全文获取类型
收费全文 | 151篇 |
免费 | 8篇 |
国内免费 | 2篇 |
出版年
2023年 | 1篇 |
2022年 | 2篇 |
2020年 | 3篇 |
2018年 | 1篇 |
2017年 | 6篇 |
2016年 | 2篇 |
2015年 | 3篇 |
2014年 | 14篇 |
2013年 | 5篇 |
2012年 | 4篇 |
2011年 | 13篇 |
2010年 | 10篇 |
2009年 | 13篇 |
2008年 | 12篇 |
2007年 | 22篇 |
2006年 | 9篇 |
2005年 | 3篇 |
2004年 | 12篇 |
2003年 | 6篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 4篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1984年 | 2篇 |
1981年 | 2篇 |
1980年 | 4篇 |
排序方式: 共有161条查询结果,搜索用时 31 毫秒
21.
22.
Chi Zhang 《Developmental biology》2009,331(2):340-3145
A NF-κB-Twist-Snail network controls axis and mesoderm formation in Drosophila. Using translation-blocking morpholinos and hormone-regulated proteins, we demonstrate the presence of an analogous network in the early Xenopus embryo. Loss of twist (twist1) function leads to a reduction of mesoderm and neural crest markers, an increase in apoptosis, and a decrease in snail1 (snail) and snail2 (slug) mRNA levels. Injection of snail2 mRNA rescues twist's loss of function phenotypes and visa versa. In the early embryo NF-κB/RelA regulates twist, snail2, and snail1 mRNA levels; similarly Nodal/Smad2 regulate twist, snail2, snail1, and relA RNA levels. Both Twist and Snail2 negatively regulate levels of cerberus RNA, which encodes a Nodal, bone morphogenic protein (BMP), and Wnt inhibitor. Cerberus's anti-Nodal activity inhibits NF-κB activity and decreases relA RNA levels. These results reveal both conserved and unexpected regulatory interactions at the core of a vertebrate's mesodermal specification network. 相似文献
23.
24.
Hiroshi Tobe 《Journal of plant research》1980,93(4):253-263
The vascular anatomy of inflorescence axes and flowers ofClematis patens have been studied. The species shows a unique behaviour of the vascular bundles in the transition node from vegetative stem
to pedicel: stelar bundles increase in number from six to eight as they ascend through the transition node so that the number
of vascular bundles coincides with that of sepals. In the pedicel stele the resulting eight bundles are disposed opposite
to eight sepals. respectively; each sepal receives its vascular supply from the bundle facing it. Morphological and anatomical
evidence suggests that the calyx of eight sepals in this species should be interpreted as having consisted originally of four
pairs of opposite organs, rather than as having been derived secondarily through chorisis of sepals from a calyx of four sepals
as seen in most other species ofClematis. 相似文献
25.
26.
V. Girijashankar 《Physiology and Molecular Biology of Plants》2012,18(1):79-87
An efficient in vitro regeneration protocol enables mass multiplication, genetic modification and germplasm conservation of desired plants. In vitro plant regeneration was achieved from nodal segments of 18-months-old superior genotypes of Eucalyptus camaldulensis trees through direct organogenesis (DO) and direct somatic embryogenesis (DSE) pathways. Initial bud break (BB) stage occurred via DO while shoot multiplication phase followed both DO and DSE pathways. Interestingly, both BB and shoot multiplication stages were achieved on shoot induction and multiplication (SIM) media composed of Murashige and Skoog (MS) basal medium supplemented with 2 mg l−1 benzyl aminopurine (BAP) and 0.1 mg l−1 naphthalene acetic acid (NAA). Best shoot elongation response was observed on half strength MS fortified with 0.5 mg l−1 BAP, while root induction and elongation was superior in 1/2 MS + 1 mg l−1 Indole butyric acid (IBA). Full strength MS fortified with cytokinins (BAP) and weak auxin (NAA) in the ratio of 20:1 favored direct regeneration pathways. Further, half strength MS supported shoot and root development. The absence of intervening callus phase in this protocol can help in minimizing the chance occurrence of somaclones. When compared to other compositions tried, hardening in 100 % coco peat resulted in maximum survival (80 %) of the in vitro raised plantlets. For mass multiplication, fortnight subculturing of a single nodal explants for eight passages on SIM medium resulted in 60–148 shoot initials. Repeated subculturing in SIM medium induced the formation of direct somatic embryos which in turn improved the turnover capacity and enabled large scale clonal multiplication of elite and desirable trees of E. camaldulensis. Following this protocol, it takes a minimum time period of four-months between in vitro explant inoculation to hardening stage. In the present study, DO and DSE pathway of plant regeneration was reported occurring simultaneously in the same nodal explants of E. camaldulensis. 相似文献
27.
