全文获取类型
收费全文 | 7640篇 |
免费 | 831篇 |
国内免费 | 628篇 |
出版年
2024年 | 32篇 |
2023年 | 226篇 |
2022年 | 304篇 |
2021年 | 504篇 |
2020年 | 565篇 |
2019年 | 738篇 |
2018年 | 470篇 |
2017年 | 275篇 |
2016年 | 317篇 |
2015年 | 338篇 |
2014年 | 531篇 |
2013年 | 564篇 |
2012年 | 367篇 |
2011年 | 449篇 |
2010年 | 308篇 |
2009年 | 340篇 |
2008年 | 356篇 |
2007年 | 340篇 |
2006年 | 274篇 |
2005年 | 294篇 |
2004年 | 228篇 |
2003年 | 199篇 |
2002年 | 167篇 |
2001年 | 79篇 |
2000年 | 79篇 |
1999年 | 78篇 |
1998年 | 68篇 |
1997年 | 57篇 |
1996年 | 56篇 |
1995年 | 46篇 |
1994年 | 41篇 |
1993年 | 47篇 |
1992年 | 32篇 |
1991年 | 27篇 |
1990年 | 31篇 |
1989年 | 22篇 |
1988年 | 25篇 |
1987年 | 23篇 |
1986年 | 26篇 |
1985年 | 25篇 |
1984年 | 29篇 |
1983年 | 18篇 |
1982年 | 23篇 |
1981年 | 13篇 |
1980年 | 19篇 |
1979年 | 6篇 |
1978年 | 10篇 |
1977年 | 6篇 |
1976年 | 7篇 |
1974年 | 6篇 |
排序方式: 共有9099条查询结果,搜索用时 125 毫秒
1.
Monica Driscoll 《Developmental neurobiology》1992,23(9):1327-1351
In C. elegans, cell death can be readily studied at the cellular, genetic, and molecular levels. Two types of death have been characterized in this nematode: (1) programmed cell death, which occurs as a normal component in development; and (2) pathological cell death which occurs aberrantly as a consequence of mutation. Analysis of mutations that disrupt programmed cell death in various ways has defined a genetic pathway for programmed cell death which includes genes that perform such functions as the determination of which cells die, the execution of cell death, the engulfment of cell corpses, and the digestion of DNA from dead cells. Molecular analysis is providing insightinto the nature of the molecules that function in these aspects of programmed cell death. Characterization of some genes that mutate to induce abnormal cell death has defined a novel gene family called degenerins that encode putative membrane proteins. Dominant alleles of at least two degenerin genes, mec-4 and deg-1, can cause cellular swelling and late onset neurodegeneration of specific groups of cells. © 1992 John Wiley & Sons, Inc. 相似文献
2.
Towards a theory of the evolution of butterfly colour patterns under directional and disruptive selection 总被引:1,自引:0,他引:1
R. I. VANE-WRIGHT 《Biological journal of the Linnean Society. Linnean Society of London》1979,11(2):141-152
Two general models for the transspecific evolution of butterfly colour patterns are advanced: directional selection acting equally on both sexes, and disruptive selection involving periods of polymorphism. To consider possible outcomes of me latter process, a morphism notation based on an integrated classification for polymorphism and sexual dimorphism is developed. This notation is used to examine the properties of all morphism transformations possible from the minimal expressions of the nine morphism categories, as reached through defined minimum step changes. The significance of such pathway models is analysed in terms of general properties of butterfly polymorphism. The potential use of pathway models in evolutionary studies is briefly discussed, mainly with respect to phylogenetics, and ideas on the evolution of genetic dominance. 相似文献
3.
《Cell》2021,184(25):6138-6156.e28
4.
5.
6.
7.
8.
Christopher A. Fraker Camillo Ricordi Luca Inverardi Juan Domínguez‐Bendala 《Biology of the cell / under the auspices of the European Cell Biology Organization》2009,101(8):431-440
Beyond its role as an electron acceptor in aerobic respiration, oxygen is also a key effector of many developmental events. The oxygen‐sensing machinery and the very fabric of cell identity and function have been shown to be deeply intertwined. Here we take a first look at how oxygen might lie at the crossroads of at least two of the major molecular pathways that shape pancreatic development. Based on recent evidence and a thorough review of the literature, we present a theoretical model whereby evolving oxygen tensions might choreograph to a large extent the sequence of molecular events resulting in the development of the organ. In particular, we propose that lower oxygenation prior to the expansion of the vasculature may favour HIF (hypoxia inducible factor)‐mediated activation of Notch and repression of Wnt/β‐catenin signalling, limiting endocrine cell differentiation. With the development of vasculature and improved oxygen delivery to the developing organ, HIF‐mediated support for Notch signalling may decline while the β‐catenin‐directed Wnt signalling is favoured, which would support endocrine cell differentiation and perhaps exocrine cell proliferation/differentiation. 相似文献
9.
《Bioorganic & medicinal chemistry》2016,24(5):1014-1022
Amino derivatives of NCI8642 were synthesized and evaluated as inhibitors of DKK1/LRP6 interactions. The new inhibitors were able to activate the Wnt signaling pathway as indicated by the increased levels of β-catenin, and decrease the DKK1-induced Tau phosphorylation at serine 396. 相似文献
10.
Binding of B‐cell maturation antigen to B‐cell activating factor induces survival of multiple myeloma cells by activating Akt and JNK signaling pathways 下载免费PDF全文
Xianjuan Shen Yuehua Guo Jing Qi Wei Shi Xinhua Wu Shaoqing Ju 《Cell biochemistry and function》2016,34(2):104-110
B‐cell maturation antigen (BCMA) is expressed on normal and malignant plasma cells and represents a potential target for therapeutic intervention. In this study, we characterized the mechanism underlying the protein kinase B (Akt) and c‐Jun N‐terminal kinase (JNK) pathways and BCMA interactions in regulating multiple myeloma (MM) cell survival. It was found that the expression levels of B cell‐activating factor (BAFF) and BCMA were increased in MM cells as compared with those in normal controls. The proliferation of U266 cells was induced by recombinant human BAFF (rhBAFF) and could also be decreased by BCMA siRNA. The expression of Bcl‐2 protein was up‐regulated, and Bax protein was down‐regulated after rhBAFF treatment, which could be reversed by BCMA siRNA. Similarly, the protein p‐JNK and p‐Akt were activated by rhBAFF and could be changed by BCMA siRNA. In addition, the BCMA mRNA and protein expression levels were decreased after treatment with Akt and JNK pathway inhibitors. These results suggest that Akt and JNK pathways are involved in the regulation of BCMA. A novel BAFF/BCMA signalling pathway in MM may be a new therapeutic target for MM. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献