全文获取类型
收费全文 | 3028篇 |
免费 | 181篇 |
国内免费 | 1篇 |
出版年
2024年 | 5篇 |
2023年 | 28篇 |
2022年 | 23篇 |
2021年 | 120篇 |
2020年 | 77篇 |
2019年 | 83篇 |
2018年 | 97篇 |
2017年 | 83篇 |
2016年 | 116篇 |
2015年 | 189篇 |
2014年 | 181篇 |
2013年 | 232篇 |
2012年 | 275篇 |
2011年 | 253篇 |
2010年 | 160篇 |
2009年 | 133篇 |
2008年 | 150篇 |
2007年 | 183篇 |
2006年 | 165篇 |
2005年 | 145篇 |
2004年 | 144篇 |
2003年 | 99篇 |
2002年 | 93篇 |
2001年 | 21篇 |
2000年 | 14篇 |
1999年 | 17篇 |
1998年 | 27篇 |
1997年 | 13篇 |
1996年 | 8篇 |
1995年 | 9篇 |
1994年 | 7篇 |
1993年 | 7篇 |
1992年 | 4篇 |
1991年 | 12篇 |
1989年 | 9篇 |
1988年 | 5篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1971年 | 2篇 |
排序方式: 共有3210条查询结果,搜索用时 15 毫秒
991.
Tiago Ant?nio de Oliveira Mendes Jo?o Luís Reis Cunha Rodrigo de Almeida Lourdes Gabriela Flávia Rodrigues Luiz Lucas Dhom Lemos Ana Rita Rocha dos Santos Ant?nia Cláudia Jácome da Camara Lúcia Maria da Cunha Galv?o Caryn Bern Robert H. Gilman Ricardo Toshio Fujiwara Ricardo Tostes Gazzinelli Daniella Castanheira Bartholomeu 《PLoS neglected tropical diseases》2013,7(10)
Background
The factors influencing variation in the clinical forms of Chagas disease have not been elucidated; however, it is likely that the genetics of both the host and the parasite are involved. Several studies have attempted to correlate the T. cruzi strains involved in infection with the clinical forms of the disease by using hemoculture and/or PCR-based genotyping of parasites from infected human tissues. However, both techniques have limitations that hamper the analysis of large numbers of samples. The goal of this work was to identify conserved and polymorphic linear B-cell epitopes of T. cruzi that could be used for serodiagnosis and serotyping of Chagas disease using ELISA.Methodology
By performing B-cell epitope prediction on proteins derived from pair of alleles of the hybrid CL Brener genome, we have identified conserved and polymorphic epitopes in the two CL Brener haplotypes. The rationale underlying this strategy is that, because CL Brener is a recent hybrid between the TcII and TcIII DTUs (discrete typing units), it is likely that polymorphic epitopes in pairs of alleles could also be polymorphic in the parental genotypes. We excluded sequences that are also present in the Leishmania major, L. infantum, L. braziliensis and T. brucei genomes to minimize the chance of cross-reactivity. A peptide array containing 150 peptides was covalently linked to a cellulose membrane, and the reactivity of the peptides was tested using sera from C57BL/6 mice chronically infected with the Colombiana (TcI) and CL Brener (TcVI) clones and Y (TcII) strain.Findings and Conclusions
A total of 36 peptides were considered reactive, and the cross-reactivity among the strains is in agreement with the evolutionary origin of the different T. cruzi DTUs. Four peptides were tested against a panel of chagasic patients using ELISA. A conserved peptide showed 95.8% sensitivity, 88.5% specificity, and 92.7% accuracy for the identification of T. cruzi in patients infected with different strains of the parasite. Therefore, this peptide, in association with other T. cruzi antigens, may improve Chagas disease serodiagnosis. Together, three polymorphic epitopes were able to discriminate between the three parasite strains used in this study and are thus potential targets for Chagas disease serotyping. 相似文献992.
