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61.
Genome‐wide comparisons reveal a clinal species pattern within a holobenthic octopod—the Australian Southern blue‐ringed octopus,Hapalochlaena maculosa (Cephalopoda: Octopodidae) 下载免费PDF全文
Peter Morse Shannon R. Kjeldsen Mark G. Meekan Mark I. Mccormick Julian K. Finn Christine L. Huffard Kyall R. Zenger 《Ecology and evolution》2018,8(4):2253-2267
The southern blue‐ringed octopus, Hapalochlaena maculosa (Hoyle, 1883) lacks a planktonic dispersal phase, yet ranges across Australia's southern coastline. This species’ brief and holobenthic life history suggests gene flow might be limited, leaving distant populations prone to strong genetic divergence. This study used 17,523 genome‐wide SNP loci to investigate genetic structuring and local adaptation patterns of H. maculosa among eight sampling sites along its reported range. Within sites, interrelatedness was very high, consistent with the limited dispersal of this taxon. However, inbreeding coefficients were proportionally lower among sites where substructuring was not detected, suggesting H. maculosa might possess a mechanism for inbreeding avoidance. Genetic divergence was extremely high among all sites, with the greatest divergence observed between both ends of the distribution, Fremantle, WA, and Stanley, TAS. Genetic distances closely followed an isolation by geographic distance pattern. Outlier analyses revealed distinct selection signatures at all sites, with the strongest divergence reported between Fremantle and the other Western Australian sites. Phylogenetic reconstructions using the described sister taxon H. fasciata (Hoyle, 1886) further supported that the genetic divergence between distal H. maculosa sites in this study was equivalent to that of between established heterospecifics within this genus. However, it is advocated that taxonomic delineations within this species should be made with caution. These data indicate that H. maculosa forms a clinal species pattern across its geographic range, with gene flow present through allele sharing between adjacent populations. Morphological investigations are recommended for a robust resolution of the taxonomic identity and ecotype boundaries of this species. 相似文献
62.
Codon bias and plasticity in immunoglobulins 总被引:6,自引:1,他引:5
Immunoglobulin genes experience Darwinian evolution twice. In addition to
the germline evolution all genes experience, immunoglobulins are subjected,
upon exposure to antigen, to somatic hypermutation. This is accompanied by
selection for high affinity to the eliciting antigen and frequently results
in a significant increase in the specificity of the responding population.
The hypermutation mechanism displays a strong sequence specificity. Thus
arises the opportunity to manipulate codon bias in a site-specific manner
so as to direct hypermutation to those parts of the gene that encode the
antigen-binding portions of the molecule and away from those that encode
the structurally conserved regions. This segregation of mutability would
clearly be advantageous; it would enhance the generation of potentially
useful variants while keeping mutational loss to acceptably low levels. But
it is not clear that the advantage gained would be large enough to produce
a measurable effect within the background stochasticity of the evolutionary
process. I have performed a pair of statistical tests to determine whether
site- specific codon bias in human immunoglobulin genes is correlated with
the sequence specificity of the somatic mutation mechanism. The sequence
specificity of the mutator was determined by analysis of a database of
published immunoglobulin intron sequences that had experienced somatic
mutation but not selection. The site-specific codon bias was determined by
analysis of published sequences of human germline immunoglobulin V genes.
Both tests strongly suggest that evolution has acted to enhance the
plasticity of immunoglobulin genes under somatic hypermutation.
相似文献
63.
Thomas Kjeldsen Annette Frost Pettersson Morten Hach Ivan Diers Svend Havelund Per Hertz Hansen Asser S. Andersen 《Protein expression and purification》1997,9(3):331-336
Secretion leaders are essential for expression of many heterologous proteins including insulin in yeast. The function of secretion leaders and their interaction with the secretory pathway is not clear. To determine what constitutes functional pre-pro-leader sequences inSaccharomyces cerevisiae,synthetic leader sequences for secretion of the insulin precursor were developed by a combination of rational design and stepwise systematic optimization. The synthetic leaders efficiently facilitate secretion of the insulin precursor fromS. cerevisiaewhen compared with the α-factor leader, leading to a high yield of correctly folded insulin precursor in the culture supernatant. The synthetic leaders feature two potential N-linked glycosylation sites which are efficiently glycosylated during secretion. Pulse–chase analysis indicates that the synthetic leaders/insulin precursor fusion protein have a prolonged residence in the endoplasmic reticulum compared to the α-factor leader/insulin precursor fusion protein. The longer transition time in the endoplasmic reticulum mediated by the synthetic leaders might provide additional time for correct folding of the insulin precursor and account for the increased fermentation yield. 相似文献
64.
