全文获取类型
收费全文 | 1090篇 |
免费 | 78篇 |
出版年
2023年 | 12篇 |
2022年 | 20篇 |
2021年 | 46篇 |
2020年 | 24篇 |
2019年 | 33篇 |
2018年 | 34篇 |
2017年 | 44篇 |
2016年 | 53篇 |
2015年 | 74篇 |
2014年 | 69篇 |
2013年 | 79篇 |
2012年 | 105篇 |
2011年 | 82篇 |
2010年 | 51篇 |
2009年 | 43篇 |
2008年 | 72篇 |
2007年 | 45篇 |
2006年 | 61篇 |
2005年 | 43篇 |
2004年 | 39篇 |
2003年 | 27篇 |
2002年 | 21篇 |
2001年 | 14篇 |
2000年 | 12篇 |
1999年 | 10篇 |
1998年 | 6篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1974年 | 1篇 |
1971年 | 1篇 |
1970年 | 4篇 |
1966年 | 2篇 |
1965年 | 3篇 |
1961年 | 1篇 |
1960年 | 2篇 |
1959年 | 1篇 |
1957年 | 3篇 |
1951年 | 1篇 |
排序方式: 共有1168条查询结果,搜索用时 281 毫秒
61.
Alvino Maestri Vinicius Albuquerque Sortica Luciana Tovo-Rodrigues Mirleide Cordeiro Santos Luana Barbagelata Milene Raiol Moraes Wyller Alencar de Mello Leonor Gusm?o Rita Catarina Medeiros Sousa Sidney Emanuel Batista dos Santos 《PloS one》2015,10(10)
Different host genetic variants may be related to the virulence and transmissibility of pandemic Influenza A(H1N1)pdm09, influencing events such as binding of the virus to the entry receptor on the cell of infected individuals and the host immune response. In the present study, two genetic variants of the ST3GAL1 gene, which encodes the Siaα2-3Galβ1- receptor to which influenza A(H1N1)pdm09 virus binds for entry into the host cell, were investigated in an admixed Brazilian population. First, the six exons encoding the ST3GAL1 gene were sequenced in 68 patients infected with strain A(H1N1)pdm09. In a second phase of the study, the rs113350588 and rs1048479 polymorphisms identified in this sample were genotyped in a sample of 356 subjects from the northern and northeastern regions of Brazil with a diagnosis of pandemic influenza. Functional analysis of the polymorphisms was performed in silico and the influence of these variants on the severity of infection was evaluated. The results suggest that rs113350588 and rs1048479 may alter the function of ST3GAL1 either directly through splicing regulation alteration and/or indirectly through LD with SNP with regulatory function. In the study the rs113350588 and rs1048479 polymorphisms were in linkage disequilibrium in the population studied (D’ = 0.65). The GC haplotype was associated with an increased risk of death in subjects with influenza (OR = 4.632, 95% CI = 2.10;1.21). The AT haplotype was associated with an increased risk of severe disease and death (OR = 1.993, 95% CI = 1.09;3.61 and OR 4.476, 95% CI = 2.37;8.44, respectively). This study demonstrated for the first time the association of ST3GAL1 gene haplotypes on the risk of more severe disease and death in patients infected with Influenza A(H1N1)pdm09 virus. 相似文献
62.
Bruno Carneiro Ana Cláudia Silva Braga Mariana Nogueira Batista Mark Harris Paula Rahal 《PloS one》2015,10(2)
Hepatitis C virus (HCV) frequently establishes persistent infections in the liver, leading to the development of chronic hepatitis and, potentially, to liver cirrhosis and hepatocellular carcinoma at later stages. The objective of this study was to test the ability of five Dicer substrate siRNAs (DsiRNA) to inhibit HCV replication and to compare these molecules to canonical 21 nt siRNA. DsiRNA molecules were designed to target five distinct regions of the HCV genome – the 5’ UTR and the coding regions for NS3, NS4B, NS5A or NS5B. These molecules were transfected into Huh7.5 cells that stably harboured an HCV subgenomic replicon expressing a firefly luciferase/neoR reporter (SGR-Feo-JFH-1) and were also tested on HCVcc-infected cells. All of the DsiRNAs inhibited HCV replication in both the subgenomic system and HCVcc-infected cells. When DsiRNAs were transfected prior to infection with HCVcc, the inhibition levels reached 99.5%. When directly compared, canonical siRNA and DsiRNA exhibited similar potency of virus inhibition. Furthermore, both types of molecules exhibited similar dynamics of inhibition and frequencies of resistant mutants after 21 days of treatment. Thus, DsiRNA molecules are as potent as 21 nt siRNAs for the inhibition of HCV replication and may provide future approaches for HCV therapy if the emergence of resistant mutants can be addressed. 相似文献
63.