Gabriela Trigo Teresa G. Martins Alexandra G. Fraga Adhemar Longatto-Filho António G. Castro Joana Azeredo Jorge Pedrosa 《PLoS neglected tropical diseases》2013,7(4)
Background
Buruli Ulcer (BU) is a neglected, necrotizing skin disease caused by Mycobacterium ulcerans. Currently, there is no vaccine against M. ulcerans infection. Although the World Health Organization recommends a combination of rifampicin and streptomycin for the treatment of BU, clinical management of advanced stages is still based on the surgical resection of infected skin. The use of bacteriophages for the control of bacterial infections has been considered as an alternative or to be used in association with antibiotherapy. Additionally, the mycobacteriophage D29 has previously been shown to display lytic activity against M. ulcerans isolates.Methodology/Principal findings
We used the mouse footpad model of M. ulcerans infection to evaluate the therapeutic efficacy of treatment with mycobacteriophage D29. Analyses of macroscopic lesions, bacterial burdens, histology and cytokine production were performed in both M. ulcerans-infected footpads and draining lymph nodes (DLN). We have demonstrated that a single subcutaneous injection of the mycobacteriophage D29, administered 33 days after bacterial challenge, was sufficient to decrease pathology and to prevent ulceration. This protection resulted in a significant reduction of M. ulcerans numbers accompanied by an increase of cytokine levels (including IFN-γ), both in footpads and DLN. Additionally, mycobacteriophage D29 treatment induced a cellular infiltrate of a lymphocytic/macrophagic profile.Conclusions/Significance
Our observations demonstrate the potential of phage therapy against M. ulcerans infection, paving the way for future studies aiming at the development of novel phage-related therapeutic approaches against BU. 相似文献993.
Siobhan Simpson Nick Blampied Gabriela Peniche Anne Dozières Tiffany Blackett Stephen Coleman Nina Cornish Jim J. Groombridge 《Ecology and evolution》2013,3(3):614-628
Wildlife populations have been introduced to new areas by people for centuries, but this human‐mediated movement can disrupt natural patterns of genetic structure by altering patterns of gene flow. Insular populations are particularly prone to these influences due to limited opportunities for natural dispersal onto islands. Consequently, understanding how genetic patterns develop in island populations is important, particularly given that islands are frequently havens for protected wildlife. We examined the evolutionary origins and extent of genetic structure within the introduced island population of red squirrels (Sciurus vulgaris) on the Channel Island of Jersey using mitochondrial DNA (mtDNA) control region sequence and nuclear microsatellite genotypes. Our findings reveal two different genetic origins and a genetic architecture reflective of the introductions 120 years ago. Genetic structure is marked within the maternally inherited mtDNA, indicating slow dispersal of female squirrels. However, nuclear markers detected only weak genetic structure, indicating substantially greater male dispersal. Data from both mitochondrial and nuclear markers support historic records that squirrels from England were introduced to the west of the island and those from mainland Europe to the east. Although some level of dispersal and introgression across the island between the two introductions is evident, there has not yet been sufficient gene flow to erase this historic genetic “footprint.” We also investigated if inbreeding has contributed to high observed levels of disease, but found no association. Genetic footprints of introductions can persist for considerable periods of time and beyond traditional timeframes of wildlife management. 相似文献
994.
Optimal Construction Morphology (OCM) is a new construction-based theory of morphology that selects the optimal combination of lexical constructions to best achieve a target meaning. OCM combines elements of realizational and item-based morphological theories. It is realizational, in that words are constructed in response to a given meaning target. It is incremental in that words are built from lexical structures, one layer at a time. It is optimizing in that, in response to a meaning target, the morphological grammar dips into the lexicon, building and assessing morphological constituents incrementally until the word being built optimally matches the target meaning. In this paper OCM is shown to illuminate a vexing optimization puzzle confronted by all theories of morphology: why is redundancy in morphology rejected as ungrammatical in some situations (“blocking”), but absolutely required in others (“multiple/extended exponence”)? The OCM analysis incorporates two notions of morphological strength that have been proposed in the literature: stem type, on a scale from root (weakest) to word (strongest), and exponence strength, related to productivity and parsability. 相似文献
995.
