全文获取类型
收费全文 | 12041篇 |
免费 | 1221篇 |
国内免费 | 17篇 |
出版年
2022年 | 80篇 |
2021年 | 132篇 |
2020年 | 75篇 |
2019年 | 125篇 |
2018年 | 128篇 |
2017年 | 156篇 |
2016年 | 262篇 |
2015年 | 412篇 |
2014年 | 497篇 |
2013年 | 578篇 |
2012年 | 828篇 |
2011年 | 821篇 |
2010年 | 575篇 |
2009年 | 498篇 |
2008年 | 738篇 |
2007年 | 773篇 |
2006年 | 700篇 |
2005年 | 740篇 |
2004年 | 697篇 |
2003年 | 691篇 |
2002年 | 714篇 |
2001年 | 142篇 |
2000年 | 113篇 |
1999年 | 133篇 |
1998年 | 207篇 |
1997年 | 140篇 |
1996年 | 125篇 |
1995年 | 124篇 |
1994年 | 125篇 |
1993年 | 111篇 |
1992年 | 97篇 |
1991年 | 105篇 |
1990年 | 83篇 |
1989年 | 97篇 |
1988年 | 90篇 |
1987年 | 85篇 |
1986年 | 87篇 |
1985年 | 80篇 |
1984年 | 105篇 |
1983年 | 89篇 |
1982年 | 110篇 |
1981年 | 117篇 |
1980年 | 107篇 |
1979年 | 68篇 |
1978年 | 60篇 |
1977年 | 51篇 |
1976年 | 66篇 |
1974年 | 51篇 |
1973年 | 50篇 |
1972年 | 44篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
Prostaglandin (PG) stimulates female spawning behavior in goldfish and in some other teleosts in which female reproductive behaviors consist of postovulatory oviposition acts. This study examined the effects of PG on female sexual behavior in a teleost fish, Cichlasoma bimaculatum, in which female reproductive behaviors involve both preovulatory courtship and substrate cleaning behaviors, and post-ovulatory oviposition behavior. In females of established pairs, PGF2 alpha injection (5 micrograms, im) at any stage of the spawning cycle, or in the parental phase, rapidly induced substrate cleaning which soon merged into oviposition behavior (without egg release). These results support a role for PG in oviposition behavior of Cichlasoma. However, indomethacin (1 mg, ip), a PG synthesis inhibitor, did not block oviposition in ovulated females which had begun to spawn. Indomethacin may not have lowered PG levels sufficiently. Alternatively, as shown by J.J. Polder (1971, Neth. J. Zool. 21, 265), oviposition behavior may be induced or maintained by other factors associated with the spawning situation. 相似文献
4.
The gorgoniid Eugorgia is exclusively an eastern Pacific genus. It has a wide geographic and bathymetric range of distribution, found from California to Perú and extends down to 65 m deep. Two new species are herein described. The morphological characters were analyzed and illustrated by light and scanning electron microscopy. Eugorgia beebei
sp. n. can be distinguished by its white, ascending, sparse colony growth. Eugorgia mutabilis
sp. n. can be distinguished by its white colony that changes color after collection, and the conspicuous sharp-crested disc sclerites. From a morphological point of view the new species are related to the daniana-group, the rubens-group and the siedenburgae-group of Eugorgia; their affiliations, and the proposal of a new group are discussed. These new species increases the number of species in the genus to 15, and contribute to the knowledge of the eastern Pacific octocoral biodiversity. 相似文献
5.
6.
Nimra Khan Dylan Pelletier Thomas S. McAlear Nathalie Croteau Simon Veyron Andrew N. Bayne Corbin Black Muneyoshi Ichikawa Ahmad Abdelzaher Zaki Khalifa Sami Chaaban Igor Kurinov Gary Brouhard Susanne Bechstedt Khanh Huy Bui Jean-François Trempe 《Structure (London, England : 1993)》2021,29(6):572-586.e6
- Download : Download high-res image (220KB)
- Download : Download full-size image
7.
8.
9.
The lipid composition of swimming spores, cysts and five hour germlings was established. Spores utilized triglycerides first, then phospholipids. Upon encystment all glycolipid components decreased, while in germlings the phospholipids, monoglycerides and sterol esters exhibited a marked increase. 相似文献
10.