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61.
Cell suspension cultures are useful for a wide range of biochemical and physiological studies, yet their production can be
technically demanding and often unreliable. Here we describe a protocol for producing Arabidopsis cell suspension cultures
that is reliable and easy to use. 相似文献
62.
63.
The incidence of severe neurologic complications from spinal anesthesia in San Diego County in a series of 32,882 cases in a five-year period was 0.012 per cent. Morbidity of 1 in 10,000 cases compares favorably with morbidity associated with general anesthesia. Meticulous technique and abandonment of continuous spinal anesthesia can further reduce the incidence of complications. More emphasis should be placed on the elimination of preexisting neurologic disease as a contraindication to spinal anesthesia. 相似文献
64.
A statistical analysis of the nucleotide sequence variability in 14
published hepatitis B virus (HBV) genomes was carried out using parametric
and nonparametric methods. A parametric statistical model revealed that the
different regions of the genome differed significantly in their
variability. The conclusion was supported by a nonparametric kernel-density
model of the HBV genome. Genes S, C, and P, region X, the precore region,
and the pre-S2/pre-S1 regions were ranked in order of increasing
variability. In many instances, conserved regions of the genome identified
with sequences of known function in HBV biology. However, other
characterized regions (such as pre-S) showed much variability despite the
involvement of their encoded peptides in specific functions. Point
mutations that may result in the formation of stop codons and amino acid
changes may affect the clinical picture of HBV infection and may be
reflected in atypical serological patterns.
相似文献
65.
Sequence, organization, and evolution of the A+T region of Drosophila melanogaster mitochondrial DNA 总被引:2,自引:0,他引:2
The long (4.6-kb) A+T region of Drosophila melanogaster mitochondrial DNA
has been cloned and sequenced. The A+T region is organized in two large
arrays of tandemly repeated DNA sequence elements, with nonrepetitive
intervening and flanking sequences comprising only 22% of its length. The
first repeat array consists of five repeats of 338-373 bp. The second
consists of four intact 464-bp repeats and a fifth partial repeat of 137
bp. Three DNA sequence elements are found to be highly conserved in D.
melanogaster and in several Drosophila species with short A+T regions.
These include a 300-bp DNA sequence element that overlaps the DNA
replication origin and two thymidylate stretches identified on opposite DNA
strands. We conclude that the length heterogeneity observed in the A+T
regulatory region in mitochondrial DNAs from the genus Drosophila results
from the expansion (and contraction) of the number of repeated DNA sequence
elements. We also propose that the 300-bp conserved DNA sequence element,
in conjunction with another primary sequence determinant, perhaps the
adjacent thymidylate stretch, functions in the regulation of mitochondrial
DNA replication.
相似文献
66.
Plantago lanceolata L. and Trifolium repens L. were grown for 16 wk in ambient (360 μmol mol−1 ) and elevated (610 μmol mol−1 ) atmospheric CO2 . Plants were inoculated with the arbuscular mycorrhizal (AM) fungus Glomus mosseae (Nicol. & Gerd.) Gerdemann & Trappe and given a phosphorus supply in the form of bonemeal, which would not be immediately available to the plants. Seven sequential harvests were taken to determine whether the effect of elevated CO2 on mycorrhizal colonization was independent of the effect of CO2 on plant growth. Plant growth analysis showed that both species grew faster in elevated CO2 and that P. lanceolata had increased carbon allocation towards the roots. Elevated CO2 did not affect the percentage of root length colonized (RLC); although total colonized root length was greater, when plant size was taken into account this effect disappeared. This finding was also true for root length colonized by arbuscules. No CO2 effect was found on hyphal density (colonization intensity) in roots. The P content of plants was increased at elevated CO2 , although both shoot and root tissue P concentration were unchanged. This was again as a result of bigger plants at elevated CO2 . Phosphorus inflow was unaffected by CO2 concentrations. It is concluded that there is no direct permanent effect of elevated CO2 on mycorrhizal functioning, as internal mycorrhizal development and the mycorrhizal P uptake mechanism are unaffected. The importance of sequential harvests in experiments is discussed. The direction for future research is highlighted, especially in relation to C storage in the soil. 相似文献
67.
ANNA J. MACDONALD STEPHEN D. SARRE NANCY N. FITZSIMMONS JENNIFER A. MARSHALL GRAVES 《Molecular ecology resources》2007,7(6):1063-1066
Microsatellites were identified from fully sequenced bacterial artificial chromosome clones from the X chromosome and chromosome 2 of the tammar wallaby, Macropus eugenii. A total of 20 microsatellites were genotyped. Seven X chromosome loci and eight loci from chromosome 2 were polymorphic, with between two and 11 alleles per locus. These markers will facilitate genetic mapping in the tammar wallaby and will have wider applications in macropod population genetics. In particular, X chromosome microsatellites will provide a novel evolutionary perspective from which to view macropod mating systems and gene flow. 相似文献
68.
J. D. CHARLWOOD P. M. GRAVES T. F. de C. MARSHALL 《Medical and veterinary entomology》1988,2(2):101-108
Evidence is presented that female Anopheles farauti Laveran released in an alien village dispersed more, in their first oviposition cycle after release, than females released in their village of capture. In a subsidiary experiment transporting the mosquitoes did not affect dispersal; wind speed or direction was not sufficient to account for the phenomenon. It is hypothesized that these permanent-pool breeding mosquitoes make appetitive long-range flights to oviposition sites. Mosquitoes blood-fed before midnight had a shorter oviposition cycle than those fed just before dawn. Nulliparous females, and those with well-defined ovariolar dilatations, predominated in the early evening whereas females that had oviposited recently were largely collected in the middle and later parts of the night. 相似文献
69.
D. S. PORTNOY J. R. MCDOWELL K. THOMPSON J. A. MUSICK J. E. GRAVES 《Molecular ecology resources》2006,6(2):431-433
Five dinucleotide markers were isolated and optimized from a microsatellite‐enriched genomic library obtained from the sandbar shark, Carcharhinus plumbeus. Genotypic distributions of all markers were found to be in conformance with the expectations of Hardy–Weinberg equilibrium with four to 39 alleles present per locus. We amplified these loci in two female sharks and their litters. A maternal allele was recovered at each locus in all progeny indicating reliable amplification. More than two paternal alleles were recovered across both litters indicating genetic polyandry. Additionally, these markers were amplified across 10 carcharhiniform species to examine their utility in other studies. 相似文献
70.
Adoption of young by unrelated adults is expected to be rare in natural populations, yet a high incidence was observed in a population of Herring Gulls on the Isle of May, Scotland. The means whereby rejection was avoided, and the resulting costs and benefits to adopting parents and adopted chicks, are described. 相似文献