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121.
A Phage Single-Stranded DNA (ssDNA) Binding Protein Complements ssDNA Accumulation of a Geminivirus and Interferes with Viral Movement 总被引:2,自引:0,他引:2 下载免费PDF全文
Geminiviruses are plant viruses with circular single-stranded DNA (ssDNA) genomes encapsidated in double icosahedral particles. Tomato leaf curl geminivirus (ToLCV) requires coat protein (CP) for the accumulation of ssDNA in protoplasts and in plants but not for systemic infection and symptom development in plants. In the absence of CP, infected protoplasts accumulate reduced levels of ssDNA and increased amounts of double-stranded DNA (dsDNA), compared to accumulation in the presence of wild-type virus. To determine whether the gene 5 protein (g5p), a ssDNA binding protein from Escherichia coli phage M13, could restore the accumulation of ssDNA, ToLCV that lacked the CP gene was modified to express g5p or g5p fused to the N-terminal 66 amino acids of CP (CP66:6G:g5). The modified viruses led to the accumulation of wild-type levels of ssDNA and high levels of dsDNA. The accumulation of ssDNA was apparently due to stable binding of g5p to viral ssDNA. The high levels of dsDNA accumulation during infections with the modified viruses suggested a direct role for CP in viral DNA replication. ToLCV that produced the CP66:6G:g5 protein did not spread efficiently in Nicotiana benthamiana plants, and inoculated plants developed only very mild symptoms. In infected protoplasts, the CP66:6G:g5 protein was immunolocalized to nuclei. We propose that the fusion protein interferes with the function of the BV1 movement protein and thereby prevents spread of the infection. 相似文献
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Peripherin is an intermediate filament protein expressed in restricted populations of neurons. Our previous study of the chromatin structure of the mouse peripherin gene in cells that do or do not express peripherin suggested that the region located between -1,500 and +800 bp of the gene could be involved in its cell specificity. In the present work, we performed an in vitro functional analysis of the 5' flanking region of the mouse peripherin gene and observed that this region up to 9 kb contained both enhancer and inhibiting activities; however, it was insufficient to achieve a complete extinction of reporter gene expression in peripherin-negative cells. Furthermore, analysis of the first three introns with the 5' flanking sequences of the gene showed that intron I greatly increased specificity of the gene expression. Intron I also conferred the same properties to thymidine kinase heterologous promoter. DNase I footprinting experiments performed with intron I revealed at least two protected regions (Inl A and Inl B). Inl A encompasses an AP-2-like binding site that interacted with both neuroblast and fibroblast nuclear factors, as well as with the recombinant AP-2alpha protein. However, gel shift experiments suggested that the interacting nuclear factors are distinct from AP-2alpha itself and probably belong to the AP-2 family. Inl B perfectly matched the consensus binding site for Sp1 and specifically interacted with nuclear protein factors that showed the same binding properties as the Sp1 family members. Fine deletion analysis of intron I indicated that the Inl A element alone is responsible for its enhancing properties, whereas a region located between +789 and +832 gives to intron I its silencer activity. 相似文献
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Jonathan CM Clark Toru Akiyama Crispin R Dass Peter FM Choong 《Cancer cell international》2010,10(1):20
Background
Chondrosarcoma responds poorly to adjuvant therapy and new, clinically relevant animal models are required to test targeted therapy. 相似文献127.
Fredy Altpeter Niranjan Baisakh Roger Beachy Ralph Bock Teresa Capell Paul Christou Henry Daniell Karabi Datta Swapan Datta Philip J. Dix Claude Fauquet Ning Huang Ajay Kohli Hans Mooibroek Liz Nicholson Thi Thanh Nguyen Gregory Nugent Krit Raemakers Andrea Romano David A. Somers Eva Stoger Nigel Taylor Richard Visser 《Molecular breeding : new strategies in plant improvement》2005,15(3):305-327
DNA transfer by particle bombardment makes use of physical processes to achieve the transformation of crop plants. There is no dependence on bacteria, so the limitations inherent in organisms such as Agrobacterium tumefaciens do not apply. The absence of biological constraints, at least until DNA has entered the plant cell, means that particle bombardment is a versatile and effective transformation method, not limited by cell type, species or genotype. There are no intrinsic vector requirements so transgenes of any size and arrangement can be introduced, and multiple gene cotransformation is straightforward. The perceived disadvantages of particle bombardment compared to Agrobacterium-mediated transformation, i.e. the tendency to generate large transgene arrays containing rearranged and broken transgene copies, are not borne out by the recent detailed structural analysis of transgene loci produced by each of the methods. There is also little evidence for major differences in the levels of transgene instability and silencing when these transformation methods are compared in agriculturally important cereals and legumes, and other non-model systems. Indeed, a major advantage of particle bombardment is that the delivered DNA can be manipulated to influence the quality and structure of the resultant transgene loci. This has been demonstrated in recently reported strategies that favor the recovery of transgenic plants containing intact, single-copy integration events, and demonstrating high-level transgene expression. At the current time, particle bombardment is the most efficient way to achieve plastid transformation in plants and is the only method so far used to achieve mitochondrial transformation. In this review, we discuss recent data highlighting the positive impact of particle bombardment on the genetic transformation of plants, focusing on the fate of exogenous DNA, its organization and its expression in the plant cell. We also discuss some of the most important applications of this technology including the deployment of transgenic plants under field conditions. 相似文献
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Anders A Bengtsson ?sa Pettersson Stina Wichert Birgitta Gullstrand Markus Hansson Thomas Hellmark ?sa CM Johansson 《Arthritis research & therapy》2014,16(3):R120