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81.
An experimental set-up which enabled non-invasive, real-time reactive oxygen species (ROS) visualization on a whole plant
level was constructed. In the test organism, Lemna minor L. (common duckweed), apoplastic and symplastic oxidative stress was evaluated by exposure to menadione (50 μM), menadione (50 μM) + ascorbate (100 μM) or neither for control. Menadione (50 μM) caused a statistically significant increase in H2DCFDA fluorescence in the apoplast after 60 minutes of exposure. The addition of ascorbate (100 μM) in the test medium significantly decreased apoplastic oxidative stress. 50 μM menadione caused an increase in symplastic H2DCFDA fluorescence in 57% of fronds. The exposure of L. minor plants to both menadione and ascorbate decreased the rate of fluorescence intensity accumulation in the symplast to control
levels. The method has proven to be quick and straightforward and could be applied to a range of chemicals in various physiological
and toxicological plant studies. The advantages of the set-up and different possible artefacts are discussed. 相似文献
82.
Veronica S. Santander Alexis N. Campetelli Noelia E. Monesterolo Juan F. Rivelli Ayelen D. Nigra Carlos A. Arce César H. Casale 《Journal of cellular physiology》2019,234(6):7752-7763
A new function for tubulin was described by our laboratory: acetylated tubulin forms a complex with Na+,K +-ATPase (NKA) and inhibits its activity. This process was shown to be a regulatory factor of physiological importance in cultured cells, human erythrocytes, and several rat tissues. Formation of the acetylated tubulin–NKA complex is reversible. We demonstrated that in cultured cells, high concentrations of glucose induce translocation of acetylated tubulin from cytoplasm to plasma membrane with a consequent inhibition of NKA activity. This effect is reversed by adding glutamate, which is coctransported to the cell with Na +. Another posttranslational modification of tubulin, detyrosinated tubulin, is also involved in the regulation of NKA activity: it enhances the NKA inhibition induced by acetylated tubulin. Manipulation of the content of these modifications of tubulin could work as a new strategy to maintain homeostasis of Na + and K +, and to regulate a variety of functions in which NKA is involved, such as osmotic fragility and deformability of human erythrocytes. The results summarized in this review show that the interaction between tubulin and NKA plays an important role in cellular physiology, both in the regulation of Na +/K + homeostasis and in the rheological properties of the cells, which is mechanically different from other roles reported up to now. 相似文献
83.
Daniel E. Brown Tupou V. Koenig Alexis M. Demorales Ka'ohulani McGuire Charlene T. Mersai 《American journal of physical anthropology》1996,99(2):239-247
Menarche age was assessed in 93 adolescent females in a sample of public schools in East Hawaii. Native Hawaiian girls had significantly lower reported age at menarche than non-Hawaiian classmates. Age at menarche was significantly correlated with total fatness as measured by the sum of six skinfolds in girls who had reached menarche at least 2 years previous to measurement. When fatness was controlled in comparisons, the ethnic differences were not significant. Fat distribution, independent of fatness, was also significantly related to age at menarche. Socioeconomic, cultural, and admixture variables were not significantly related to age at menarche. Adiposity appears to be both a cause and a consequence of early age at menarche, with the relationship dependent on the elapsed time between menarche and measurement. This suggests that studies relating body composition to age at menarche must carefully control for the time interval between measurement and the date of menarche. © 1996 Wiley-Liss, Inc. 相似文献
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87.
This study attempted to develop a 'less meiotically competent' murine model for oocyte in vitro maturation (IVM), which could more readily be extrapolated to human clinical assisted reproduction. Oocyte meiotic competence was drastically reduced upon shortening the standard duration of in vivo gonadotrophin stimulation from 48 h to 24 h, and by selecting only naked or partially naked germinal vesicle oocytes, instead of fully cumulus enclosed oocyte complexes. With such a less meiotically competent model, only porcine granulosa coculture significantly enhanced the oocyte maturation rate in vitro, whereas no significant enhancement was observed with macaque and murine granulosa coculture. Increased serum concentrations and the supplementation of gonadotrophins, follicular fluid and extracellular matrix gel within the culture medium did not enhance IVM under either cell-free or coculture conditions. Culture medium conditioned by porcine granulosa also enhanced the maturation rate, and this beneficial effect was not diminished upon freeze-thawing. Enhanced IVM in the presence of porcine granulosa coculture did not, however, translate into improved developmental competence, as assessed by in vitro fertilization and embryo culture to the blastocyst stage. 相似文献
88.
