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931.
Michel C Ouerd A Battaglia-Brunet F Guigues N Grasa JP Bruschi M Ignatiadis I 《Biosensors & bioelectronics》2006,22(2):285-290
The development of an amperometric enzyme-based sensor for chromate (CrO(4)(2-)) quantification in ground waters was investigated. Crucial physical and chemical factors characterising ground waters were tested for their influence or interference on chromate quantification: pH (7.6-8.5), temperature (9-25 degrees C), ionic strength (0-0.2M), oxygen, metals, bicarbonate and sulphate. The biosensor's response was dependent on temperature and pH as sensitivity increased with temperature and was higher at pH 7.6 than at pH 8.5. Sensitivity decreased with ionic strength until 0.1M, and was stable for higher values. Dissolved oxygen did not allow chromate quantification when it was present, but O(2) could be eliminated by adding Na(2)SO(3) or bubbling nitrogen gas into the solution. Bicarbonate did not interfere with chromate quantification by the biosensor. Sulphate was detected with a detection threshold 80 times higher than that of chromate and a lower sensitivity. Several metals (V(V), W(VI), Mn(VII), Mo(VI)) similar to chromate due to their oxidative properties and structure (oxyanions) were tested as possible interfering compounds. The sensitivity of the biosensor for these metals was low and the detection level was 30 times higher than that of chromate. These metal concentrations are usually weaker than chromate concentration in polluted ground waters so that dilution of the sample should allow chromate quantification by the biosensor. This study shows that the cytochrome c(3)-based sensor can detect compounds other than chromate but with a lower sensitivity. Although non-specific for the detection of chromate, it can however be adapted and used for the quantification of chromate in ground waters containing low sulphate concentration. 相似文献
932.
Ayme V Souche S Caranta C Jacquemond M Chadoeuf J Palloix A Moury B 《Molecular plant-microbe interactions : MPMI》2006,19(5):557-563
Five different amino acid substitutions in the VPg of Potato virus Y were shown to be independently responsible for virulence toward pvr2(3) resistance gene of pepper. A consequence of these multiple mutations toward virulence involving single nucleotide substitutions is a particularly high frequency of resistance breaking (37% of inoculated plants from the first inoculation) and suggests a potentially low durability of pvr2(3) resistance. These five mutants were observed with significantly different frequencies, one of them being overrepresented. Genetic drift alone could not explain the observed distribution of virulent mutants. More plausible scenarios were obtained by taking into account either the relative substitution rates, the relative fitness of the mutants in pvr2(3) pepper plants, or both. 相似文献
933.
Silver staining of proteins in polyacrylamide gels 总被引:1,自引:0,他引:1
Silver staining is used to detect proteins after electrophoretic separation on polyacrylamide gels. It combines excellent sensitivity (in the low nanogram range) with the use of very simple and cheap equipment and chemicals. It is compatible with downstream processing, such as mass spectrometry analysis after protein digestion. The sequential phases of silver staining are protein fixation, then sensitization, then silver impregnation and finally image development. Several variants of silver staining are described here, which can be completed in a time range from 2 h to 1 d after the end of the electrophoretic separation. Once completed, the stain is stable for several weeks. 相似文献
934.
François Blachier Anne-Marie Davila Sabria Mimoun Pierre-Henri Benetti Calina Atanasiu Mireille Andriamihaja Robert Benamouzig Frédéric Bouillaud Daniel Tomé 《Amino acids》2010,39(2):335-347
Hydrogen sulfide (H2S) is present in the lumen of the human large intestine at millimolar concentrations. However, the concentration of free (unbound)
sulfide is in the micromolar range due to a large capacity of fecal components to bind the sulfide. H2S can be produced by the intestinal microbiota from alimentary and endogenous sulfur-containing compounds including amino
acids. At excessive concentration, H2S is known to severely inhibit cytochrome c oxidase, the terminal oxidase of the mitochondrial electron transport chain, and thus mitochondrial oxygen (O2) consumption. However, the concept that sulfide is simply a metabolic troublemaker toward colonic epithelial cells has been
challenged by the discovery that micromolar concentration of H2S is able to increase the cell respiration and to energize mitochondria allowing these cells to detoxify and to recover energy
from luminal sulfide. The main product of H2S metabolism by the colonic mucosa is thiosulfate. The enzymatic activities involved in sulfide oxidation by the colonic epithelial
cells appear to be sulfide quinone oxidoreductase considered as the first and rate-limiting step followed presumably by the
action of sulfur dioxygenase and rhodanese. From clinical studies with human volunteers and experimental works with rodents,
it appears that H2S can exert mostly pro- but also anti-inflammatory effects on the colonic mucosa. From the available data, it is tempting
to propose that imbalance between the luminal concentration of free sulfide and the capacity of colonic epithelial cells to
metabolize this compound will result in an impairment of the colonic epithelial cell O2 consumption with consequences on the process of mucosal inflammation. In addition, endogenously produced sulfide is emerging
as a prosecretory neuromodulator and as a relaxant agent toward the intestinal contractibility. Lastly, sulfide has been recently
described as an agent involved in nociception in the large intestine although, depending on the experimental design, both
pro- and anti-nociceptive effects have been reported. 相似文献
935.
