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401.
402.
Lindsay DS Collins MV Mitchell SM Wetch CN Rosypal AC Flick GJ Zajac AM Lindquist A Dubey JP 《The Journal of parasitology》2004,90(5):1054-1057
Toxoplasma gondii has recently been recognized to be widely prevalent in the marine environment. It has previously been determined that Eastern oysters (Crassostrea virginica) can remove sporulated T. gondii oocysts from seawater and that oocysts retain their infectivity for mice. This study examined the long-term survival of T. gondii oocysts in oysters and examined how efficient oysters were at removing oocysts from seawater. Oysters in 76-L aquaria (15 oysters per aquarium) were exposed to 1 x 10(6) oocysts for 24 hr and examined at intervals up to 85 days postexposure (PE). Ninety percent (9 of 10) of these oysters were positive on day 1 PE using mouse bioassay. Tissue cysts were observed in 1 of 2 mice fed tissue from oysters exposed 21 days previously. Toxoplasma gondii antibodies were found in 2 of 3 mice fed oysters that had been exposed 85 days previously. In another study, groups of 10 oysters in 76-L aquaria were exposed to 1 x 10(5), 5 x 10(4), or 1 x 10(4) sporulated T. gondii oocysts for 24 hr and then processed for bioassay in mice. All oysters exposed to 1 x 10(5) oocysts were infected, and 60% of oysters exposed to 5 x 10(4) oocysts were positive when fed to mice. The studies with exposure to 1 x 10(4) oocysts were repeated twice, and 10 and 25% of oysters were positive when fed to mice. These studies indicate that T. gondii can survive for several months in oysters and that oysters can readily remove T. gondii oocysts from seawater. Infected filter feeders may serve as a source of T. gondii for marine mammals and possibly humans. 相似文献
403.
Potent cytotoxins produced by a microbial symbiont protect host larvae from predation 总被引:3,自引:0,他引:3
Larvae of the sessile marine invertebrate Bugula neritina (Bryozoa) are protected by an effective chemical defense. From the larvae, we isolated three bryostatin-class macrocyclic polyketides, including the novel bryostatin 20, that deterred feeding by a common planktivorous fish that co-occurs with B. neritina. A unique bacterial symbiont of B. neritina, Endobugula sertula, was hypothesized as the putative source of the bryostatins. We show that: (1) bryostatins are concentrated in B. neritina larvae and protect them against predation by fish; (2) the adults are not defended by bryostatins; and (3) E. sertula produces bryostatins. This study represents the first example from the marine environment of a microbial symbiont producing an anti-predator defense for its host and, in this case, specifically for the hosts larval stage, which is exceptionally vulnerable to predators.Electronic Supplementary Material Supplementary material is available in the online version of this article at 相似文献
404.
Michael K. Schwartz Kristine L. Pilgrim Kevin S. McKelvey Edward L. Lindquist James J. Claar Steve Loch Leonard F. Ruggiero 《Conservation Genetics》2004,5(3):349-355
Hybridization between taxonomically similar species is an often-overlooked mechanism limiting the recovery of threatened and endangered species. We present molecular genetic data for the first time demonstrating that Canada lynx and bobcats hybridize in the wild. We verify that two microsatellite loci Lc106 and Lc110 have non-overlapping allele ranges between Canada lynx and bobcats, and that three putative lynx from Minnesota contain DNA from both bobcats and lynx. Additionally, we use a published test for the 16S rRNA region of mitochondrial DNA (mtDNA) to determine the maternal species; all hybrids had lynx mothers. Fifteen per cent (3/20) of our putative lynx samples were hybrids, although these data are not from a representative sampling effort. Hybridization may be an under-appreciated factor limiting the distribution and recovery of lynx. The presence of hybrids is thus a new factor in the population management of both species with potential implications for hunting and trapping of bobcats. 相似文献
405.
Receveur JM Bjurling E Ulven T Little PB Nørregaard PK Högberg T 《Bioorganic & medicinal chemistry letters》2004,14(20):5075-5080
Synthesis, in vitro biological evaluation and structure-activity relationships of 4-acylamino-and 4-ureidobenzamides as novel hMCH1R-antagonists are disclosed. The nature of the amine side chains could be varied considerably in contrast to the central benzamide scaffold and aromatic substituents. 相似文献
406.
Serio TR Cashikar AG Kowal AS Sawicki GJ Lindquist SL 《Biochemical Society symposium》2001,(68):35-43
Recently, a novel mode of inheritance has been described in the yeast Saccharomyces cerevisiae. The mechanism is based on the prion hypothesis, which posits that self-perpetuating changes in the conformation of single protein, PrP, underlie the severe neurodegeneration associated with the transmissible spongiform enchephalopathies in mammals. In yeast, two prions, [URE3] and [PSI+], have been identified, but these factors confer unique phenotypes rather than disease to the organism. In each case, the prion-associated phenotype has been linked to alternative conformations of the Ure2 and Sup35 proteins. Remarkably, Ure2 and Sup35 proteins existing in the alternative conformations have the unique capacity to transmit this physical state to the newly synthesized protein in vivo. Thus, a mechanism exists to ensure replication of the conformational information that underlies protein-only inheritance. We have characterized the mechanism by which Sup35 conformational information is replicated in vitro. The assembly of amyloid fibres by a region of Sup35 encompassing the N-terminal 254 amino acids faithfully recapitulates the in vivo propagation of [PSI+]. Mutations that alter [PSI+] inheritance in vivo change the kinetics of amyloid assembly in vitro in a complementary fashion, and lysates from [PSI+] cells, but not [psi-] cells, accelerate assembly in vitro. Using this system we propose a mechanism by which the alternative conformation of Sup35 is adopted by an unstructured oilgomeric intermediate at the time of assembly. 相似文献
407.
