全文获取类型
收费全文 | 192篇 |
免费 | 13篇 |
出版年
2023年 | 3篇 |
2022年 | 3篇 |
2021年 | 16篇 |
2020年 | 11篇 |
2019年 | 9篇 |
2018年 | 6篇 |
2017年 | 12篇 |
2016年 | 8篇 |
2015年 | 18篇 |
2014年 | 18篇 |
2013年 | 21篇 |
2012年 | 20篇 |
2011年 | 11篇 |
2010年 | 6篇 |
2009年 | 5篇 |
2008年 | 4篇 |
2007年 | 4篇 |
2006年 | 5篇 |
2005年 | 1篇 |
2004年 | 1篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1997年 | 3篇 |
1995年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1973年 | 1篇 |
1963年 | 1篇 |
1951年 | 1篇 |
1950年 | 1篇 |
1949年 | 1篇 |
1948年 | 2篇 |
1947年 | 1篇 |
1867年 | 1篇 |
1866年 | 1篇 |
排序方式: 共有205条查询结果,搜索用时 140 毫秒
101.
Katelyn M. Gostic Lauren McGough Edward B. Baskerville Sam Abbott Keya Joshi Christine Tedijanto Rebecca Kahn Rene Niehus James A. Hay Pablo M. De Salazar Joel Hellewell Sophie Meakin James D. Munday Nikos I. Bosse Katharine Sherrat Robin N. Thompson Laura F. White Jana S. Huisman Jrmie Scire Sebastian Bonhoeffer Tanja Stadler Jacco Wallinga Sebastian Funk Marc Lipsitch Sarah Cobey 《PLoS computational biology》2020,16(12)
Estimation of the effective reproductive number Rt is important for detecting changes in disease transmission over time. During the Coronavirus Disease 2019 (COVID-19) pandemic, policy makers and public health officials are using Rt to assess the effectiveness of interventions and to inform policy. However, estimation of Rt from available data presents several challenges, with critical implications for the interpretation of the course of the pandemic. The purpose of this document is to summarize these challenges, illustrate them with examples from synthetic data, and, where possible, make recommendations. For near real-time estimation of Rt, we recommend the approach of Cori and colleagues, which uses data from before time t and empirical estimates of the distribution of time between infections. Methods that require data from after time t, such as Wallinga and Teunis, are conceptually and methodologically less suited for near real-time estimation, but may be appropriate for retrospective analyses of how individuals infected at different time points contributed to the spread. We advise caution when using methods derived from the approach of Bettencourt and Ribeiro, as the resulting Rt estimates may be biased if the underlying structural assumptions are not met. Two key challenges common to all approaches are accurate specification of the generation interval and reconstruction of the time series of new infections from observations occurring long after the moment of transmission. Naive approaches for dealing with observation delays, such as subtracting delays sampled from a distribution, can introduce bias. We provide suggestions for how to mitigate this and other technical challenges and highlight open problems in Rt estimation. 相似文献
102.
103.
Alicia S Linford Heriberto Moreno Katelyn R Good Hanbang Zhang Upinder Singh William A Petri 《BMC microbiology》2009,9(1):38
Background
Entamoeba histolytica is an intestinal protozoan parasite of humans. The genome has been sequenced, but the study of individual gene products has been hampered by the lack of the ability to generate gene knockouts. We chose to test the use of RNA interference to knock down gene expression in Entamoeba histolytica. 相似文献104.
Mark P. Rubinstein Ee Wern Su Samantha Suriano Colleen A. Cloud Kristina Andrijauskaite Pravin Kesarwani Kristina M. Schwartz Katelyn M. Williams C. Bryce Johnson Mingli Li Gina M. Scurti Mohamed L. Salem Chrystal M. Paulos Elizabeth Garrett-Mayer Shikhar Mehrotra David J. Cole 《Cancer immunology, immunotherapy : CII》2015,64(5):539-549
105.
