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Analysis of hematopoietic Src homology 2 (HSH2) protein expression in mouse immune cells demonstrated that it is expressed at low levels in resting B cells but not T cells or macrophages. However, HSH2 expression is up-regulated within 6-12 h in response to multiple stimuli that promote activation, differentiation, and survival of splenic B cells. HSH2 expression is increased in response to anti-CD40 mAb, the TLR ligands LPS and CpG DNA, and B lymphocyte stimulator (BLyS), a key regulator of peripheral B cell survival and homeostasis. Stimulation of B cells with anti-CD40 mAb, LPS, CpG DNA, or BLyS has previously been shown to induce activation of NF-kappaB. In agreement with this finding, up-regulation of HSH2 expression in response to these stimuli is blocked by inhibitors of NF-kappaB activation and is potentiated by stimulation with PMA, suggesting that HSH2 expression is dependent on NF-kappaB activation. In contrast to CD40, BAFF receptor, TLR4, and TLR9 mediated signaling, stimulation of splenic B cells via the BCR was not observed to induce expression of HSH2 unless the cells had been stimulated previously through CD40. Finally, HSH2 expression is down-regulated in splenic B cells in response to stimulation with IL-21, which has been shown to induce apoptosis, even in the presence of anti-CD40 mAb, LPS, or CpG DNA. IL-21 stimulation also results in down-regulation of antiapoptotic proteins such as Bcl-x(L) and up-regulation of proapoptotic proteins like Bim. Therefore, HSH2 expression is coordinately up-regulated with known antiapoptotic molecules and directly correlates with B cell survival. 相似文献
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Daniel W. Norbeck Hing L. Sham William Rosenbrook Thomas Herrin Jacob J. Plattner 《Nucleosides, nucleotides & nucleic acids》2013,32(7):1383-1391
Abstract Synthesis of the novel phosphonate isostere of the monophosphate of (±)Cyclobut-G and its biological activities against HSV-1 and HSV-2 in Vero cells are reported. The cyclobutane ring was constructed by a [2+2] thermal cycloaddition. The relative stereochemistry of the substituents on the ring was determined by NOE experiments. 相似文献
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In vitro self-splicing reactions of the chloroplast group I intron Cr.LSU from Chlamydomonas reinhardtii and in vivo manipulation via gene-replacement. 下载免费PDF全文
The group I intron from the chloroplast rRNA large subunit of Chlamydomonas reinhardtii (Cr.LSU) undergoes autocatalytic splicing in vitro. Cr.LSU displays a range of reactions typical of other group I introns. Under optimal conditions, the 5' cleavage step proceeds rapidly, but the exon-ligation step is relatively slow, and no pH dependent hydrolysis of the 3' splice site occurs. A requirement for high temperature and high [Mg2+] suggests involvement of additional splicing factors in vivo. The positions of three cyclization sites of the free intron have been mapped; two of these sites represent reactions analogous to 5'-splice site cleavage, whereas the third is an example of G-exchange. Cr.LSU contains an open reading frame (ORF) potentially encoding an 163 amino acid polypeptide. ORF function has been investigated by using chloroplast gene replacement via particle bombardment. We have shown that the ORF can be deleted from Cr.LSU without affecting splicing in vivo and it thus does not encode an essential splicing factor. 相似文献
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Minko I Holloway SP Nikaido S Carter M Odom OW Johnson CH Herrin DL 《Molecular & general genetics : MGG》1999,262(3):421-425
The use of luciferases as reporters of gene expression in living cells has been extended to the chloroplast genome. We show
that the luciferase from the soft coral Renilla reniformis (Rluc) can be successfully expressed in the chloroplast of Chlamydomonas reinhardtii. Expression of the rluc cDNA was driven by the promoter and 5′ untranslated regions of the atpA gene. Western analysis with an anti-Rluc antibody detected a single polypeptide of 38 kDa in the luminescent cells. This
is 3 kDa larger than native Rluc, and suggests that translation of the chimeric mRNA begins at the atpA start codon, 29 codons upstream from the rluc start site. We also show that the luminescence of the transformants was sufficient to enable imaging of colonies using a
cooled CCD camera.
Received: 12 April 1999 / Accepted: 24 June 1999 相似文献
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