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991.
Kwon MC Choi WY Seo YC Kim JS Yoon CS Lim HW Kim HS Ahn Jh Lee HY 《Journal of biotechnology》2012,157(1):100-106
Aqueous extracts of Centella asiatica L. Urban were encapsulated by an edible biopolymer, gelatin, which has no effect on their cosmetic activities. The nanoparticles were w/o-type spherical liposomes that had an average diameter of 115.0nm. The encapsulation efficiency was estimated to be approximately 67%, which was relatively high for these aqueous extracts. The nanoparticles showed lower cytotoxicity (10%) in human skin fibroblast cells than the unencapsulated crude extract (15%) at 1.0mg/ml, this was possibly because a smaller amount of the extract was present in the nanoparticles. The nanoparticles efficiently reduced the expression of matrix metalloproteinase (MMP)-1 in UV-irradiated cells from 136.1% to 77.6% (UV-irradiated control) and inhibited hyaluronidase expression (>60%) at a concentration of 0.5mg/ml, which was higher than the levels produced by the unencapsulated crude extracts. The nanoparticles had a very high flux through mouse skin and also remained at relatively large concentrations in the derma when compared to the unencapsulated crude extracts. These results clearly indicate that the skin-protective activities of C. asiatica were significantly improved through the nano-encapsulation process. These findings also imply that a crude extract can be used and have the same efficacy as purified compounds, which should reduce the purification process and production costs. 相似文献
992.
Mukherjee M Chow SY Yusoff P Seetharaman J Ng C Sinniah S Koh XW Asgar NF Li D Yim D Jackson RA Yew J Qian J Iyu A Lim YP Zhou X Sze SK Guy GR Sivaraman J 《The EMBO journal》2012,31(5):1308-1319
Phosphotyrosine-binding domains, typified by the SH2 (Src homology 2) and PTB domains, are critical upstream components of signal transduction pathways. The E3 ubiquitin ligase Hakai targets tyrosine-phosphorylated E-cadherin via an uncharacterized domain. In this study, the crystal structure of Hakai (amino acids 106-206) revealed that it forms an atypical, zinc-coordinated homodimer by utilizing residues from the phosphotyrosine-binding domain of two Hakai monomers. Hakai dimerization allows the formation of a phosphotyrosine-binding pocket that recognizes specific phosphorylated tyrosines and flanking acidic amino acids of Src substrates, such as E-cadherin, cortactin and DOK1. NMR and mutational analysis identified the Hakai residues required for target binding within the binding pocket, now named the HYB domain. ZNF645 also possesses a HYB domain but demonstrates different target specificities. The HYB domain is structurally different from other phosphotyrosine-binding domains and is a potential drug target due to its novel structural features. 相似文献
993.
Herbert G Kasler Hyung W Lim Amy M Collins Intelly S Lee Eric Verdin 《The EMBO journal》2012,31(23):4453-4465
Histone deacetylase 7 (HDAC7) is a T‐cell receptor (TCR) signal‐dependent regulator of differentiation that is highly expressed in CD4/CD8 double‐positive (DP) thymocytes. Here, we examine the effect of blocking TCR‐dependent nuclear export of HDAC7 during thymic selection, through expression of a signal‐resistant mutant of HDAC7 (HDAC7‐ΔP) in thymocytes. We find that HDAC7‐ΔP transgenic thymocytes exhibit a profound block in negative thymic selection, but can still undergo positive selection, resulting in the escape of autoreactive T cells into the periphery. Gene expression profiling reveals a comprehensive suppression of the negative selection‐associated gene expression programme in DP thymocytes, associated with a defect in the activation of MAP kinase pathways by TCR signals. The consequence of this block in vivo is a lethal autoimmune syndrome involving the exocrine pancreas and other abdominal organs. These experiments establish a novel molecular model of autoimmunity and cast new light on the relationship between thymic selection and immune self‐tolerance. 相似文献
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996.
Some apicomplexan parasites have evolved distinct protein kinase families to modulate host cell structure and function. Toxoplasma gondii rhoptry protein kinases and pseudokinases are involved in virulence and modulation of host cell signalling. The proteome of Plasmodium falciparum contains a family of putative kinases called FIKKs, some of which are exported to the host red blood cell and might play a role in erythrocyte remodelling. In this review we will discuss kinases known to be critical for host cell invasion, intracellular growth and egress, focusing on (i) calcium-dependent protein kinases and (ii) the secreted kinases that are unique to Toxoplasma (rhoptry protein kinases and pseudokinases) and Plasmodium (FIKKs). 相似文献
997.
