全文获取类型
收费全文 | 800篇 |
免费 | 67篇 |
专业分类
867篇 |
出版年
2024年 | 3篇 |
2023年 | 9篇 |
2022年 | 11篇 |
2021年 | 24篇 |
2020年 | 11篇 |
2019年 | 21篇 |
2018年 | 21篇 |
2017年 | 15篇 |
2016年 | 36篇 |
2015年 | 61篇 |
2014年 | 67篇 |
2013年 | 76篇 |
2012年 | 83篇 |
2011年 | 70篇 |
2010年 | 58篇 |
2009年 | 41篇 |
2008年 | 42篇 |
2007年 | 58篇 |
2006年 | 35篇 |
2005年 | 31篇 |
2004年 | 30篇 |
2003年 | 24篇 |
2002年 | 25篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1994年 | 1篇 |
1992年 | 1篇 |
排序方式: 共有867条查询结果,搜索用时 15 毫秒
851.
Alessia Cappelli Ulisse Ulissi Matteo Valzano Claudia Damiani Sara Epis Maria Gabriella Gabrielli Stefania Conti Luciano Polonelli Claudio Bandi Guido Favia Irene Ricci 《PloS one》2014,9(5)
The yeast Wickerhamomyces anomalus has been investigated for several years for its wide biotechnological potential, especially for applications in the food industry. Specifically, the antimicrobial activity of this yeast, associated with the production of Killer Toxins (KTs), has attracted a great deal of attention. The strains of W. anomalus able to produce KTs, called “killer” yeasts, have been shown to be highly competitive in the environment. Different W. anomalus strains have been isolated from diverse habitats and recently even from insects. In the malaria mosquito vector Anopheles stephensi these yeasts have been detected in the midgut and gonads. Here we show that the strain of W. anomalus isolated from An. stephensi, namely WaF17.12, is a killer yeast able to produce a KT in a cell-free medium (in vitro) as well as in the mosquito body (in vivo). We showed a constant production of WaF17.12-KT over time, after stimulation of toxin secretion in yeast cultures and reintroduction of the activated cells into the mosquito through the diet. Furthermore, the antimicrobial activity of WaF17.12-KT has been demonstrated in vitro against sensitive microbes, showing that strain WaF17.12 releases a functional toxin. The mosquito-associated yeast WaF17.12 thus possesses an antimicrobial activity, which makes this yeast worthy of further investigations, in view of its potential as an agent for the symbiotic control of malaria. 相似文献
852.
This work is the first attempt to quantify the overall effects of a 13-valent pneumococcal conjugate vaccine (PCV13) vaccination programme in the Dutch population taking into account all the direct and indirect effects of the vaccine on invasive pneumococcal disease. Using available Dutch data, a dynamic transmission model for the spread of pneumococci and potential subsequent invasive pneumococcal disease has been adapted to the Dutch setting. Overall, invasive pneumococcal disease cases in the Netherlands are predicted to decrease from a pre-vaccination level of 2623 cases annually to 2475, 2289, 2185, 2179, and 2178 cases annually 5-, 10-, 20-, 30-, and 40-years, respectively, post-vaccination. Therefore, vaccination with PCV13 in the Netherlands is predicted to lower invasive pneumococcal disease cases per year by up to 445 cases in the medium- to long-term. The results are quite robust for the sensitivity analyses performed on the parameters that regulate herd immunity and competition between vaccine and non-vaccine types. 相似文献
853.
854.
Zhao WQ Chen GH Chen H Pascale A Ravindranath L Quon MJ Alkon DL 《The Journal of biological chemistry》2003,278(6):4205-4215
Annexin II is secreted into the extracellular environment, where, via interactions with specific proteases and extracellular matrix proteins, it participates in plasminogen activation, cell adhesion, and tumor metastasis and invasion. However, mechanisms regulating annexin II transport across the cellular membrane are unknown. In this study, we used coimmunoprecipitation to show that Annexin-II was bound to insulin and insulin-like growth factor-1 (IGF-1) receptors in PC12 cells and NIH-3T3 cells overexpressing insulin (NIH-3T3(IR)) or IGF-1 receptor (NIH-3T3(IGF-1R)). Stimulation of insulin and IGF-1 receptors by insulin caused a temporary dissociation of annexin II from these receptors, which was accompanied by an increased amount of extracellular annexin II detected in the media of PC12, NIH-3T3(IR), and NIH-3T3(IGF-1R) cells but not in that of untransfected NIH-3T3 cells. Activation of a different growth factor receptor, the platelet-derived growth factor receptor, did not produce such results. Tyrphostin AG1024, a tyrosine kinase inhibitor of insulin and IGF-1 receptor, was shown to inhibit annexin II secretion along with reduced receptor phosphorylation. Inhibitors of a few downstream signaling enzymes including phosphatidylinositol 3-kinase, pp60c-Src, and protein kinase C had no effect on insulin-induced annexin II secretion, suggesting a possible direct link between receptor activation and annexin II secretion. Immunocytochemistry revealed that insulin also induced transport of the membrane-bound form of annexin II to the outside layer of the cell membrane and appeared to promote cell aggregation. These results suggest that the insulin receptor and its signaling pathways may participate in molecular mechanisms mediating annexin II secretion. 相似文献
855.
