全文获取类型
收费全文 | 1545篇 |
免费 | 89篇 |
国内免费 | 2篇 |
出版年
2022年 | 21篇 |
2021年 | 22篇 |
2020年 | 11篇 |
2019年 | 24篇 |
2018年 | 21篇 |
2017年 | 21篇 |
2016年 | 36篇 |
2015年 | 92篇 |
2014年 | 67篇 |
2013年 | 88篇 |
2012年 | 147篇 |
2011年 | 125篇 |
2010年 | 81篇 |
2009年 | 68篇 |
2008年 | 102篇 |
2007年 | 100篇 |
2006年 | 102篇 |
2005年 | 108篇 |
2004年 | 88篇 |
2003年 | 64篇 |
2002年 | 67篇 |
2001年 | 18篇 |
2000年 | 20篇 |
1999年 | 11篇 |
1998年 | 20篇 |
1997年 | 9篇 |
1996年 | 4篇 |
1995年 | 7篇 |
1994年 | 6篇 |
1993年 | 6篇 |
1992年 | 16篇 |
1991年 | 4篇 |
1990年 | 6篇 |
1989年 | 9篇 |
1988年 | 3篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 6篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1978年 | 6篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1973年 | 2篇 |
1966年 | 1篇 |
1965年 | 2篇 |
1964年 | 1篇 |
1929年 | 1篇 |
排序方式: 共有1636条查询结果,搜索用时 156 毫秒
81.
Kemajittra Jenjaroen Suchintana Chumseng Manutsanun Sumonwiriya Pitchayanant Ariyaprasert Narisara Chantratita Piyanate Sunyakumthorn Maliwan Hongsuwan Vanaporn Wuthiekanun Helen A. Fletcher Prapit Teparrukkul Direk Limmathurotsakul Nicholas P. J. Day Susanna J. Dunachie 《PLoS neglected tropical diseases》2015,9(10)
Background
Melioidosis is an increasingly recognised cause of sepsis and death across South East Asia and Northern Australia, caused by the bacterium Burkholderia pseudomallei. Risk factors include diabetes, alcoholism and renal disease, and a vaccine targeting at-risk populations is urgently required. A better understanding of the protective immune response in naturally infected patients is essential for vaccine design.Methods
We conducted a longitudinal clinical and immunological study of 200 patients with melioidosis on admission, 12 weeks (n = 113) and 52 weeks (n = 65) later. Responses to whole killed B. pseudomallei were measured in peripheral blood mononuclear cells (PBMC) by interferon-gamma (IFN-γ) ELIspot assay and flow cytometry and compared to those of control subjects in the region with diabetes (n = 45) and without diabetes (n = 43).Results
We demonstrated strong CD4+ and CD8+ responses to B. pseudomallei during acute disease, 12 weeks and 52 weeks later. 28-day mortality was 26% for melioidosis patients, and B. pseudomallei-specific cellular responses in fatal cases (mean 98 IFN-γ cells per million PBMC) were significantly lower than those in the survivors (mean 142 IFN-γ cells per million PBMC) in a multivariable logistic regression model (P = 0.01). A J-shaped curve association between circulating neutrophil count and mortality was seen with an optimal count of 4000 to 8000 neutrophils/μl.Melioidosis patients with known diabetes had poor diabetic control (median glycated haemoglobin HbA1c 10.2%, interquartile range 9.2–13.1) and showed a stunted B. pseudomallei-specific cellular response during acute illness compared to those without diabetes.Conclusions
The results demonstrate the role of both CD4+ and CD8+ T-cells in protection against melioidosis, and an interaction between diabetes and cellular responses. This supports development of vaccine strategies that induce strong T-cell responses for the control of intracellular pathogens such as B. pseudomallei. 相似文献82.
