全文获取类型
收费全文 | 1044952篇 |
免费 | 121929篇 |
国内免费 | 556篇 |
出版年
2016年 | 11819篇 |
2015年 | 17247篇 |
2014年 | 19910篇 |
2013年 | 28340篇 |
2012年 | 32045篇 |
2011年 | 32243篇 |
2010年 | 21817篇 |
2009年 | 20515篇 |
2008年 | 29333篇 |
2007年 | 30129篇 |
2006年 | 28426篇 |
2005年 | 27227篇 |
2004年 | 26972篇 |
2003年 | 26026篇 |
2002年 | 25349篇 |
2001年 | 44549篇 |
2000年 | 45030篇 |
1999年 | 36270篇 |
1998年 | 14018篇 |
1997年 | 14660篇 |
1996年 | 14030篇 |
1995年 | 13193篇 |
1994年 | 13140篇 |
1993年 | 12901篇 |
1992年 | 30867篇 |
1991年 | 29992篇 |
1990年 | 29504篇 |
1989年 | 28931篇 |
1988年 | 26563篇 |
1987年 | 25952篇 |
1986年 | 23942篇 |
1985年 | 24174篇 |
1984年 | 20126篇 |
1983年 | 17531篇 |
1982年 | 13844篇 |
1981年 | 12386篇 |
1980年 | 11853篇 |
1979年 | 19512篇 |
1978年 | 15516篇 |
1977年 | 13951篇 |
1976年 | 13335篇 |
1975年 | 14521篇 |
1974年 | 15495篇 |
1973年 | 15334篇 |
1972年 | 13735篇 |
1971年 | 12655篇 |
1970年 | 10929篇 |
1969年 | 10338篇 |
1968年 | 9354篇 |
1967年 | 8446篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
871.
872.
The ultrasonic calls produced by three day old mice when separated from the nest mother and siblings increase in number when naloxone is injected. 相似文献
873.
874.
875.
876.
877.
Delays in the development of exploratory and locomotor behavior in neonatal male rats (up to 21 days of age) are shown to accrue as a consequence of low level lead exposure. Cross fostering experiments indicate that these delays are primarily due to prenatal exposure. These Pb induced behavioral modifications appear to be associated with the delays in synaptogenesis and biochemical development of the cerebral cortex reported previously (4, 18). A new behavioral bioassay for detecting delays in brain development is described. 相似文献
878.
879.
880.
Rat lens beta-crystallins are internally duplicated and homologous to gamma-crystallins 总被引:1,自引:0,他引:1
The nucleotide sequence of two cloned rat lens beta-crystallin cDNAs pRL beta B3-2 and pRL beta B1-3 has been determined. pRL beta B3-2 contains the complete coding information for a beta-crystallin, designated beta B3, of 210 amino acid residues. pRL beta B1-3 is incomplete at its 5' end; the 5' codogenic information which is not present in this cDNA clone was deduced from the cloned gene. pRL beta B1-3 codes for a beta-crystallin polypeptide, designated beta B1, whose full length is 247 amino acid residues. Considerable sequence homology is noted between the amino- and carboxy-terminal halves of each protein. The two rat beta-crystallins show a substantial sequence homology with each other (60%) as well as with the published sequences of rat gamma-crystallin (37%) and bovine and murine beta-crystallins (55 and 45%). All these proteins have a two-domain structure which, like the bovine gamma II-crystallin, might be folded into four remarkably similar protein motifs. Our data further indicate that the beta-crystallins can be subdivided into two groups which are evolutionarily related. Both groups are, although more distantly, also related to the gamma-crystallins. 相似文献