Gabriela Campanholle Kristen Mittelsteadt Shunsaku Nakagawa Akio Kobayashi Shuei-Liong Lin Sina A. Gharib Jay W. Heinecke Jessica A. Hamerman William A. Altemeier Jeremy S. Duffield 《PloS one》2013,8(7)
Inflammatory macrophages are abundant in kidney disease, stimulating repair, or driving chronic inflammation and fibrosis. Damage associated molecules (DAMPs), released from injured cells engage pattern recognition receptors (PRRs) on macrophages, contributing to activation. Understanding mechanisms of macrophage activation during kidney injury may lead to strategies to alleviate chronic disease. We identified Triggering-Receptor-in-Myeloid-cells (TREM)-1, a regulator of TLR signaling, as highly upregulated in kidney inflammatory macrophages and tested the roles of these receptors in macrophage activation and kidney disease. Kidney DAMPs activated macrophages in vitro, independently of TREM-1, but partially dependent on TLR-2/−4, MyD88. In two models of progressive interstitial kidney disease, TREM-1 blockade had no impact on disease or macrophage activation in vivo, but TLR-2/−4, or MyD88 deficiency was anti-inflammatory and anti-fibrotic. When MyD88 was mutated only in the myeloid lineage, however, there was no bearing on macrophage activation or disease progression. Instead, TLR-2/−4 or MyD88 deficiency reduced activation of mesenchyme lineage cells resulting in reduced inflammation and fibrosis, indicating that these pathways play dominant roles in activation of myofibroblasts but not macrophages. To conclude, TREM-1, TLR2/4 and MyD88 signaling pathways are redundant in myeloid cell activation in kidney injury, but the latter appear to regulate activation of mesenchymal cells. 相似文献
996.
Jean de Dieu Tamokou Jean Rodolphe Chouna Eva Fischer-Fodor Gabriela Chereches Otilia Barbos Grigore Damian Daniela Benedec Mihaela Duma Alango Pépin Nkeng Efouet Hippolyte Kamdem Wabo Jules Roger Kuiate Augustin Mot Radu Silaghi-Dumitrescu 《PloS one》2013,8(2)
Traditional remedies have a long-standing history in Cameroon and continue to provide useful and applicable tools for treating ailments. Here, the anticancer, antimicrobial and antioxidant activities of ten antioxidant-rich Cameroonian medicinal plants and of some of their isolated compounds are evaluated.The plant extracts were prepared by maceration in organic solvents. Fractionation of plant extract was performed by column chromatography and the structures of isolated compounds (emodin, 3-geranyloxyemodin, 2-geranylemodin) were confirmed spectroscopically. The antioxidant activity (AOA) was determined using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) bleaching method, the trolox equivalent antioxidant capacity (TEAC), and the hemoglobin ascorbate peroxidase activity inhibition (HAPX) assays. The anticancer activity was evaluated against A431 squamous epidermal carcinoma, WM35 melanoma, A2780 ovary carcinoma and cisplatin-resistant A2780cis cells, using a direct colorimetric assay. The total phenolic content in the extracts was determined spectrophotometrically by the Folin–Ciocalteu method. Rumex abyssinicus showed the best AOA among the three assays employed. The AOA of emodin was significantly higher than that of 3-geranyloxyemodin and 2-geranylemodin for both TEAC and HAPX methods. The lowest IC50 values (i.e., highest cytotoxicity) were found for the extracts of Vismia laurentii, Psorospermum febrifugum, Pentadesma butyracea and Ficus asperifolia. The Ficus asperifolia and Psorospermum febrifugum extracts are selective against A2780cis ovary cells, a cell line which is resistant to the standard anticancer drug cisplatin. Emodin is more toxic compared to the whole extract, 3-geranyloxyemodin and 2-geranylemodin. Its selectivity against the platinum-resistant A2780cis cell line is highest. All of the extracts display antimicrobial activity, in some cases comparable to that of gentamycin. 相似文献
997.
Maria Noel Badano Gabriela Lorena Camicia Gabriela Lombardi Andrea Maglioco Gabriel Cabrera Hector Costa Roberto Pablo Meiss Isabel Piazzon Irene Nepomnaschy 《PloS one》2013,8(4)
Cathepsin L (CTSL) is a ubiquitously expressed lysosomal cysteine peptidase with diverse and highly specific functions. The involvement of CTSL in thymic CD4+ T-cell positive selection has been well documented. Using CTSLnkt/nkt mice that lack CTSL activity, we have previously demonstrated that the absence of CTSL activity affects the homeostasis of the T-cell pool by decreasing CD4+ cell thymic production and increasing CD8+ thymocyte production. Herein we investigated the influence of CTSL activity on the homeostasis of peripheral B-cell populations and bone marrow (BM) B-cell maturation. B-cell numbers were increased in lymph nodes (LN), spleen and blood from CTSLnkt/nkt mice. Increases in splenic B-cell numbers were restricted to transitional T1 and T2 cells and to the marginal zone (MZ) cell subpopulation. No alterations in the proliferative or apoptosis levels were detected in peripheral B-cell populations from CTSLnkt/nkt mice. In the BM, the percentage and the absolute number of pre-pro-B, pro-B, pre-B, immature and mature B cells were not altered. However, in vitro and in vivo experiments showed that BM B-cell production was markedly increased in CTSLnkt/nkt mice. Besides, BM B-cell emigration to the spleen was increased in CTSLnkt/nkt mice. Colony-forming unit pre-B (CFU pre-B) assays in the presence of BM stromal cells (SC) and reciprocal BM chimeras revealed that both BM B-cell precursors and SC would contribute to sustain the increased B-cell hematopoiesis in CTSLnkt/nkt mice. Overall, our data clearly demonstrate that CTSL negatively regulates BM B-cell production and output therefore influencing the homeostasis of peripheral B cells. 相似文献
998.
