全文获取类型
收费全文 | 76101篇 |
免费 | 5068篇 |
国内免费 | 7篇 |
出版年
2023年 | 515篇 |
2022年 | 645篇 |
2021年 | 1385篇 |
2020年 | 1106篇 |
2019年 | 1299篇 |
2018年 | 2316篇 |
2017年 | 2147篇 |
2016年 | 2827篇 |
2015年 | 3685篇 |
2014年 | 3797篇 |
2013年 | 5034篇 |
2012年 | 5902篇 |
2011年 | 5357篇 |
2010年 | 3457篇 |
2009年 | 2801篇 |
2008年 | 4066篇 |
2007年 | 3831篇 |
2006年 | 3637篇 |
2005年 | 3099篇 |
2004年 | 3000篇 |
2003年 | 2695篇 |
2002年 | 2464篇 |
2001年 | 1695篇 |
2000年 | 1654篇 |
1999年 | 1311篇 |
1998年 | 646篇 |
1997年 | 477篇 |
1996年 | 479篇 |
1995年 | 439篇 |
1994年 | 336篇 |
1993年 | 325篇 |
1992年 | 666篇 |
1991年 | 580篇 |
1990年 | 525篇 |
1989年 | 514篇 |
1988年 | 485篇 |
1987年 | 440篇 |
1986年 | 418篇 |
1985年 | 411篇 |
1984年 | 418篇 |
1983年 | 281篇 |
1982年 | 267篇 |
1981年 | 202篇 |
1980年 | 212篇 |
1979年 | 262篇 |
1978年 | 242篇 |
1975年 | 223篇 |
1974年 | 250篇 |
1973年 | 252篇 |
1972年 | 219篇 |
排序方式: 共有10000条查询结果,搜索用时 421 毫秒
1.
2.
Cristian A. Acevedo Elizabeth Y. Sanchez Juan G. Reyes Manuel E. Young 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2010,878(3-4):449-455
It is known that skin releases volatile organic compounds to the environment, and also that its emission pattern changes with aging of the skin. It could be considered, that these compounds are intermediaries in cell metabolism, since many intermediaries of metabolic pathways have a volatile potential. In this work, a simple and non-destructive method consisting of SPME sampling and GC/MS analysis was developed to identify volatile organic emanations from cell cultures. This technique, applied to skin cells culture, indicates that the cells or cell metabolism produce several skin emissions. Chemometric analysis was performed in order to explore the relationship between a volatile profile and the senescence of cell cultures. Volatile profiles were different for cell cultures in different degrees of senescence, indicating that volatile compound patterns could be used to provide information about the age of skin cells. 相似文献
3.
4.
5.
Sebastián Moran Miguel Vizoso Anna Martinez-Cardús Antonio Gomez Xavier Matías-Guiu Sebastián M Chiavenna Andrés G Fernandez Manel Esteller 《Epigenetics》2014,9(6):829-833
A formalin-fixed paraffin-embedded (FFPE) sample usually yields highly degraded DNA, which limits the use of techniques requiring high-quality DNA, such as Infinium Methylation microarrays. To overcome this restriction, we have applied an FFPE restoration procedure consisting of DNA repair and ligation processes in a set of paired fresh-frozen (FF) and FFPE samples. We validated the FFPE results in comparison with matched FF samples, enabling us to use FFPE samples on the Infinium HumanMethylation450 Methylation array. 相似文献
6.
Amiloride fluxes across erythrocyte membranes 总被引:3,自引:0,他引:3
Amiloride is known to inhibit both the influx of Na+ and the activation of mitogenesis in many cultured cell lines. This paper describes experiments in which the permeability coefficient of amiloride was determined from measurements of tracer fluxes across human erythrocytes and resealed ghosts. From an analysis of these fluxes, a permeability coefficient of 10(-7) cm/s for the uncharged form of amiloride was deduced. Based upon this measured permeability value, we present calculations of intracellular accumulation times of amiloride in cells of differing surface-to-volume ratio. 相似文献
7.
8.
M del Mar Medina-Puerta A Garrido-Pertierra 《Comparative biochemistry and physiology. B, Comparative biochemistry》1986,83(1):215-220
The enzyme 6-phosphogluconate dehydrogenase (6-phospho-D-gluconate: NADP+ oxidoreductase, decarboxylating EC 1.1.1.44) from bass liver has been purified to over 95% of homogeneity by gel filtration, affinity and ion exchange chromatographies. The apparent molecular weight was estimated by gel filtration chromatography to about 100,000. Analysis of the enzyme on sodium dodecyl sulphate polyacrylamide gel electrophoresis showed to be a dimeric protein. The effect of pH and kinetic properties were studied. 相似文献
9.
"Pertussis toxin induces tachycardia and impairs the increase in blood pressure produced by alpha 2-adrenergic agonists" 总被引:4,自引:0,他引:4
Administration of purified pertussis toxin to rats induced persistent tachycardia, (observed in conscious rats but not after pithing); as little as 0.05 microgram/100 g produced a significant effect. Pertussis toxin-treatment did not affected the pressor response produced in the pithed rats by the alpha 2-adrenergic agonist methoxamine but markedly diminished the pressor effect of the alpha 2-adrenergic agonists clonidine and azepexole. A role of adenylate cyclase inhibition in the action of postsynaptic vascular alpha 2-adrenergic receptors is suggested. 相似文献
10.