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Cecilia Forcato Luz Bavassi Gabriela De Pino Rodrigo Sebastián Fernández Mirta Fabiana Villarreal María Eugenia Pedreira 《PloS one》2016,11(3)
Consolidated memories return to a labile state after the presentation of cues (reminders) associated with acquisition, followed by a period of stabilization (reconsolidation). However not all cues are equally effective in initiating the process, unpredictable cues triggered it, predictable cues do not. We hypothesize that the different effects observed by the different reminder types on memory labilization-reconsolidation depend on a differential neural involvement during reminder presentation. To test it, we developed a declarative task and compared the efficacy of three reminder types in triggering the process in humans (Experiment 1). Finally, we compared the brain activation patterns between the different conditions using functional magnetic resonance imaging (fMRI) (Experiment 2). We confirmed that the unpredictable reminder is the most effective in initiating the labilization-reconsolidation process. Furthermore, only under this condition there was differential left hippocampal activation during its presentation. We suggest that the left hippocampus is detecting the incongruence between actual and past events and allows the memory to be updated. 相似文献
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Mears D Zimliki CL Atwater I Rojas E Glassman M Leighton X Pollard HB Srivastava M 《Cellular physiology and biochemistry》2012,29(5-6):697-704
Insulin secretion from the pancreatic β-cell is controlled by changes in membrane potential and intracellular Ca(2+). The contribution of intracellular Ca(2+) stores to this process is poorly understood. We have previously shown that β-cells of mice lacking one copy of the Annexin 7 gene (Anx7(+/-)) express reduced levels of IP(3) receptors and defects in IP(3)-dependent Ca(2+) signaling. To further elucidate the effect of the Anx7(+/-) mutation on signaling related to intracellular Ca(2+) stores in the β-cell, we measured the effects of Ca(2+) mobilizing agents on electrical activity, intracellular Ca(2+) and insulin secretion in control and mutant β-cells. We found that the muscarinic agonist carbachol and the ryanodine receptor agonists caffeine and 4-chloro-m-cresol had more potent depolarizing effects on Anx7(+/-) β-cells compared to controls. Accordingly, glucose-induced insulin secretion was augmented to a greater extent by caffeine in mutant islets. Surprisingly, ryanodine receptor-mediated Ca(2+) mobilization was not affected by the Anx7(+/-) mutation, suggesting that the mechanism underlying the observed differences in electrical and secretory responsiveness does not involve intracellular Ca(2+) stores. Our results provide evidence that both IP3 receptors and ryanodine receptors play important roles in regulating β-cell membrane potential and insulin secretion, and that the Anx7(+/-) mutation is associated with alterations in the signaling pathways related to these receptors. 相似文献
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Mirta M. Faloci Osvaldo M. Yantorno Horacio A. Marino Jorge A. Arcas Rodolfo J. Ertola 《World journal of microbiology & biotechnology》1990,6(1):32-38
The effects of media composition on growth parameters, total protein production (including delta-endotoxin) and its relation to the biological properties ofBacillus thuringiensis var.israelensis was investigated. The replacement of glucose by glycerol as the carbon source yielded higher concentrations of delta-endotoxin. This increase in toxicity was associated with increased amounts of the 130 kDa polypeptide fraction. The biocide activity was not related to haemolytic activity. specific growth rate nor spore count.
Résumé On a étudié les effets de la composition du milieu sur les paramètres de croissance, sur la production de protéines totales, ce qui inclut la delta-endotoxine, ainsi que sur sa relation avec les propriétés biologiques deBacillus thuringiensis var.israelensis. Le remplacement du glucose par le glycerol comme source de carbone resulte en des concentrations plus élevées de delta-endotoxine. Cet accroissement en toxicité est associé avec une quantité croissante de la fraction polypeptidique de 130 kDa. L'activité biocide n'est liée ni à l'activité hémolytique, ni à la vitesse specifique de croissance ni à l'énumération des spores.相似文献
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Sabatté J Maggini J Nahmod K Amaral MM Martínez D Salamone G Ceballos A Giordano M Vermeulen M Geffner J 《Cytokine & growth factor reviews》2007,18(1-2):5-17
Dendritic cells (DCs) are the only antigen-presenting cell capable of activating na?ve T lymphocytes, and hence they play a crucial role in the induction of adaptive immunity. Immature DCs sample and process antigens, and efficiently sense a large variety of signals from the surrounding environment. Upon activation, they become capable to activate na?ve T cells and to direct the differentiation and polarization of effector T lymphocytes. It is becoming increasingly clear that different signals are able to determine distinct programs of DC differentiation and different forms of immunity and tolerance. In the past few years many advances have been made in addressing the action exerted by pathogen-associated molecular patterns (PAMPs), cytokines, chemokines, and other less characterized stress molecules on the activity of DCs. In this review we focus on the multiplicity of innate signals able to modulate the functional profile of DCs. 相似文献
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The reduction of photosynthetic rates with tree age has been proposed as a major driver of the productivity declination along
ontogeny. It is not clear, however, how environmental humidity affects stomatal conductance and biochemical potential of photosynthesis
in trees belonging to different age-classes. We assessed daily cycles of gas exchange on leaves of juvenile and mature individuals
of the tropical high-elevation tree Alnus jorullensis Kunth (Betulaceae), at two sites with contrasting precipitation in the Venezuelan Andes. Photosynthesis and stomatal conductance
were higher in juvenile trees during the morning and at noon in the mesic site, and were in general similar between age-classes
in the wet site. Under light-saturating conditions, the net photosynthetic rate was similar between the age-classes at the
wet site and higher for juvenile trees at the mesic site, whereas stomatal conductance did not differ between age-classes
and was higher at the wet site. Daily cycles of gas exchange and a type II regression model between photosynthesis and intercellular
CO2 concentration indicated that the better performance of juvenile trees at the mesic site was due to lower non-stomatal limitations.
These results support the proposal that non-stomatal limitations—rather than stomatal ones—are involved in the decay of photosynthesis
in mature trees, and suggest that such limitations may be evident only under drier conditions. 相似文献
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Question: Does the facilitative effect of cushion plants increase with elevation as a result of increases in environmental harshness? Does this hypothesis apply in the Sino‐Himalayan Mountains? Location: Lakaka Pass on the Baima Snow Mountains (28°20′N, 99°05′E), SW China. Methods: We evaluated the spatial association of several plant species with the cushion plant Arenaria polytrichoides (Caryophyllaceae) at two elevations (4500 m and 4700 m) in the study site and monitored temperature, moisture and nutritional status of soil beneath and outside the cushions. Results: While 14 species grow more frequently associated with the cushions at the higher elevation, at the lower site only three species were positively associated with cushions. Eleven of the species that occurred at both elevations changed their spatial association from neutral or negative with cushions at the lower site to positive at the higher elevation site. Substrate temperatures were rather similar between the cushions and areas of bare ground. Cushions maintained higher moisture than areas of bare ground at both elevations. Soils beneath cushions contained significantly more available nitrogen and potassium compared to open areas at the higher elevation. Conclusions: Our results show that facilitation by A. polytrichoides cushions increases with elevation in the Sino‐Himalayan region. This facilitation effect of A. polytrichoides cushions is probably due to the improved nutrient availability provided by cushion plants in the higher elevation, and these conditions probably permit increased plant recruitment, growth and survival. 相似文献
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