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排序方式: 共有2725条查询结果,搜索用时 31 毫秒
1.
Shannon L. Ballard Daniel L. Miller Barry Ganetzky 《The Journal of cell biology》2014,204(7):1157-1172
Toll-like receptors (TLRs) are best characterized for their roles in mediating dorsoventral patterning and the innate immune response. However, recent studies indicate that TLRs are also involved in regulating neuronal growth and development. Here, we demonstrate that the TLR Tollo positively regulates growth of the Drosophila melanogaster larval neuromuscular junction (NMJ). Tollo mutants exhibited NMJ undergrowth, whereas increased expression of Tollo led to NMJ overgrowth. Tollo expression in the motoneuron was both necessary and sufficient for regulating NMJ growth. Dominant genetic interactions together with altered levels of phosphorylated c-Jun N-terminal kinase (JNK) and puc-lacZ expression revealed that Tollo signals through the JNK pathway at the NMJ. Genetic interactions also revealed that the neurotrophin Spätzle3 (Spz3) is a likely Tollo ligand. Spz3 expression in muscle and proteolytic activation via the Easter protease was necessary and sufficient to promote NMJ growth. These results demonstrate the existence of a novel neurotrophin signaling pathway that is required for synaptic development in Drosophila. 相似文献
2.
Shannon N Tessier Jing Zhang Kyle K Biggar Cheng-Wei Wu Fabien Pifferi Martine Perret f Kenneth B Storey 《基因组蛋白质组与生物信息学报(英文版)》2015,13(2):91-102
Gray mouse lemurs (Microcebus murinus) from Madagascar present an excellent model for studies of torpor regulation in a primate species. In the present study, we analyzed the response of the insulin si... 相似文献
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Anna Eisenstein Shannon H. Carroll Hillary Johnston-Cox Melissa Farb Noyan Gokce Katya Ravid 《The Journal of biological chemistry》2014,289(30):21071-21081
Adipogenesis represents a key process in adipose tissue development and remodeling, including during obesity. Exploring the regulation of adipogenesis by extracellular ligands is fundamental to our understanding of this process. Adenosine, an extracellular nucleoside signaling molecule found in adipose tissue depots, acts on adenosine receptors. Here we report that, among these receptors, the A2b adenosine receptor (A2bAR) is highly expressed in adipocyte progenitors. Activation of the A2bAR potently inhibits differentiation of mouse stromal vascular cells into adipocytes, whereas A2bAR knockdown stimulates adipogenesis. The A2bAR inhibits differentiation through a novel signaling cascade involving sustained expression of Krüppel-like factor 4 (KLF4), a regulator of stem cell maintenance. Knockdown of KLF4 ablates the ability of the A2bAR to inhibit differentiation. A2bAR activation also inhibits adipogenesis in a human primary preadipocyte culture system. We analyzed the A2bAR-KLF4 axis in adipose tissue of obese subjects and, intriguingly, found a strong correlation between A2bAR and KLF4 expression in both subcutaneous and visceral human fat. Hence, our study implicates the A2bAR as a regulator of adipocyte differentiation and the A2bAR-KLF4 axis as a potentially significant modulator of adipose biology. 相似文献
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Simon Dellicour Shannon Fearnley Anicée Lombal Sarah Heidl Elizabeth P. Dahlhoff Nathan E. Rank Patrick Mardulyn 《Evolution; international journal of organic evolution》2014,68(8):2371-2385
The leaf beetle Chrysomela aeneicollis occurs across Western North America, either at high elevation or in small, isolated populations along the coast, and thus has a highly fragmented distribution. DNA sequence data (three loci) were collected from five regions across the species range. Population connectivity was examined using traditional ecological niche modeling, which suggested that gene flow could occur among regions now and in the past. We developed geographically explicit coalescence models of sequence evolution that incorporated a two‐dimensional representation of the hypothesized ranges suggested by the niche‐modeling estimates. We simulated sequence data according to these models and compared them to observed sequences to identify most probable scenarios regarding the migration history of C. aeneicollis. Our results disagreed with initial niche‐modeling estimates by clearly rejecting recent connectivity among regions, and were instead most consistent with a long period of range fragmentation, extending well beyond the last glacial maximum. This application of geographically explicit models of coalescence has highlighted some limitations of the use of climatic variables for predicting the present and past range of a species and has explained aspects of the Pleistocene evolutionary history of a cold‐adapted organism in Western North America. 相似文献
7.
