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91.
92.
Chloe?KB?Mortimer Tansy?M?Peters Saheer?E?Gharbia Julie?MJ?Logan Catherine?ArnoldEmail author 《BMC microbiology》2004,4(1):31
Background
The fliC and fljB genes in Salmonella code for the phase 1 (H1) and phase 2 (H2) flagellin respectively, the rfb cluster encodes the majority of enzymes for polysaccharide (O) antigen biosynthesis, together they determine the antigenic profile by which Salmonella are identified. Sequencing and characterisation of fliC was performed in the development of a molecular serotyping technique. 相似文献93.
Molecular phylogenetics of Stenodermatini bat genera: congruence of data from nuclear and mitochondrial DNA 总被引:2,自引:1,他引:1
Van den Bussche RA; Baker RJ; Wichman HA; Hamilton MJ 《Molecular biology and evolution》1993,10(5):944-959
Within the tribe Stenodermatini the systematics of the complex of species
allied with the genus Artibeus has generated several alternative
phylogenetic hypotheses. The most recent treatment recognized four genera
(Artibeus, Dermanura, Enchisthenes, and Koopmania) and suggested that the
most recent common ancestor of these four genera would include the common
ancestor of all other currently recognized Stenodermatini genera except
Sturnira. To test this hypothesis, we examined an EcoRI-defined nuclear
satellite DNA repeat and 402 bp of DNA sequence variation from the
mitochondrial cytochrome b gene. Phylogenetic conclusions based on Southern
blot analyses, in situ hybridization, and mitochondrial DNA sequence data
indicate that Enchisthenes is not closely related to Dermanura, Artibeus,
or Koopmania and that Dermanura, Artibeus, and Koopmania shared a common
ancestor after diverging from the remainder of the Stenodermatini. If our
conclusions are correct, then justification for recognizing Dermanura and
Koopmania as generically distinct from Artibeus must be based on the
magnitude of difference that distinguishes each rather than on the
conclusion that to place them as congeneric with Artibeus creates a
paraphyletic taxon.
相似文献
94.
Multidimensional heteronuclear NMR studies have been applied to the
resonance assignment and conformational analysis of 13C-enriched
Neu5Acalpha2-3Galbeta1-4Glc. It is demonstrated that three-dimensional
ROESY-HSQC experiments provide through-space distance restraints which
cannot be observed with conventional homonuclear 1H techniques due to
resonance overlap. In particular, connectivities demonstrating the
existence of the "anti" conformation about the Galbeta1-4Glc glycosidic
linkage are unambiguously observed. It is shown that 13C isotopic
enrichment of the trisaccharide at a level >95% enables straightforward
measurement of trans-glycosidic 1H-13C and 13C-13C coupling constants and a
Karplus-type relation is derived for the latter. In total 15 conformational
restraints were obtained for the trisaccharide in aqueous solution, all of
which were in excellent agreement with theoretical parameters computed from
a 5 ns molecular dynamics simulation of the glycan.
相似文献
95.
Sanchez D; Ganfornina MD; Gutierrez G; Bastiani MJ 《Molecular biology and evolution》1998,15(4):415-426
Arthropodan hemocyanins, prophenoloxidases (PPOs), and insect hexamerins
form a superfamily of hemolymph proteins that we propose to call the AHPH
superfamily. The evolutionary and functional relationships of these
proteins are illuminated by a new embryonic hemolymph protein (EHP) that is
expressed during early stages of development in the grasshopper embryo. EHP
is a 78-kDa soluble protein present initially in the yolk sac content, and
later in the embryonic hemolymph. Protein purification and peptide
sequencing were used to identify an embryonic cDNA clone coding for EHP. In
situ hybridization identifies hemocytes as EHP-expressing cells. As deduced
from the cDNA clone, EHP is a secreted protein with two potential
glycosylation sites. Sequence analysis defines EHP as a member of the AHPH
superfamily. Phylogenetic analyses with all the currently available AHPH
proteins, including EHP, were performed to ascertain the evolutionary
history of this protein superfamily. We used both the entire protein
sequence and each of the three domains present in the AHPH proteins. The
phylogenies inferred for each of the domains suggest a mosaic evolution of
these protein modules. Phylogenetic and multivariate analyses consistently
group EHP with crustacean hemocyanins and, less closely, with insect
hexamerins, relative to cheliceratan hemocyanins and PPOs. The grasshopper
protein rigorously preserves the residues involved in oxygen binding,
oligomerization, and allosteric regulation of the oxygen transport
proteins. Although insects were thought not to have hemocyanins, we propose
that EHP functions as an oxygen transport or storage protein during
embryonic development.
相似文献
96.
97.
Evolution of alcohol dehydrogenase genes in peonies (Paeonia): phylogenetic relationships of putative nonhybrid species 总被引:11,自引:0,他引:11
Alcohol dehydrogenase genes were amplified by PCR, cloned, and sequenced
from 11 putative nonhybrid species of the angiosperm genus Paeonia.
