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991.
Constructing an in vitro cornea from cultures of the three specific corneal cell types 总被引:7,自引:0,他引:7
Adelheid I. Schneider Katharina Maier-Reif Thomas Graeve 《In vitro cellular & developmental biology. Animal》1999,35(9):515-526
Summary This paper presents a reliable method for establishing pure cultures of the three types of corneal cells. This is believed
to be the first time, corneal cells have been cultured from fetal pig corneas. Cell growth studies were performed in different
media. Subcultures of the three corneal cell types were passaged until the 30th generation without their showing signs of
senescence. For engineering an in vitro cornea, corneal epithelial cells were cultured over corneal stromal cells in an artificial
biomatrix of collagen with an underlying layer of corneal endothelial cells. The morphology, histology, and differentiation
of the in vitro cornea were investigated to determine the degree of comparability to the cornea in vivo. The in vitro construct
displayed signs of transition to an organotypic phenotype of which the most prominent was the formation of two basement membranes. 相似文献
992.
993.
Leonardo F. Lemos Rocha Katharina Peters Jacob Biboy Jamie S. Depelteau Ariane Briegel Waldemar Vollmer Melanie Blokesch 《PLoS genetics》2022,18(3)
Despite extensive studies on the curve-shaped bacterium Vibrio cholerae, the causative agent of the diarrheal disease cholera, its virulence-associated regulatory two-component signal transduction system VarS/VarA is not well understood. This pathway, which mainly signals through the downstream protein CsrA, is highly conserved among gamma-proteobacteria, indicating there is likely a broader function of this system beyond virulence regulation. In this study, we investigated the VarA-CsrA signaling pathway and discovered a previously unrecognized link to the shape of the bacterium. We observed that varA-deficient V. cholerae cells showed an abnormal spherical morphology during late-stage growth. Through peptidoglycan (PG) composition analyses, we discovered that these mutant bacteria contained an increased content of disaccharide dipeptides and reduced peptide crosslinks, consistent with the atypical cellular shape. The spherical shape correlated with the CsrA-dependent overproduction of aspartate ammonia lyase (AspA) in varA mutant cells, which likely depleted the cellular aspartate pool; therefore, the synthesis of the PG precursor amino acid meso-diaminopimelic acid was impaired. Importantly, this phenotype, and the overall cell rounding, could be prevented by means of cell wall recycling. Collectively, our data provide new insights into how V. cholerae use the VarA-CsrA signaling system to adjust its morphology upon unidentified external cues in its environment. 相似文献
994.
995.
Otto Quintus Russe Christine V. Möser Katharina L. Kynast Tanya S. King Katrin Olbrich Sabine Grösch Gerd Geisslinger Ellen Niederberger 《Biochemical and biophysical research communications》2014
AMP-activated kinase is a cellular energy sensor which is activated in stages of increased ATP consumption. Its activation has been associated with a number of beneficial effects such as decreasing inflammatory processes and the disease progress of diabetes and obesity, respectively. Furthermore, AMPK activation has been linked with induction of cell cycle arrest and apoptosis in cancer and vascular cells, indicating that it might have a therapeutic impact for the treatment of cancer and atherosclerosis. However, the impact of AMPK on the proliferation of macrophages, which also play a key role in the formation of atherosclerotic plaques and in inflammatory processes, has not been focused so far. We have assessed the influence of AICAR- and metformin-induced AMPK activation on cell viability of macrophages with and without inflammatory stimulation, respectively. In cells without inflammatory stimulation, we found a strong induction of caspase 3-dependent apoptosis associated with decreased mTOR levels and increased expression of p21. Interestingly, these effects could be inhibited by co-stimulation with bacterial lipopolysaccharide (LPS) but not by other proinflammatory cytokines suggesting that AICAR induces apoptosis via AMPK in a TLR4-pathway dependent manner. 相似文献
996.
Songlei Liu Sukanya Punthambaker Eswar P R Iyer Thomas Ferrante Daniel Goodwin Daniel Fürth Andrew C Pawlowski Kunal Jindal Jenny M Tam Lauren Mifflin Shahar Alon Anubhav Sinha Asmamaw T Wassie Fei Chen Anne Cheng Valerie Willocq Katharina Meyer King-Hwa Ling Conor
K Camplisson Richie E Kohman John Aach Je Hyuk Lee Bruce
A Yankner Edward S Boyden George M Church 《Nucleic acids research》2021,49(10):e58
997.
Oxido-pincer ligands with phenolate-groups [2,6-bis(2-methoxyphenyl)pyridine (LOMe2), 2,6-bis(2-hydroxyphenyl)-pyridine (LOH2), 2,6-bis-(2,4-dimethoxyphenyl)-pyridine (LOMe4)] coordinate to CuII forming binuclear complexes which can be easily and reliably converted into mononuclear species. Their physical properties were analysed using EPR, optical spectroscopy and (spectro-)electrochemical methods. The results were compared to those of related NiII complexes and discussed in view of Cu-containing metalloenzymes. Due to the ligands flexibility the CuII/CuI redox couple exhibits high reversibility, while the ligand-centred oxidation leads to highly reactive phenoxy radicals. Reduction of the LOH2 complex leads to sequential deprotonation. The ligand LOMe4 and the derived complexes show blue luminescence, which can be rationalised from its molecular structure (analysed by XRD). 相似文献
998.
