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971.
R. Schwamborn W. Ekau A. P. Silva S. H. L. Schwamborn T. A. Silva S. Neumann-Leitão U. Saint-Paul 《Hydrobiologia》2006,560(1):1-13
Ingestion rates of zoeae of Aratus pisonii Milne Edwards (Brachyura: Grapsidae) were determined offering natural plankton-detritus mixtures in laboratory food selection
experiments. The food mixtures were sampled in the Itamaracá estuary, north-eastern Brazil, and standardised to a size range
of 50–200 μm. Zoeae ingested significant amounts of large centric diatoms (Coscinodiscus spp.), mangrove detritus, tintinnids (Favella ehrenbergi) and adult copepods during feeding experiments. Diatoms were positively selected by A. pisonii zoeae in all three experiments, with ingestion rates of 3.3–21.3 cells zoea−1 day−1. Detritus particles were always more abundant than phytoplankton and zooplankton in the particle size spectrum offered. Detritus
was ingested in two of three experiments, with ingestion rates of up to 34.1 particles zoea−1 day−1, being the most important food item during one experiment. Adult copepods (up to 1.8 ind. zoea−1 day−1) and tintinnids (up to 0.4 ind. zoea−1 day−1) were ingested by A. pisonii zoeae during one experiment each. In spite of a wide range of zoeal density, food particle composition, and density, zoeae
of A. pisonii displayed a consistent pattern of food selectivity. This hints at a consistent sensory and behavioural mechanism related
to capture and handling of food particles, that most likely also affects larval feeding under natural conditions. Although
detritus showed to be quantitatively ingested under estuarine conditions, zoeae of A. pisonii preferred large diatoms and ingested zooplankton only occasionally. 相似文献
972.
973.
Velasco-García R Zaldívar-Machorro VJ Mújica-Jiménez C González-Segura L Muñoz-Clares RA 《Biochemical and biophysical research communications》2006,341(2):408-415
In the human pathogen Pseudomonas aeruginosa, betaine aldehyde dehydrogenase (PaBADH) may play the dual role of assimilating carbon and nitrogen from choline or choline precursors--abundant at infection sites--and producing glycine betaine, which protects the bacterium against the high-osmolality stress prevalent in the infected tissues. This tetrameric enzyme contains four cysteine residues per subunit and is a potential drug target. In our search for specific inhibitors, we mutated the catalytic Cys286 to alanine and chemically modified the recombinant wild-type and the four Cys-->Ala single mutants with thiol reagents. The small methyl-methanethiosulfonate inactivated the enzymes without affecting their stability while the bulkier dithionitrobenzoic acid (DTNB) and bis[diethylthiocarbamyl] disulfide (disulfiram) induced enzyme dissociation--at 23 degrees C--and irreversible aggregation--at 37 degrees C. Of the four Cys-->Ala mutants only C286A retained its tetrameric structure after DTNB or disulfiram treatments, suggesting that steric constraints arising upon the covalent attachment of a bulky group to C286 resulted in distortion of the backbone configuration in the active site region followed by a severe decrease in enzyme stability. Since neither NAD(P)H nor betaine aldehyde prevented disulfiram-induced PaBADH inactivation or aggregation, and reduced glutathione was unable to restore the activity of the modified enzyme, we propose that disulfiram could be a useful drug to combat infection by P. aeruginosa. 相似文献
974.
Coelho ER Rodrigues Dde C Urményi TP Rondinelli E Silva R 《Biochemical and biophysical research communications》2006,341(2):382-390
DNA replication mechanisms are poorly understood in most of trypanosomatids, in particular the replication of the peculiar mitochondrial DNA, the kinetoplast DNA (kDNA). To contribute to the knowledge on the mechanism of kDNA replication in Trypanosoma cruzi, we have previously characterized the Universal Minicircle Sequence Binding Protein of this parasite (TcUMSBP), which was first called PDZ5 [E.R. Coelho, T.P. Urmenyi, J. Franco da Silveira, E. Rondinelli, R. Silva, Identification of PDZ5, a candidate universal minicircle sequence binding protein of Trypanosoma cruzi, Int. J. Parasitol. 33 (2003) 853-858]. In this work, we describe two highly polymorphic alleles of the TcUMSBP locus in the T. cruzi reference clone CL Brener and the differential expression pattern of these alleles. A 62 bp sequence in the TcUMSBP upstream intergenic region in one of its alleles affects the efficiency of polycistronic RNA processing and the polyadenylation sites, and therefore regulates the differential expression of TcUMSBP alleles of this locus. 相似文献
975.