Sequences of five exons and six intron regions of the Adh gene were used to
reconstruct the phylogeny of these species. Two paralogous genes, Adh1A,
and Adh2, were found; an additional gene, Adh1B, is also present in section
Moutan. Phylogenetic analyses of exon sequences of the Adh genes of Paeonia
and a variety of other angiosperms imply that duplication of Adh1 and Adh2
occurred prior to the divergence of Paeonia species and was followed by a
duplication resulting in Adh1A and Adh1B. Concerted evolution appears to be
absent between these paralogous loci. Phylogenetic analysis of only the
Paeonia Adh exon sequences, positioning the root of the tree between the
paralogous genes Adh1 and Adh2, suggests that the first evolutionary split
within the genus occurred between the shrubby section Moutan and the other
two herbaceous sections Oneapia and Paeonia. Restriction of Adh1B genes to
section Moutan may have resulted from deletion of Adh1B from the common
ancestor of sections Oneapia and Paeonia. A relative-rate test was designed
to compare rates of molecular change among lineages based on the divergence
of paralogous genes, and the results indicate a slower rate of evolution
within the shrubby section Moutan than in section Oneapia. This may be
responsible for the relatively long branch length of section Oneapia and
the short branch length between section Moutan and the other two sections
found on the Adh, ITS (nrDNA), and matK (cpDNA) phylogenies of the genus.
Adh1 and Adh2 intron sequences cannot be aligned, and we therefore carried
out separate analyses of Adh1A and Adh2 genes using exon and intron
sequences together. The Templeton test suggested that there is not
significant incongruence among Adh1A, ITS, and matK data sets, but that
these three data sets conflict significantly with Adh2 sequence data. A
combined analysis of Adh1A, ITS, and matK sequences produced a tree that is
better resolved than that of any individual gene, and congruent with
morphology and the results of artificial hybridization. It is therefore
considered to be the current best estimate of the species phylogeny.
Paraphyly of section Paeonia in the Adh2 gene tree may be caused by longer
coalescence times and random sorting of ancestral alleles.
相似文献
98.
A. Laperche Y. Aigu M. Jubault M. Ollier S. Guichard P. Glory SE. Strelkov A. Gravot MJ. Manzanares-Dauleux 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2017,130(4):669-684
Key message
Nitrogen levels can modulate the effectiveness of clubroot resistance in an isolate- and host-specific manner. While the same QTL were detected under high and low nitrogen, their effects were altered.Abstract
Clubroot, caused by Plasmodiophora brassicae, is one of the most damaging diseases of oilseed rape and is known to be affected by nitrogen fertilization. However, the genetic factors involved in clubroot resistance have not been characterized under nitrogen-limiting conditions. This study aimed to assess the variability of clubroot resistance under different nitrogen levels and to characterize the impact of nitrogen supply on genetic resistance factors. Linkage analyses and a genome-wide association study were conducted to detect QTL for clubroot resistance and evaluate their sensitivity to nitrogen. The clubroot response of a set of 92 diverse oilseed rape accessions and 108 lines derived from a cross between ‘Darmor-bzh’ (resistant) and ‘Yudal’ (susceptible) was studied in the greenhouse under high- and low-nitrogen conditions, following inoculation with the P. brassicae isolates eH and K92-16. Resistance to each isolate was controlled by a major QTL and a few small-effects QTL. While the same QTL were detected under both high and low nitrogen, their effects were altered. Clubroot resistance to isolate eH, but not K92-16, was greater under a low-N supply versus a high-N supply. New sources of resistance were found among the oilseed rape accessions under both low and high-N conditions. The results are discussed relative to the literature and from a crop improvement perspective.99.
Mirjam MJ Jacobs Ronald G van den Berg Vivianne GAA Vleeshouwers Marcel Visser Rolf Mank Mariëlle Sengers Roel Hoekstra Ben Vosman 《BMC evolutionary biology》2008,8(1):145
Background
The secondary genepool of our modern cultivated potato (Solanum tuberosum L.) consists of a large number of tuber-bearing wild Solanum species under Solanum section Petota. One of the major taxonomic problems in section Petota is that the series classification (as put forward by Hawkes) is problematic and the boundaries of some series are unclear. In addition, the classification has received only partial cladistic support in all molecular studies carried out to date. 相似文献100.
目的: 由于传统呼吸调控环路忽略了对血液循环的决定性作用,肺(静脉)血管容量相关研究甚少,亟需建立肺血管容量测量方法。方法: 选择正常志愿者完成CT全肺扫描,图像数据经过计算机软件分析处理,从肺尖到肺底以40~50层进行肺野手工切划,相邻层间由计算机自动模拟连接,在去除干扰后进行全肺血管(≥0.6 mm)高精度三维立体成像技术处理,进而计算全肺和肺血管容积。结果: 12例正常志愿者从肺尖到肺底CT扫描图片层数为530±98(431~841)张。全肺和肺血管的总容积是3705±857(2398~5383)ml ,肺血管血液总的容积是125±32(94~201)ml。按肺静脉系统血管容量约为全肺血管血液容量一半计算,应该是63±16(47~100)ml。结论: 肺CT扫描数据分析三维立体成像建立肺血管容量无创测量方法精确可行。 相似文献