全文获取类型
收费全文 | 3272篇 |
免费 | 280篇 |
出版年
2022年 | 15篇 |
2021年 | 33篇 |
2020年 | 18篇 |
2019年 | 19篇 |
2018年 | 40篇 |
2017年 | 34篇 |
2016年 | 47篇 |
2015年 | 93篇 |
2014年 | 92篇 |
2013年 | 178篇 |
2012年 | 137篇 |
2011年 | 128篇 |
2010年 | 72篇 |
2009年 | 86篇 |
2008年 | 125篇 |
2007年 | 144篇 |
2006年 | 161篇 |
2005年 | 164篇 |
2004年 | 149篇 |
2003年 | 160篇 |
2002年 | 163篇 |
2001年 | 132篇 |
2000年 | 145篇 |
1999年 | 99篇 |
1998年 | 43篇 |
1997年 | 55篇 |
1996年 | 44篇 |
1995年 | 50篇 |
1994年 | 36篇 |
1993年 | 25篇 |
1992年 | 85篇 |
1991年 | 80篇 |
1990年 | 69篇 |
1989年 | 75篇 |
1988年 | 72篇 |
1987年 | 55篇 |
1986年 | 44篇 |
1985年 | 43篇 |
1984年 | 35篇 |
1983年 | 28篇 |
1982年 | 20篇 |
1981年 | 16篇 |
1980年 | 15篇 |
1979年 | 28篇 |
1978年 | 19篇 |
1975年 | 14篇 |
1974年 | 27篇 |
1973年 | 19篇 |
1972年 | 17篇 |
1967年 | 13篇 |
排序方式: 共有3552条查询结果,搜索用时 34 毫秒
61.
62.
Rapid isolation of nucleoli from detergent purified nuclei of various tumor and tissue culture cells 总被引:1,自引:0,他引:1
A rapid isolation procedure of nucleoli from detergent purified nuclei of some tumor and tissue culture cells is described. The procedure makes use of a non-ionic detergent, Nonidet P40 and sodium deoxycholate to purify nuclei followed by the addition of Ca2+ or Mg2+ to strengthen the nucleoli against sonication. Enzymatically active (with respect to nucleolar RNA polymerase) nucleoli containing undegraded nucleolar RNAs may be isolated from a mouse hepatoma MH134, Ehrlich ascites tumor, HeLa cells, L cells and C3H2K cells with this procedure. 相似文献
63.
64.
During the past two years a pilot project was conducted in which 19 inactive physicians were retrained in preparation for resumption of active practice. The initial program consisted of a flexible training program of six months to one year patterned after conventional internship-residency concepts. During the second year the program was modified by providing an initial condensed indoctrination period of two months'' duration especially designed for this purpose, followed by a preceptorship type of training.The project was considered successful in permitting trainees to enter some form of active medical work, or to enroll in formal specialty training. The observations made by the faculty of the program and its accomplishments are discussed in the light of the effort expended and the cost of the project. 相似文献
65.
66.
67.
68.
69.
70.
Survival of cultured cells and somatic embryos of Asparagus officinalis cryopreserved by vitrification 总被引:2,自引:0,他引:2
Cultured cells and somatic embryos derived from the mesophyll tissue of asparagus (Asparagus officinalis L.) were cryopreserved by vitrification. The vitrification solution (PVS) contains (w/v) 22% glycerol, 15% ethylene glycol, 15% propylene glycol and 7% DMSO in Murashige-Skoog medium enriched with 0.5M sorbitol. After initial cryoprotection with sorbitol supplemented MS medium containing 12% ethylene glycol, cells or embryos were exposed stepwise to 85% PVS at 0°C. They were loaded into 0.5 ml transparent straws, and were then plunged directly into liquid nitrogen. After rapid warming, PVS was removed and diluted stepwise. The highest survivals of vitrified cells and embryos were about 65 and 50%, respectively. Surviving embryos developed into plantlets.Abbreviations DMSO
dimetyl sulfoxide
- PVS
vitrification solution
- LN
liquid nitrogen
- DSC
differential scanning calorimeter
- MS
Murashige-Skoog salt medium
- NAA
naphthalene acetic acid
- BA
6-benzyladenine 相似文献