Xiaoning Han Michael Chen Fushun Wang Martha Windrem Su Wang Steven Shanz Qiwu Xu Nancy Ann Oberheim Lane Bekar Sarah Betstadt Alcino J. Silva Takahiro Takano Steven A. Goldman Maiken Nedergaard 《Cell Stem Cell》2013,12(3):342-353
Download : Download video (32MB) 相似文献
976.
J. Jaime Miranda Victor M. Herrera Julio A. Chirinos Luis F. Gómez Pablo Perel Rafael Pichardo Angel González José R. Sánchez Catterina Ferreccio Ximena Aguilera Eglé Silva Myriam Oróstegui Josefina Medina-Lezama Cynthia M. Pérez Erick Suárez Ana P. Ortiz Luis Rosero Noberto Schapochnik Zulma Ortiz Daniel Ferrante Juan P. Casas Leonelo E. Bautista 《PloS one》2013,8(1)
Background
Limited knowledge on the prevalence and distribution of risk factors impairs the planning and implementation of cardiovascular prevention programs in the Latin American and Caribbean (LAC) region.Methods and Findings
Prevalence of hypertension, diabetes mellitus, abnormal lipoprotein levels, obesity, and smoking were estimated from individual-level patient data pooled from population-based surveys (1998–2007, n = 31,009) from eight LAC countries and from a national survey of the United States (US) population (1999–2004) Age and gender specific prevalence were estimated and age-gender adjusted comparisons between both populations were conducted. Prevalence of diabetes mellitus, hypertension, and low high-density lipoprotein (HDL)-cholesterol in LAC were 5% (95% confidence interval [95% CI]: 3.4, 7.9), 20.2% (95% CI: 12.5, 31), and 53.3% (95% CI: 47, 63.4), respectively. Compared to LAC region’s average, the prevalence of each risk factor tended to be lower in Peru and higher in Chile. LAC women had higher prevalence of obesity and low HDL-cholesterol than men. Obesity, hypercholesterolemia, and hypertriglyceridemia were more prevalent in the US population than in LAC population (31 vs. 16.1%, 16.8 vs. 8.9%, and 36.2 vs. 26.5%, respectively). However, the prevalence of low HDL-cholesterol was higher in LAC than in the US (53.3 vs. 33.7%).Conclusions
Major cardiovascular risk factors are highly prevalent in LAC region, in particular low HDL-cholesterol. In addition, marked differences do exist in this prevalence profile between LAC and the US. The observed patterns of obesity-related risk factors and their current and future impact on the burden of cardiovascular diseases remain to be explained. 相似文献977.
Melania Melis Maria Carla Aragoni Massimiliano Arca Tiziana Cabras Claudia Caltagirone Massimo Castagnola Roberto Crnjar Irene Messana Beverly J. Tepper Iole Tomassini Barbarossa 《PloS one》2013,8(3)
The genetic predisposition to taste 6-n-propylthiouracil (PROP) varies among individuals and is associated with salivary levels of Ps-1 and II-2 peptides, belonging to the basic proline-rich protein family (bPRP). We evaluated the role of these proteins and free amino acids that selectively interact with the PROP molecule, in modulating bitter taste responsiveness. Subjects were classified by their PROP taster status based on ratings of perceived taste intensity for PROP and NaCl solutions. Quantitative and qualitative determinations of Ps-1 and II-2 proteins in unstimulated saliva were performed by HPLC-ESI-MS analysis. Subjects rated PROP bitterness after supplementation with Ps-1 and II-2, and two amino acids (L-Arg and L-Lys) whose interaction with PROP was demonstrated by 1H-NMR spectroscopy. ANOVA showed that salivary levels of II-2 and Ps-1 proteins were higher in unstimulated saliva of PROP super-tasters and medium tasters than in non-tasters. Supplementation of Ps-1 protein in individuals lacking it in saliva enhanced their PROP bitter taste responsiveness, and this effect was specific to the non-taster group.1H-NMR results showed that the interaction between PROP and L-Arg is stronger than that involving L-Lys, and taste experiments confirmed that oral supplementation with these two amino acids increased PROP bitterness intensity, more for L-Arg than for L-Lys. These data suggest that Ps-1 protein facilitates PROP bitter taste perception and identifies a role for free L-Arg and L-Lys in PROP tasting. 相似文献
978.
