958篇 |
1967年 | 8093篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
42.
Maternal serum alpha-fetoprotein screening activities of state health agencies: a survey. 总被引:5,自引:5,他引:0 下载免费PDF全文
Maternal serum alpha-fetoprotein (MSAFP) screening has been demonstrated to be cost-effective on a population basis and is becoming standard practice. The American Society of Human Genetics has twice published policy statements to define the essential elements of a quality screening program. The present study reviewed the impact of these policy statements on state public-health agencies with respect to regulation or provision of MSAFP screening in their jurisdictions. With a few exceptions, states have not elected to play a major role in provision or regulation of this test. There is need to address issues of funding, standards, and data collection in a collaborative effort, if policy statements on genetic services are to be translated into effective state population screening. 相似文献
43.
Huie M. J.; Casazza G. A.; Horning M. A.; Brooks G. A. 《Journal of applied physiology》1996,80(5):1554-1559
44.
45.
46.
Abstract: Age-related changes in the expression of Na,K-ATPase α1- and α3-isoform mRNAs were analyzed by in situ hybridization in the Fischer-344 rat hippocampus. Quantification of signal density with cRNA probes in rat hippocampus at 3 months of age showed (a) α1 content is 1.5 times higher in granule than in pyramidal cell layers, whereas α3 content shows the opposite ratio and (b) α3 label is found in large clusters related to mossy cells and basket cells and in medium clusters corresponding to interneurons within the dendritic fields of CA1–3. In the 24-month-old rats as compared with the young animals, the α1 signal is increased more than sevenfold in the dendritic fields and is not significantly changed in perikaryal layers. The α3 signal is reduced about threefold ( p < 0.0001, ANOVA, n = 6) in perikaryal layers, is almost completely absent over the interneurons, basket cells, and mossy cells, and is not significantly changed in dendritic fields. These data indicate age-related, cell- and isoform-specific alterations in pretranslational regulation of Na,K-ATPase α isoforms. The striking changes in the dendritic fields, mossy cells, and GABAergic basket cells and interneurons may constitute early and sensitive markers for age-related alterations in hippocampal function, before cell loss. 相似文献
47.
48.
49.
50.
J. Kevany 《BMJ (Clinical research ed.)》1996,313(7049):65-66