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101.
Ryuichi Masaka Makoto Ogata Yoshinori Misawa Megumi Yano Chika Hashimoto Takeomi Murata Hirokazu Kawagishi Taichi Usui 《Bioorganic & medicinal chemistry》2010,18(2):621-629
Two types of nonspacer- and spacer-N-linked tetravalent glycosides bearing N-acetylglucosamine (GlcNAc), N,N′-diacetylchitobiose [(GlcNAc)2] and N-acetyllactosamine (LacNAc) were designed and prepared as glycomimetics. The interactions of wheat germ (Triticum vulgaris) agglutinin (WGA) and coral tree (Erythrina cristagalli) agglutinin (ECA) with a series of tetravalent glycosides and related compounds were studied using a hemagglutination inhibition assay, a precipitation assay, double-diffusion test, and an optical biosensor based on surface plasmon resonance (SPR). The tetravalent glycosides were found to be capable of binding and precipitating the lectins as tetravalent ligands. Strong interactions with WGA, due to a combination of multivalency effects and spacer effects, were observed for tetravalent glycosides bearing flexible tandem GlcNAc. The chelate effect leads to large rate enhancement for the tetravalent system with favorable orientation of ligands. Our simple strategy produced multivalent glycosides with strong cross-linking activity for lectin as a specific coagulant. 相似文献
102.
Regeneration of the intestinal epithelia: Regulation of bone marrow-derived epithelial cell differentiation towards secretory lineage cells 总被引:3,自引:0,他引:3
The intestinal epithelia consists of four lineages of differentiated cells, all of which arise from stem cells residing in the intestinal crypt. For proper regeneration from epithelial damage, both expansion of the epithelial cell number and appropriate regulation of lineage differentiation from the remaining stem cells are thought to be required. In a series of studies, we have shown that bone-marrow derived cells could promote the regeneration of damaged epithelia in the human intestinal tract. Donor-derived epithelial cells substantially repopulated the gastrointestinal tract of bone-marrow transplant recipients during epithelial regeneration after graft-versus-host disease. Furthermore, precise analysis of epithelial cell lineages revealed that during epithelial regeneration, secretory lineage epithelial cells that originated from bone-marrow significantly increased in number. These findings may lead to a novel therapy to repair damaged intestinal epithelia using bone marrow cells, and provide an alternative therapy for refractory inflammatory bowel diseases. 相似文献
103.
Identification of multipotent progenitors in the embryonic mouse kidney by a novel colony-forming assay 总被引:2,自引:0,他引:2
Osafune K Takasato M Kispert A Asashima M Nishinakamura R 《Development (Cambridge, England)》2006,133(1):151-161
Renal stem or progenitor cells with a multilineage differentiation potential remain to be isolated, and the differentiation mechanism of these cell types in kidney development or regeneration processes is unknown. In an attempt to resolve this issue, we set up an in vitro culture system using NIH3T3 cells stably expressing Wnt4 (3T3Wnt4) as a feeder layer, in which a single renal progenitor in the metanephric mesenchyme forms colonies consisting of several types of epithelial cells that exist in glomeruli and renal tubules. We found that only cells strongly expressing Sall1 (Sall1-GFP(high) cells), a zinc-finger nuclear factor essential for kidney development, form colonies, and that they reconstitute a three-dimensional kidney structure in an organ culture setting. We also found that Rac- and JNK-dependent planar cell polarity (PCP) pathways downstream of Wnt4 positively regulate the colony size, and that the JNK pathway is also involved in mesenchymal-to-epithelial transformation of colony-forming progenitors. Thus our colony-forming assay, which identifies multipotent progenitors in the embryonic mouse kidney, can be used for examining mechanisms of renal progenitor differentiation. 相似文献
104.
