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991.
A comparative study of glucose-6-phosphatase, alcaline RNase, ATPase, inosine diphosphatase and 5'-nucleotidase activities in isolated rat liver and hepatoma-27 nuclei and nuclear envelopes was performed. The tumor nuclear membranes were shown to be free from G-6-Pase activity in contrast to the liver nuclear membranes. The nuclear RNase activity was strongly inhibited in the hepatoma and could be unmasked in the presence of 3-10(-4) M pCMB. Hepatoma nuclear and nuclear envelopes ATP-ase activity was found to be moderately decreased as compared to those of the normal tissue. The values of inosine diphosphatase activity in hepatoma were similar to those in liver. The role of the nuclear envelope in nuclear-cytoplasmic interactions as well as nuclear location of G-6-Pase are discussed. 相似文献
992.
993.
994.
The epidemiology of Helicobacter pylori infection in Europe and the impact of lifestyle on its natural evolution toward stomach cancer after infection: A systematic review
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995.
Koen Bavelaar Ilpo Mutikainen Patricia Marquès-Gallego Gerard A. van Albada Jan Reedijk 《Inorganica chimica acta》2011,366(1):81-84
A new dinuclear coordination compound with the ligand 5,6,7-trimethyl[1,2,4]triazolo[1,5-a]pyrimidine (abbreviated as tmtp) is described, together with its 3D crystal structures and spectroscopic properties. The compound shows a high cytostatic activity in ovarian cancer cell lines.The solid state structure of the compound is dinuclear based, in which the ligand tmtp uses two nitrogens (N3 and N4) to chelate to two different Ag(I) ions. The Ag-Ag distance is relatively short (3.109 Å), but is considered as too long for M-M bonding. The Ag(I) coordination is completed by weakly coordinated, asymmetric bidentate nitrate anions (Ag-O = 2.481-2.819 Å). 相似文献
996.
Sita M. ter Haar Wiebke Kaemper Koen Stam Clara C. Levelt Carel ten Cate 《Proceedings. Biological sciences / The Royal Society》2014,281(1796)
Vocal acquisition in songbirds and humans shows many similarities, one of which is that both involve a combination of experience and perceptual predispositions. Among languages some speech sounds are shared, while others are not. This could reflect a predisposition in young infants for learning some speech sounds over others, which combines with exposure-based learning. Similarly, in songbirds, some sounds are common across populations, while others are more specific to populations or individuals. We examine whether this is also due to perceptual preferences for certain within-species element types in naive juvenile male birds, and how such preferences interact with exposure to guide subsequent song learning. We show that young zebra finches lacking previous song exposure perceptually prefer songs with more common zebra finch song element types over songs with less common elements. Next, we demonstrate that after subsequent tutoring, birds prefer tutor songs regardless of whether these contain more common or less common elements. In adulthood, birds tutored with more common elements showed a higher song similarity to their tutor song, indicating that the early bias influenced song learning. Our findings help to understand the maintenance of similarities and the presence of differences among birds'' songs, their dialects and human languages. 相似文献
997.
Koen A. J. Pelsma Niels A. G. M. van Helmond Wytze K. Lenstra Thomas Röckmann Mike S. M. Jetten Caroline P. Slomp Cornelia U. Welte 《Environmental microbiology》2023,25(12):3104-3115
Anthropogenic activities are influencing aquatic environments through increased chemical pollution and thus are greatly affecting the biogeochemical cycling of elements. This has increased greenhouse gas emissions, particularly methane, from lakes, wetlands, and canals. Most of the methane produced in anoxic sediments is converted into carbon dioxide by methanotrophs before it reaches the atmosphere. Anaerobic oxidation of methane requires an electron acceptor such as sulphate, nitrate, or metal oxides. Here, we explore the anaerobic methanotrophy in sediments of three urban canals in Amsterdam, covering a gradient from freshwater to brackish conditions. Biogeochemical analysis showed the presence of a shallow sulphate–methane transition zone in sediments of the most brackish canal, suggesting that sulphate could be a relevant electron acceptor for anaerobic methanotrophy in this setting. However, sediment incubations amended with sulphate or iron oxides (ferrihydrite) did not lead to detectable rates of methanotrophy. Despite the presence of known nitrate-dependent anaerobic methanotrophs (Methanoperedenaceae), no nitrate-driven methanotrophy was observed in any of the investigated sediments either. Interestingly, graphene oxide stimulated anaerobic methanotrophy in incubations of brackish canal sediment, possibly catalysed by anaerobic methanotrophs of the ANME-2a/b clade. We propose that natural organic matter serving as electron acceptor drives anaerobic methanotrophy in brackish sediments. 相似文献
998.
Hamid Aslami Charlotte J.P. Beurskens Friso M. de Beer Maria T. Kuipers Joris J.T.H. Roelofs Maria A. Hegeman Koen F. Van der Sluijs Marcus J. Schultz Nicole P. Juffermans 《Cytokine》2013,61(2):614-621
Organ failure is associated with increased mortality and morbidity in patients with systemic inflammatory response syndrome. Previously, we showed that a short course of infusion of a hydrogen sulfide (H2S) donor reduced metabolism with concurrent reduction of lung injury. Here, we hypothesize that prolonged H2S infusion is more protective than a short course in endotoxemia with organ failure. Also, as H2S has both pro- and anti-inflammatory effects, we explored the effect of H2S on interleukin production.Endotoxemia was induced by an intravenous bolus injection of LPS (7.5 mg/kg) in mechanically ventilated rats. H2S donor NaHS (2 mg/kg) or vehicle (saline) was infused and organ injury was determined after either 4 or 8 h. A short course of H2S infusion was associated with reduction of lung and kidney injury. Prolonged infusion did not enhance protection. Systemically, infusion of H2S increased both the pro-inflammatory response during endotoxemia, as demonstrated by increased TNF-α levels, as well as the anti-inflammatory response, as demonstrated by increased IL-10 levels. In LPS-stimulated whole blood of healthy volunteers, co-incubation with H2S had solely anti-inflammatory effects, resulting in decreased TNF-α levels and increased IL-10 levels. Co-incubation with a neutralizing IL-10 antibody partly abrogated the decrease in TNF-α levels. In conclusion, a short course of H2S infusion reduced organ injury during endotoxemia, at least in part via upregulation of IL-10. 相似文献
999.
Terrestrial soil diatom assemblages from different vegetation types in Zackenberg (Northeast Greenland) 总被引:1,自引:0,他引:1
A total of 81 taxa were observed from 30 soil samples taken from 5 different vegetation types in Northeast Greenland. Most
of the dominant diatoms are well-known cosmopolitan aerophilic taxa; only Caloneis aerophila and Pinnularia lagerstedtii are less widespread species. The valve lengths of P. borealis and Hantzschia amphioxys are correlated with the moisture content of the soils. Average cell number/g dry weight of soil amounts to 1,120,000 ± 740,000.
In a TWINSPAN classification, the soils of the different vegetation types are separated, with the exception of the Vaccinium soils, which are grouped partly with the Cassiope samples and partly with the Salix soils. In a CCA ordination diagram, the Navicula atomus–Fragilaria elliptica assemblage shows a positive correlation with organic content and pH and a negative one with permafrost depth. The Pinnularia divergentissima var. martinii–P. obscura assemblage is positively correlated with moisture. The Pinnularia lagerstedtii–Caloneis aerophila assemblage is positively correlated with permafrost depth and negatively with pH and moisture.
Accepted: 27 November 1999 相似文献