全文获取类型
收费全文 | 7930篇 |
免费 | 829篇 |
国内免费 | 6篇 |
出版年
2021年 | 79篇 |
2020年 | 55篇 |
2019年 | 82篇 |
2018年 | 102篇 |
2017年 | 99篇 |
2016年 | 154篇 |
2015年 | 285篇 |
2014年 | 289篇 |
2013年 | 397篇 |
2012年 | 544篇 |
2011年 | 509篇 |
2010年 | 321篇 |
2009年 | 317篇 |
2008年 | 503篇 |
2007年 | 514篇 |
2006年 | 462篇 |
2005年 | 475篇 |
2004年 | 454篇 |
2003年 | 434篇 |
2002年 | 352篇 |
2001年 | 87篇 |
2000年 | 75篇 |
1999年 | 90篇 |
1998年 | 110篇 |
1997年 | 89篇 |
1996年 | 73篇 |
1995年 | 80篇 |
1994年 | 58篇 |
1993年 | 72篇 |
1992年 | 75篇 |
1991年 | 58篇 |
1990年 | 74篇 |
1989年 | 71篇 |
1988年 | 70篇 |
1987年 | 60篇 |
1986年 | 49篇 |
1985年 | 60篇 |
1984年 | 67篇 |
1983年 | 66篇 |
1982年 | 69篇 |
1981年 | 62篇 |
1980年 | 67篇 |
1979年 | 60篇 |
1978年 | 49篇 |
1977年 | 41篇 |
1976年 | 45篇 |
1975年 | 38篇 |
1974年 | 56篇 |
1973年 | 49篇 |
1972年 | 41篇 |
排序方式: 共有8765条查询结果,搜索用时 15 毫秒
1.
2.
3.
N. L. Biddington P. A. Brocklehurst A. S. Dearman Jane Dearman 《Physiologia plantarum》1982,55(4):407-410
Celery seeds ( Apium graveolens L.) given a germination induction period (3 days imbibition at 17°C in the light) could be prevented from germinating by up to 14 days subsequent exposure to high temperature (32°C), polyethylene glycol (PEG), abscisic acid (ABA) or dark (22°C). When the seeds were returned to 17°C in the light, germination occurred and, except for the high temperature treatment, was more rapid compared to seeds given a germination induction period only.
Celery seeds incubated for 3 days at 17°C in the light and then air-dried at 20°C germinated slowly when re-sown at 17°C in the light, and achieved only 19% germination after 21 days. Exposing the seeds to high temperature, PEG, ABA or dark for up to 14 days before drying maintained seed viability and subsequent germination was faster. The longer treatment periods gave increased benefit, and PEG was the most effective treatment. It is suggested that the effectiveness of the treatments in inducing dehydration tolerance relates to their ability to inhibit germination possibly via their prevention of cell expansion. 相似文献
Celery seeds incubated for 3 days at 17°C in the light and then air-dried at 20°C germinated slowly when re-sown at 17°C in the light, and achieved only 19% germination after 21 days. Exposing the seeds to high temperature, PEG, ABA or dark for up to 14 days before drying maintained seed viability and subsequent germination was faster. The longer treatment periods gave increased benefit, and PEG was the most effective treatment. It is suggested that the effectiveness of the treatments in inducing dehydration tolerance relates to their ability to inhibit germination possibly via their prevention of cell expansion. 相似文献
4.
The health profile of cloned animals. 总被引:17,自引:0,他引:17
5.
6.
Elizabeth Storer Scholl Antonella Pirone Daniel H Cox R Keith Duncan Michele H Jacob 《Channels (Austin, Tex.)》2014,8(1):62-75
Small conductance Ca2+-sensitive potassium (SK2) channels are voltage-independent, Ca2+-activated ion channels that conduct potassium cations and thereby modulate the intrinsic excitability and synaptic transmission of neurons and sensory hair cells. In the cochlea, SK2 channels are functionally coupled to the highly Ca2+ permeant α9/10-nicotinic acetylcholine receptors (nAChRs) at olivocochlear postsynaptic sites. SK2 activation leads to outer hair cell hyperpolarization and frequency-selective suppression of afferent sound transmission. These inhibitory responses are essential for normal regulation of sound sensitivity, frequency selectivity, and suppression of background noise. However, little is known about the molecular interactions of these key functional channels. Here we show that SK2 channels co-precipitate with α9/10-nAChRs and with the actin-binding protein α-actinin-1. SK2 alternative splicing, resulting in a 3 amino acid insertion in the intracellular 3′ terminus, modulates these interactions. Further, relative abundance of the SK2 splice variants changes during developmental stages of synapse maturation in both the avian cochlea and the mammalian forebrain. Using heterologous cell expression to separately study the 2 distinct isoforms, we show that the variants differ in protein interactions and surface expression levels, and that Ca2+ and Ca2+-bound calmodulin differentially regulate their protein interactions. Our findings suggest that the SK2 isoforms may be distinctly modulated by activity-induced Ca2+ influx. Alternative splicing of SK2 may serve as a novel mechanism to differentially regulate the maturation and function of olivocochlear and neuronal synapses. 相似文献
7.
8.
Keith G. Danielson Janice E. Knepper Frances S. Kittrell Janet S. Butel Daniel Medina Elisa M. Durban 《In vitro cellular & developmental biology. Plant》1989,25(6):535-543
Summary Clonal populations were isolated from the mouse mammary cell line, COMMA-D, by transfection with a dominant-selectable gene,
pSV2Neo, which confers resistance to the antibiotic, G418. Seven of twenty-four clones isolated retained the ability of the
parental line to repopulate cleared mammary fat pads in vivo as ductal-alveolar hyperplasias. Two sublines designated CDNR2
and CDNR4 retained hyperplastic growth potential after multiple passages in vitro with low incidence of tumor formation. A
third subpopulation, CDNR1, contained a single integration site for the pSV2Neo plasmid indicating a bonafide clonal origin
for this subline. CDNR1 cells displayed heterogeneous growth phenotypes in vivo including hyperplasia, adenocarcinoma, and
bone formation. Functional differentiation of CDNR1 cells organized as alveolarlike structures in vivo or on floating collagen
gels in vitro was observed as determined by immunoperoxidase staining for the milk-specific protein, casein. Overall, the
results indicate that a subset of cells from the COMMA-D cell line may be functionally analogous to stem cells existing in
the mammary gland.
Supported by NCI research grants CA-38650, CA-33369, CA-39017, and CA-25215. 相似文献
9.
10.