In Escherichia coli, the corA gene encodes a transporter that mediates the influx of Co(2+), Mg(2+), and Ni(2+) into the cell. During the course of experiments aimed at identifying RNase III-dependent genes in E. coli, we observed that steady-state levels of corA mRNA as well as the degree of cobalt influx into the cell were dependent on cellular concentrations of RNase III. In addition, changes in corA expression levels by different cellular concentrations of RNase III were closely correlated with degrees of resistance of E. coli cells to Co(2+) and Ni(2+). In vitro and in vivo cleavage analyses of corA mRNA identified RNase III cleavage sites in the 5'-untranslated region of the corA mRNA. The introduction of nucleotide substitutions at the identified RNase III cleavage sites abolished RNase III cleavage activity on corA mRNA and resulted in prolonged half-lives of the mRNA, which demonstrates that RNase III cleavage constitutes a rate-determining step for corA mRNA degradation. These findings reveal an RNase III-mediated regulatory pathway that functions to modulate corA expression and, in turn, the influx of metal ions transported by CorA in E. coli. 相似文献
998.
Shin SH Kim S Kim JY Song HY Cho SJ Kim DR Lee KI Lim HK Park NJ Hwang IT Yang KS 《Journal of bacteriology》2012,194(5):1266
This article reports on the full genome sequence of Paenibacillus terrae HPL-003, which is a gram-positive, endospore-forming, xylanase-producing bacterium isolated from soil found in forest residue on Gara Mountain. The strain HPL-003 contains 6,083,395 bp with a G+C content of 46.77 mol%, 2,633 protein-coding genes, and 117 structural RNAs. 相似文献
999.
Stefano G. A. Draisma Marcel C. M. Eurlings Phaik-Eem Lim 《Journal of applied phycology》2012,24(6):1373-1379
Of four species of Sargassaceae, representing the genera Carpophyllum, Cystoseira, Landsburgia, and Sargassum, the intergenic spacer of the ribosomal cistron was amplified using a forward primer annealing at the 3′-end of the large subunit (LSU) of the ribosomal cistron and a reverse primer annealing at the 5S rRNA gene. The PCR products were cloned and the DNA sequences of multiple clones were determined. Almost each clone showed a unique DNA sequence. Intra-individual variation of this LSU-5S intergenic spacer was extremely high and was characterized by great length variation and a high number of short tandem repeats. Sequences were unalignable and therefore it was concluded that the LSU-5S intergenic spacer is unsuitable for phylogenetic and phylogeographic studies of sargassacean taxa. 相似文献
1000.
We investigated the in vitro and in vivo osteogenic activity of licochalcone A. At low concentrations, licochalcone A stimulated
the differentiation of mouse pre-osteoblastic MC3T3-E1 subclone 4 (MC4) cells and enhanced the bone morphogenetic protein
(BMP)-2-induced stimulation of mouse bi-potential mesenchymal precursor C2C12 cells to commit to the osteoblast differentiation
pathway. This osteogenic activity of licochalcone A was accompanied by the activation of extracellular-signal regulated kinase
(ERK). The involvement of ERK was confirmed in a pharmacologic inhibition study. Additionally, noggin (a BMP antagonist) inhibited
the osteogenic activity of licochalcone A in C2C12 cells. Licochalcone A also enhanced the BMP-2-stimulated expression of
various BMP mRNAs. This suggested that the osteogenic action of licochalcone A in C2C12 cells could be dependent on BMP signaling
and/or expression. We then tested the in vivo osteogenic activity of licochalcone A in two independent animal models. Licochalcone
A accelerated the rate of skeletal development in zebrafish and enhanced woven bone formation over the periosteum of mouse
calvarial bones. In summary, licochalcone A induced osteoblast differentiation with ERK activation in both MC4 and C2C12 cells
and it exhibited in vivo osteogenic activity in zebrafish skeletal development and mouse calvarial bone formation. The dual
action of licochalcone A in stimulating bone formation and inhibiting bone resorption, as described in a previous study, might
be beneficial in treating bone-related disorders. 相似文献