Clara Braian Mattias Svensson Susanna Brighenti Maria Lerm Venkata R. Parasa 《Journal of visualized experiments : JoVE》2015,(104)
Tuberculosis (TB) still holds a major threat to the health of people worldwide, and there is a need for cost-efficient but reliable models to help us understand the disease mechanisms and advance the discoveries of new treatment options. In vitro cell cultures of monolayers or co-cultures lack the three-dimensional (3D) environment and tissue responses. Herein, we describe an innovative in vitro model of a human lung tissue, which holds promise to be an effective tool for studying the complex events that occur during infection with Mycobacterium tuberculosis (M. tuberculosis). The 3D tissue model consists of tissue-specific epithelial cells and fibroblasts, which are cultured in a matrix of collagen on top of a porous membrane. Upon air exposure, the epithelial cells stratify and secrete mucus at the apical side. By introducing human primary macrophages infected with M. tuberculosis to the tissue model, we have shown that immune cells migrate into the infected-tissue and form early stages of TB granuloma. These structures recapitulate the distinct feature of human TB, the granuloma, which is fundamentally different or not commonly observed in widely used experimental animal models. This organotypic culture method enables the 3D visualization and robust quantitative analysis that provides pivotal information on spatial and temporal features of host cell-pathogen interactions. Taken together, the lung tissue model provides a physiologically relevant tissue micro-environment for studies on TB. Thus, the lung tissue model has potential implications for both basic mechanistic and applied studies. Importantly, the model allows addition or manipulation of individual cell types, which thereby widens its use for modelling a variety of infectious diseases that affect the lungs. 相似文献
83.
84.
Seema Singh Susanna A. Braus-Stromeyer Christian Timpner Van Tuan Tran Gertrud Lohaus Michael Reusche Jessica Knüfer Thomas Teichmann Andreas von Tiedemann Gerhard H. Braus 《Applied microbiology and biotechnology》2010,85(6):1961-1976
The first leaky auxotrophic mutant for aromatic amino acids of the near-diploid fungal plant pathogen Verticillium longisporum (VL) has been generated. VL enters its host Brassica napus through the roots and colonizes the xylem vessels. The xylem contains little nutrients including low concentrations of amino
acids. We isolated the gene Vlaro2 encoding chorismate synthase by complementation of the corresponding yeast mutant strain. Chorismate synthase produces the
first branch point intermediate of aromatic amino acid biosynthesis. A novel RNA-mediated gene silencing method reduced gene
expression of both isogenes by 80% and resulted in a bradytrophic mutant, which is a leaky auxotroph due to impaired expression
of chorismate synthase. In contrast to the wild type, silencing resulted in increased expression of the cross-pathway regulatory
gene VlcpcA (similar to cpcA/GCN4) during saprotrophic life. The mutant fungus is still able to infect the host plant B. napus and the model Arabidopsis thaliana with reduced efficiency. VlcpcA expression is increased in planta in the mutant and the wild-type fungus. We assume that xylem colonization requires induction
of the cross-pathway control, presumably because the fungus has to overcome imbalanced amino acid supply in the xylem. 相似文献
85.
86.
Magda Gioia Giovanni Francesco Fasciglione Susanna Monaco Riccardo Iundusi Diego Sbardella Stefano Marini Umberto Tarantino Massimo Coletta 《Journal of biological inorganic chemistry》2010,15(8):1219-1232
The proteolytic processing of collagen I by three matrix metalloproteinases (MMPs), a collagenase (MMP-1), a gelatinase (MMP-2),
and the ectodomain of a membrane-type metalloproteinase (MMP-14), has been investigated at 37 °C between pH 6.0 and 9.2, a
pH range reflecting conditions found in different body compartments under various physiopathological processes. In the proteolytic
degradation the native collagen triple helix must be partially unwound to allow the binding of α chains to the protease’s
active-site cleft. We have found that MMP-1 interacts with the two types of collagen I α chains in a similar fashion, whereas
both MMP-2 and MMP-14 bind the two α chains in a different way. The overall enzymatic activity is higher on the α-2 chain
for both MMP-1 and MMP-2, whereas the MMP-14 ectodomain preferentially cleaves the α-1 chain. In MMP-2 a marked difference
for substrate affinity (higher for the α-1 chain) is overwhelmed by an even more marked propensity to cleave the α-2 chain.