28.
Gorivodsky M Mukhopadhyay M Wilsch-Braeuninger M Phillips M Teufel A Kim C Malik N Huttner W Westphal H 《Developmental biology》2009,325(1):24-32
IFT172, also known as Selective Lim-domain Binding protein (SLB), is a component of the intraflagellar transport (IFT) complex. In order to evaluate the biological role of the Ift172 gene, we generated a loss-of-function mutation in the mouse. The resulting Slb mutant embryos die between E12.5 and 13.0, and exhibit severe cranio-facial malformations, failure to close the cranial neural tube, holoprosencephaly, heart edema and extensive hemorrhages. Cilia outgrowth in cells of the neuroepithelium is initiated but the axonemes are severely truncated and do not contain visible microtubules. Morphological and molecular analyses revealed a global brain-patterning defect along the dorsal-ventral (DV) and anterior-posterior (AP) axes. We demonstrate that Ift172 gene function is required for early regulation of Fgf8 at the midbrain-hindbrain boundary and maintenance of the isthmic organizer. In addition, Ift172 is required for proper function of the embryonic node, the early embryonic organizer and for formation of the head organizing center (the anterior mesendoderm, or AME). We propose a model suggesting that forebrain and mid-hindbrain growth and AP patterning depends on the early function of Ift172 at gastrulation. Our data suggest that the formation and function of the node and AME in the mouse embryo relies on an indispensable role of Ift172 in cilia morphogenesis and cilia-mediated signaling. 相似文献
29.
A simple, rapid and efficient protocol for micropropagation of Cardiospermum halicacabum via axillary bud multiplication has been successfully developed. The organogenic competence of nodal segments was investigated
on Murashige and Skoog (MS) medium supplemented with different concentrations of benzyladenine (BA), kinetin (Kn), thidiazuron
(TDZ) and 2-isopentenyladenine (2-iP). Multiple shoots differentiated directly without callus mediation within 4 weeks when
explants were cultured on a medium fortified with cytokinins. The maximum number of shoots (14.83 ± 0.52) was developed on
a medium supplemented with 0.3 μM TDZ. Such proliferating shoots when subcultured onto MS media devoid of TDZ gave the highest
rate of shoot multiplication (35.66 ± 1.00) by the end of fourth subculture passage. Elongated shoots were rooted on 1/3 MS
medium augmented with 0.5 μM IAA. The plantlets thus obtained were successfully hardened and transferred to greenhouse. 相似文献
30.
M. Frabetti P. Gutiérrez-Pesce E. Mendoza-de Gyves E. Rugini 《In vitro cellular & developmental biology. Plant》2009,45(2):129-134
An efficient protocol for in vitro propagation of the valuable ornamental and medicinal plant Bush germander (Teucrium fruticans L.) was developed through axillary shoot proliferation. A Murashige and Skoog agar medium supplemented with benzylaminopurine
(6.6 μM), α-naphthaleneacetic acid (0.053 μM), and sucrose (3%) significantly improved the production of multiple shoots directly
from nodal segment explants, resulting in an average of 2.8 shoots per segment with an average of 6.8 nodes per shoot that
would be potential newly formed explants. The new shoots were developed without a marked decrease in the average height of
the shoots. Shoots treated with 2.5 μM indole-3-butyric acid showed the highest average root number (7.9) and the highest
percentage of rooting (94%). Plantlets were hardened off and transferred to jiffy pots for acclimatization under greenhouse
conditions, resulting in a 100% survival rate. 相似文献