Hudson T. Pinheiro Eric Mazzei Rodrigo L. Moura Gilberto M. Amado-Filho Alfredo Carvalho-Filho Adriana C. Braga Paulo A. S. Costa Beatrice P. Ferreira Carlos Eduardo L. Ferreira Sergio R. Floeter Ronaldo B. Francini-Filho Jo?o Luiz Gasparini Raphael M. Macieira Agnaldo S. Martins George Olavo Caio R. Pimentel Luiz A. Rocha Ivan Sazima Thiony Simon Jo?o Batista Teixeira Lucas B. Xavier Jean-Christophe Joyeux 《PloS one》2015,10(3)
Despite a strong increase in research on seamounts and oceanic islands ecology and biogeography, many basic aspects of their biodiversity are still unknown. In the southwestern Atlantic, the Vitória-Trindade Seamount Chain (VTC) extends ca. 1,200 km offshore the Brazilian continental shelf, from the Vitória seamount to the oceanic islands of Trindade and Martin Vaz. For a long time, most of the biological information available regarded its islands. Our study presents and analyzes an extensive database on the VTC fish biodiversity, built on data compiled from literature and recent scientific expeditions that assessed both shallow to mesophotic environments. A total of 273 species were recorded, 211 of which occur on seamounts and 173 at the islands. New records for seamounts or islands include 191 reef fish species and 64 depth range extensions. The structure of fish assemblages was similar between islands and seamounts, not differing in species geographic distribution, trophic composition, or spawning strategies. Main differences were related to endemism, higher at the islands, and to the number of endangered species, higher at the seamounts. Since unregulated fishing activities are common in the region, and mining activities are expected to drastically increase in the near future (carbonates on seamount summits and metals on slopes), this unique biodiversity needs urgent attention and management. 相似文献
64.
Deysi V. T. Wong Roberto C. P. Lima-Júnior Cibele B. M. Carvalho Vanessa F. Borges Carlos W. S. Wanderley Amanda X. C. Bem Caio A. V. G. Leite Maraiza A. Teixeira Gabriela L. P. Batista Rangel L. Silva Thiago M. Cunha Gerly A. C. Brito Paulo R. C. Almeida Fernando Q. Cunha Ronaldo A. Ribeiro 《PloS one》2015,10(10)
Intestinal mucositis is a common side effect of irinotecan-based anticancer regimens. Mucositis causes cell damage, bacterial/endotoxin translocation and production of cytokines including IL–1 and IL–18. These molecules and toll-like receptors (TLRs) activate a common signaling pathway that involves the Myeloid Differentiation adaptor protein, MyD88, whose role in intestinal mucositis is unknown. Then, we evaluated the involvement of TLRs and MyD88 in the pathogenesis of irinotecan-induced intestinal mucositis. MyD88-, TLR2- or TLR9-knockout mice and C57BL/6 (WT) mice were given either saline or irinotecan (75 mg/kg, i.p. for 4 days). On day 7, animal survival, diarrhea and bacteremia were assessed, and following euthanasia, samples of the ileum were obtained for morphometric analysis, myeloperoxidase (MPO) assay and measurement of pro-inflammatory markers. Irinotecan reduced the animal survival (50%) and induced a pronounced diarrhea, increased bacteremia, neutrophil accumulation in the intestinal tissue, intestinal damage and more than twofold increased expression of MyD88 (200%), TLR9 (400%), TRAF6 (236%), IL–1β (405%), IL–18 (365%), COX–2 (2,777%) and NF-κB (245%) in the WT animals when compared with saline-injected group (P<0.05). Genetic deletion of MyD88, TLR2 or TLR9 effectively controlled the signs of intestinal injury when compared with irinotecan-administered WT controls (P<0.05). In contrast to the MyD88-/- and TLR2-/- mice, the irinotecan-injected TLR9-/- mice showed a reduced survival, a marked diarrhea and an enhanced expression of IL–18 versus irinotecan-injected WT controls. Additionally, the expression of MyD88 was reduced in the TLR2-/- or TLR9-/- mice. This study shows a critical role of the MyD88-mediated TLR2 and TLR9 signaling in the pathogenesis of irinotecan-induced intestinal mucositis. 相似文献
65.
