全文获取类型
收费全文 | 1778篇 |
免费 | 104篇 |
出版年
2022年 | 18篇 |
2021年 | 30篇 |
2020年 | 23篇 |
2019年 | 26篇 |
2018年 | 43篇 |
2017年 | 21篇 |
2016年 | 49篇 |
2015年 | 67篇 |
2014年 | 58篇 |
2013年 | 80篇 |
2012年 | 104篇 |
2011年 | 95篇 |
2010年 | 57篇 |
2009年 | 59篇 |
2008年 | 81篇 |
2007年 | 78篇 |
2006年 | 82篇 |
2005年 | 74篇 |
2004年 | 76篇 |
2003年 | 69篇 |
2002年 | 67篇 |
2001年 | 18篇 |
2000年 | 30篇 |
1999年 | 22篇 |
1998年 | 15篇 |
1997年 | 13篇 |
1995年 | 12篇 |
1992年 | 21篇 |
1990年 | 28篇 |
1989年 | 19篇 |
1988年 | 17篇 |
1987年 | 24篇 |
1986年 | 40篇 |
1985年 | 26篇 |
1984年 | 21篇 |
1983年 | 17篇 |
1982年 | 17篇 |
1981年 | 15篇 |
1980年 | 19篇 |
1979年 | 20篇 |
1978年 | 15篇 |
1977年 | 21篇 |
1975年 | 16篇 |
1974年 | 24篇 |
1973年 | 13篇 |
1972年 | 16篇 |
1971年 | 14篇 |
1970年 | 19篇 |
1969年 | 10篇 |
1968年 | 13篇 |
排序方式: 共有1882条查询结果,搜索用时 31 毫秒
1.
Daniel A. Vardy Csaba Kari Gerald S. Lazarus Pamela J. Jensen Asher Zilberstein Gregory D. Plowman Ulrich Rodeck 《Journal of cellular physiology》1995,163(2):257-265
Autocrine activation of the epidermal growth factor (EGF) receptor on keratinocytes has been recognized as an important growth regulatory mechanism involved in epithelial homeostasis, and, possibly, hyperproliferative diseases. Insulin-like growth factor (IGF)-1 and insulin have been shown to be paracrine keratinocyte mitogens that bind to the type I IGF receptor which is expressed on actively proliferating keratinocytes in situ. In this report, we demonstrate that IGF-1/insulin induced production of keratinocyte-derived autocrine growth factors that bind to the EGF receptor. Increased steady-state mRNA levels for transforming growth factor alpha (TGF-α) and for amphiregulin (AR) were observed upon incubation of keratinocytes with mitogenic concentrations of IGF-1. IGF-1 also induced production and secretion of TGF-α and AR proteins as detected by immunoassays. An EGF receptor antagonistic monoclonal antibody abolished the mitogenic effect of IGF-1 on cultured keratinocytes. These results suggest that stimulation of keratinocyte growth by IGF-1 requires activation of an EGF receptor-mediated autocrine loop. © 1995 Wiley-Liss, Inc. 相似文献
2.
Bnk G. Fenyves Gbor S. Szilgyi Zsolt Vassy Csaba Sti Peter Csermely 《PLoS computational biology》2020,16(12)
Graph theoretical analyses of nervous systems usually omit the aspect of connection polarity, due to data insufficiency. The chemical synapse network of Caenorhabditis elegans is a well-reconstructed directed network, but the signs of its connections are yet to be elucidated. Here, we present the gene expression-based sign prediction of the ionotropic chemical synapse connectome of C. elegans (3,638 connections and 20,589 synapses total), incorporating available presynaptic neurotransmitter and postsynaptic receptor gene expression data for three major neurotransmitter systems. We made predictions for more than two-thirds of these chemical synapses and observed an excitatory-inhibitory (E:I) ratio close to 4:1 which was found similar to that observed in many real-world networks. Our open source tool (http://EleganSign.linkgroup.hu) is simple but efficient in predicting polarities by integrating neuronal connectome and gene expression data. 相似文献
3.
4.
5.
Purification and properties of the components from tropinin 总被引:16,自引:0,他引:16
6.
7.
Weanling female rats were stressed (by water and food deprivation for two days) and three months later the following indexes were studied: 5-HT and 5-HIAA levels in five brain regions, blood plasma and cerebrospinal fluid (CSF), sexual activity and nocistatin level of the plasma and CSF. The 5-HIAA content of hypothalamus and brainstem was significantly decreased (in the brainstem with one third) and in the striatum significantly increased. Plasma nocistatin level was significantly increased. Meyerson index and lordosis quotient were similar to control, but the estrus frequency almost doubled in the stressed animals. Much more defense reactions were observed in the stressed females during trials of mating. The results demonstrate that, 1) the perinatal period is not only sensitive to the remote-effects of stress but later could also be stress-sensitive critical periods, and 2) the continuously differentiating (e.g. bone marrow) cells are sensitive to late imprinting by stress, as well as to the brain and the sexual system. 相似文献
8.
A single neonatal treatment of rats with vitamin D3, gibberellin, allylestrenol or diethylstilbestrol (DES) influenced the ouabain binding capacity of myocardial Na, K-dependent ATP-ase. Of the active molecules tested, vitamin D3, DES and gibberellin had appreciable impact on myocardial ouabain receptors, enhancing and depressing their activity, respectively. The thymic dexamethasone and uterine estrogen receptors did not alter their binding capacity in response to neonatal exposure to vitamin D3 or gibberellin. 相似文献
9.
It is known from model experiments on Tetrahymena that primary exposure to a hormone induces receptor formation or amplification, in other words a hormonal imprinting. Substances acting on the intracellular Ca2+ level of the Tetrahymena, such as TMB-8, EDTA, EGTA, NiCl2 and La(NO3)3, interfered with hormonal imprinting of the unicellular to different degrees, and some of them influenced hormone (insulin, TSH) binding also independently of imprinting. Interference with the intracellular Ca-metabolism generally influenced imprinting by insulin and TSH, which were mediated by different mechanisms, to dissimilar degrees, or in opposite directions. On combined application of the agents acting on Ca-metabolism, their effects were additive. It appears that intact Ca-mediation is an essential prerequisite for normal hormonal imprinting. 相似文献
10.
pH-dependent structural transition in rabbit skeletal troponin C 总被引:1,自引:0,他引:1
Although the crystal structure of troponin C is known (Herzberg, O., and James, M. N. G. (1985) Nature 313, 653-659; Sundaralingam, M., Bergstrom, R., Strasburg, G., Rao, S. T., Roychowdhury, P., Greaser, M., and Wang, B. C. (1985) Science 227, 945-948), its structure in solution, particularly under physiological conditions, has not been established. We examined the conformation of troponin C under a variety of conditions by measuring the distance between sites located in the N- and C-terminal domains using the technique of resonance energy transfer. The donor was the luminescent lanthanide ion Tb3+ bound at the low affinity metal sites in the N-terminal domain. The acceptor was 4-dimethylaminophenylazophenyl-4'-maleimide attached at Cys-98 in the C-terminal domain. The distance between these sites was found to be greater than 5.2 nm at pH 5.0, 2.7 nm at pH 6.8 for uncomplexed troponin C, and 4.1 nm for troponin C complexed with troponin I at pH 6.8. These findings suggest that uncomplexed troponin C undergoes a pH-dependent transition from an elongated conformation, compatible with the crystal structure at acidic pH, to a more compact conformation at neutral pH. When complexed with troponin I, troponin C adopts a conformation of intermediate length compared to the uncomplexed molecule at pH 6.8 and 5.0. 相似文献