Jenson Qi Wensheng Lang Edward Giardino Gary W. Caldwell Charles Smith Lisa K. Minor Andrew L. Darrow Gustaaf Willemsens Katharina DeWaepenaert Peter Roevens Joannes T. M. Linders Yin Liang Margery A. Connelly 《Journal of lipid research》2010,51(12):3559-3567
Acyl-CoA:diacylglycerol acyltransferase (DGAT) catalyzes the terminal step in triglyceride (TG) synthesis using diacylglycerol (DAG) and fatty acyl-CoA as substrates. In the liver, the production of VLDL permits the delivery of hydrophobic TG from the liver to peripheral tissues for energy metabolism. We describe here a novel high-content, high-throughput LC/MS/MS-based cellular assay for determining DGAT activity. We treated endogenous DGAT-expressing cells with stable isotope-labeled [13C18]oleic acid. The [13C18]oleoyl-incorporated TG and DAG lipid species were profiled. The TG synthesis pathway assay was optimized to a one-step extraction, followed by LC/MS/MS quantification. Further, we report a novel LC/MS/MS method for tracing hepatic TG synthesis and VLDL-TG secretion in vivo by administering [13C18]oleic acid to rats. The [13C18]oleic acid-incorporated VLDL-TG was detected after one-step extraction without conventional separation of TG and recovery by derivatizing [13C18]oleic acid for detection. Using potent and selective DGAT1 inhibitors as pharmacological tools, we measured changes in [13C18]oleoyl-incorporated TG and DAG and demonstrated that DGAT1 inhibition significantly reduced [13C18]oleoyl-incorporated VLDL-TG. This DGAT1-selective assay will enable researchers to discern differences between the roles of DGAT1 and DGAT2 in TG synthesis in vitro and in vivo. 相似文献
999.
Alpine ecosystems are, similar to arctic ecosystems, characterized by a very long snow season. Previous studies investigating arctic or alpine ecosystems have shown that winter CO2 effluxes can dominate the annual balance and that the timing and duration of the snow cover plays a crucial role for plant growth and phenology and might also influence the growing season ecosystem CO2 strength and dynamics. The objective of this study was to analyze seasonal and annual CO2 balances of a grassland site at an elevation of 2440 m a.s.l in the Swiss central Alps. We continuously measured the NEP using the eddy covariance method from June 2013 to October 2014, covering two growing seasons and one winter. We analyzed the influence of snow melt date on the CO2 exchange dynamics at this site, because snow melt differed about 24 days between the 2 years. To this end, we employed a process-based ecosystem carbon cycling model to disentangle the co-occurring effects of growing season length, environmental conditions during the growing season, and physiological/structural properties of the canopy on the ecosystem carbon balance. During the measurement period, the site was a net sink for CO2 although winter efflux contributed significantly to the total balance. The cumulative growing season NEP as well as mean and maximum daily CO2 uptake rates was lower during the year with the later snow melt, and the results indicated that the differences were mainly due to differing growing season lengths. 相似文献
1000.
Antonia Torcasio Katharina J?hn Maarten Van Guyse Pieter Spaepen Andrea E. Tami Jos Vander Sloten Martin J. Stoddart G. Harry van Lenthe 《PloS one》2014,9(5)
Exposure to microgravity causes loss of lower body bone mass in some astronauts. Low-magnitude high-frequency loading can stimulate bone formation on earth. Here we hypothesized that low-magnitude high-frequency loading will also stimulate bone formation under microgravity conditions. Two groups of six bovine cancellous bone explants were cultured at microgravity on a Russian Foton-M3 spacecraft and were either loaded dynamically using a sinusoidal curve or experienced only a static load. Comparable reference groups were investigated at normal gravity. Bone structure was assessed by histology, and mechanical competence was quantified using μCT and FE modelling; bone remodelling was assessed by fluorescent labelling and secreted bone turnover markers. Statistical analyses on morphometric parameters and apparent stiffness did not reveal significant differences between the treatment groups. The release of bone formation marker from the groups cultured at normal gravity increased significantly from the first to the second week of the experiment by 90.4% and 82.5% in response to static and dynamic loading, respectively. Bone resorption markers decreased significantly for the groups cultured at microgravity by 7.5% and 8.0% in response to static and dynamic loading, respectively. We found low strain magnitudes to drive bone turnover when applied at high frequency, and this to be valid at normal as well as at microgravity. In conclusion, we found the effect of mechanical loading on trabecular bone to be regulated mainly by an increase of bone formation at normal gravity and by a decrease in bone resorption at microgravity. Additional studies with extended experimental time and increased samples number appear necessary for a further understanding of the anabolic potential of dynamic loading on bone quality and mechanical competence. 相似文献