Ana Paula Ribeiro Silvia Maria Amado Jo?o Roberto Casanova Dinato Vitor Daniel Tessutti Isabel Camargo Neves Sacco 《PloS one》2015,10(9)
Aim/Hypothesis
The etiology of plantar fasciitis (PF) has been related to several risk factors, but the magnitude of the plantar load is the most commonly described factor. Although PF is the third most-common injury in runners, only two studies have investigated this factor in runners, and their results are still inconclusive regarding the injury stage.Objective
Analyze and compare the plantar loads and vertical loading rate during running of runners in the acute stage of PF to those in the chronic stage of the injury in relation to healthy runners.Methods
Forty-five runners with unilateral PF (30 acute and 15 chronic) and 30 healthy control runners were evaluated while running at 12 km/h for 40 meters wearing standardized running shoes and Pedar-X insoles. The contact area and time, maximum force, and force-time integral over the rearfoot, midfoot, and forefoot were recorded and the loading rate (20–80% of the first vertical peak) was calculated. Groups were compared by ANOVAs (p<0.05).Results
Maximum force and force-time integral over the rearfoot and the loading rate was higher in runners with PF (acute and chronic) compared with controls (p<0.01). Runners with PF in the acute stage showed lower loading rate and maximum force over the rearfoot compared to runners in the chronic stage (p<0.01).Conclusion
Runners with PF showed different dynamic patterns of plantar loads during running over the rearfoot area depending on the injury stage (acute or chronic). In the acute stage of PF, runners presented lower loading rate and forces over the rearfoot, possibly due to dynamic mechanisms related to pain protection of the calcaneal area. 相似文献66.
Fernanda A. H. Batista Leandro S. Goto Wanius Garcia Derminda I. de Moraes Mario de Oliveira Neto Igor Polikarpov Marcia R. Cominetti Heloísa S. Selistre-de-Araújo Leila M. Beltramini Ana Paula Ulian Araújo 《European biophysics journal : EBJ》2010,39(8):1193-1205
Lectins have been classified into a structurally diverse group of proteins that bind carbohydrates and glycoconjugates with
high specificity. They are extremely useful molecules in the characterization of saccharides, as drug delivery mediators,
and even as cellular surface makers. In this study, we present camptosemin, a new lectin from Camptosema ellipticum. It was characterized as an N-acetyl-d-galactosamine-binding homo-tetrameric lectin, with a molecular weight around 26 kDa/monomers. The monomers were stable over
a wide range of pH values and exhibited pH-dependent oligomerization. Camptosemin promoted adhesion of breast cancer cells
and hemagglutination, and both activities were inhibited by its binding of sugar. The stability and unfolding/folding behavior
of this lectin was characterized using fluorescence and far-UV circular dichroism spectroscopies. The results indicate that
chemical unfolding of camptosemin proceeds as a two-state monomer-tetramer process. In addition, small-angle X-ray scattering
shows that camptosemin behaves as a soluble and stable homo-tetramer molecule in solution. 相似文献
67.
Urška Batista Maja Garvas Marjana Nemec Milan Schara Peter Veranič Tilen Koklic 《Cell biology international》2010,34(6):663-668
Cell detachment procedures can cause severe damage to cells. Many studies require cells to be detached before measurements; therefore, research on cells that have been grown attached to the bottom of the culture dish and later detached represents a special problem with respect to the experimental results when the properties of cell membranes undergo small changes such as in spectroscopic studies of membrane permeability. We characterized the influence of three different detachment procedures: cell scraping by rubber policeman, trypsinization and a citrate buffer treatment on V‐79 cells in the plateau phase of growth (arrested in G1). We have measured cell viability by a dye‐exclusion test; nitroxide reduction kinetics and membrane fluidity by EPR (electron paramagnetic resonance) method using the lipophilic spin‐probe MeFASL(10,3) (5‐doxylpalmitoyl‐methylester), which partitions mainly in cell membranes and the hydrophilic spin‐probe TEMPONE (4‐oxo‐2,2,6,6‐tetramethylpiperidine‐1‐oxyl). The resulting cell damage due to the detachment process was observed with SEM (scanning electron microscopy). We found out that cell viability was 91% for trypsin treatment, 85% for citrate treatment and 70% for cell scraping. Though the plasma membrane was mechanically damaged by scraping, the membrane domain structure was not significantly altered compared with other detachment methods. On the other hand, the spin‐probe reduction rate, which depends both on the transport across plasma membrane as well as on metabolic properties of cells, was the highest for trypsin method, suggesting that metabolic rate was the least influenced. Only the reduction rate of trypsin‐treated cells stayed unchanged after 4 h of stirring in suspension. These results suggest that, compared with scraping cells or using citrate buffer, the most suitable detachment method for V‐79 cells is detachment by trypsin and keeping cells in the stirred cell suspension until measurement. This method provides the highest cell viability, less visible damage on SEM micrographs and leaves the metabolic rate of cells unchanged. 相似文献
68.