Christopher P. Kenaley Shannon C. DeVaney Taylor T. Fjeran 《Evolution; international journal of organic evolution》2014,68(4):996-1013
The vast majority of deep‐sea fishes have retinas composed of only rod cells sensitive to only shortwave blue light, approximately 480–490 nm. A group of deep‐sea dragonfishes, the loosejaws (family Stomiidae), possesses far‐red emitting photophores and rhodopsins sensitive to long‐wave emissions greater than 650 nm. In this study, the rhodopsin diversity within the Stomiidae is surveyed based on an analysis of rod opsin‐coding sequences from representatives of 23 of the 28 genera. Using phylogenetic inference, fossil‐calibrated estimates of divergence times, and a comparative approach scanning the stomiid phylogeny for shared genotypes and substitution histories, we explore the evolution and timing of spectral tuning in the family. Our results challenge both the monophyly of the family Stomiidae and the loosejaws. Despite paraphyly of the loosejaws, we infer for the first time that far‐red visual systems have a single evolutionary origin within the family and that this shift in phenotype occurred at approximately 15.4 Ma. In addition, we found strong evidence that at approximately 11.2 Ma the most recent common ancestor of two dragonfish genera reverted to a primitive shortwave visual system during its evolution from a far‐red sensitive dragonfish. According to branch‐site tests for adaptive evolution, we hypothesize that positive selection may be driving spectral tuning in the Stomiidae. These results indicate that the evolutionary history of visual systems in deep‐sea species is complex and a more thorough understanding of this system requires an integrative comparative approach. 相似文献
8.
Natalia Amigo Elsa Mercado Adriana Bentancor Pallavi Singh Daniel Vilte Elisabeth Gerhardt Elsa Zotta Cristina Ibarra Shannon D. Manning Mariano Larzábal Angel Cataldi 《PloS one》2015,10(6)
The hemolytic uremic syndrome (HUS) whose main causative agent is enterohemorrhagic Escherichia coli (EHEC) O157:H7 is a disease that mainly affects children under 5 years of age. Argentina is the country with the highest incidence of HUS in the world. Cattle are a major reservoir and source of infection with E. coli O157:H7. To date, the epidemiological factors that contribute to its prevalence are poorly understood. Single nucleotide polymorphism (SNP) typing has helped to define nine E. coli O157:H7 clades and the clade 8 strains were associated with most of the cases of severe disease. In this study, eight randomly selected isolates of EHEC O157:H7 from cattle in Argentina were studied as well as two human isolates. Four of them were classified as clade 8 through the screening for 23 SNPs; the two human isolates grouped in this clade as well, while two strains were closely related to strains representing clade 6. To assess the pathogenicity of these strains, we assayed correlates of virulence. Shiga toxin production was determined by an ELISA kit. Four strains were high producers and one of these strains that belonged to a novel genotype showed high verocytotoxic activity in cultured cells. Also, these clade 8 and 6 strains showed high RBC lysis and adherence to epithelial cells. One of the clade 6 strains showed stronger inhibition of normal water absorption than E. coli O157:H7 EDL933 in human colonic explants. In addition, two of the strains showing high levels of Stx2 production and RBC lysis activity were associated with lethality and uremia in a mouse model. Consequently, circulation of such strains in cattle may partially contribute to the high incidence of HUS in Argentina. 相似文献
9.
Zhuo Li Jon D. Gabbard Scott Johnson Daniel Dlugolenski Shannon Phan S. Mark Tompkins Biao He 《PloS one》2015,10(3)
H7N9 has caused fatal infections in humans. A safe and effective vaccine is the best way to prevent large-scale outbreaks in the human population. Parainfluenza virus 5 (PIV5), an avirulent paramyxovirus, is a promising vaccine vector. In this work, we generated a recombinant PIV5 expressing the HA gene of H7N9 (PIV5-H7) and tested its efficacy against infection with influenza virus A/Anhui/1/2013 (H7N9) in mice and guinea pigs. PIV5-H7 protected the mice against lethal H7N9 challenge. Interestingly, the protection did not require antibody since PIV5-H7 protected JhD mice that do not produce antibody against lethal H7N9 challenge. Furthermore, transfer of anti-H7 serum did not protect mice against H7N9 challenge. PIV5-H7 generated high HAI titers in guinea pigs, however it did not protect against H7N9 infection or transmission. Intriguingly, immunization of guinea pigs with PIV5-H7 and PIV5 expressing NP of influenza A virus H5N1 (PIV5-NP) conferred protection against H7N9 infection and transmission. Thus, we have obtained a H7N9 vaccine that protected both mice and guinea pigs against lethal H7N9 challenge and infection respectively. 相似文献
10.
Bo-Keun Ha Hyun-Jee Kim Vijayanand Velusamy Tri D. Vuong Henry T. Nguyen J. Grover Shannon Jeong-Dong Lee 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2014,127(7):1501-1512