全文获取类型
收费全文 | 808140篇 |
免费 | 88956篇 |
国内免费 | 555篇 |
专业分类
897651篇 |
出版年
2018年 | 7646篇 |
2017年 | 7162篇 |
2016年 | 10376篇 |
2015年 | 14300篇 |
2014年 | 16696篇 |
2013年 | 23680篇 |
2012年 | 26522篇 |
2011年 | 26899篇 |
2010年 | 18269篇 |
2009年 | 16623篇 |
2008年 | 23768篇 |
2007年 | 24350篇 |
2006年 | 22963篇 |
2005年 | 22144篇 |
2004年 | 22037篇 |
2003年 | 21152篇 |
2002年 | 20371篇 |
2001年 | 38364篇 |
2000年 | 38574篇 |
1999年 | 30633篇 |
1998年 | 10707篇 |
1997年 | 11202篇 |
1996年 | 10512篇 |
1995年 | 9822篇 |
1994年 | 9552篇 |
1993年 | 9335篇 |
1992年 | 24777篇 |
1991年 | 24033篇 |
1990年 | 23424篇 |
1989年 | 22793篇 |
1988年 | 21153篇 |
1987年 | 19754篇 |
1986年 | 18310篇 |
1985年 | 18134篇 |
1984年 | 15043篇 |
1983年 | 12548篇 |
1982年 | 9515篇 |
1981年 | 8489篇 |
1980年 | 7946篇 |
1979年 | 13485篇 |
1978年 | 10493篇 |
1977年 | 9432篇 |
1976年 | 8538篇 |
1975年 | 9496篇 |
1974年 | 10128篇 |
1973年 | 10026篇 |
1972年 | 8956篇 |
1971年 | 8167篇 |
1970年 | 6971篇 |
1969年 | 6732篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
901.
902.
903.
904.
905.
906.
O M Grindel' 《Zhurnal vysshe? nervno? deiatelnosti imeni I P Pavlova》1985,35(1):60-67
Power spectra and coherence function of EEG of various cortical areas of both hemispheres were analyzed in 9 patients with extremely protracted loss of consciousness. Five patients were in the state of posttraumatic apallic syndrome lasting for more than 4 years in one patient, and 4-9 months with successive lethal outcome in 4 patients. One patient for more than 2 years was in a state of areactivity to external signals. In 3 patients the process of recovery of consciousness and speech began in 1-2 months. At the apallic syndrome, only low-frequency EEG components were present in spectrograms, and the values of coherence function were sharply decreased. With recovering consciousness and speech, a gradual appearance of alpha-activity was observed as well as an increase of coherence values at the frequency of the alpha-rhythm. The recovery of intercentral EEG relations in the motor-verbal cortical area was shown to play a special role in further normalization of connections in the cerebral cortex. 相似文献
907.
908.
909.
R Varela-Calvino G Sgarbi L R Wedderburn C M Dayan J Tremble M Peakman 《Journal of immunology (Baltimore, Md. : 1950)》2001,167(6):3513-3520
Numerous clinical and epidemiological studies link enteroviruses such as the Coxsackie virus group with the autoimmune disease type 1 diabetes mellitus (DM). In addition, there are reports that patients with type 1 DM are characterized by skewing of TCR Vbeta chain selection among peripheral blood and intraislet T lymphocytes. To examine these issues, we analyzed TCR Vbeta chain-specific up-regulation of the early T cell activation marker, CD69, on CD4 T cells after incubation with Coxsackievirus B4 (CVB4) Ags. CD4 T cells bearing the Vbeta chains 2, 7, and 8 were the most frequently activated by CVB4. Up-regulation of CD69 by different TCR families was significantly more frequent in new onset type 1 DM patients (p = 0.04), 100% of whom (n = 8) showed activation of CD4 T cells bearing Vbeta8, compared with 50% of control subjects (n = 8; p = 0.04). T cell proliferation after incubation with CVB4 Ags required live, nonfixed APCs, suggesting that the selective expansion of CD4 T cells with particular Vbeta chains resulted from conventional antigen processing and presentation rather than superantigen activity. Heteroduplex analysis of TCR Vbeta chain usage after CVB4 stimulation indicated a relatively polyclonal, rather than oligo- or monoclonal response to viral Ags. These results provide evidence that new-onset patients with type 1 DM and healthy controls are primed against CVB4, and that CD4 T cell responses to the virus have a selective TCR Vbeta chain usage which is driven by viral Ags rather than a superantigen. 相似文献
910.
Cytokine regulation of facilitated glucose transport in human articular chondrocytes. 总被引:10,自引:0,他引:10
A R Shikhman D C Brinson J Valbracht M K Lotz 《Journal of immunology (Baltimore, Md. : 1950)》2001,167(12):7001-7008
Glucose serves as the major energy substrate and the main precursor for the synthesis of glycosaminoglycans in chondrocytes. Facilitated glucose transport represents the first rate-limiting step in glucose metabolism. This study examines molecular regulation of facilitated glucose transport in normal human articular chondrocytes by proinflammatory cytokines. IL-1beta and TNF-alpha, and to a lesser degree IL-6, accelerate facilitated glucose transport as measured by [(3)H]2-deoxyglucose uptake. IL-1beta induces an increased expression of glucose transporter (GLUT) 1 mRNA and protein, and GLUT9 mRNA. GLUT3 and GLUT8 mRNA are constitutively expressed in chondrocytes and are not regulated by IL-1beta. GLUT2 and GLUT4 mRNA are not detected in chondrocytes. IL-1beta stimulates GLUT1 protein glycosylation and plasma membrane incorporation. IL-1beta regulation of glucose transport in chondrocytes depends on protein kinase C and p38 signal transduction pathways, and does not require phosphoinositide 3-kinase, extracellular signal-related kinase, or c-Jun N-terminal kinase activation. IL-1beta-accelerated glucose transport in chondrocytes is not mediated by endogenous NO or eicosanoids. These results demonstrate that stimulation of glucose transport represents a component of the chondrocyte response to IL-1beta. Two classes of GLUTs are identified in chondrocytes, constitutively expressed GLUT3 and GLUT8, and the inducible GLUT1 and GLUT9. 相似文献