全文获取类型
收费全文 | 16885篇 |
免费 | 809篇 |
国内免费 | 15篇 |
出版年
2021年 | 132篇 |
2020年 | 226篇 |
2019年 | 242篇 |
2018年 | 358篇 |
2017年 | 362篇 |
2016年 | 367篇 |
2015年 | 282篇 |
2014年 | 309篇 |
2013年 | 1318篇 |
2012年 | 570篇 |
2011年 | 646篇 |
2010年 | 371篇 |
2009年 | 349篇 |
2008年 | 472篇 |
2007年 | 451篇 |
2006年 | 393篇 |
2005年 | 334篇 |
2004年 | 338篇 |
2003年 | 318篇 |
2002年 | 323篇 |
2001年 | 700篇 |
2000年 | 699篇 |
1999年 | 461篇 |
1998年 | 180篇 |
1997年 | 173篇 |
1996年 | 138篇 |
1995年 | 135篇 |
1993年 | 138篇 |
1992年 | 360篇 |
1991年 | 321篇 |
1990年 | 345篇 |
1989年 | 334篇 |
1988年 | 317篇 |
1987年 | 289篇 |
1986年 | 310篇 |
1985年 | 298篇 |
1984年 | 236篇 |
1983年 | 200篇 |
1979年 | 190篇 |
1978年 | 161篇 |
1975年 | 187篇 |
1974年 | 241篇 |
1973年 | 197篇 |
1972年 | 203篇 |
1971年 | 167篇 |
1970年 | 149篇 |
1969年 | 198篇 |
1968年 | 202篇 |
1967年 | 161篇 |
1966年 | 182篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
5-Hydroxytrypotophan at a dose of 50 mg/kg intraperitoneally (i.p.) sharply increased neural serotonin (5-HT) levels in mink and considerably inhibited that animal's predatory attack on rats. Intraperitoneal injection of 5-HT (10 and 20 mg/kg) did not influence such rat-killing. Neural levels of 5-HT or 5-hydroxyindoleacetic acid (5-HIAA) and subsequent aggression by the predator did not change to any great degree after ingestion of a single meal. Abundance of natural mink food for 3 days was associated with an increased level of 5-HIAA in the lateral hypothalamus and the amygdala as well as with an increased latency to attack and to kill rats. 5-HT seems to represent an endogenous factor that inhibits predatory attack by the mink; this effect appears to function through increased metabolism of 5-HT in some brain regions, which is evident after abundant intake of tryptophan with the natural diet. 相似文献
982.
Rape has been posited to be an outgrowth of male reproductive strategies. Forced copulations may have evolved as a consequence of the low parental investment made by males in producing and raising offspring. We designed a laboratory experiment which paired rhesus macaque males with females in order to assess the influence of intersexual aggression on male sexual activity. Younger and older adult males had comparable levels of sexual behavior, but younger males were more aggressive towards females than were older males. In addition, females threatened younger males more than older males. Male attacks on females did not result in sexual intercourse. On the contrary, a negative correlation existed between male aggression towards females and male success at achieving intromissions. Female aggression towards males appeared to be an effective tactic which reduced the chances of sexual intercourse. We conclude that intersexual aggression acts either as a mechanism of dominance assertion or as a means to increase spatial distance between individuals. These data do not support the idea that rape in humans has an evolutionary foundation derived from male reproductive strategies. 相似文献
983.
984.
985.
986.
987.
The Psychological Record - 相似文献
988.
989.
990.