全文获取类型
收费全文 | 19222篇 |
免费 | 2838篇 |
国内免费 | 203篇 |
专业分类
22263篇 |
出版年
2023年 | 45篇 |
2022年 | 112篇 |
2021年 | 210篇 |
2020年 | 183篇 |
2019年 | 211篇 |
2018年 | 320篇 |
2017年 | 292篇 |
2016年 | 427篇 |
2015年 | 515篇 |
2014年 | 625篇 |
2013年 | 717篇 |
2012年 | 799篇 |
2011年 | 921篇 |
2010年 | 534篇 |
2009年 | 532篇 |
2008年 | 662篇 |
2007年 | 647篇 |
2006年 | 634篇 |
2005年 | 552篇 |
2004年 | 507篇 |
2003年 | 504篇 |
2002年 | 472篇 |
2001年 | 2283篇 |
2000年 | 2115篇 |
1999年 | 1484篇 |
1998年 | 428篇 |
1997年 | 449篇 |
1996年 | 380篇 |
1995年 | 350篇 |
1994年 | 262篇 |
1993年 | 221篇 |
1992年 | 717篇 |
1991年 | 586篇 |
1990年 | 499篇 |
1989年 | 389篇 |
1988年 | 307篇 |
1987年 | 240篇 |
1986年 | 179篇 |
1985年 | 136篇 |
1984年 | 85篇 |
1983年 | 65篇 |
1982年 | 44篇 |
1981年 | 41篇 |
1980年 | 26篇 |
1979年 | 30篇 |
1978年 | 27篇 |
1976年 | 30篇 |
1974年 | 24篇 |
1973年 | 30篇 |
1970年 | 24篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
32.
A. Benito E. Viaplana J.L. Corchero X. Carbonell A. Villaverde 《FEMS microbiology letters》1995,129(2-3):157-162
Abstract The 3D gene of foot-and-mouth disease virus encodes the viral RNA dependent RNA polymerase, also called virus infection associated (VIA) antigen, which is the most important serological marker of virus infection. This 3D gene from a serotype Cl virus has been cloned and overexpressed in Escherichia coli under the control of the strong lambda lytic promoters. The resulting 51 kDa recombinant protein has been shown to be immunoreactive with sera from infected animals. After induction of gene expression, an immediate and dramatic arrest of cell DNA synthesis occurs, similar to that produced by genotoxic doses of the drug mitomycin C. This effect does not occur during the production of either a truncated VIA antigen or other related and non-related viral proteins. The inhibition of DNA replication results in a subsequent induction of the host SOS DNA-repair response and in an increase of the mutation frequency in the surviving cells. 相似文献
33.
34.
Aurin tricarboxylic acid, the anti-AIDS compound, prevents the binding of interferon-alpha to its receptor 总被引:2,自引:0,他引:2
Y X Gan J L Weaver P S Pine K C Zoon A Aszalos 《Biochemical and biophysical research communications》1990,172(3):1298-1303
Binding of HIV to its receptor, the CD4 molecule of lymphocytes, can be prevented by chemical agents. These agents could be considered as potential anti-AIDS drugs. We have shown that aurin tricarboxylic acid (ATA, 3 microM) specifically blocks the binding of gp120, the HIV coat protein, to the CD4 molecule. We have also found that ATA prevents the binding of interferon-alpha to its receptor in a dose-dependent manner (12-50 microM range). Membrane potential shift, associated with binding of interferon-alpha to its receptor, was also blocked by ATA in a dose-dependent fashion. Our results indicate that potential anti-AIDS drugs should be screened for such undesired side effects. 相似文献
35.
A method based on the infection of CaCo-2 cells and molecular hybridization with a specific cDNA probe has been developed for the detection of infectious astroviruses in environmental samples. By this procedure wild-type astroviruses have been detected in water from an area where a concurrent gastroenteritis outbreak was reported. 相似文献
36.
X. M. Zhou P. H.-S. Jen 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2000,186(4):389-398
This study examines the role of neural inhibition in auditory spatial selectivity of inferior collicular neurons of the big
brown bat, Eptesicus fuscus, using a two-tone inhibition paradigm. Two-tone inhibition decreases auditory spatial response areas but increases the slopes
of directional sensitivity curves of inferior collicular neurons. Inferior collicular neurons have either directionally-selective
or hemifield directional sensitivity curves. A directionally-selective curve always has a peak which is at least 50% larger
than the minimum. A hemifield directional sensitivity curve rises from an ipsilateral angle by more than 50% and either reaches
a plateau or declines by less than 50% over a range of contralateral angles. Two-tone inhibition does not change directionally-selective
curves but changes most hemifield directional sensitivity curves into directionally-selective curves. Auditory spatial selectivity
determined both with and without two-tone inhibition increases with increasing best-excitatory frequency. Sharpening of auditory
spatial selectivity by two-tone inhibition is larger for neurons with smaller differences between excitatory and inhibitory
best frequencies. The effect of two-tone inhibition on auditory spatial selectivity increases with increasing inhibitory tone
intensity but decreases with increasing intertone interval. The implications of these findings in bat echolocation are discussed.
Accepted: 18 January 2000 相似文献
37.
X. Y. Li C. M. Han Y. Wang H. Z. Liu Z. F. Wu Q. H. Gao S. H. Zhao 《Animal genetics》2010,41(5):537-540
RIG-1 signalling is responsible for the detection of cytoplasmic viral RNA molecules. DEXH (Asp-Glu-X-His) box polypeptide 58 (encoded by DHX58) is a negative regulator of the RIG-1 signalling pathway. In human, the DHX58 gene can be upregulated and can inhibit the RIG-1 signalling pathway during viral infection. In this study, porcine DHX58 gene expression patterns were studied. According to our results, the porcine DHX58 gene was upregulated not only by the stimulation of Poly I:C but also by the stimulation of 1ipopolysaccharides (LPS). One polymorphism (g.4919G>C), detected in the ninth intron, was significantly associated with some blood parameters including the red cell distribution width of 1-day-old pigs and white blood cell counts, lymphocyte absolute counts, and platelet distribution width of 17-day-old pigs (P < 0.05). Moreover, the individuals with the genotype GG have a significantly higher mean white blood cell count than individuals with genotype CC or GC (P < 0.05). Our study indicates that DHX58 is an important gene that is associated with the immune response in swine. 相似文献
38.
39.
40.