全文获取类型
收费全文 | 437篇 |
免费 | 50篇 |
国内免费 | 61篇 |
出版年
2023年 | 8篇 |
2022年 | 6篇 |
2021年 | 13篇 |
2020年 | 12篇 |
2019年 | 24篇 |
2018年 | 19篇 |
2017年 | 20篇 |
2016年 | 32篇 |
2015年 | 26篇 |
2014年 | 35篇 |
2013年 | 47篇 |
2012年 | 31篇 |
2011年 | 15篇 |
2010年 | 35篇 |
2009年 | 21篇 |
2008年 | 23篇 |
2007年 | 10篇 |
2006年 | 21篇 |
2005年 | 10篇 |
2004年 | 7篇 |
2003年 | 3篇 |
2002年 | 8篇 |
2001年 | 6篇 |
2000年 | 7篇 |
1999年 | 7篇 |
1998年 | 6篇 |
1997年 | 7篇 |
1996年 | 6篇 |
1995年 | 7篇 |
1994年 | 2篇 |
1992年 | 3篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 8篇 |
1988年 | 4篇 |
1985年 | 2篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1982年 | 3篇 |
1980年 | 4篇 |
1979年 | 5篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1970年 | 3篇 |
1969年 | 2篇 |
1958年 | 1篇 |
1956年 | 1篇 |
1954年 | 3篇 |
1953年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有548条查询结果,搜索用时 193 毫秒
541.
542.
543.
544.
545.
Ewa Dubas Jana Moravčíková Jana Libantová Ildikó Matušíková Eva Benková Iwona Żur Monika Krzewska 《Protoplasma》2014,251(5):1077-1087
Plant embryogenesis is regulated by differential distribution of the plant hormone auxin. However, the cells establishing these gradients during microspore embryogenesis remain to be identified. For the first time, we describe, using the DR5 or DR5rev reporter gene systems, the GFP- and GUS-based auxin biosensors to monitor auxin during Brassica napus androgenesis at cellular resolution in the initial stages. Our study provides evidence that the distribution of auxin changes during embryo development and depends on the temperature-inducible in vitro culture conditions. For this, microspores (mcs) were induced to embryogenesis by heat treatment and then subjected to genetic modification via Agrobacterium tumefaciens. The duration of high temperature treatment had a significant influence on auxin distribution in isolated and in vitro-cultured microspores and on microspore-derived embryo development. In the “mild” heat-treated (1 day at 32 °C) mcs, auxin localized in a polar way already at the uni-nucleate microspore, which was critical for the initiation of embryos with suspensor-like structure. Assuming a mean mcs radius of 20 μm, endogenous auxin content in a single cell corresponded to concentration of 1.01 μM. In mcs subjected to a prolonged heat (5 days at 32 °C), although auxin concentration increased dozen times, auxin polarization was set up at a few-celled pro-embryos without suspensor. Those embryos were enclosed in the outer wall called the exine. The exine rupture was accompanied by the auxin gradient polarization. Relative quantitative estimation of auxin, using time-lapse imaging, revealed that primordia possess up to 1.3-fold higher amounts than those found in the root apices of transgenic MDEs in the presence of exogenous auxin. Our results show, for the first time, which concentration of endogenous auxin coincides with the first cell division and how the high temperature interplays with auxin, by what affects delay early establishing microspore polarity. Moreover, we present how the local auxin accumulation demonstrates the apical–basal axis formation of the androgenic embryo and directs the axiality of the adult haploid plant. 相似文献
546.
547.
Ludmi̵a Żylińska Ewa Gromadzińska Lilla Lachowicz 《Biochimica et Biophysica Acta (BBA)/Molecular and Cell Biology of Lipids》1999,1437(2):257-264
Recent experimental evidence indicates that some steroid hormones, apart from their well-documented genomic actions, could produce non-genomic rapid effects, and are potent modulators of the plasma membrane proteins, including voltage- and ligand-operated ion channels or G protein-coupled receptors. Neuroactive steroids, 17β-estradiol, testosterone, pregnenolone sulfate and dehydroepiandrosterone sulfate, after a short-time incubation directly modulated the activity of plasma membrane Ca2+-ATPase purified from synaptosomal membranes of rat cortex. The sulfate derivatives of dehydroepiandrosterone and pregnenolone applied at concentrations of 10?11–10?6 M, showed an inverted U-shape potency in the regulation of Ca2+-ATPase activity. At physiologically relevant concentrations (10?8–10?9 M) a maximal enhancement of the basal activity reached 200%. Testosterone (10?11–10?6 M) and 17β-estradiol (10?12–10?9 M) caused a dose-dependent increase in the hydrolytic ability of Ca2+-ATPase, and the activity with the highest concentration of steroids reached 470% and 200%, respectively. All examined steroids decreased the stimulatory effect of a naturally existing activator of the calcium pump, calmodulin. The present study strongly suggests that the plasma membrane calcium pump could be one of the possible membrane targets for a non-genomic neuroactive steroid action. 相似文献
548.