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941.
942.
We investigated collective movements in a flock of domestic geese (Anser domesticus) to test the consistency of group orders and the influence of individual traits and social relationships on movement patterns.
The subjects were 20 juvenile females kept in an herbaceous enclosure. Two observers continuously videotaped their movements.
Although the positions of individuals might change during moves, the geese tended to hold predictable positions in different
movements. We found that geese more reactive to unexpected noises more often held front positions. Moreover, the higher the
associativity of a bird as measured by number of neighbors at rest, the more frequent the bird acted as first mover. The analysis
did not evidence any influence of dominance status on the positions of geese during progression. In contrast, geese linked
by close bonds clustered during progression. The structuring influence of social bonds in collective movements might be a
general feature of animals gifted with individual recognition abilities. 相似文献
943.
944.
Elodie Pradines Damien Loubet Sophie Mouillet-Richard Philippe Manivet† Jean-Marie Launay†‡ Odile Kellermann Benoît Schneider 《Journal of neurochemistry》2009,110(3):912-923
Despite considerable efforts to unravel the role of cellular prion protein (PrPC ) in neuronal functions, the mechanisms by which PrPC takes part in the homeostasis of a defined neuronal phenotype remain poorly characterized. By taking advantage of a neuroectodermal cell line (1C11) endowed with the capacity to differentiate into serotonergic (1C115-HT ) or noradrenergic (1C11NE ) neurons, we assessed the contribution of PrPC to bioaminergic cell functions. We established that in 1C11-derived neuronal cells antibody-mediated PrPC ligation triggered tumor necrosis factor (TNF)-α release, through recruitement of the metalloproteinase TNF-α converting enzyme (TACE). TNF-α shed in response to PrPC acts as a second message signal, eliciting serotonin (5-HT) or norepinephrine (NE) degradation in 1C115-HT or 1C11NE cells, respectively. Our data thus introduced TNF-α as a PrPC -dependent modulator of neuronal metabolism. Of note, we previously reported on a control of neurotransmitter catabolism by 5-HT2B or α1D autoreceptors in 1C11 bioaminergic neurons, via the same TACE/TNF-α pathway (Ann. N Y Acad. Sci. 1091, 123). Here, we show that combined stimulation of PrPC and these two bioaminergic receptors add their effects on neurotransmitter degradation. Overall, these observations unveil a novel contribution of PrPC to the control of neuronal functions and may have implications regarding dysfunction of the bioaminergic systems in prion diseases. 相似文献
945.
The possible origins of the 12 superfamilies of the Spirurida are considered, based on comparative morphology, host and geographic distributions. The available evidence suggests a complex origin of these nematodes, some families being derived from the Seuratoidea, and others from the Cosmocercoidea (Ascaridida). The spirurid radiation is an old one and seems to have occurred primarily in the Secondary or early Tertiary eras. Since then, expansion has occurred with host capture as a prominent mechanism. The Dracunculoidea Procamallanidae and Camallanidae are probably derived from the Chitwoodchabaudiidae and the Rictularioidea from the Schneidernematidae. The Seuratidae may have given rise to the Gnathostomatoidea, the Physalopteroidea, the Thelazioidea, the Habronematoidea, the Spiruroidea and the Acuarioidea. The filarioid nematodes appear to have several origins with the Diplotriaenoidea derived from the Spiruroidea, while constituents of the Aproctoidea derived from the Cystidicolinae, the Seuratoidea and the Spiruroidea. The Filarioidea are thought to have arisen from the Spiruroidea and the Thelazioidea. The evolution of tissue parasitism as a secondary phenomenon is considered in various groups. 相似文献
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949.
Armelle Baeza-Squiban Emmanuelle Boisvieux-Ulrich Catherine Guilianelli Odile Houcine Gérard Geraud Christiane Guennou Francelyne Marano 《In vitro cellular & developmental biology. Animal》1994,30(1):56-67
Summary The differentiation of tracheal epithelial cells in primary culture was investigated according to the nature of the extracellular
matrix used. Cultures obtained by the explant technique were realized on a type I collagen substratum either as a thin, dried
coating or as a thick, hydrated gel supplemented with culture medium and serum. These two types of substratum induced distinct
cell morphology and cytokeratin expression in the explant derived cells. Where cells are less proliferating (from Day 7 to
10 of culture), differentiation was evaluated by morphologic ultrastructural observations, immunocytochemical detection of
cytokeratins, and determination of cytokeratin pattern by biochemical analysis.
The epithelium obtained on gel was multilayered, with small, round basal cells under large, flattened upper cells. The determination
of the keratin pattern expressed by cells grown on gel revealed an expression of keratin 13, already considered as a specific
marker of squamous metaplasia, that diminished with retinoic acid treatment. Present results demonstrated by confocal microscopy
that K13-positive cells were large upper cells with a dense keratin network, whereas lower cells were positively stained with
a specific monoclonal antibody to basal cells (KB37). Moreover, keratin neosynthesis analysis pointed out a higher expression
of K6, a marker of hyperproliferation, on gel than on coating. All these data suggest a differentiation of rabbit tracheal
epithelial cells grown on gel toward squamous metaplasia. By contrast, the epithelium observed on coating is nearly a monolayer
of very large and spread out cells. No K13-positive cells were observed, but an increase in the synthesis of simple epithelium
marker (K18) was detected. These two substrata, similar in composition and different in structure, induce separate differentiation
and appear as good tools to explore the mechanisms of differentiation of epithelial tracheal cells. 相似文献
950.
Mustapha Amyere Virginie Aerts Pascal Brouillard Brendan?A.S. McIntyre Fran?ois?P. Duhoux Michel Wassef Odile Enjolras John?B. Mulliken Olivier Devuyst Hélène Antoine-Poirel Laurence?M. Boon Miikka Vikkula 《American journal of human genetics》2013,92(2):188-196
Inherited vascular malformations are commonly autosomal dominantly inherited with high, but incomplete, penetrance; they often present as multiple lesions. We hypothesized that Knudson’s two-hit model could explain this multifocality and partial penetrance. We performed a systematic analysis of inherited glomuvenous malformations (GVMs) by using multiple approaches, including a sensitive allele-specific pairwise SNP-chip method. Overall, we identified 16 somatic mutations, most of which were not intragenic but were cases of acquired uniparental isodisomy (aUPID) involving chromosome 1p. The breakpoint of each aUPID is located in an A- and T-rich, high-DNA-flexibility region (1p13.1–1p12). This region corresponds to a possible new fragile site. Occurrences of these mutations render the inherited glomulin variant in 1p22.1 homozygous in the affected tissues without loss of genetic material. This finding demonstrates that a double hit is needed to trigger formation of a GVM. It also suggests that somatic UPID, only detectable by sensitive pairwise analysis in heterogeneous tissues, might be a common phenomenon in human cells. Thus, aUPID might play a role in the pathogenesis of various nonmalignant disorders and might explain local impaired function and/or clinical variability. Furthermore, these data suggest that pairwise analysis of blood and tissue, even on heterogeneous tissue, can be used for localizing double-hit mutations in disease-causing genes. 相似文献