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An experimental study was undertaken to evaluate alternative insect cell lines to Sf9 [from Spodoptera frugiperda (fall armyworm)] for the production of recombinant proteins. Insect cell lines from two different organisms were considered: IPLB-LdEIta (LdEIta) from Lymantria dispar (gypsy moth) and IPLB-HvT1 (HvT1) from Heliothis virescens (tobacco budworm). Both LdEIta and HvT1 produced higher total activity levels of recombinant beta-galactosidase in monolayer culture than Sf9 after infection with the Autographa californica nuclear polyhedrosis virus (AcMNPV). However, only LdEIta generated a product yield (activity per milligram of total protein) which exceeded that of Sf9 (by 25%), so its growth and production characteristics were investigated in depth. LdEIta generated production levels and yields of a recombinant rotaviral protein, VP4, which exceeded those of Sf9 by 84 and 38%, respectively. In suspension culture, the LdEIta cells grew as aggregates with a doubling time several hours longer than Sf9, but the recombinant product yields of LdEIta were still higher than Sf9 by 38% in this culture environment. beta-Galactosidase expression rates and cell death rates suggested that the difference in productivity between the two hosts was due to the ability of LdEIta to survive the baculovirus infection and produce recombinant proteins longer than Sf9. The presence of LdEIta aggregates in suspension culture may be used as a method to separate live cells from dead cells, labile product, and spent medium in recombinant protein production processes. 相似文献
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The phylogeny of Greya Busck (Lepidoptera: Prodoxidae) was inferred from
nucleotide sequence variation across a 765-bp region in the cytochrome
oxidase I and II genes of the mitochondrial genome. Most parsimonious
relationships of 25 haplotypes from 16 Greya species and two outgroup
genera (Tetragma and Prodoxus) showed substantial congruence with the
species relationships indicated by morphological variation. Differences
between mitochondrial and morphological trees were found primarily in the
positions of two species, G. variabilis and G. pectinifera, and in the
branching order of the three major species groups in the genus. Conflicts
between the data sets were examined by comparing levels of homoplasy in
characters supporting alternative hypotheses. The phylogeny of Greya
species suggests that host-plant association at the family level and larval
feeding mode are conservative characters. Transition/transversion ratios
estimated by reconstruction of nucleotide substitutions on the phylogeny
had a range of 2.0-9.3, when different subsets of the phylogeny were used.
The decline of this ratio with the increase in maximum sequence divergence
among taxa indicates that transitions are masked by transversions along
deeper internodes or long branches of the phylogeny. Among transitions,
substitutions of A-->G and T-->C outnumbered their reciprocal
substitutions by 2-6 times, presumably because of the approximately 4:1
(77%) A+T-bias in nucleotide base composition. Of all transversions,
73%-80% were A<-->T substitutions, 85% of which occurred at third
positions of codons; these estimates did not decrease with an increase in
maximum sequence divergence of taxa included in the analysis. The high
frequency of A<-->T substitutions is either a reflection or an
explanation of the 92% A+T bias at third codon positions.
相似文献
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Smith P. R.; Ropelewski A. J.; Balog D.A.; Gottesman S.; Deerfield D. W. II 《Bioinformatics (Oxford, England)》1991,7(4):501-507
A method has been developed to link the display ability of ahigh-resolution graphics workstation with the computationalpower of a local mainframe or a remote supercomputer via anelectronic data network. The method allows this link to be establishedin a manner largely transparent to the user. The applicationof the method is illustrated by our successful distributionof the computationally intensive portions of an imaging program(MDPP) from a small VAX workstation to a VAX mainframe and CrayY-MP8/832 using a simple message-passing technique. This techniquecan be applied to almost any configuration of networked machines.
Received on February 5, 1991; accepted on April 23, 1991 相似文献
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