Characterization of the interaction between alphaCP(2) and the 3'-untranslated region of collagen alpha1(I) mRNA
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Lindquist JN Kauschke SG Stefanovic B Burchardt ER Brenner DA 《Nucleic acids research》2000,28(21):4306-4316
Activated hepatic stellate cells produce increased type I collagen in hepatic fibrosis. The increase in type I collagen protein results from an increase in mRNA levels that is mainly mediated by increased mRNA stability. Protein–RNA interactions in the 3′-UTR of the collagen α1(I) mRNA correlate with stabilization of the mRNA during hepatic stellate cell activation. A component of the binding complex is αCP2. Recombinant αCP2 is sufficient for binding to the 3′-UTR of collagen α1(I). To characterize the binding affinity of and specificity for αCP2, we performed electrophoretic mobility shift assays using the poly(C)-rich sequence in the 3′-UTR of collagen α1(I) as probe. The binding affinity of αCP2 for the 3′-UTR sequence is ~2 nM in vitro and the wild-type 3′ sequence binds with high specificity. Furthermore, we demonstrate a system for detecting protein–nucleotide interactions that is suitable for high throughput assays using molecular beacons. Molecular beacons, developed for DNA–DNA hybridization, are oligonucleotides with a fluorophore and quencher brought together by a hairpin sequence. Fluorescence increases when the hairpin is disrupted by binding to an antisense sequence or interaction with a protein. Molecular beacons displayed a similar high affinity for binding to recombinant αCP2 to the wild-type 3′ sequence, although the kinetics of binding were slower. 相似文献
408.
Hester JD Lindquist HD Bobst AM Schaefer FW 《The Journal of eukaryotic microbiology》2000,47(3):299-308
A fluorescent in situ hybridization assay has been developed for the detection of the human-pathogenic microsporidian, Encephalitozoon hellem in water samples using epifluorescence microscopy. The assay employs a 19-nucleotide species-specific 6-carboxyfluorescein-labeled oligonucleotide probe, HEL878F, designed to be complementary to the nucleic acid sequence 878-896, a highly variable segment of the 16S ribosomal RNA of E. hellem spores. The specificity of this probe for its ribosomal RNA target site was confirmed using RNA degradation, ribosomal RNA target site competition, and nucleotide base mismatch control probe assays. Furthermore, the specificity of the HEL878F oligonucleotide probe for E. hellem spores was established when it was evaluated on spores from all three species of the genus Encephalitozoon that had been seeded in reagent water and environmental water concentrates. The specificity of the HEL878F oligonucleotide probe was further corroborated when tested on algae, bacteria, and protozoa commonly found in environmental water. The study demonstrates the applicability of a fluorescent in situ hybridization assay using a species-specific fluorescent-labeled oligonucleotide probe for the detection of E. hellem spores in water samples. 相似文献
409.
Padamsee M Kumar TK Riley R Binder M Boyd A Calvo AM Furukawa K Hesse C Hohmann S James TY LaButti K Lapidus A Lindquist E Lucas S Miller K Shantappa S Grigoriev IV Hibbett DS McLaughlin DJ Spatafora JW Aime MC 《Fungal genetics and biology : FG & B》2012,49(3):217-226
Wallemia (Wallemiales, Wallemiomycetes) is a genus of xerophilic Fungi of uncertain phylogenetic position within Basidiomycota. Most commonly found as food contaminants, species of Wallemia have also been isolated from hypersaline environments. The ability to tolerate environments with reduced water activity is rare in Basidiomycota. We sequenced the genome of W. sebi in order to understand its adaptations for surviving in osmotically challenging environments, and we performed phylogenomic and ultrastructural analyses to address its systematic placement and reproductive biology. W. sebi has a compact genome (9.8 Mb), with few repeats and the largest fraction of genes with functional domains compared with other Basidiomycota. We applied several approaches to searching for osmotic stress-related proteins. In silico analyses identified 93 putative osmotic stress proteins; homology searches showed the HOG (High Osmolarity Glycerol) pathway to be mostly conserved. Despite the seemingly reduced genome, several gene family expansions and a high number of transporters (549) were found that also provide clues to the ability of W. sebi to colonize harsh environments. Phylogenetic analyses of a 71-protein dataset support the position of Wallemia as the earliest diverging lineage of Agaricomycotina, which is confirmed by septal pore ultrastructure that shows the septal pore apparatus as a variant of the Tremella-type. Mating type gene homologs were identified although we found no evidence of meiosis during conidiogenesis, suggesting there may be aspects of the life cycle of W. sebi that remain cryptic. 相似文献
410.