全文获取类型
收费全文 | 578574篇 |
免费 | 63195篇 |
国内免费 | 411篇 |
出版年
2018年 | 4856篇 |
2016年 | 6629篇 |
2015年 | 9209篇 |
2014年 | 10594篇 |
2013年 | 15507篇 |
2012年 | 17176篇 |
2011年 | 17412篇 |
2010年 | 11724篇 |
2009年 | 10741篇 |
2008年 | 15587篇 |
2007年 | 16143篇 |
2006年 | 15131篇 |
2005年 | 14540篇 |
2004年 | 14202篇 |
2003年 | 13786篇 |
2002年 | 13622篇 |
2001年 | 27886篇 |
2000年 | 28177篇 |
1999年 | 21866篇 |
1998年 | 7111篇 |
1997年 | 7485篇 |
1996年 | 7135篇 |
1995年 | 6747篇 |
1994年 | 6689篇 |
1993年 | 6534篇 |
1992年 | 18206篇 |
1991年 | 17806篇 |
1990年 | 17131篇 |
1989年 | 16667篇 |
1988年 | 15420篇 |
1987年 | 14578篇 |
1986年 | 13358篇 |
1985年 | 13429篇 |
1984年 | 10938篇 |
1983年 | 9474篇 |
1982年 | 7125篇 |
1981年 | 6452篇 |
1980年 | 6055篇 |
1979年 | 10507篇 |
1978年 | 7984篇 |
1977年 | 7483篇 |
1976年 | 6873篇 |
1975年 | 7753篇 |
1974年 | 8294篇 |
1973年 | 8112篇 |
1972年 | 7473篇 |
1971年 | 6644篇 |
1970年 | 5990篇 |
1969年 | 5703篇 |
1968年 | 5213篇 |
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
1.
2.
Laura C. Burzynski Melanie Humphry Martin R. Bennett Murray C. H. Clarke 《The Journal of biological chemistry》2015,290(41):25188-25196
Inflammation is a key instigator of the immune responses that drive atherosclerosis and allograft rejection. IL-1α, a powerful cytokine that activates both innate and adaptive immunity, induces vessel inflammation after release from necrotic vascular smooth muscle cells (VSMCs). Similarly, IL-1α released from endothelial cells (ECs) damaged during transplant drives allograft rejection. However, IL-1α requires cleavage for full cytokine activity, and what controls cleavage in necrotic ECs is currently unknown. We find that ECs have very low levels of IL-1α activity upon necrosis. However, TNFα or IL-1 induces significant levels of active IL-1α in EC necrotic lysates without alteration in protein levels. Increased activity requires cleavage of IL-1α by calpain to the more active mature form. Immunofluorescence and proximity ligation assays show that IL-1α associates with interleukin-1 receptor-2, and this association is decreased by TNFα or IL-1 and requires caspase activity. Thus, TNFα or IL-1 treatment of ECs leads to caspase proteolytic activity that cleaves interleukin-1 receptor-2, allowing IL-1α dissociation and subsequent processing by calpain. Importantly, ECs could be primed by IL-1α from adjacent damaged VSMCs, and necrotic ECs could activate neighboring normal ECs and VSMCs, causing them to release inflammatory cytokines and up-regulate adhesion molecules, thus amplifying inflammation. These data unravel the molecular mechanisms and interplay between damaged ECs and VSMCs that lead to activation of IL-1α and, thus, initiation of adaptive responses that cause graft rejection. 相似文献
3.
4.
5.
6.
N. Cappetti A. Naddeo G. F. Solitro 《Computer methods in biomechanics and biomedical engineering》2016,19(12):1278-1285
The aim of this work is to show a quick and simple procedure able to identify the geometrical parameters of the intervertebral disc that strongly affect the behavior of the FEM model. First, we allocated a selection criterion for the minimum number of geometrical parameters that describe, with a good degree of approximation, a healthy human vertebra. Next, we carried out a sensitivity analysis using the ‘Taguchi orthogonal array’ to arrive at a quick identification of the parameters that strongly affect the behavior of the Fem model. 相似文献
7.
Joyce S. F. D. de Almeida Teobaldo R. Cuya Guizado Ana P. Guimarães Teodorico C. Ramalho Arlan S. Gonçalves Martijn C. de Koning 《Journal of biomolecular structure & dynamics》2016,34(12):2632-2642
In the present work, we performed docking and molecular dynamics simulations studies on two groups of long-tailored oximes designed as peripheral site binders of acetylcholinesterase (AChE) and potential penetrators on the blood brain barrier. Our studies permitted to determine how the tails anchor in the peripheral site of sarin-inhibited human AChE, and which aminoacids are important to their stabilization. Also the energy values obtained in the docking studies corroborated quite well with the experimental results obtained before for these oximes. 相似文献
8.
9.
10.
Laura De Pretto Stephen Acreman Matthew J. Ashfold Suresh K. Mohankumar Ahimsa Campos-Arceiz 《PloS one》2015,10(12)
Transboundary haze episodes caused by seasonal forest fires have become a recurrent phenomenon in Southeast Asia, with serious environmental, economic, and public health implications. Here we present a cross-sectional survey conducted among people in Kuala Lumpur and surrounds to assess the links between knowledge, attitudes, and practices in relation to the transboundary haze episodes. Of 305 respondents, 125 were amateur athletes participating in a duathlon event and the remainder were surveyed in an inner-city shopping mall. Across the whole sample, people who possessed more factual information about the haze phenomenon showed significantly higher levels of concern. Duathletes were more knowledgeable than non-duathletes and also more concerned about the negative effects of haze, especially on health. For all people who regularly practice outdoor sports (including people interviewed at the shopping mall), higher levels of knowledge and concerned attitudes translated into a greater likelihood of engaging in protective practices, such as cancelling their outdoor training sessions, while those with greater knowledge were more likely to check the relevant air pollution index on a daily basis. Our results indicate that the provision of accurate and timely information about air quality to residents will translate into beneficial practices, at least among particularly exposed individuals, such as amateur athletes who regularly practice outdoor sports. 相似文献