3'-Exonuclease resistance of DNA oligodeoxynucleotides containing O6-[4-oxo-4-(3-pyridyl)butyl]guanine
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Tobacco-specific nitrosamine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), is a chemical carcinogen thought to be involved in the initiation of lung cancer in smokers. NNK is metabolically activated to methylating and pyridyloxobutylating species that form promutagenic adducts with DNA nucleobases, e.g. O6-[4-oxo-4-(3-pyridyl)butyl]guanine (O6-POB-dG). O6-POB-dG is a strongly mispairing DNA lesion capable of inducing both G→A and G→T base changes, suggesting its importance in NNK mutagenesis and carcinogenesis. Our earlier investigations have identified the ability of O6-POB-dG to hinder DNA digestion by snake venom phosphodiesterase (SVPDE), a 3′-exonuclease commonly used for DNA ladder sequencing and as a model enzyme to test nuclease sensitivity of anti-sense oligonucleotide drugs. We now extend our investigation to three other enzymes possessing 3′-exonuclease activity: bacteriophage T4 DNA polymerase, Escherichia coli DNA polymerase I, and E.coli exonuclease III. Our results indicate that, unlike SVPDE, 3′-exonuclease activities of these three enzymes are not blocked by O6-POB-dG lesion. Conformational analysis and molecular dynamics simulations of DNA containing O6-POB-dG suggest that the observed resistance of the O6-POB-dG lesion to SVPDE-catalyzed hydrolysis may result from the structural changes in the DNA strand induced by the O6-POB group, including C3′-endo sugar puckering and the loss of stacking interaction between the pyridyloxobutylated guanine and its flanking bases. In contrast, O6-methylguanine lesion used as a control does not induce similar structural changes in DNA and does not prevent its digestion by SVPDE. 相似文献
89.
Marchesan D Rutberg M Andersson L Asp L Larsson T Borén J Johansson BR Olofsson SO 《The Journal of biological chemistry》2003,278(29):27293-27300
We developed a microsome-based, cell-free system that assembles newly formed triglyceride (TG) into spherical lipid droplets. These droplets were recovered in the d = 1.055 g/ml fraction by gradient ultracentrifugation and were similar in size and appearance to those isolated from rat adipocytes and 3T3-L1 cells. Caveolin 1 and 2, vimentin, adipocyte differentiation-related protein, and the 78-kDa glucose regulatory protein were identified on the droplets from the cell-free system. The caveolin was soluble in 1% Triton X-100, as was the caveolin on lipid droplets from 3T3-L1 cells. The lipid droplets from the cell-free system, like those from 3T3-L1 cells, contained TG, diacylglycerol, phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine. The assembly of these TG-containing structures was dependent on the rate of TG biosynthesis and required an activator present in the 160,000 x g supernatant from homogenized rat adipocytes. The activator induced phospholipase D (PLD) activity, and its effect on the release of the TG-containing structures from the microsomes was inhibited by 1-butanol (but not 2-butanol) or 2,3-diphosphoglycerate. The activator could be replaced by a constitutively active PLD or phosphatidic acid. These results indicate that PLD and the formation of phosphatidic acid are important in the assembly of the TG-containing structures. 相似文献
90.
Distribution of [14C]-trans-resveratrol,a cancer chemopreventive polyphenol,in mouse tissues after oral administration 总被引:8,自引:0,他引:8
Vitrac X Desmoulière A Brouillaud B Krisa S Deffieux G Barthe N Rosenbaum J Mérillon JM 《Life sciences》2003,72(20):2219-2233
Trans-resveratrol, a phenolic compound present in wine, has been reported to be a potential cancer chemopreventive agent. However, although it has numerous biological activities in vitro, there are few data about its bioavailability and tissue distribution in vivo. The objectives of this study were to investigate the absorption and tissue distribution of 14C-trans-resveratrol following oral administration to mice. Male Balb/c mice were given a single oral dose of 14C-trans-resveratrol and were sacrificed at 1.5, 3 or 6 h postdose. The distribution of radioactivity in tissues was evaluated using whole-body autoradiography, quantitative organ-level determination and microautoradiography. In addition, identification of radioactive compounds in kidney and liver was done with high-performance liquid chromatography. Autoradiographic survey of mice sections as well as radioactivity quantification in various organs revealed a preferential fixation of 14C-trans-resveratrol in the organs and biological liquids of absorption and elimination (stomach, liver, kidney, intestine, bile, urine). Moreover, we show that 14C-trans-resveratrol derived radioactivity is able to penetrate the tissues of liver and kidney, a finding supported by microautoradiography. The presence of intact 14C-trans-resveratrol together with glucurono- and/or sulfoconjugates in these tissues was also shown. This study demonstrates that trans-resveratrol is bioavailable following oral administration and remains mostly in intact form. The results also suggest a wide range of target organs for cancer chemoprevention by wine polyphenols in humans. 相似文献