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81.
82.
Evolutionary dynamics of tandem repeats in the mitochondrial DNA control region of the minnow Cyprinella spiloptera 总被引:3,自引:0,他引:3
Length variation due to tandem repeats is now recognized as a common
feature of animal mitochondrial DNA; however, the evolutionary dynamics of
repeated sequences are not well understood. Using phylogenetic analysis,
predictions of three models of repeat evolution were tested for arrays of
260-bp repeats in the cyprinid fish Cyprinella spiloptera. Variation at
different nucleotide positions in individual repeats supported different
models of repeat evolution. One set of characters included several
nucleotide variants found in all copies from a limited number of
individuals, while the other set included an 8- bp deletion found in a
limited number of copies in all individuals. The deletion and an associated
nucleotide change appear to be the result of a deterministic, rather than
stochastic, mutation process. Parallel origins of repeat arrays in
different mitochondrial lineages, possibly coupled with a homogenization
mechanism, best explain the distribution of nucleotide variation.
相似文献
83.
Conserved sequence motifs, alignment, and secondary structure for the third domain of animal 12S rRNA 总被引:17,自引:3,他引:14
Hickson RE; Simon C; Cooper A; Spicer GS; Sullivan J; Penny D 《Molecular biology and evolution》1996,13(1):150-169
Secondary structure models are an important step for aligning sequences,
understanding probabilities of nucleotide substitutions, and evaluating the
reliability of phylogenetic reconstructions. A set of conserved sequence
motifs is derived from comparative sequence analysis of 184 invertebrate
and vertebrate taxa (including many taxa from the same genera, families,
and orders) with reference to a secondary structure model for domain III of
animal mitochondrial small subunit (12S) ribosomal RNA. A template is
presented to assist with secondary structure drawing. Our model is similar
to previous models but is more specific to mitochondrial DNA, fitting both
invertebrate and vertebrate groups, including taxa with markedly different
nucleotide compositions. The second half of the domain III sequence can be
difficult to align precisely, even when secondary structure information is
considered. This is especially true for comparisons of anciently diverged
taxa, but well-conserved motifs assist in determining biologically
meaningful alignments. Patterns of conservation and variability in both
paired and unpaired regions make differential phylogenetic weighting in
terms of "stems" and "loops" unsatisfactory. We emphasize looking carefully
at the sequence data before and during analyses, and advocate the use of
conserved motifs and other secondary structure information for assessing
sequencing fidelity.
相似文献
84.
85.
John Haskew Veronica Kenyi Juma William Rebecca Alum Anu Puri Yehia Mostafa Robert Davis 《PloS one》2015,10(8)
Background
Use of mobile information technology may aid collection of real-time, standardised data to inform and improve decision-making for polio programming and response. We utilised Android-based smartphones to collect data electronically from more than 8,000 households during a national round of polio immunisation in South Sudan. The results of the household surveys are presented here, together with discussion of the application of mobile information technology for polio campaign planning, implementation and evaluation in a real-time setting.Methods
Electronic questionnaires were programmed onto Android-based smartphones for mapping, supervision and survey activities during a national round of polio immunisation. National census data were used to determine the sampling frame for each activity and select the payam (district). Individual supervisors, in consultation with the local district health team, selected villages and households within each payam. Data visualisation tools were utilised for analysis and reporting.Results
Implementation of mobile information technology and local management was feasible during a national round of polio immunisation in South Sudan. Red Cross visits during the polio campaign were equitable according to household wealth index and households who received a Red Cross visit had significantly higher odds of being aware of the polio campaign than those who did not. Nearly 95% of children under five were reported to have received polio immunisation (according to maternal recall) during the immunisation round, which varied by state, county and payam. A total of 11 payams surveyed were identified with less than 90% reported immunisation coverage and the least poor households had significantly higher odds of being vaccinated than the most poor. More than 95% of households were aware of the immunisation round and households had significantly higher odds of being vaccinated if they had prior awareness of the campaign taking place.Conclusion
Pre-campaign community education and household awareness of polio is important to increase campaign participation and subsequent immunisation coverage in South Sudan. More emphasis should be placed on ensuring immunisation is equitable according to geographic area and household socio-economic index in future rounds. We demonstrate the utility of mobile information technology for household mapping, supervision and survey activities during a national round of polio immunisation and encourage future studies to compare the effectiveness of electronic data collection and its application in polio planning and programming. 相似文献86.
