全文获取类型
收费全文 | 1106087篇 |
免费 | 121881篇 |
国内免费 | 1243篇 |
出版年
2018年 | 10402篇 |
2017年 | 9759篇 |
2016年 | 14242篇 |
2015年 | 19908篇 |
2014年 | 23248篇 |
2013年 | 32585篇 |
2012年 | 37003篇 |
2011年 | 37631篇 |
2010年 | 25479篇 |
2009年 | 23252篇 |
2008年 | 33180篇 |
2007年 | 34141篇 |
2006年 | 32166篇 |
2005年 | 30937篇 |
2004年 | 30837篇 |
2003年 | 29397篇 |
2002年 | 28540篇 |
2001年 | 48414篇 |
2000年 | 48458篇 |
1999年 | 38823篇 |
1998年 | 14391篇 |
1997年 | 14648篇 |
1996年 | 13875篇 |
1995年 | 13054篇 |
1994年 | 12591篇 |
1993年 | 12470篇 |
1992年 | 32182篇 |
1991年 | 31401篇 |
1990年 | 30626篇 |
1989年 | 29790篇 |
1988年 | 27726篇 |
1987年 | 26112篇 |
1986年 | 24346篇 |
1985年 | 24250篇 |
1984年 | 20172篇 |
1983年 | 17205篇 |
1982年 | 13111篇 |
1981年 | 11813篇 |
1980年 | 10949篇 |
1979年 | 18611篇 |
1978年 | 14719篇 |
1977年 | 13190篇 |
1976年 | 12198篇 |
1975年 | 13715篇 |
1974年 | 14747篇 |
1973年 | 14595篇 |
1972年 | 13051篇 |
1971年 | 11981篇 |
1970年 | 10244篇 |
1969年 | 9929篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
C Toga-Piquet A S Henderson J M Grillo A M Vagner-Capodano A Stahl 《Comptes rendus de l'Académie des sciences. Série III, Sciences de la vie》1984,298(14):383-386
The Pig chromosomes that contain rDNA sites displayed a polymorphism in the distribution of the genes among the nucleolar organizers located on pairs Nos. 8 and 10. Two, or more often three, active sites were observed in the chromosomes of lymphocytes stimulated with phytohemagglutinin. Only 5% of the metaphases showed a 4th small active site. At the onset of stimulation most cells contained one-two nucleoli; four nucleoli were never observed. After prolonged stimulation, the number of nuclei containing three nucleoli increased. A 4th small nucleolus appeared in a few cells, presumably formed by activation of the smallest rDNA site. 相似文献
962.
963.
Summary It has been suggested that the immune system might figure prominently in the regulation of forelimb regeneration. However, neither the nature of this influence nor the aspect(s) of regeneration influenced are clearly known. The determination of which components of the immune system are indispensable for regeneration would be a logical first step in attempting to address such questions. This investigation, therefore, examined the effects of removing the spleen, a major lymphoid organ in the newt, upon the progress of regeneration. Splenectomies performed concomitantly with or after forelimb amputation failed to alter the time course of regeneration. Splenectomies, but not sham-splenectomies, performed prior to amputation reduced the time required to achieve successive stages of regeneration under some, but not all conditions, i.e., when performed 10–20 days before amputation, during the late fall and winter. Up until 35 days after amputation, no gross morphological distortions were observed as a result of splenectomy. It was concluded that the spleen is not required for regeneration to occur.Portions of this work constitute part of the thesis submitted by M.E. Fini in partial fulfillment of the requirements for the M.S. degree in Biology at Boston College 相似文献
964.
965.
M A Chamberlain 《BMJ (Clinical research ed.)》1985,290(6480):1449-1450
966.
Substratum topography and cell traction on sulphuric acid treated bacteriological-grade plastic 总被引:1,自引:0,他引:1
Treatment of bacteriological-grade plastic with concentrated sulphuric acid is a well known technique which increases the wettability of the surface and renders it suitable for eukaryotic cell adhesion. We have noticed that these substrata present a distinctive surface topography in the presence of a serum supplement under normal culture conditions. The adsorbed serum layer is comprised of fine furrows and ridges and the influence of adherent cells on this layer leads to minute tears and distortions in the direction of the corrugations. This provides a novel system for the investigation of cell spreading and locomotion by scanning electron microscopy. 相似文献
967.
968.
Inhibition of protein and lipid synthesis in muscle by 2,4-dinitrofluorobenzene, an inhibitor of creatine phosphokinase 总被引:2,自引:0,他引:2
C L Carpenter C Mohan S P Bessman 《Biochemical and biophysical research communications》1983,111(3):884-889
A photoaffinity label, 4-azidobenzoyltrimethionine has been synthesized. It competitively inhibits trimethionine uptake in the yeast C. albicans. Upon UV irradiation it irreversibly and specifically blocks oligopeptide uptake. These results give the first example of photoinhibition of peptide uptake in yeast. 相似文献
969.
970.
Minor nucleotides in tRNA from blue-green algae [proceedings 总被引:1,自引:0,他引:1