Ana C. Silva Sandra Almeida Mário Laço Ana I. Duarte Joana Domingues Catarina R. Oliveira Cristina Januário A. Cristina Rego 《Mitochondrion》2013,13(6):801-809
Mitochondrial dysfunction has been implicated in Huntington's disease (HD) pathogenesis. We analyzed the activity of mitochondrial complexes (Cx) I–IV, protein levels of selected Cx subunits and adenine nucleotides in platelet mitochondria from pre-symptomatic versus symptomatic HD human carriers and age-matched control individuals. Mitochondrial platelets exhibited reduced activity of citrate synthase in pre-symptomatic and Cx-I in pre-symptomatic and symptomatic HD carriers. Positive correlation between Cx activity and protein subunits was observed for Cx-I in symptomatic HD patient's mitochondria. Moreover, AMP increased in mitochondria from pre-symptomatic HD carriers. Results highlight mitochondrial changes occurring before the onset of HD clinical symptoms. 相似文献
979.
Mart Roosimaa Taavi Põdramägi Lumme Kadaja Arno Ruusalepp Kalju Paju Raivo Puhke Margus Eimre Ehte Orlova Andres Piirsoo Nadežda Peet Frank N. Gellerich Enn Seppet 《Mitochondrion》2013,13(5):399-409
Cardiac energy metabolism with emphasis on mitochondria was addressed in atrial tissue from patients with overload-induced atrial dilation. Structural remodeling of dilated (D) atria manifested as intracellular accumulation of fibrillar aggregates, lipofuscin, signs of myolysis and autophagy. Despite impaired complex I dependent respiration and increased diffusion restriction for ADP, no changes regarding adenylate and creatine kinase occurred. We observed 7-fold overexpression of HK2 gene in D atria with concomitant 2-fold greater activation of mitochondrial oxygen consumption by glucose, which might represent an adaption to increased energy requirements and impaired mitochondrial function by effectively joining glycolysis and oxidative phosphorylation. 相似文献
980.
Matteo Ferrari Benjamin Tamilselvan Nachimuthu Roberto Antonio Donnianni Hannah Klein Achille Pellicioli 《DNA Repair》2013,12(5):347-355
Saccharomyces cerevisiae cells with a single double-strand break (DSB) activate the ATR/Mec1-dependent checkpoint response as a consequence of extensive ssDNA accumulation. The recombination factor Tid1/Rdh54, a member of the Swi2-like family proteins, has an ATPase activity and may contribute to the remodelling of nucleosomes on DNA. Tid1 dislocates Rad51 recombinase from dsDNA, can unwind and supercoil DNA filaments, and has been implicated in checkpoint adaptation from a G2/M arrest induced by an unrepaired DSB.Here we show that both ATR/Mec1 and Chk2/Rad53 kinases are implicated in the phosphorylation of Tid1 in the presence of DNA damage, indicating that the protein is regulated during the DNA damage response. We show that Tid1 ATPase activity is dispensable for its phosphorylation and for its recruitment near a DSB, but it is required to switch off Rad53 activation and for checkpoint adaptation. Mec1 and Rad53 kinases, together with Rad51 recombinase, are also implicated in the hyper-phosphorylation of the ATPase defective Tid1-K318R variant and in the efficient binding of the protein to the DSB site.In summary, Tid1 is a novel target of the DNA damage checkpoint pathway that is also involved in checkpoint adaptation. 相似文献