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91.
Fas and Fas ligand expressed on cells of the immune system, not on the target tissue, control induction of experimental autoimmune uveitis 总被引:1,自引:0,他引:1
Wahlsten JL Gitchell HL Chan CC Wiggert B Caspi RR 《Journal of immunology (Baltimore, Md. : 1950)》2000,165(10):5480-5486
The Fas-Fas ligand (FasL) interaction is important for maintaining lymphocyte homeostasis by signaling for activation-induced cell death. Mice homozygous for the lpr or gld mutations do not express functional Fas or FasL, respectively, and spontaneously develop progressive autoimmune symptoms. Recent studies implicated expression of FasL on immunologically privileged tissues in protection from immune-mediated damage. Conversely, tissue expression of Fas may facilitate damage. We evaluated the susceptibility of lpr and gld mice to induction of experimental autoimmune uveitis (EAU), a T cell-mediated autoimmune disease induced with retinal Ags, which targets the neural retina. gld as well as lpr mice immunized with a retinal Ag developed disease of lower incidence and severity than wild-type controls. Delayed hypersensitivity responses were not significantly different among immunized gld, lpr, or wild-type mice, although in vitro Ag-specific lymphocyte responses of the mutant mice were lower. To evaluate whether the diminished ability of gld and lpr mice to develop EAU was due to a defect at the level of the tissue or the immune system, radiation bone marrow chimeras constructed between wild-type and mutant mice were immunized to induce EAU. Mutant recipients of wild-type bone marrow, but not wild-type recipients of mutant bone marrow, developed normal disease scores. These results indicate that normal expression of Fas and of FasL on cells of the immune system is important for EAU expression. Unexpectedly, neither lack of Fas nor lack of FasL on the ocular tissues affected expression of EAU. 相似文献
92.
Halinen K Jokela J Fewer DP Wahlsten M Sivonen K 《Applied and environmental microbiology》2007,73(20):6543-6550
Anabaena is a filamentous, N(2)-fixing, and morphologically diverse genus of cyanobacteria found in freshwater and brackish water environments worldwide. It contributes to the formation of toxic blooms in freshwater bodies through the production of a range of hepatotoxins or neurotoxins. In the Baltic Sea, Anabaena spp. form late summer blooms, together with Nodularia spumigena and Aphanizomenon flos-aquae. It has been long suspected that Baltic Sea Anabaena may produce microcystins. The presence of microcystins has been reported for the coastal regions of the Baltic proper, and a recent report also indicated the presence of the toxin in the open Gulf of Finland. However, at present there is no direct evidence linking Baltic Sea Anabaena spp. to microcystin production. Here we report on the isolation of microcystin-producing strains of the genus Anabaena in the open Gulf of Finland. The dominant microcystin variants produced by these strains included the highly toxic MCYST-LR as well as [d-Asp(3)]MCYST-LR, [d-Asp(3)]MCYST-HtyR, MCYST-HtyR, [d-Asp(3),Dha(7)]MCYST-HtyR, and [Dha(7)]MCYST-HtyR variants. Toxic strains were isolated from the coastal Gulf of Finland as well as from the easternmost open-sea sampling station, where there were lower salinities than at other stations. This result suggests that lower salinity may favor microcystin-producing Anabaena strains. Furthermore, we sequenced 16S rRNA genes and found evidence for pronounced genetic heterogeneity of the microcystin-producing Anabaena strains. Future studies should take into account the potential presence of microcystin-producing Anabaena sp. in the Gulf of Finland. 相似文献
93.
Background
Computational prediction methods are currently used to identify genes in prokaryote genomes. However, identification of the correct translation initiation sites remains a difficult task. Accurate translation initiation sites (TISs) are important not only for the annotation of unknown proteins but also for the prediction of operons, promoters, and small non-coding RNA genes, as this typically makes use of the intergenic distance. A further problem is that most existing methods are optimized for Escherichia coli data sets; applying these methods to newly sequenced bacterial genomes may not result in an equivalent level of accuracy. 相似文献94.
95.
Cyanobactins are cyclic peptides assembled through the cleavage and modification of short precursor proteins. An inactive cyanobactin gene cluster has been described from the genome Microcystis aeruginosa NIES843. Here we report the discovery of active counterparts in strains of the genus Microcystis guided by this silent cyanobactin gene cluster. The end products of the gene clusters were structurally diverse cyclic peptides, which we named piricyclamides. Some of the piricyclamides consisted solely of proteinogenic amino acids while others contained disulfide bridges and some were prenylated or geranylated. The piricyclamide gene clusters encoded between 1 and 4 precursor genes. They encoded highly diverse core peptides ranging in length from 7-17 amino acids with just a single conserved amino acid. Heterologous expression of the pir gene cluster from Microcystis aeruginosa PCC7005 in Escherichia coli confirmed that this gene cluster is responsible for the biosynthesis of piricyclamides. Chemical analysis demonstrated that Microcystis strains could produce an array of piricyclamides some of which are geranylated or prenylated. The genetic diversity of piricyclamides in a bloom sample was explored and 19 different piricyclamide precursor genes were found. This study provides evidence for a stunning array of piricyclamides in Microcystis, a worldwide occurring bloom forming cyanobacteria. 相似文献
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Anke Wesselius Martijn JL Bours Niklas R Jørgensen James Wiley Ben Gu Svenjhalmar van Helden Lodewijk van Rhijn Pieter C Dagnelie 《Purinergic signalling》2013,9(1):123-130
In the present study we investigated whether single nucleotide polymorphisms (SNPs) in the P2RX4, which alter the P2X4R function, are associated with the development of osteoporosis and whether an interaction between the P2X4R and P2X7R confer a synergistic effect of these two receptors on osteoporosis risk. Patients with fracture (690 females and 231 males, aged ≥50 years) were genotyped for three non-synonymous P2X4R SNPs. Bone mineral density (BMD) was measured at the total hip, lumbar spine, and femoral neck. Subject carrying the variant allele of the Tyr315Cys polymorphism showed a 2.68-fold (95 % CI, 1.20–6.02) higher risk of osteoporosis compared with wild-type subject. Furthermore, significant lower lumbar spine BMD values were observed in subjects carrying the Cys315 allele as compared with wild-type (0.85 ± 0.17 and 0.93 ± 0.17 g/cm2, respectively; p < 0.001). Assuming a recessive model, carriers of the variant allele of the Ser242Gly polymorphism showed increased BMD values at the lumbar spine compare to wild-type subject (1.11 ± 0.35 and 0.92 ± 0.17 g/cm2, respectively; p = 0.0045). This is the first study demonstrating an association of non-synonymous polymorphisms in the P2RX4 and the risk of osteoporosis, suggesting a role of the P2X4R in the regulation of bone mass.
Electronic supplementary material
The online version of this article (doi:10.1007/s11302-012-9337-0) contains supplementary material, which is available to authorized users. 相似文献98.
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