全文获取类型
收费全文 | 12567篇 |
免费 | 1109篇 |
国内免费 | 4篇 |
专业分类
13680篇 |
出版年
2023年 | 44篇 |
2022年 | 98篇 |
2021年 | 209篇 |
2020年 | 100篇 |
2019年 | 160篇 |
2018年 | 178篇 |
2017年 | 164篇 |
2016年 | 343篇 |
2015年 | 541篇 |
2014年 | 692篇 |
2013年 | 786篇 |
2012年 | 1006篇 |
2011年 | 985篇 |
2010年 | 654篇 |
2009年 | 566篇 |
2008年 | 825篇 |
2007年 | 809篇 |
2006年 | 780篇 |
2005年 | 708篇 |
2004年 | 674篇 |
2003年 | 690篇 |
2002年 | 633篇 |
2001年 | 95篇 |
2000年 | 80篇 |
1999年 | 125篇 |
1998年 | 205篇 |
1997年 | 123篇 |
1996年 | 112篇 |
1995年 | 130篇 |
1994年 | 97篇 |
1993年 | 117篇 |
1992年 | 103篇 |
1991年 | 70篇 |
1990年 | 69篇 |
1989年 | 57篇 |
1988年 | 54篇 |
1987年 | 39篇 |
1986年 | 50篇 |
1985年 | 49篇 |
1984年 | 63篇 |
1983年 | 40篇 |
1982年 | 52篇 |
1981年 | 42篇 |
1980年 | 33篇 |
1979年 | 27篇 |
1978年 | 23篇 |
1977年 | 35篇 |
1976年 | 23篇 |
1974年 | 25篇 |
1973年 | 18篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
33.
34.
Shuttling RNAs are recognized as molecules that migrate against steep concentration gradients from one nucleus (through the cytoplasm) into another nucleus in the same cell. In previous work these molecules were identified through experiments involving the separation of two kinds of nuclei utilizing differences in the nuclei that may have produced misleading results. In the experiments reported here normal, randomly-chosen ameba (A. proteus) nuclei containing [32P]RNA were implanted into unlabeled normal, randomly-chosen cells and, after suitable incubation, the labeled RNAs present in each kind of nucleus were characterized by gel electrophoresis. The previously obtained results were confirmed: i.e. (a) the recipient cell nuclei acquired the same four small, distinct RNAs, which are recognized as shuttling ones because they migrate from one nucleus to the other; (b) the grafted nuclei possess, in addition to the four shuttling RNAs, three small, distinct RNAs, which are recognized as non-shuttling RNAs. New evidence also is presented to show that the acquisition by a nucleus of labeled RNAs in the above kind of experiment is not a result of new synthesis of RNAs from the labeled turnover products emanating from the transplanted nucleus. 相似文献
35.
Aline Frville Bndicte Gnangnon Annie Z. Tremp Caroline De Witte Katia Cailliau Alain Martoriati El Moukthar Aliouat Priyanka Fernandes Cerina Chhuon Olivier Silvie Sabrina Marion Ida Chiara Guerrera Johannes T. Dessens Christine Pierrot Jamal Khalife 《Open biology》2022,12(8)
Protein phosphatase 1 (PP1) is a key enzyme for Plasmodium development. However, the detailed mechanisms underlying its regulation remain to be deciphered. Here, we report the functional characterization of the Plasmodium berghei leucine-rich repeat protein 1 (PbLRR1), an orthologue of SDS22, one of the most ancient and conserved PP1 interactors. Our study shows that PbLRR1 is expressed during intra-erythrocytic development of the parasite, and up to the zygote stage in mosquitoes. PbLRR1 can be found in complex with PbPP1 in both asexual and sexual stages and inhibits its phosphatase activity. Genetic analysis demonstrates that PbLRR1 depletion adversely affects the development of oocysts. PbLRR1 interactome analysis associated with phospho-proteomics studies identifies several novel putative PbLRR1/PbPP1 partners. Some of these partners have previously been characterized as essential for the parasite sexual development. Interestingly, and for the first time, Inhibitor 3 (I3), a well-known and direct interactant of Plasmodium PP1, was found to be drastically hypophosphorylated in PbLRR1-depleted parasites. These data, along with the detection of I3 with PP1 in the LRR1 interactome, strongly suggest that the phosphorylation status of PbI3 is under the control of the PP1–LRR1 complex and could contribute (in)directly to oocyst development. This study provides new insights into previously unrecognized PbPP1 fine regulation of Plasmodium oocyst development through its interaction with PbLRR1. 相似文献
36.
Joshua C Bufton Kyle T Powers Jenn-Yeu A Szeto Christine Toelzer Imre Berger Christiane Schaffitzel 《Nucleic acids research》2022,50(10):5934
UPF3 is a key nonsense-mediated mRNA decay (NMD) factor required for mRNA surveillance and eukaryotic gene expression regulation. UPF3 exists as two paralogs (A and B) which are differentially expressed depending on cell type and developmental stage and believed to regulate NMD activity based on cellular requirements. UPF3B mutations cause intellectual disability. The underlying molecular mechanisms remain elusive, as many of the mutations lie in the poorly characterized middle-domain of UPF3B. Here, we show that UPF3A and UPF3B share structural and functional homology to paraspeckle proteins comprising an RNA-recognition motif-like domain (RRM-L), a NONA/paraspeckle-like domain (NOPS-L), and extended α-helical domain. These domains are essential for RNA/ribosome-binding, RNA-induced oligomerization and UPF2 interaction. Structures of UPF2′s third middle-domain of eukaryotic initiation factor 4G (MIF4GIII) in complex with either UPF3B or UPF3A reveal unexpectedly intimate binding interfaces. UPF3B’s disease-causing mutation Y160D in the NOPS-L domain displaces Y160 from a hydrophobic cleft in UPF2 reducing the binding affinity ∼40-fold compared to wildtype. UPF3A, which is upregulated in patients with the UPF3B-Y160D mutation, binds UPF2 with ∼10-fold higher affinity than UPF3B reliant mainly on NOPS-L residues. Our characterization of RNA- and UPF2-binding by UPF3′s middle-domain elucidates its essential role in NMD. 相似文献
37.
38.
39.
40.
Animals living in extreme environments with predictable seasonality may have important life history events correlated to favourable periods. These animals pass critical life stages in protected habitats, especially during early life, often receiving parental care. It is thus hypothesized that juveniles rely on protective microhabitats provided by their parents, becoming independent only during favourable seasons. Semi-terrestrial crayfish Parastacus pugnax inhabit burrows in highly seasonal and predictable environments, thus being well suited to test this hypothesis. Following marked burrows and individual crayfish we examined the life history patterns of P. pugnax in their natural environment to test the predictions that (i) burrowing activity is higher during the wet season, (ii) reproductive events occur during favourable seasons and (iii) juveniles only disperse after reaching larger sizes. There was little or no burrowing activity during the dry season, when soil was more compact, but burrows became wider and had more openings during the wet season. After hatching, juveniles cohabited with adults for at least 4 months during the dry season. During this period juveniles grew considerably, starting independent lives during the wet season. These results suggest that the prolonged parent-offspring cohabitation evolved in response to the predictable seasonal variations in the crayfish habitat. 相似文献