Eder Jorge de Oliveira Vanusia Batista Oliveira Amorim Edneide Luciana Santiago Matos Juliana Leles Costa Milene da Silva Castellen Juliano Gomes Pádua Jorge Luiz Loyola Dantas 《Plant Molecular Biology Reporter》2010,28(3):519-530
A set of 81 new microsatellite markers for Carica papaya L. previously identified by data mining using freely available sequence information from Genbank were tested for polymorphism
using 30 germplasm accessions from the Papaya Germplasm Bank (PGM) at Embrapa Mandioca e Fruticultura Tropical (CNPMF) and
18 landraces. The data were used to estimate pairwise genetic distances between the genotypes. A neighbor-joining based dendrogram
was used to define clusters and infer possible genetic structuring of the collection. Most microsatellites were polymorphic
(73%), with an observed number of alleles per locus ranging from one to eleven. The levels of observed and expected heterozygosity
for 51 polymorphic loci varied from 0.00 to 0.85 and from 0.08 to 0.82, averaging 0.19 and 0.59, respectively. Forty-four
percent of microsatellites showed polymorphism information content (PIC) higher than 0.50. The compound microsatellites seem
to be more informative than dinucleotide and trinucleotide repeats in average alleles per locus and PIC. Among dinucleotides,
AG/TC or GA/CT repeat motifs exhibited more informativeness than TA/AT, GT/CA and TG/AC repeat motifs. The neighbor-joining
analysis based on shared allele distance could differentiate all the papaya accessions and landraces as well as differences
in their genetic structure. This set of markers will be useful for examining parentage, inbreeding and population structure
in papaya. 相似文献
69.
Flavio M. Lopes Karla A. Batista Gustavo L. A. Batista Sydnei Mitidieri Luiz Artur M. Bataus Kátia F. Fernandes 《World journal of microbiology & biotechnology》2010,26(7):1155-1161
Three bacterial strains have been isolated from soil in which soybean had been continuously cropped and treated with Opera®, a fungicide containing epoxyconazole and pyraclostrobin. The three strains (1,805, 2,801 and 3,803), obtained from soil at 80–100 cm depth, were selected on medium containing 0.03% Opera®. Morphological examination revealed that the strains were Gram-negative, and two of them (1,805 and 2,801) exhibited polymorphism. The growth profiles demonstrated that 1,805 and 3,803 were more efficient growing in the presence of Opera® than 2,801. Maximum growth was reached between 24 and 48 h, however, 2,801 was not able to survive after this period. The total protein content produced by 1,805, 2,801 and 3,803 in liquid selective medium containing Opera® were 111.0 ± 0.02, 80.0 ± 0.05 and 130.5 ± 0.07 μg/ml, respectively. According to its biochemical and molecular features, strain 1,805 was identified as Klebsiella sp. On the basis of the characteristics presented (facultative anaerobic nature, polymorphic character and capacity of growing in the presence of Opera®) strain 1,805 seems to be able to degrade the epoxyconazole and pyraclostrobin. 相似文献
70.
Rita Ferreira Rui Vitorino Renato M. P. Alves Hans Joachim Appell Scott K. Powers José Alberto Duarte Francisco Amado 《Proteomics》2010,10(17):3142-3154
Skeletal muscle is a highly specialized tissue that contains two distinct mitochondria subpopulations, the subsarcolemmal (SS) and the intermyofibrillar (IMF) mitochondria. Although it is established that these mitochondrial subpopulations differ functionally in several ways, limited information exists about the proteomic differences underlying these functional differences. Therefore, the objective of this study was to biochemically characterize the SS and IMF mitochondria isolated from rat red gastrocnemius skeletal muscle. We separated the two mitochondrial subpopulations from skeletal muscle using a refined method that provides an excellent division of these unique mitochondrial subpopulations. Using proteomics of mitochondria and its subfractions (intermembrane space, matrix and inner membrane), a total of 325 distinct proteins were identified, most of which belong to the functional clusters of oxidative phosphorylation, metabolism and signal transduction. Although more gel spots were observed in SS mitochondria, 38 of the identified proteins were differentially expressed between the SS and IMF subpopulations. Compared to the SS mitochondrial, IMF mitochondria expressed a higher level of proteins associated with oxidative phosphorylation. This observation, coupled with the finding of a higher respiratory chain complex activity in IMF mitochondria, suggests a specialization of IMF mitochondria toward energy production for contractile activity. 相似文献