全文获取类型
收费全文 | 251636篇 |
免费 | 20703篇 |
国内免费 | 20823篇 |
出版年
2024年 | 386篇 |
2023年 | 2585篇 |
2022年 | 5803篇 |
2021年 | 10954篇 |
2020年 | 7553篇 |
2019年 | 9501篇 |
2018年 | 9332篇 |
2017年 | 7033篇 |
2016年 | 9887篇 |
2015年 | 14475篇 |
2014年 | 17218篇 |
2013年 | 18337篇 |
2012年 | 22410篇 |
2011年 | 20678篇 |
2010年 | 13105篇 |
2009年 | 11647篇 |
2008年 | 13913篇 |
2007年 | 12633篇 |
2006年 | 11202篇 |
2005年 | 9264篇 |
2004年 | 7992篇 |
2003年 | 7260篇 |
2002年 | 6224篇 |
2001年 | 5267篇 |
2000年 | 4885篇 |
1999年 | 4715篇 |
1998年 | 2715篇 |
1997年 | 2720篇 |
1996年 | 2536篇 |
1995年 | 2268篇 |
1994年 | 2225篇 |
1993年 | 1700篇 |
1992年 | 2375篇 |
1991年 | 1883篇 |
1990年 | 1488篇 |
1989年 | 1378篇 |
1988年 | 1112篇 |
1987年 | 957篇 |
1986年 | 858篇 |
1985年 | 848篇 |
1984年 | 526篇 |
1983年 | 476篇 |
1982年 | 351篇 |
1981年 | 244篇 |
1980年 | 218篇 |
1979年 | 260篇 |
1978年 | 166篇 |
1974年 | 180篇 |
1973年 | 153篇 |
1972年 | 161篇 |
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
41.
42.
43.
We isolated a recombinant H9N2 avian influenza virus (AIV) from fresh egret feces in the Ardeidae protection region of the Dongting Lake wetland area in China, and it was designated A/Egret/Hunan/1/2012(H9N2). This is the first report of isolating H9N2 AIV from wild birds in the Dongting Lake wetland. Its eight gene segments are generated by reassortment of gene segments of different AIV subtypes. These results are helpful for understanding the epidemiology and evolution of AIV in wild birds during migration. 相似文献
44.
45.
Inflammatory responses mediated by activated microglia play a pivotal role in the pathogenesis of human immunodeficiency virus type 1 (HIV-1)-associated neurocognitive disorders. Studies on identification of specific targets to control microglia activation and resultant neurotoxic activity are imperative. Increasing evidence indicate that voltage-gated K+ (Kv) channels are involved in the regulation of microglia functionality. In this study, we investigated Kv1.3 channels in the regulation of neurotoxic activity mediated by HIV-1 glycoprotein 120 (gp120)-stimulated rat microglia. Our results showed treatment of microglia with gp120 increased the expression levels of Kv1.3 mRNA and protein. In parallel, whole-cell patch-clamp studies revealed that gp120 enhanced microglia Kv1.3 current, which was blocked by margatoxin, a Kv1.3 blocker. The association of gp120 enhancement of Kv1.3 current with microglia neurotoxicity was demonstrated by experimental results that blocking microglia Kv1.3 attenuated gp120-associated microglia production of neurotoxins and neurotoxicity. Knockdown of Kv1.3 gene by transfection of microglia with Kv1.3-siRNA abrogated gp120-associated microglia neurotoxic activity. Further investigation unraveled an involvement of p38 MAPK in gp120 enhancement of microglia Kv1.3 expression and resultant neurotoxic activity. These results suggest not only a role Kv1.3 may have in gp120-associated microglia neurotoxic activity, but also a potential target for the development of therapeutic strategies. 相似文献
46.
47.
48.
M N Lorenzo R Y Khan Y Wang S C Tai G C Chan A H Cheung P A Marsden 《Biochimica et biophysica acta》2001,1522(1):46-52
Generation of the functionally pleiotropic members of the endothelin vasoactive peptide family is critically catalyzed by unique type II metalloproteases, termed endothelin converting enzymes (ECE). Isolation of human ECE-2 (EC 3.4.24.71) cDNAs revealed deduced open reading frames of 787 and 765 amino acids with approximately 60% identity with human ECE-1. Characterization of mRNA variants revealed mRNA structural diversity at the 5'-terminus. Two mRNA species exist containing distinct first and second exons. Furthermore, in one of these species, an in-frame deletion of the intracytoplasmic domain removed 29 amino acids. Because of the previously reported human genetic diseases ascribed to germline mutations of member genes of the endothelin family, ECE2 was localized in human chromosomes with fluorescence in situ hybridization and radiation hybrid mapping to 3q28-q29 and SHGC-20171/D3S1571, respectively. 相似文献
49.
50.
<正>Aristolochic acids, mutational signature, and hepatocellular carcinoma Aristolochic acids (AA) are the etiologic agents of aristolochic acid nephropathy (AAN) and contribute to the global prevalence of chronic kidney disease and urothelial cancer (Grollman et al., 2007). DNA adducts formed by AA generate a unique AT transversions mutation spectrum at 相似文献