Austin Chen Christopher Bayly Olivier Bezençon Sylvia Richard-Bildstein Daniel Dubé Laurence Dubé Sébastien Gagné Michel Gallant Mireille Gaudreault Erich Grimm Robert Houle Patrick Lacombe Sébastien Laliberté Jean-François Lévesque Suzanna Liu Dwight MacDonald Bruce Mackay David Martin Dan McKay David Powell Sylvie Toulmond 《Bioorganic & medicinal chemistry letters》2010,20(7):2204-2209
The discovery and SAR of a new series of substituted amino propanamide renin inhibitors are herein described. This work has led to the preparation of compounds with in vitro and in vivo profiles suitable for further development. Specifically, challenges pertaining to oral bioavailability, covalent binding and time-dependent CYP 3A4 inhibition were overcome thereby culminating in the identification of compound 50 as an optimized renin inhibitor with good efficacy in the hypertensive double-transgenic rat model. 相似文献
936.
Benhamouche S Decaens T Godard C Chambrey R Rickman DS Moinard C Vasseur-Cognet M Kuo CJ Kahn A Perret C Colnot S 《Developmental cell》2006,10(6):759-770
The molecular mechanisms by which liver genes are differentially expressed along a portocentral axis, allowing for metabolic zonation, are poorly understood. We provide here compelling evidence that the Wnt/beta-catenin pathway plays a key role in liver zonation. First, we show the complementary localization of activated beta-catenin in the perivenous area and the negative regulator Apc in periportal hepatocytes. We then analyzed the immediate consequences of either a liver-inducible Apc disruption or a blockade of Wnt signaling after infection with an adenovirus encoding Dkk1, and we show that Wnt/beta-catenin signaling inversely controls the perivenous and periportal genetic programs. Finally, we show that genes involved in the periportal urea cycle and the perivenous glutamine synthesis systems are critical targets of beta-catenin signaling, and that perturbations to ammonia metabolism are likely responsible for the death of mice with liver-targeted Apc loss. From our results, we propose that Apc is the liver "zonation-keeper" gene. 相似文献
937.
Louise Gilbert Moftah Alhagdow Adriano Nunes-Nesi Bernard Quemener Fabienne Guillon Brigitte Bouchet Mireille Faurobert Barbara Gouble David Page Virginie Garcia Johann Petit Rebecca Stevens Mathilde Causse Alisdair R. Fernie Marc Lahaye Christophe Rothan Pierre Baldet 《The Plant journal : for cell and molecular biology》2009,60(3):499-508
938.
Smitha C. Mathew Nandita Ghosh Youlet By Aurélie Berthault Marie-Alice Virolleaud Louis Carrega Gaëlle Chouraqui Laurent Commeiras Jocelyne Condo Mireille Attolini Anouk Gaudel-Siri Jean Ruf Jean-Luc Parrain Jean Rodriguez Régis Guieu 《Bioorganic & medicinal chemistry letters》2009,19(23):6736-6739
The cross talk between different membrane receptors is the source of increasing research. We designed and synthesized a new hetero-bivalent ligand that has antagonist properties on both A1 adenosine and μ opiate receptors with a Ki of 0.8 ± 0.05 and 0.7 ± 0.03 μM, respectively. This hybrid molecule increases cAMP production in cells that over express the μ receptor as well as those over expressing the A1 adenosine receptor and reverses the antalgic effects of μ and A1 adenosine receptor agonists in animals. 相似文献
939.
FRAXE-associated mental retardation protein (FMR2) is an RNA-binding protein with high affinity for G-quartet RNA forming structure
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940.
Hiroyuki Niida Kazuhiro Murata Midori Shimada Kumiko Ogawa Kumiko Ohta Kyoko Suzuki Hidetsugu Fujigaki Aik Kia Khaw Birendranath Banerjee M Prakash Hande Tomomi Miyamoto Ichiro Miyoshi Tomoyuki Shirai Noboru Motoyama Mireille Delhase Ettore Appella Makoto Nakanishi 《The EMBO journal》2010,29(20):3558-3570
Although the linkage of Chk1 and Chk2 to important cancer signalling suggests that these kinases have functions as tumour suppressors, neither Chk1+/− nor Chk2−/− mice show a predisposition to cancer under unperturbed conditions. We show here that Chk1+/−Chk2−/− and Chk1+/−Chk2+/− mice have a progressive cancer-prone phenotype. Deletion of a single Chk1 allele compromises G2/M checkpoint function that is not further affected by Chk2 depletion, whereas Chk1 and Chk2 cooperatively affect G1/S and intra-S phase checkpoints. Either or both of the kinases are required for DNA repair depending on the type of DNA damage. Mouse embryonic fibroblasts from the double-mutant mice showed a higher level of p53 with spontaneous DNA damage under unperturbed conditions, but failed to phosphorylate p53 at S23 and further induce p53 expression upon additional DNA damage. Neither Chk1 nor Chk2 is apparently essential for p53- or Rb-dependent oncogene-induced senescence. Our results suggest that the double Chk mutation leads to a high level of spontaneous DNA damage, but fails to eliminate cells with damaged DNA, which may ultimately increase cancer susceptibility independently of senescence. 相似文献