全文获取类型
收费全文 | 109852篇 |
免费 | 1996篇 |
国内免费 | 820篇 |
出版年
2021年 | 220篇 |
2020年 | 150篇 |
2019年 | 173篇 |
2018年 | 12020篇 |
2017年 | 10814篇 |
2016年 | 7775篇 |
2015年 | 1077篇 |
2014年 | 874篇 |
2013年 | 1033篇 |
2012年 | 5191篇 |
2011年 | 13766篇 |
2010年 | 12554篇 |
2009年 | 8794篇 |
2008年 | 10576篇 |
2007年 | 12148篇 |
2006年 | 1091篇 |
2005年 | 1305篇 |
2004年 | 1746篇 |
2003年 | 1797篇 |
2002年 | 1529篇 |
2001年 | 591篇 |
2000年 | 446篇 |
1999年 | 321篇 |
1998年 | 245篇 |
1997年 | 204篇 |
1996年 | 198篇 |
1995年 | 168篇 |
1994年 | 200篇 |
1993年 | 206篇 |
1992年 | 261篇 |
1991年 | 277篇 |
1990年 | 219篇 |
1989年 | 218篇 |
1988年 | 220篇 |
1987年 | 228篇 |
1986年 | 176篇 |
1985年 | 195篇 |
1984年 | 191篇 |
1983年 | 187篇 |
1982年 | 166篇 |
1981年 | 158篇 |
1980年 | 142篇 |
1979年 | 149篇 |
1978年 | 119篇 |
1977年 | 111篇 |
1976年 | 110篇 |
1974年 | 120篇 |
1973年 | 115篇 |
1972年 | 359篇 |
1971年 | 330篇 |
排序方式: 共有10000条查询结果,搜索用时 162 毫秒
991.
992.
993.
994.
995.
996.
997.
Research has revealed that most chlorophyllous explants/plants in vitro have the ability to grow photoautotrophically (without
sugar in the culture medium), and that the low or negative net photosynthetic rate of plants in vitro is not due to poor photosynthetic
ability, but to the low CO2 concentration in the air-tight culture vessel during the photoperiod. Moreover, numerous studies have been conducted on improving
the in vitro environment and investigating its effects on growth and development of cultures/plantlets on nearly 50 species
since the concept of photoautotrophic micropropagation was developed more than two decades ago. These studies indicate that
the photoautotrophic growth in vitro of many plant species can be significantly promoted by increasing the CO2 concentration and light intensity in the vessel, by decreasing the relative humidity in the vessel, and by using a fibrous
or porous supporting material with high air porosity instead of gelling agents such as agar. This paper reviews the development
and characteristics of photoautotrophic micropropagation systems and the effects of environmental conditions on the growth
and development of the plantlets. The commercial applications and the perspective of photoautotrophic micropropagation systems
are discussed. 相似文献
998.
999.
1000.
Christian P Craddock Nicolette Adams Fiona M Bryant Smita Kurup Peter J Eastmond 《Plant signaling & behavior》2015,10(10)
Coordination of membrane lipid biosynthesis is important for cell function during plant growth and development. Here we summarize our recent work on PHOSPHATIDIC ACID PHOSPHOHYDROLASE (PAH) which suggests that this enzyme is a key regulator of phosphaticylcholine (PC) biosynthesis in Arabidopsis thaliana. Disruption of PAH activity elevates phosphatidic acid (PA) levels and stimulates PC biosynthesis and biogenesis of the endoplasmic reticulum (ER). Furthermore, the activity of PHOSPHOCHOLINE CYTIDYLYLTRANSFERASE (CCT), which is the key enzyme controlling the rate of PC biosynthesis, is directly stimulated by PA and expression of a constitutively active version of CCT replicates the effects of PAH disruption. Hence PAH activity can control the abundance of PA, which in turn can modulate CCT activity to govern the rate of PC biosynthesis. Crucially it is not yet clear how PAH activity is regulated in Arabidopsis but there is evidence that PAH1 and PAH2 are both phosphorylated and further work will be required to investigate whether this is functionally significant. 相似文献