Masayama A Fukuoka H Kato S Yoshimura T Moriyama M Moriyama R 《Genes & genetic systems》2006,81(3):163-169
The subcellular localization of a germination-specific cortex-lytic enzyme, SleB, of Bacillus subtilis during sporulation was observed by using fusions of N-terminal region of SleB to the green fluorescent protein (GFP). A fusion with a putative peptidoglycan-binding motif (SleB1-108-GFP) formed a fluorescent ring around the forespore of the wild type strain, as expected from the known location of the intact SleB in the dormant spore. SleB1-108-GFP formed a similar fluorescent ring around the forespore of the gerE mutant which has a severe defect in the coat structure, and of the cwlD mutant which lacks a muramic delta-lactam unique to the spore peptidoglycan (cortex), whereas the fusion could not attach to the spore of the cwlDgerE mutant. By contrast, a fusion without the motif (SleB1-45-GFP) could not be recruited around the forespore of the gerE mutant though it appeared to be accumulated on the outside of the spore of the wild type strain. Since SleB was shown to degrade only the cortex with muramic delta-lactam, these results suggested that a proper localization of SleB requires a strict interaction between the motif of the enzyme and the delta-lactam structure of the cortex, not the formation of normal coat layer. 相似文献
105.
106.
Selection for more of the same product as a force to enhance concerted evolution of duplicated genes
The duration of concerted evolution after gene duplication is highly variable across genes. To identify the cause of the variation, we analyzed of duplicated genes in yeast that originate from a whole genome duplication event. There appears to be a strong positive correlation between the duration of concerted evolution and the gene expression level. This observation can be explained by selection favoring more of the same product, which could enhance concerted evolution in dosage-sensitive genes. 相似文献
107.
A genome must locate its coding genes on the chromosomes in a meaningful manner with the help of natural selection, but the mechanism of gene order evolution is poorly understood. To explore the role of selection in shaping the current order of coding genes and their cis-regulatory elements, a comparative genomic approach was applied to the baker's yeast Saccharomyces cerevisiae and its close relatives. S. cerevisiae have experienced a whole-genome duplication followed by an extensive reorganization process of gene order, during which a number of new adjacent gene pairs appeared. We found that the proportion of new adjacent gene pairs in divergent orientation is significantly reduced, suggesting that such new divergent gene pairs may be disfavored most likely because their coregulation may be deleterious. It is also found that such new divergent gene pairs have particularly long intergenic regions. These observations suggest that selection specifically worked against deletions in intergenic regions of new divergent gene pairs, perhaps because they should be physically kept away so that they are not coregulated. It is indicated that gene regulation would be one of the major factors to determine the order of coding genes. 相似文献
108.
Kayama S Shigemoto N Kuwahara R Onodera M Yokozaki M Ohge H Kato F Hisatsune J Sugai M 《Journal of microbiological methods》2012,88(1):182-184
Klebsiella pneumoniae resistant to almost all ß-lactams except imipenem designated as ISMRK (imipenem-susceptible meropenem-resistant Klebsiella) is emerging in Japan. All ISMRK carries blaIMP-6 which differs from blaIMP-1 by only a single nucleotide at position 640. We devised a rapid detection system of blaIMP-6 by using ARMS PCR. 相似文献
109.
The Blakiston's fish owl (Bubo blakistoni) population on Hokkaido Island, Japan, decreased to less than one hundred individuals over the last century due to habitat disruption by human activity. Although the ongoing conservation management has slightly restored the population, it remains endangered. In order to assess the genetic variation and population structure of the Blakiston's fish owl in Hokkaido, we genotyped eight microsatellite loci on 120 individuals sampled over the past three decades. The genotype data set showed low levels of genetic variation and gene flow among the geographically isolated five subpopulations. Comparative analysis of past and current populations indicated that some alleles shared by past individuals had been lost, and that genetic variation had declined over the last three decades. The result suggests that the genetic decline may have resulted from inbreeding and/or genetic drift due to bottlenecks in the Hokkaido population. The present study provides invaluable genetic information for the conservation and management of the endangered Blakiston's fish owl in Hokkaido. 相似文献
110.
LM Hedges R Yamada SL O'Neill KN Johnson 《Applied and environmental microbiology》2012,78(18):6773-6776
Wolbachia pipientis delays RNA virus-induced mortality in Drosophila spp. We investigated whether Wolbachia-mediated protection was dependent on the small interfering RNA (siRNA) pathway, a key antiviral defense. Compared to Wolbachia-free flies, virus-induced mortality was delayed in Wolbachia-infected flies with loss-of-function of siRNA pathway components, indicating that Wolbachia-mediated protection functions in the absence of the canonical siRNA pathway. 相似文献