Morten Juhl Corydon Brage Storstein Andresen Peter Bross Margrethe Kjeldsen Per Hove Andreasen Hans Eiberg Steen Kølvraa Nils Gregersen 《Mammalian genome》1997,8(12):922-926
Short-chain acyl-CoA dehydrogenase (SCAD) is a homotetrameric mitochondrial flavoenzyme that catalyzes the initial reaction
in short-chain fatty acid β-oxidation. Defects in the SCAD enzyme are associated with failure to thrive, often with neuromuscular
dysfunction and elevated urinary excretion of ethylmalonic acid (EMA). To define the genetic basis of SCAD deficiency and
ethylmalonic aciduria in patients, we have determined the sequence of the complete coding portion of the human SCAD gene (ACADS)
and all of the intron-exon boundaries. The SCAD gene is approximately 13 kb in length and consists of 10 exons. Four polymorphic
sites have previously been detected by sequencing of cDNA from fibroblasts of patients excreting elevated amounts of EMA.
Three of these polymorphisms (321T/C, 990C/T, 1260G/C) are silent variants, while a 625G/A polymorphism results in an amino
acid replacement and has been shown to be associated with ethylmalonic aciduria. From analysis of 18 unrelated Danish families,
we show that the four SCAD gene polymorphisms constitute five allelic variants of the SCAD gene, and that the 625A variant
together with the less frequent variant form of the three other polymorphisms (321C, 990T, 1260C) constitutes an allelic variant
with a frequency of 22% in the general Danish population. Using fluorescence in-situ hybridization, we confirm the localization
of the human SCAD gene to the distal part of Chromosome (Chr) 12 and suggest that the SCAD gene is a single-copy gene. The
evolutionary relationship between SCAD and five other members of the acyl-CoA dehydrogenase family was investigated by two
independent approaches that gave similar phylogenetic trees.
Received: 10 April 1997 / Accepted: 8 August 1997 相似文献
65.
Nineteen strains of Drosophila virilis from diverse geographic locations
were examined by genetic and molecular analyses, revealing (a) 12 strains
with a single copy of the urate oxidase (UO) gene per haploid genome and
(b) 7 strains with a tandem duplication of the UO locus. The D. virilis
strains with the UO duplication appear to have identical restriction maps
of this region, implying either a single origin for the duplication or
several similar events occurring at a hot spot. On the basis of the
location of the duplication breakpoints and the restriction sites flanking
these breakpoints, this duplication probably arose through nonhomologous
recombination involving either a breakage and rejoining event or
replication slippage. because documented cases of intraspecific gene
duplication polymorphism are rare, the D. virilis UO duplication will be
useful in identifying the molecular event giving rise to a gene
duplication.
相似文献
66.
K. W. Finster C. S. Cockell M. A. Voytek A. L. Gronstal K. U. Kjeldsen 《Antonie van Leeuwenhoek》2009,96(4):515-526
A novel actinobacterium, designated CB31T, was isolated from a 940 m depth sample of a drilling core obtained from the Chesapeake meteor impact crater. The strain
was isolated aerobically on R2A medium agar plates supplemented with NaCl (20 g l−1) and MgCl2·6H2O (3 g l−1). The colonies were circular, convex, smooth and orange. Cells were slightly curved, rod-shaped in young cultures and often
appeared in pairs. In older cultures cells were coccoid. Cells stained Gram-positive, were non-motile and did not form endospores.
The diagnostic diamino acid of the peptidoglycan was ll-diaminopimelic acid. The polar lipids included phosphatidylglycerol, diphosphatidglycerol, four different glycolipids, two
further phospholipids and one unidentified lipid. The dominant menaquinone was MK-9(H4) (70%). The major cellular fatty acid was anteiso C15:0 (83%). The DNA G + C content was 68 mol%. The strain grew anaerobically by reducing nitrate to nitrite or by fermenting
glucose. It was catalase positive and oxidase negative. It grew between 10 and 45°C, with an optimum between 35 and 40°C.
The pH range for growth was 5.7–9.3, with an optimum at pH 7.5. The closest phylogenetic neighbors based on 16S rRNA gene
sequence identity were members of the genus Tessaracoccus (95–96% identity). On the basis of phenotypic and phylogenetic distinctiveness, strain CB31T is considered to represent a novel species of the genus Tessaracoccus, for which we propose the name Tessaracoccus profundi sp. nov.. It is the first member of this genus that has been isolated from a deep subsurface environment. The type strain
is CB31T (=NCIMB 14440T = DSM 21240T). 相似文献
67.