87.
SAMILA SIAVOSHIAN HERV M BLOTTIRE ERIC LE FOLL BERTRAND KAEFFER CHRISTINE CHERBUT JEAN-PAUL GALMICHE 《Cell biology international》1997,21(5):281-287
The aim of this study was to compare the effects of acetate, propionate, butyrate, iso-butyrate, valerate, iso-valerate and caproate on cell growth and on the activities of alkaline phosphatase (AP) and dipeptidyl aminopeptidase IV (DPP IV) by three human colonic adenocarcinoma cell lines. In addition to butyrate, propionate and valerate inhibited cell proliferation of the three cell lines. The other SCFAs did not influence cell proliferation. AP and DPP IV activities were strongly stimulated by butyrate on two of the three cell lines. On HT-29, AP was strongly stimulated, however DPPIV expression remained undetectable. Propionate and valerate exhibited a weaker stimulation, the other SCFAs being ineffective. The effect of SCFAs on cell proliferation and differentiation clearly depends on the number of carbons and on the configuration of the basic structure of the molecule. 相似文献
88.
Ixodes (Pholeoixodes) hexagonus, an efficient vector of Borrelia burgdorferi in the laboratory 总被引:2,自引:0,他引:2
LISE GERN LINA N. TOUTOUNGI CHANG MIN HU RE AESCHLIMANN 《Medical and veterinary entomology》1991,5(4):431-435
Borrelia burgdorferi Johnson et al. was first isolated from the midgut of Ixodes dammini Spielman et al. in the U.S.A. and from the midgut of I.ricinus (L.) in Europe. I.ricinus was considered to be the only tick vector of this borrelia, in Europe, until I.hexagonus Leach, the hedgehog tick, was found to harbour spirochaetes. This paper reports an evaluation of the vector competence of I.hexagonus for the spirochaete B.burgdorferi. Transovarial and trans-stadial survival were demonstrated and the spirochaete was transmitted to laboratory mice via the bites of trans-stadially infected I.hexagonus females. 相似文献
89.
LESLIE G. UNDERHILL PETER A. BARTLETT LUKAS BAUMANN ROBERT J.M. CRAWFORD BRUCE M. DYER RE GILDENHUYS DEON C. NEL TERENCE B. OATLEY MEREDITH THORNTON LEISHA UPFOLD ANTHONY J. WILLIAMS PHILIP A. WHITTINGTON ANTON C. WOLFAARDT 《Ibis》1999,141(1):29-37
The bulk ore carrier Apollo Sea sank near Dassen Island, South Africa, on 20 June 1994 during a period of winter storms. Approximately 10 000 African (Jackass) Penguins Spheniscus demersus were oiled, collected and transported to the SANCCOB rescue centre; 5213 were released after cleaning, 4076 with flipper bands. We believe that most of the penguins oiled during this incident reached an island or the mainland alive, and that there was no mass mortality in the wild at the time of the oil spill. Birds from all parts of the breeding range were oiled, but most were from Robben and Dassen Islands. The overwhelming majority of released birds made the transition from the rescue centre to the wild successfully; 2652 had been resighted at breeding colonies within two years of their release; the cumulative number of birds was increasing steadily and an asymptote had not been reached by August 1996. There was a wide dispersal of released penguins, with recoveries and resightings over 1800 km of coastline between Algoa Bay and Walvis Bay. 相似文献
90.