Erich A. Heise Lauren M. Marozas Sean A. Grafton Katelyn M. Green Stefanie J. Kirwin Patrice E. Fort 《PloS one》2013,8(12)
Diabetic retinopathy is the leading cause of vision loss in working-age individuals in the United States and is expected to continue growing with the increased prevalence of diabetes. Streptozotocin-induced hyperglycemia in rats is the most commonly used model for diabetic retinopathy. Previous studies have shown that this model can lead to different inflammatory changes in the retina depending on the strain of rat. Our previous work has shown that crystallin proteins, including members of the alpha- and beta/gamma-crystallin subfamilies, are upregulated in the STZ rat retina. Crystallin proteins have been implicated in a number of cellular processes, such as neuroprotection, non-native protein folding and vascular remodeling. In this current study, we have demonstrated that unlike other strain-dependent changes, such as inflammatory cytokines and growth factor levels, in the STZ rat, the protein upregulation of crystallins is consistent across the Brown Norway, Long-Evans and Sprague-Dawley rat strains in the context of diabetes. Taken together, these data illustrate the potential critical role played by crystallins, and especially alpha-crystallins, in the retina in the context of diabetes. 相似文献
106.
107.
Differential Expression of Estrogen Receptor Variants in Response to Inflammation Signals in Human Airway Smooth Muscle
下载免费PDF全文
![点击此处可从《Journal of cellular physiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
108.
109.
Michael Z. Levy Aaron Tustin Ricardo Castillo-Neyra Tarub S. Mabud Katelyn Levy Corentin M. Barbu Victor R. Quispe-Machaca Jenny Ancca-Juarez Katty Borrini-Mayori Cesar Naquira-Velarde Richard S. Ostfeld and the Chagas Disease Working Group in Arequipa 《Proceedings. Biological sciences / The Royal Society》2015,282(1810)
Faeces-mediated transmission of Trypanosoma cruzi (the aetiological agent of Chagas disease) by triatomine insects is extremely inefficient. Still, the parasite emerges frequently, and has infected millions of people and domestic animals. We synthesize here the results of field and laboratory studies of T. cruzi transmission conducted in and around Arequipa, Peru. We document the repeated occurrence of large colonies of triatomine bugs (more than 1000) with very high infection prevalence (more than 85%). By inoculating guinea pigs, an important reservoir of T. cruzi in Peru, and feeding triatomine bugs on them weekly, we demonstrate that, while most animals quickly control parasitaemia, a subset of animals remains highly infectious to vectors for many months. However, we argue that the presence of these persistently infectious hosts is insufficient to explain the observed prevalence of T. cruzi in vector colonies. We posit that seasonal rains, leading to a fluctuation in the price of guinea pig food (alfalfa), leading to annual guinea pig roasts, leading to a concentration of vectors on a small subpopulation of animals maintained for reproduction, can propel T. cruzi through vector colonies and create a considerable force of infection for a pathogen whose transmission might otherwise fizzle out. 相似文献
110.
Hoffmann GR Gessner GS Hughes JF Ronan MV Sylvia KE Willett CJ 《Mutation research》2007,623(1-2):41-52
The effects of amines on the induction of mitotic gene conversion by bleomycin (BLM) were studied at the trp5 locus in Saccharomyces cerevisiae strain D7. BLM induces double-strand breaks in DNA and is a potent recombinagen in this assay. The polyamine spermidine causes concentration-dependent protection against the genotoxicity of BLM, reducing the convertant frequency by over 90% under the most protective conditions. Spermine, diethylenetriamine, ethylenediamine, putrescine, and ethylamine were also antigenotoxic in combined treatments with BLM. There was a general correspondence between the protective effect and the number of amino groups, suggesting that more strongly cationic amines tend to be stronger antirecombinagens. Electrostatic association of the amines with DNA probably hinders BLM access to the 4' position of deoxyribose where it generates a free radical. Other amines interact with BLM differently from these unbranched aliphatic amines. The aminothiol cysteamine inhibits the genotoxicity of BLM under hypoxic conditions but increases it under euoxic conditions. In contrast, pargyline potentiates the genotoxicity of BLM under hypoxic conditions but not under euoxic conditions. The antirecombinagenic effect of cysteamine apparently involves DNA binding and depletion of oxygen needed for BLM activity, whereas its potentiation of BLM entails its serving as an electron source for the activation of BLM. Pargyline may enhance BLM indirectly by preventing the depletion of oxygen by monoamine and polyamine oxidase. The planar 9-aminoacridine weakly induces gene conversion in strain D7, but it is strongly synergistic with BLM. Enhancement of BLM activity by this compound and by the related nitroacridine Entozon is apparently mediated by intercalation of the acridine ring system into DNA. Thus, the influence of amines on the genotoxicity of BLM in yeast encompasses antigenotoxic, potentiating, and synergistic interactions. The underlying mechanisms involve noncovalent association with DNA, altered BLM access to DNA, and modulation of physiological conditions. 相似文献