全文获取类型
收费全文 | 4129篇 |
免费 | 356篇 |
国内免费 | 2篇 |
专业分类
4487篇 |
出版年
2024年 | 2篇 |
2023年 | 17篇 |
2022年 | 38篇 |
2021年 | 58篇 |
2020年 | 37篇 |
2019年 | 46篇 |
2018年 | 63篇 |
2017年 | 54篇 |
2016年 | 103篇 |
2015年 | 194篇 |
2014年 | 211篇 |
2013年 | 250篇 |
2012年 | 342篇 |
2011年 | 329篇 |
2010年 | 201篇 |
2009年 | 187篇 |
2008年 | 236篇 |
2007年 | 287篇 |
2006年 | 300篇 |
2005年 | 279篇 |
2004年 | 237篇 |
2003年 | 235篇 |
2002年 | 214篇 |
2001年 | 40篇 |
2000年 | 42篇 |
1999年 | 50篇 |
1998年 | 77篇 |
1997年 | 45篇 |
1996年 | 35篇 |
1995年 | 38篇 |
1994年 | 27篇 |
1993年 | 29篇 |
1992年 | 27篇 |
1991年 | 21篇 |
1990年 | 19篇 |
1989年 | 11篇 |
1988年 | 10篇 |
1987年 | 14篇 |
1986年 | 11篇 |
1985年 | 10篇 |
1984年 | 11篇 |
1983年 | 10篇 |
1982年 | 12篇 |
1981年 | 8篇 |
1979年 | 8篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1967年 | 2篇 |
1966年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有4487条查询结果,搜索用时 0 毫秒
31.
Motion repulsion is the perceived enlargement of the angle between the directions of motion of two transparently moving patterns. An explanation of this illusion has long been sought for in the neural circuitry of the brain. We show that motion repulsion already arises from the statistical properties of the motion transparency problem when analyzed with a clustering algorithm. 相似文献
32.
33.
Simon J. Watson Pinky Langat Scott M. Reid Tommy Tsan-Yuk Lam Matthew Cotten Michael Kelly Kristien Van Reeth Yu Qiu Ga?lle Simon Emilie Bonin Emanuela Foni Chiara Chiapponi Lars Larsen Charlotte Hjulsager Iwona Markowska-Daniel Kinga Urbaniak Ralf Dürrwald Michael Schlegel Anita Huovilainen Irit Davidson ádám Dán Willie Loeffen Stephanie Edwards Michel Bublot Thais Vila Jaime Maldonado Laura Valls ESNIP Consortium Ian H. Brown Oliver G. Pybus Paul Kellam 《Journal of virology》2015,89(19):9920-9931
34.
Kevin K. Lin Vivek Kumar Mikhail Geyfman Darya Chudova Alexander T. Ihler Padhraic Smyth Ralf Paus Joseph S. Takahashi Bogi Andersen 《PLoS genetics》2009,5(7)
Hair follicles undergo recurrent cycling of controlled growth (anagen), regression (catagen), and relative quiescence (telogen) with a defined periodicity. Taking a genomics approach to study gene expression during synchronized mouse hair follicle cycling, we discovered that, in addition to circadian fluctuation, CLOCK–regulated genes are also modulated in phase with the hair growth cycle. During telogen and early anagen, circadian clock genes are prominently expressed in the secondary hair germ, which contains precursor cells for the growing follicle. Analysis of Clock and Bmal1 mutant mice reveals a delay in anagen progression, and the secondary hair germ cells show decreased levels of phosphorylated Rb and lack mitotic cells, suggesting that circadian clock genes regulate anagen progression via their effect on the cell cycle. Consistent with a block at the G1 phase of the cell cycle, we show a significant upregulation of p21 in Bmal1 mutant skin. While circadian clock mechanisms have been implicated in a variety of diurnal biological processes, our findings indicate that circadian clock genes may be utilized to modulate the progression of non-diurnal cyclic processes. 相似文献
35.
Construction of a 'unigene' cDNA clone set by oligonucleotide fingerprinting allows access to 25 000 potential sugar beet genes 总被引:1,自引:0,他引:1
36.
37.
Beno?t de Chassey Anne Aublin-Gex Alessia Ruggieri Laurène Meyniel-Schicklin Fabrine Pradezynski Nathalie Davoust Thibault Chantier Lionel Tafforeau Philippe-Emmanuel Mangeot Claire Ciancia Laure Perrin-Cocon Ralf Bartenschlager Patrice André Vincent Lotteau 《PLoS pathogens》2013,9(7)
Influenza A NS1 and NS2 proteins are encoded by the RNA segment 8 of the viral genome. NS1 is a multifunctional protein and a virulence factor while NS2 is involved in nuclear export of viral ribonucleoprotein complexes. A yeast two-hybrid screening strategy was used to identify host factors supporting NS1 and NS2 functions. More than 560 interactions between 79 cellular proteins and NS1 and NS2 proteins from 9 different influenza virus strains have been identified. These interacting proteins are potentially involved in each step of the infectious process and their contribution to viral replication was tested by RNA interference. Validation of the relevance of these host cell proteins for the viral replication cycle revealed that 7 of the 79 NS1 and/or NS2-interacting proteins positively or negatively controlled virus replication. One of the main factors targeted by NS1 of all virus strains was double-stranded RNA binding domain protein family. In particular, adenosine deaminase acting on RNA 1 (ADAR1) appeared as a pro-viral host factor whose expression is necessary for optimal viral protein synthesis and replication. Surprisingly, ADAR1 also appeared as a pro-viral host factor for dengue virus replication and directly interacted with the viral NS3 protein. ADAR1 editing activity was enhanced by both viruses through dengue virus NS3 and influenza virus NS1 proteins, suggesting a similar virus-host co-evolution. 相似文献
38.