856.
Marta Parazzini Federica Sibella Alessia Paglialonga Paolo Ravazzani 《Bioelectromagnetics》2010,31(7):546-555
In the last few years, significant developments have taken place in the field of Wireless Local Area Networks (WLAN), and the popularity of portable devices supporting Wireless Fidelity (Wi‐Fi) is continuously growing. At the same time, the number of Active Implanted Medical Devices (AIMD) being placed in patients is widely increasing and among them, cochlear implants (CI) are becoming a common aid. The goal of this study is to investigate the effect on the electromagnetic field distribution and the specific absorption rate (SAR) due to the presence of a CI in a head model during far‐field exposure to Wi‐Fi frequencies. The head model was obtained by image segmentation, the implant was modelled as a geometric structure, and the exposure sources were modelled as a uniform plane wave (power density = 10 W/m2) at 2.4, 5.2 and 5.8 GHz. Vertical and horizontal polarizations were simulated. Conditions with and without CI were compared. The findings of that are: (1) local differences in the field distribution close to the CI, comparing the head models with or without the CI; (2) higher field strength and point SAR value in the cochlear region very close to the CI; (3) negligible differences in the field strength and point SAR value in the cochlear region far from the CI; (4) negligible variations in the average SAR values in the cochlea and head due to the presence of the CI. The results of this study conclude that insertion of a CI brings moderate localized differences in the E, H and point SAR distribution when evaluated close to the electrode array in the cochlea, while negligible differences are found in the average SAR values both in the cochlea and head, independent of frequency and wave polarization. Bioelectromagnetics 31:546–555, 2010. © 2010 Wiley‐Liss, Inc. 相似文献
857.
Yassin Refahi Argyris Zardilis Gaël Michelin Raymond Wightman Bruno Leggio Jonathan Legrand Emmanuel Faure Laetitia Vachez Alessia Armezzani Anne-Evodie Risson Feng Zhao Pradeep Das Nathanaël Prunet Elliot M. Meyerowitz Christophe Godin Grégoire Malandain Henrik Jönsson Jan Traas 《Developmental cell》2021,56(4):540-556.e8
858.
Alessia Pasqualato Vittorio Lei Alessandra Cucina Simona Dinicola Fabrizio D'Anselmi Sara Proietti Maria Grazia Masiello Alessandro Palombo Mariano Bizzarri 《Cell Adhesion & Migration》2013,7(5):450-459
Unsuccessful cytotoxic anticancer treatments may contribute to tumor morphologic instability and consequent tissue invasion, promoting the selection of a more malignant phenotype. Indeed, morphological changes have been demonstrated to be more pronounced in strongly vs. weakly metastatic cells.By means of normalized bending energy, we have previously quantitatively defined the link between cell shape modifications and the acquisition of a more malignant phenotype by 5-FU-resistant colon cancer cells (HCT-8FUres). Such changes were significantly correlated with an increase in motility speed. Herein, we propose a method to quantitatively analyze the shape of wild and chemoresistant HCT-8 migration front cells during wound healing assay. We evaluated the reliability of parameters (area/perimeter ratio [A/p], circularity, roundness, fractal dimension, and solidity) in describing the biological behavior of the two cell lines, enabling hence in distinguishing the chemoresistant line from the other one. We found solidity index the parameter that better described the difference between chemoresistant and wild cells. Moreover, solidity is able to capture the differences between chemoresistant and wild cells at each time point of the migration process. Indeed, motility speed was found to be inversely correlated with solidity, a quantitative index of cell deformability. Deformability is an outstanding hallmark of the process leading to metastatic spread; consequently, solidity may be considered a marker of acquired metastatic property. 相似文献
859.
860.