As a whole, the three classes of MMPs investigated appear to process collagen I in a significantly different fashion, so various
MMPs play different roles in the collagen homeostasis in various compartments (such as bloodstream, synovial fluid, normal
and tumoral tissues), where different pH values are observed. 相似文献
87.
Cilurzo F Cupone IE Minghetti P Buratti S Selmin F Gennari CG Montanari L 《AAPS PharmSciTech》2010,11(4):1511-1517
This work aimed to develop a fast-dissolving film made of low dextrose equivalent maltodextrins (MDX) containing nicotine
hydrogen tartrate salt (NHT). Particular attention was given to the selection of the suitable taste-masking agent (TMA) and
the characterisation of the ductility and flexibility under different mechanical stresses. MDX with two different dextrose
equivalents (DEs), namely DE 6 and DE 12, were selected in order to evaluate the effect of polymer molecular weight on film
tensile properties. The bitterness and astringency intensity of NHT and the suppression effect of several TMA were evaluated
by a Taste-Sensing System. The films were characterised in term of NHT content, tensile properties, disintegration time and
drug dissolution test. As expected, placebo films made of MDX DE 6 appeared stiffer and less ductile than film prepared using
MDX DE 12. The films disintegrated within 10 s. Among the tested TMA, the milk and mint flavours resulted particularly suitable
to mask the taste of NHT. The addition of NHT and taste-masking agents affected film tensile properties; however, the effect
of the addition of these components can be counterweighted by modulating the glycerine content and/or the MDX molecular weight.
The feasibility of NHT loaded fast-dissolving films was demonstrated. 相似文献
88.
89.
Among 21 human strains of Laribacter hongkongensis, small plasmids were observed in four strains, and large ones in six strains. The smallest, 3264-bp plasmid, pHLHK19, has only one ORF that encodes a putative replication initiator protein and a predicted origin of replication (ori) with a DnaA box, three 18-bp direct repeats and five pairs of inverted repeats. An Escherichia coli-L. hongkongensis shuttle vector was constructed by ligating the HindIII-digested pHLHK19, containing the replication initiator protein and ori of pHLHK19, to HindIII-digested pBK-CMV. This shuttle vector can propagate in E. coli and L. hongkongensis with good transformation efficiencies. 相似文献
90.
Regulation of DMBT1 via NOD2 and TLR4 in intestinal epithelial cells modulates bacterial recognition and invasion 总被引:3,自引:0,他引:3
Rosenstiel P Sina C End C Renner M Lyer S Till A Hellmig S Nikolaus S Fölsch UR Helmke B Autschbach F Schirmacher P Kioschis P Hafner M Poustka A Mollenhauer J Schreiber S 《Journal of immunology (Baltimore, Md. : 1950)》2007,178(12):8203-8211
Mucosal epithelial cell layers are constantly exposed to a complex resident microflora. Deleted in malignant brain tumors 1 (DMBT1) belongs to the group of secreted scavenger receptor cysteine-rich proteins and is considered to be involved in host defense by pathogen binding. This report describes the regulation and function of DMBT1 in intestinal epithelial cells, which form the primary immunological barrier for invading pathogens. We report that intestinal epithelial cells up-regulate DMBT1 upon proinflammatory stimuli (e.g., TNF-alpha, LPS). We demonstrate that DMBT1 is a target gene for the intracellular pathogen receptor NOD2 via NF-kappaB activation. DMBT1 is strongly up-regulated in the inflamed intestinal mucosa of Crohn's disease patients with wild-type, but not with mutant NOD2. We show that DMBT1 inhibits cytoinvasion of Salmonella enterica and LPS- and muramyl dipeptide-induced NF-kappaB activation and cytokine secretion in vitro. Thus, DMBT1 may play an important role in the first line of mucosal defense conferring immune exclusion of bacterial cell wall components. Dysregulated intestinal DMBT1 expression due to mutations in the NOD2/CARD15 gene may be part of the complex pathophysiology of barrier dysfunction in Crohn's disease. 相似文献