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11.
Sara L Goodacre Oliver Y Martin Dries Bonte Linda Hutchings Chris Woolley Kamal Ibrahim CF George Thomas Godfrey M Hewitt 《BMC biology》2009,7(1):32-8
Background
Dispersal plays a key role in shaping biological and ecological processes such as the distribution of spatially-structured populations or the pace and scale of invasion. Here we have studied the relationship between long-distance dispersal behaviour of a pest-controlling money spider,Erigone atra, and the distribution of maternally acquired endosymbionts within the wider meta-population. This spider persists in heterogeneous environments because of its ability to recolonise areas through active long-distance airborne dispersal using silk as a sail, in a process termed 'ballooning'. 相似文献12.
13.
European Working Group on CF Genetics 《Human genetics》1990,85(4):436-445
Summary In this collaborative European study, a total of 4871 cystic fibrosis (CF) chromosomes and 3539 normal chromosomes have been
characterized for the haplotypes defined by the 2 extragenic polymorphic sequences revealed by XV2c and KM19. The association
between one of these haplotypes (B haplotype) and the most frequent CF mutation, ΔF508, suggests for the latter a single origin
and a subsequent diffusion according to a South East-North West gradient. The linkage disequilibrium data between CF and the
B haplotype in different European populations are compatible with a relatively more recent appearance of the mutation in Northern
Europe whereas in Southern Europe a longer history of the same mutation would have allowed time for recombination with other
haplotypes. This model is also compatible with a selective advantage of carriers but does not account for (1) the excess of
B haplotypes observed among both normal and non-ΔF508 CF chromosomes; (2) the correlation between the B haplotype and the
severity of the phenotypic effect caused by CF mutations, as measured by pancreatic insufficiency and meconium ileus. 相似文献
14.
Nicholas C. Wheeler Raymond P. Guries David M. O''Malley 《Biochemical Systematics and Ecology》1983,11(4):333-340
Gene frequency data from 42 isoenzyme loci were used to assess the phylogeny of taxa in the genus Pinus, subsection Contortae. The classification inferred from a phenogram based on Nei's genetic distance measure (DN) was generally in good agreement with the current taxonomic treatment of the subsection. Pinus contorta appears to most closely resemble the ancestral taxon from which all other taxa in the subsection are derived. An alternative classification based upon Mahalonobis squared distances (DR) obtained from seed and cone measurements differed from the isoenzyme treatment by placing P. contorta subsp. murrayana in close association with P. virginiana. 相似文献
15.
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17.
L Klein-Hitpass S Y Tsai G L Greene J H Clark M J Tsai B W O''Malley 《Molecular and cellular biology》1989,9(1):43-49
Gene transfer studies have shown that estrogen regulation of specific genes is mediated by estrogen response elements (ERE). We report that binding of the estrogen receptor to the ERE can be detected by a gel retardation (band shift) assay. This binding interaction was highly sequence and receptor specific. Methylation interference analysis showed that the ERE contact sites of estrogen receptor displayed a perfect twofold rotational symmetry. This is compatible with estrogen receptor binding to the ERE as a head-to-head dimer. 相似文献
18.
Márcia R Soares Agda P Facincani Rafael M Ferreira Leandro M Moreira Julio CF de Oliveira Jesus A Ferro Maria IT Ferro Rogério Meneghini Fábio C Gozzo 《Proteome science》2010,8(1):55
Background
Citrus canker is a disease caused by Xantomonas citri subsp.citri (Xac), and has emerged as one of the major threats to the worldwide citrus crop because it affects all commercial citrus varieties, decreases the production and quality of the fruits and can spread rapidly in citrus growing areas. In this work, the first proteome of Xac was analyzed using two methodologies, two-dimensional liquid chromatography (2D LC) and tandem mass spectrometry (MS/MS). 相似文献19.
Haug Marion F Biehlmaier Oliver Mueller Kaspar P Neuhauss Stephan CF 《Frontiers in zoology》2010,7(1):1-7
Background
Mating plugs that males place onto the female genital tract are generally assumed to prevent remating with other males. Mating plugs are usually explained as a consequence of male-male competition in multiply mating species. Here, we investigated whether mating plugs also have collateral effects on female fitness. These effects are negative when plugging reduces female mating rate below an optimum. However, plugging may also be positive when plugging prevents excessive forced mating and keeps mating rate closer to a females' optimum. Here, we studied these consequences in the gonochoristic nematode Caenorhabditis remanei. We employed a new CO2-sedation technique to interrupt matings before or after the production of a plug. We then measured mating rate, attractiveness and offspring number.Results
The presence of a mating plug did not affect mating rate or attractiveness to roving males. Instead, females with mating plugs produced more offspring than females without copulatory plugs.Conclusions
Our experiment suggests that plugging might have evolved under male-male competition but represents a poor protection against competing males in our experiment. Even if plugging does not reduce mating rate, our results indicate that females may benefit from being plugged in a different sense than remating prevention. 相似文献20.
Microsatellite variation in Drosophila melanogaster and Drosophila simulans: a reciprocal test of the ascertainment bias hypothesis 总被引:2,自引:1,他引:1
Interspecific comparisons of microsatellite loci have repeatedly shown that
the loci are longer and more variable in the species from which they are
derived (the focal species) than are homologous loci in other (nonfocal)
species. There is debate as to whether this is due to directional evolution
or to an ascertainment bias during the cloning and locus selection
processes. This study tests these hypotheses by performing a reciprocal
study. Eighteen perfect dinucleotide microsatellite loci identified from a
Drosophila simulans library screen and 18 previously identified in an
identical Drosophila melanogaster library screen were used to survey
natural populations of each species. No difference between focal and
nonfocal species was observed for mean PCR fragment length. However,
heterozygosity and number of alleles were significantly higher in the focal
species than in the nonfocal species. The most common allele in the
Zimbabwe population of both species was sequenced for 31 of the 36 loci.
The length of the longest stretch of perfect repeat units is, on average,
longer in the focal species than in the non-focal species. There is a
positive correlation between the length of the longest stretch of perfect
repeats and heterozygosity. The difference in heterozygosity can thus be
explained by a reduction in the length of the longest stretch of perfect
repeats in the nonfocal species. Furthermore, flanking-sequence length
difference was noted between the two species at 58% of the loci sequenced.
These data do not support the predictions of the directional-evolution
hypothesis; however, consistent with the ascertainment bias hypothesis, the
lower variability in nonfocal species is an artifact of the microsatellite
cloning and isolation process. Our results also suggest that the magnitude
of ascertainment bias for repeat unit length is a function of the
microsatellite size distribution in the genomes of different species.
相似文献