Lund MB Davidson SK Holmstrup M James S Kjeldsen KU Stahl DA Schramm A 《Environmental microbiology》2010,12(8):2142-2151
Symbiotic bacteria of the genus Verminephrobacter (Betaproteobacteria) were detected in the nephridia of 19 out of 23 investigated earthworm species (Oligochaeta: Lumbricidae) by 16S rRNA gene sequence analysis and fluorescence in situ hybridization (FISH). While all four Lumbricus species and three out of five Aporrectodea species were densely colonized by a mono-species culture of Verminephrobacter, other earthworm species contained mixed bacterial populations with varying proportions of Verminephrobacter; four species did not contain Verminephrobacter at all. The Verminephrobacter symbionts could be grouped into earthworm species-specific sequence clusters based on their 16S rRNA and RNA polymerase subunit B (rpoB) genes. Closely related host species harboured more closely related symbionts than did distantly related hosts. Co-diversification of the symbiotic partners could not be demonstrated unambiguously due to the poor resolution of the host phylogeny [based on histone H3 and cytochrome c oxidase subunit I (COI) gene sequence analyses]. However, there was a pattern of symbiont diversification within four groups of closely related hosts. The mean rate of symbiont 16S rRNA gene evolution was determined using a relaxed clock model, and the rate was calibrated with paleogeographical estimates of the time of origin of Lumbricid earthworms. The calibrated rates of symbiont 16S rRNA gene evolution are 0.012-0.026 substitutions per site per 50 million years and thus similar to rates reported from other symbiotic bacteria. 相似文献
68.
Fatigue depresses maximal in vitro skeletal muscle Na(+)-K(+)-ATPase activity in untrained and trained individuals. 总被引:11,自引:0,他引:11
Steve F Fraser Jia L Li Michael F Carey Xiao N Wang Termboon Sangkabutra Simon Sostaric Steve E Selig Keld Kjeldsen Michael J McKenna 《Journal of applied physiology》2002,93(5):1650-1659
This study investigated whether fatiguing dynamic exercise depresses maximal in vitro Na(+)-K(+)-ATPase activity and whether any depression is attenuated with chronic training. Eight untrained (UT), eight resistance-trained (RT), and eight endurance-trained (ET) subjects performed a quadriceps fatigue test, comprising 50 maximal isokinetic contractions (180 degrees /s, 0.5 Hz). Muscle biopsies (vastus lateralis) were taken before and immediately after exercise and were analyzed for maximal in vitro Na(+)-K(+)-ATPase (K(+)-stimulated 3-O-methylfluoroscein phosphatase) activity. Resting samples were analyzed for [(3)H]ouabain binding site content, which was 16.6 and 18.3% higher (P < 0.05) in ET than RT and UT, respectively (UT 311 +/- 41, RT 302 +/- 52, ET 357 +/- 29 pmol/g wet wt). 3-O-methylfluoroscein phosphatase activity was depressed at fatigue by -13.8 +/- 4.1% (P < 0.05), with no differences between groups (UT -13 +/- 4, RT -9 +/- 6, ET -22 +/- 6%). During incremental exercise, ET had a lower ratio of rise in plasma K(+) concentration to work than UT (P < 0.05) and tended (P = 0.09) to be lower than RT (UT 18.5 +/- 2.3, RT 16.2 +/- 2.2, ET 11.8 +/- 0.4 nmol. l(-1). J(-1)). In conclusion, maximal in vitro Na(+)-K(+)-ATPase activity was depressed with fatigue, regardless of training state, suggesting that this may be an important determinant of fatigue. 相似文献
69.
Kjeldsen KU Kjellerup BV Egli K Frølund B Nielsen PH Ingvorsen K 《FEMS microbiology ecology》2007,61(2):384-397
District heating systems (DHS) are extreme aqueous environments characterized by high temperatures, high pH (9.5-10.0), and low nutrient availability. Culture-independent and culture-dependent techniques showed that DHS may nevertheless harbour geno- and phenotypically diverse bacterial biofilm communities. Approximately 50% of the cells in biofilms growing on mild steel coupons in rotortorque reactors connected to the return line (40 degrees C) of a Danish DHS were detectable by FISH analysis and thus were probably metabolically active. A bacterial 16S rRNA gene clone library generated from the biofilms was dominated by proteobacterial phylotypes (closely related to known aerobic species) and by phylotypes affiliated to the anaerobic class Clostridia. Anoxic enrichment cultures derived from biofilms primarily contained 16S rRNA gene and dsrAB (encoding major subunits of dissimilatory sulfite reductase) phylotypes affiliated to the latter class. Alkalitolerant and neutrophilic anaerobic bacteria were isolated from the DHS, including novel Gram-positive and deltaproteobacterial sulfate-reducers and sulfite-reducers constituting novel Gram-positive lineages. In total, 39 distinct 16S rRNA gene phylotypes representing ten classes were identified. The detection of several alkalitolerant, sulfide-producing, and, thus, potentially biocorrosive species underlines the need to maintain a high water quality in the DHS in order to prevent the proliferation of these species. 相似文献
70.
JC de Mauroy HR Weiss AG Aulisa L Aulisa JI Brox J Durmala C Fusco TB Grivas J Hermus T Kotwicki G Le Blay A Lebel L Marcotte S Negrini L Neuhaus T Neuhaus P Pizzetti L Revzina B Torres PJM Van Loon E Vasiliadis M Villagrasa M Werkman M Wernicka MS Wong F Zaina 《Scoliosis》2010,5(1):1-15