Thalita Ewellyn Batista Sales Marques Leila Rodrigues de Mendon?a Marília Gabriela Pereira Tiago Gomes de Andrade Norberto Garcia-Cairasco Maria Luisa Pa?ó-Larson Daniel Leite Góes Gitaí 《PloS one》2013,8(8)
It is well recognized that the reference gene in a RT-qPCR should be properly validated to ensure that gene expression is unaffected by the experimental condition. We investigated eight potential reference genes in two different pilocarpine PILO-models of mesial temporal lobe epilepsy (MTLE) performing a stability expression analysis using geNorm, NormFinder and BestKepeer softwares. Then, as a validation strategy, we conducted a relative expression analysis of the Gfap gene. Our results indicate that in the systemic PILO-model Actb, Gapdh, Rplp1, Tubb2a and Polr1a mRNAs were highly stable in hippocampus of rats from all experimental and control groups, whereas Gusb revealed to be the most variable one. In fact, we observed that using Gusb for normalization, the relative mRNA levels of the Gfap gene differed from those obtained with stable genes. On the contrary, in the intrahippocampal PILO-model, all softwares included Gusb as a stable gene, whereas B2m was indicated as the worst candidate gene. The results obtained for the other reference genes were comparable to those observed for the systemic Pilo-model. The validation of these data by the analysis of the relative expression of Gfap showed that the upregulation of the Gfap gene in the hippocampus of rats sacrificed 24 hours after status epilepticus (SE) was undetected only when B2m was used as the normalizer. These findings emphasize that a gene that is stable in one pathology model may not be stable in a different experimental condition related to the same pathology and therefore, the choice of reference genes depends on study design. 相似文献
999.
Health Disparities from Economic Burden of Diabetes in Middle-income Countries: Evidence from México
The rapid growth of diabetes in middle-income countries is generating disparities in global health. In this context we conducted a study to quantify the health disparities from the economic burden of diabetes in México. Evaluative research based on a longitudinal design, using cost methodology by instrumentation. For the estimation of epidemiological changes during the 2010–2012 period, several probabilistic models were developed using the Box-Jenkins technique. The financial requirements were obtained from expected case management costs by disease and the application of an econometric adjustment factor to control the effects of inflation. Comparing the economic impact in 2010 versus 2012 (p<0.05), there was a 33% increase in financial requirements. The total amount for diabetes in 2011 (US dollars) was $7.7 billion. It includes $3.4 billion in direct costs and $4.3 in indirect costs. The total direct costs were $.4 billion to the Ministry of Health (SSA), serving the uninsured population; $1.2 to the institutions serving the insured population (Mexican Institute for Social Security–IMSS-, and Institute for Social Security and Services for State Workers-ISSSTE-); $1.8 to users; and $.1 to Private Health Insurance (PHI). If the risk factors and the different health care models remain as they currently are in the analyzed institutions, health disparities in terms of financial implications will have the greatest impact on users’ pockets. In middle-income countries, health disparities generated by the economic burden of diabetes is one of the main reasons for catastrophic health expenditure. Health disparities generated by the economic burden of diabetes suggests the need to design and review the current organization of health systems and the relevance of moving from biomedical models and curative health care to preventive and socio-medical models to meet expected challenges from diseases like diabetes in middle-income countries. 相似文献
1000.
Lukas Fenner Marie Ballif Claire Graber Venerandah Nhandu Jean Claude Dusingize Claudia P. Cortes Gabriela Carriquiry Kathryn Anastos Daniela Garone Eefje Jong Joachim Charles Gnokoro Omar Sued Samuel Ajayi Lameck Diero Kara Wools-Kaloustian Sasisopin Kiertiburanakul Barbara Castelnuovo Charlotte Lewden Nicolas Durier Timothy R. Sterling Matthias Egger for the International epidemiological Databases to Evaluate AIDS 《PloS one》2013,8(10)