Discovery of new genes and deletion editing in Physarum mitochondria enabled by a novel algorithm for finding edited mRNAs 下载免费PDF全文
Gene finding is complicated in organisms that exhibit insertional RNA editing. Here, we demonstrate how our new algorithm Predictor of Insertional Editing (PIE) can be used to locate genes whose mRNAs are subjected to multiple frameshifting events, and extend the algorithm to include probabilistic predictions for sites of nucleotide insertion; this feature is particularly useful when designing primers for sequencing edited RNAs. Applying this algorithm, we successfully identified the nad2, nad4L, nad6 and atp8 genes within the mitochondrial genome of Physarum polycephalum, which had gone undetected by existing programs. Characterization of their mRNA products led to the unanticipated discovery of nucleotide deletion editing in Physarum. The deletion event, which results in the removal of three adjacent A residues, was confirmed by primer extension sequencing of total RNA. This finding is remarkable in that it comprises the first known instance of nucleotide deletion in this organelle, to be contrasted with nearly 500 sites of single and dinucleotide addition in characterized mitochondrial RNAs. Statistical analysis of this larger pool of editing sites indicates that there are significant biases in the 2 nt immediately upstream of editing sites, including a reduced incidence of nucleotide repeats, in addition to the previously identified purine-U bias. 相似文献
39.
The dynamic recruitment of TRBP to neuronal membranes mediates dendritogenesis during development 下载免费PDF全文
Anna Antoniou Sharof Khudayberdiev Agata Idziak Silvia Bicker Ralf Jacob Gerhard Schratt 《EMBO reports》2018,19(3)
MicroRNAs are important regulators of local protein synthesis during neuronal development. We investigated the dynamic regulation of microRNA production and found that the majority of the microRNA‐generating complex, consisting of Dicer, TRBP, and PACT, specifically associates with intracellular membranes in developing neurons. Stimulation with brain‐derived neurotrophic factor (BDNF), which promotes dendritogenesis, caused the redistribution of TRBP from the endoplasmic reticulum into the cytoplasm, and its dissociation from Dicer, in a Ca2+‐dependent manner. As a result, the processing of a subset of neuronal precursor microRNAs, among them the dendritically localized pre‐miR16, was impaired. Decreased production of miR‐16‐5p, which targeted the BDNF mRNA itself, was rescued by expression of a membrane‐targeted TRBP. Moreover, miR‐16‐5p or membrane‐targeted TRBP expression blocked BDNF‐induced dendritogenesis, demonstrating the importance of neuronal TRBP dynamics for activity‐dependent neuronal development. We propose that neurons employ specialized mechanisms to modulate local gene expression in dendrites, via the dynamic regulation of microRNA biogenesis factors at intracellular membranes of the endoplasmic reticulum, which in turn is crucial for neuronal dendrite complexity and therefore neuronal circuit formation and function. 相似文献
40.
Borkham-Kamphorst E van Roeyen CR Van de Leur E Floege J Weiskirchen R 《Journal of cell communication and signaling》2012,6(1):11-25
Nephroblastoma overexpressed gene encodes a matricellular protein (CCN3/NOV) of the CCN family, comprising CCN1 (CYR61), CCN2
(CTGF), CCN4 (WISP-1), CCN5 (WISP-2), and CCN6 (WISP-3). CCN proteins are involved in the regulation of mitosis, adhesion,
apoptosis, extracellular matrix production, growth arrest and migration in multiple cell types. Compared to CCN2/CTGF, known
as a profibrotic protein, the biological role of CCN3/NOV in liver fibrosis remains obscure. In this study we showed ccn3/nov mRNA to increase dramatically following hepatic stellate cell activation, reaching peak levels in fully transdifferentiated
myofibroblasts. In models of experimental hepatic fibrosis, CCN3/NOV increased significantly at the mRNA and protein levels.
CCN3/NOV was found mainly in non-parenchymal cells along the areas of tissue damage and repair. In the bile-duct ligation
model, CCN3/NOV was localized mainly along portal tracts, while the repeated application of carbon tetrachloride resulted
in CCN3/NOV expression mainly in the centrilobular areas. In contrast to CCN2/CTGF, the profibrotic cytokines platelet-derived
growth factor-B and -D as well as transforming growth factor-β suppressed CCN3/NOV expression. In vitro, CCN3/NOV siRNA attenuated
migration in the cirrhotic fat storing cell line CFSC well in line with in vivo findings that various types of cells expressing
CCN3/NOV migrate into the area of tissue damage and regeneration. The suppression of CCN3/NOV enhanced expression of profibrotic
marker proteins, such as α-smooth muscle actin, collagen type I, fibronectin, CCN2/CTGF and TIMP-1 in primary rat hepatic
stellate cells and in CFSC. We further found that adenoviral overexpression of CCN2/CTGF suppressed CCN3/NOV expression, while
the overexpression of CCN3/NOV as well as the suppression of CCN3/NOV by targeting siRNAs both resulted in enhanced CCN2/CTGF
expression. These results indicate the complexity of CCN actions that are far beyond the classic Yin/Yang interplay. 相似文献