全文获取类型
收费全文 | 2674篇 |
免费 | 255篇 |
出版年
2023年 | 24篇 |
2022年 | 35篇 |
2021年 | 82篇 |
2020年 | 46篇 |
2019年 | 60篇 |
2018年 | 72篇 |
2017年 | 76篇 |
2016年 | 102篇 |
2015年 | 143篇 |
2014年 | 167篇 |
2013年 | 185篇 |
2012年 | 221篇 |
2011年 | 188篇 |
2010年 | 121篇 |
2009年 | 129篇 |
2008年 | 118篇 |
2007年 | 130篇 |
2006年 | 106篇 |
2005年 | 115篇 |
2004年 | 96篇 |
2003年 | 93篇 |
2002年 | 99篇 |
2001年 | 49篇 |
2000年 | 41篇 |
1999年 | 46篇 |
1998年 | 23篇 |
1997年 | 21篇 |
1996年 | 21篇 |
1995年 | 21篇 |
1994年 | 11篇 |
1993年 | 14篇 |
1992年 | 17篇 |
1991年 | 23篇 |
1990年 | 19篇 |
1989年 | 24篇 |
1988年 | 20篇 |
1987年 | 16篇 |
1986年 | 6篇 |
1985年 | 14篇 |
1984年 | 11篇 |
1983年 | 11篇 |
1982年 | 12篇 |
1980年 | 13篇 |
1979年 | 8篇 |
1978年 | 6篇 |
1977年 | 8篇 |
1975年 | 7篇 |
1973年 | 14篇 |
1970年 | 6篇 |
1969年 | 5篇 |
排序方式: 共有2929条查询结果,搜索用时 15 毫秒
1.
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
2.
Amy Chapman Gonzalo Gonzales Wayne R. Burrowes Paul Assanah Bernadette Iannone Michael K. Leung George B. Stefano 《Cellular and molecular neurobiology》1984,4(2):143-155
In Mytilus and Leucophaea the high-affinity binding site density is significantly lower in old animals than in young animals, whereas the low-affinity site density remains unchanged. In Mytilus the estimated met-enkephalin and met-enkephalin-Arg6-Phe7 levels are significantly higher in old than in young animals. In Leucophaea only the met-enkephalin level can be determined, and it is also higher in old animals. The decrease in the high-affinity binding site density and the corresponding increase in endogenous enkephalin levels suggest the existence of an opioid compensatory mechanism associated with the aging process. In Mytilus there is a demonstrated decrease with age in intraganglionic dopamine levels in response to applied opiates. In addition, the inhibition of dopamine-stimulated adenylate cyclase activity by opiates also decreases in older animals. In Leucophaea the sex difference in opioid binding densities diminishes with age. 相似文献
3.
4.
Some basic parameters of the lytic development of phage phi A7 in Streptomyces antibioticus are described. One-step growth experiments demonstrated that at 28 degrees C phi A7 has a latent period of about 60 min and an exponential growth period of about 35 min. The average burst size ranged from 70-100 plaque forming units per infected cell. At the same temperature 50% of the virions were adsorbed to germ tubes of S. antibioticus in about 10 min. This corresponds to an adsorption constant of 6.5 x 10(-10) ml/min. The phage was unable to adsorb the host at other stages of the life cycle (spores or mycelium). Divalent cations are not required for phi A7 stability but Ca2+ proved to be essential for adsorption and also for a later stage of the vegetative development of the phage. 相似文献
5.
6.
7.
8.
9.
10.
The effect of chronic alcoholism on the amygdaloid complex was studied in 16 humans and 10 rats. Eighteen patients whose death was due to extraneural causes were selected as controls with 3 rats. The alcoholic cases, in addition to the data collected in their clinical history, showed, microscopically confirmed, liver cirrhosis or steatosis. The alcoholics and controls were divided into 4 groups: 35-44 years old (4 cases), 45-54 (5 cases), 55-64 (5 cases) over 65 (2 alcoholics and 4 controls). The alcoholic ingestion in the rats (Wistar, 10 weeks old) was 3 ml at a concentration of 30% in water solution administered by esophagic intubation, for 48 (5 rats) or 58 weeks (5 rats). To judge the state of the amygdaloid nuclei, a neuronal count and caryometry were carried out. The numerical data obtained in this study were analyzed statistically. The results in humans have paralleled those obtained in rats and the behaviour of the different nuclei of the amygdala was uniform and can be summarized as follows: 1) ethanol provoked a prominent and early loss of neurons, and 2) the remainder of non-affected neurons did not react in order to compensate for this neuronal loss. 相似文献