首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   7887篇
  免费   853篇
  国内免费   2篇
  8742篇
  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.
Rackham O  Brown CM 《The EMBO journal》2004,23(16):3346-3355
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.
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.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号