全文获取类型
收费全文 | 7887篇 |
免费 | 853篇 |
国内免费 | 2篇 |
专业分类
8742篇 |
出版年
2023年 | 46篇 |
2022年 | 75篇 |
2021年 | 187篇 |
2020年 | 111篇 |
2019年 | 132篇 |
2018年 | 163篇 |
2017年 | 156篇 |
2016年 | 229篇 |
2015年 | 363篇 |
2014年 | 409篇 |
2013年 | 454篇 |
2012年 | 618篇 |
2011年 | 615篇 |
2010年 | 386篇 |
2009年 | 319篇 |
2008年 | 464篇 |
2007年 | 453篇 |
2006年 | 388篇 |
2005年 | 379篇 |
2004年 | 396篇 |
2003年 | 342篇 |
2002年 | 313篇 |
2001年 | 117篇 |
2000年 | 86篇 |
1999年 | 103篇 |
1998年 | 79篇 |
1997年 | 69篇 |
1996年 | 52篇 |
1995年 | 49篇 |
1994年 | 40篇 |
1993年 | 34篇 |
1992年 | 74篇 |
1991年 | 71篇 |
1990年 | 48篇 |
1989年 | 55篇 |
1988年 | 39篇 |
1987年 | 41篇 |
1986年 | 43篇 |
1985年 | 52篇 |
1984年 | 55篇 |
1983年 | 40篇 |
1982年 | 27篇 |
1981年 | 28篇 |
1980年 | 30篇 |
1979年 | 32篇 |
1978年 | 32篇 |
1977年 | 35篇 |
1976年 | 28篇 |
1974年 | 29篇 |
1972年 | 29篇 |
排序方式: 共有8742条查询结果,搜索用时 0 毫秒
91.
Visualization of RNA-protein interactions in living cells: FMRP and IMP1 interact on mRNAs 总被引:10,自引:0,他引:10
Protein expression depends significantly on the stability, translation efficiency and localization of mRNA. These qualities are largely dictated by the RNA-binding proteins associated with an mRNA. Here, we report a method to visualize and localize RNA-protein interactions in living mammalian cells. Using this method, we found that the fragile X mental retardation protein (FMRP) isoform 18 and the human zipcode-binding protein 1 ortholog IMP1, an RNA transport factor, were present on common mRNAs. These interactions occurred predominantly in the cytoplasm, in granular structures. In addition, FMRP and IMP1 interacted independently of RNA. Tethering of FMRP to an mRNA caused IMP1 to be recruited to the same mRNA and resulted in granule formation. The intimate association of FMRP and IMP1 suggests a link between mRNA transport and translational repression in mammalian cells. 相似文献
92.
Aim Gondwanan lineages are a prominent component of the Australian terrestrial biota. However, most squamate (lizard and snake) lineages in Australia appear to be derived from relatively recent dispersal from Asia (< 30 Ma) and in situ diversification, subsequent to the isolation of Australia from other Gondwanan landmasses. We test the hypothesis that the Australian radiation of diplodactyloid geckos (families Carphodactylidae, Diplodactylidae and Pygopodidae), in contrast to other endemic squamate groups, has a Gondwanan origin and comprises multiple lineages that originated before the separation of Australia from Antarctica. Location Australasia. Methods Bayesian (beast ) and penalized likelihood rate smoothing (PLRS) (r 8s ) molecular dating methods and two long nuclear DNA sequences (RAG‐1 and c‐mos) were used to estimate a timeframe for divergence events among 18 genera and 30 species of Australian diplodactyloids. Results At least five lineages of Australian diplodactyloid geckos are estimated to have originated > 34 Ma (pre‐Oligocene) and basal splits among the Australian diplodactyloids occurred c. 70 Ma. However, most extant generic and intergeneric diversity within diplodactyloid lineages appears to post‐date the late Oligocene (< 30 Ma). Main conclusions Basal divergences within the diplodactyloids significantly pre‐date the final break‐up of East Gondwana, indicating that the group is one of the most ancient extant endemic vertebrate radiations east of Wallace’s Line. At least five Australian lineages of diplodactyloid gecko are each as old or older than other well‐dated Australian squamate radiations (e.g. elapid snakes and agamids). The limbless Pygopodidae (morphologically the most aberrant living geckos) appears to have radiated before Australia was occupied by potential ecological analogues. However, in spite of the great age of the diplodactyloid radiation, most extant diversity appears to be of relatively recent origin, a pattern that is shared with other Australian squamate lineages. 相似文献
93.
Hemocoelic injection and vaginal insertion of selected male reproductive and non-reproductive tissue homogenates into fed-virgin female Ornithodoros parkeri stimulated varying degrees of ovum maturation and/or oviposition during 14 and 30 day observation periods, respectively. Mean times for oviposition and mean numbers of eggs laid per ovipositing female receiving hemocoelic injections of male reproductive tissue homogenates did not differ significantly from fed-mated controls. In addition, hemocoelic injection of male salivary glandular homogenate induced oviposition, yet synganglial homogenate did not. Although vaginal insertion induced both ovum maturation and oviposition, the effect was not as pronounced as when similar doses were administered by hemocoelic injection. These results indicate that a complex interrelated series of precopulatory and copulatory stimuli are necessary for oviposition to occur in fed O. parkeri. 相似文献
94.
95.
96.
97.
98.
99.
Cordella Mauro Alfieri Felice Sanfelix Javier Donatello Shane Kaps Renata Wolf Oliver 《The International Journal of Life Cycle Assessment》2020,25(5):921-935
The International Journal of Life Cycle Assessment - Material efficiency encompasses a range of strategies that support a reduction of material consumption and waste production from a... 相似文献
100.