全文获取类型
收费全文 | 17304篇 |
免费 | 2053篇 |
国内免费 | 5篇 |
出版年
2021年 | 234篇 |
2019年 | 139篇 |
2018年 | 188篇 |
2017年 | 183篇 |
2016年 | 300篇 |
2015年 | 471篇 |
2014年 | 558篇 |
2013年 | 725篇 |
2012年 | 833篇 |
2011年 | 855篇 |
2010年 | 551篇 |
2009年 | 490篇 |
2008年 | 694篇 |
2007年 | 739篇 |
2006年 | 667篇 |
2005年 | 639篇 |
2004年 | 609篇 |
2003年 | 562篇 |
2002年 | 547篇 |
2001年 | 490篇 |
2000年 | 508篇 |
1999年 | 445篇 |
1998年 | 264篇 |
1997年 | 215篇 |
1996年 | 202篇 |
1995年 | 187篇 |
1994年 | 176篇 |
1993年 | 183篇 |
1992年 | 379篇 |
1991年 | 294篇 |
1990年 | 328篇 |
1989年 | 290篇 |
1988年 | 311篇 |
1987年 | 318篇 |
1986年 | 252篇 |
1985年 | 281篇 |
1984年 | 225篇 |
1983年 | 234篇 |
1982年 | 202篇 |
1981年 | 183篇 |
1980年 | 173篇 |
1979年 | 242篇 |
1978年 | 211篇 |
1977年 | 184篇 |
1976年 | 185篇 |
1975年 | 171篇 |
1974年 | 172篇 |
1973年 | 183篇 |
1972年 | 163篇 |
1971年 | 135篇 |
排序方式: 共有10000条查询结果,搜索用时 12 毫秒
41.
42.
Kateryna Raykova Melina V. Jones Hwa Huang Paul F. Hoffman Michael Levy 《Journal of visualized experiments : JoVE》2015,(99)
The rat optic nerve is a useful model for stem cell regeneration research. Direct injection into the rat optic nerve allows delivery into the central nervous system in a minimally-invasive surgery without bone removal. This technique describes an approach to visualization and direct injection of the optic nerve following minor fascial dissection from the orbital ridge, using a conjunctival traction suture to gently pull the eye down and out. Representative examples of an injected optic nerve show successful injection of dyed beads. 相似文献
43.
44.
The cold-shock response — a hot topic 总被引:4,自引:2,他引:2
45.
46.
47.
R S Jones 《BMJ (Clinical research ed.)》1981,282(6280):1914-1916
48.
Techniques are described for capturing and marking redtail monkeys (Cercopithecus ascanius). An air-powered darting rifle and syringe darts loaded with a Ketamine-Rompun mixture were used for capture. Ketamine was used for maintaining anesthesia. Monkeys were darted 48 times and captured 27 times. In 24 of the 27 captures, the monkeys were released unharmed. Adult males were marked with radiotransmitters attached to collars of nylon webbing. Females received nylon webbing collars with colorcoded plastic washers for identification. 相似文献
49.
D. J. Jones 《BMJ (Clinical research ed.)》1992,305(6853):575-577
50.
Major and minor electrophoretic variants of juvenile hormone esterase (JHE) were found in the hemolymph of last instar larvae of Trichoplusia ni, both before and after metamorphic commitment. The average ratios of activity of the two major forms were similar during both last stadium peaks in activity. Immunological analysis showed that the hemolymph concentration of JHE during this stadium paralleled the level of enzymatic activity, and no putative higher molecular weight, inactive forms were detected. Immunological analysis provided the first evidence of relatedness of major and minor forms. After hormonal stimulation, the concentration of the two major forms increased concomitantly and by a similar proportion, suggesting that charge variation, at least for these two major forms, is not a point of hormonal or developmental regulation of JHE. 相似文献