全文获取类型
收费全文 | 7315篇 |
免费 | 537篇 |
国内免费 | 14篇 |
出版年
2023年 | 29篇 |
2022年 | 31篇 |
2021年 | 124篇 |
2020年 | 86篇 |
2019年 | 98篇 |
2018年 | 127篇 |
2017年 | 103篇 |
2016年 | 202篇 |
2015年 | 321篇 |
2014年 | 342篇 |
2013年 | 424篇 |
2012年 | 531篇 |
2011年 | 574篇 |
2010年 | 366篇 |
2009年 | 293篇 |
2008年 | 410篇 |
2007年 | 438篇 |
2006年 | 411篇 |
2005年 | 354篇 |
2004年 | 321篇 |
2003年 | 324篇 |
2002年 | 315篇 |
2001年 | 65篇 |
2000年 | 45篇 |
1999年 | 68篇 |
1998年 | 71篇 |
1997年 | 57篇 |
1996年 | 45篇 |
1995年 | 62篇 |
1994年 | 47篇 |
1993年 | 55篇 |
1992年 | 52篇 |
1991年 | 22篇 |
1990年 | 28篇 |
1989年 | 23篇 |
1988年 | 33篇 |
1987年 | 27篇 |
1986年 | 27篇 |
1985年 | 37篇 |
1984年 | 51篇 |
1983年 | 34篇 |
1982年 | 52篇 |
1981年 | 44篇 |
1980年 | 49篇 |
1979年 | 23篇 |
1978年 | 34篇 |
1977年 | 30篇 |
1976年 | 26篇 |
1975年 | 21篇 |
1973年 | 26篇 |
排序方式: 共有7866条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
Nikolay Kutuzov Alexander Gulin Vladimir Lyaskovskiy Victor Nadtochenko Georgy Maksimov 《PloS one》2015,10(11)
In the present paper we addressed a mechanism of the myelin reorganization initiated by extracellular ATP and adenosine in sciatic nerves of the frog Rana temporaria. In combination with Raman microspectroscopy, allowing noninvasive live-cell measurements, we employed time-of-flight secondary ion mass spectrometry (TOF-SIMS) to follow the underlying changes in chemical composition of myelin membranes triggered by the purinergic agents. The simultaneous increase in lipid ordering degree, decrease in membrane fluidity and the degree of fatty acid unsaturation were induced by both ATP and adenosine. Mass spectrometry measurements revealed that ATP administration also led to the marked elevation of membrane cholesterol and decrease of phosphotidylcholine amounts. Vesicular lipid transport pathways are considered as possible mechanisms of compositional and structural changes of myelin. 相似文献
6.
7.
8.
Microparticles (MPs) are small membrane fragments shed from normal as well as activated, apoptotic or injured cells. Emerging evidence implicates MPs as a causal and/or contributing factor in altering normal vascular cell phenotype through initiation of proinflammatory signal transduction events and paracrine delivery of proteins, mRNA and miRNA. However, little is known regarding the mechanism by which MPs influence these events. Caveolae are important membrane microdomains that function as centers of signal transduction and endocytosis. Here, we tested the concept that the MP-induced pro-inflammatory phenotype shift in endothelial cells (ECs) depends on caveolae. Consistent with previous reports, MP challenge activated ECs as evidenced by upregulation of intracellular adhesion molecule-1 (ICAM-1) expression. ICAM-1 upregulation was mediated by activation of NF-κB, Poly [ADP-ribose] polymerase 1 (PARP-1) and the epidermal growth factor receptor (EGFR). This response was absent in ECs lacking caveolin-1/caveolae. To test whether caveolae-mediated endocytosis, a dynamin-2 dependent process, is a feature of the proinflammatory response, EC’s were pretreated with the dynamin-2 inhibitor dynasore. Similar to observations in cells lacking caveolin-1, inhibition of endocytosis significantly attenuated MPs effects including, EGFR phosphorylation, activation of NF-κB and upregulation of ICAM-1 expression. Thus, our results indicate that caveolae play a role in mediating the pro-inflammatory signaling pathways which lead to EC activation in response to MPs. 相似文献
9.
Household‐level correlates of children's physical activity levels in and across 12 countries 下载免费PDF全文
Deirdre M. Harrington Fiona Gillison Stephanie T. Broyles Jean‐Philippe Chaput Mikael Fogelholm Gang Hu Rebecca Kuriyan Anura Kurpad Allana G. LeBlanc Carol Maher Jose Maia Victor Matsudo Timothy Olds Vincent Onywera Olga L. Sarmiento Martyn Standage Mark S. Tremblay Catrine Tudor‐Locke Pei Zhao Peter T. Katzmarzyk for the ISCOLE Research Group 《Obesity (Silver Spring, Md.)》2016,24(10):2150-2157
10.
In this paper we propose an instrument for collecting sensitive data that allows for each participant to customize the amount of information that she is comfortable revealing. Current methods adopt a uniform approach where all subjects are afforded the same privacy guarantees; however, privacy is a highly subjective property with intermediate points between total disclosure and non-disclosure: each respondent has a different criterion regarding the sensitivity of a particular topic. The method we propose empowers respondents in this respect while still allowing for the discovery of interesting findings through the application of well-known inferential procedures. 相似文献