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71.
Five cold temperature germinating (ctg) mutants, completing germination at 10 degrees C faster than wild type, have been recovered from activation-tagged populations of Arabidopsis thaliana. Three (ctg10-D, 41-D, and 144-D) were tagged and segregated 3:1 for BASTA resistance in the F2 when crossed with wild type. None of the tagged ctg mutants was disturbed in sensitivity to abscisic acid or glucose but all were less sensitive to GA4+7 and osmoticum. The other two mutants (ctg156 and ctg225) were recessive, BASTA sensitive, and exhibited a transparent testa (tt) phenotype. They were more sensitive to abscisic acid, paclobutrazol, and GA4+7 than wild type but had similar sensitivity to osmoticum. Dimethylaminocinnamaldehyde staining of seeds from the two tt mutants, compared with stained seeds from the publicly available tt lines 1-10, suggested that ctg156 was a new allele of tt1, while ctg225 was similar to tt7-1. However, reciprocal crosses determined that ctg156 was not allelic to tt1 while ctg225 was a new allele of tt7. When the gene was sequenced from ctg225 it was missing 10 bp in the second exon, resulting in the incorporation of two spurious amino acids (G282E and D283A) followed by a stop. The screen successfully recovered mutants completing germination faster than wild type at 10 degrees C. 相似文献
72.
Evolution of transposable elements: an IS10 insertion increases fitness in Escherichia coli 总被引:3,自引:0,他引:3
Strains of Escherichia coli carrying Tn10, a transposon consisting of two
IS10 insertion sequences flanking a segment encoding for a
tetracycline-resistance determinant, gain a competitive advantage in
chemostat cultures. All Tn10-bearing strains that increase in frequency
during competition have a new IS10 insertion that is found in the same
location in the genome of those strains. We mapped, by a gradient of
transmission, the position of the new IS10 insertion. We examined 11
isolates whose IS10 insertion was deleted by recombinational crossing-
over, and in all cases the competitive fitness of the isolates was
decreased. These results show that the IS10-generated insertion increases
fitness in chemostat cultures. We named the insertion fit::IS10 and suggest
that transposable elements may speed the rate of evolution by promoting
nonhomologous recombination between preexisting variations within a genome
and thereby generating adaptive variation.
相似文献
73.
Members of the ZFY and ZNF6 gene families have been cloned from species
representing different taxa and different modes of sex determination.
Comparisons of these genes show the ZFY-like and ZNF6 sequences to be
strongly conserved across marsupials, birds, and lepidosaurians. Sequence
analyzed by neighbor-joining indicated that both gene families are
monophyletic with a high bootstrap value. Pairing of sequences from males
and females of nonmammalian species showed there to be no significant
difference between male and female sequences from a single species,
consistent with autosomal locations. The molecular distances between murine
Zfy-1, Zfy-2, and other ZFY-like sequences suggested that Zfy genes have
undergone a period of rapid evolutionary change not seen in human ZFY.
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Reddy PK Reddy SG Narala VR Majee SS Konda S Gunwar S Reddy RC 《Protein expression and purification》2007,52(1):123-130
Increasing therapeutic applications for recombinant human interferon-gamma (rhIFN-gamma), an antiviral proinflammatory cytokine, has broadened interest in optimizing methods for its production and purification. We describe a reversed phase chromatography (RPC) procedure using Source-30 matrix in the purification of rhIFN-gamma from Escherichia coli that results in a higher yield than previously reported. The purified rhIFN-gamma monomer from the RPC column is refolded in Tris buffer. Optimal refolding occurs at protein concentrations between 50 and 100 microg/ml. This method yields greater than 90% of the dimer form with a yield of 40 mg/g cell mass. Greater than 99% purity is achieved with further purification over a Superdex G-75 column to obtain specific activities of from 2 x 10(7) to 4 x 10(7)IU/mg protein as determined via cytopathic antiviral assay. The improved yield of rhIFN-gamma in a simple chromatographic purification procedure promises to enhance the development and therapeutic application of this biologically potent molecule. 相似文献
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