全文获取类型
收费全文 | 167篇 |
免费 | 35篇 |
出版年
2022年 | 4篇 |
2020年 | 1篇 |
2018年 | 1篇 |
2016年 | 1篇 |
2015年 | 2篇 |
2014年 | 4篇 |
2013年 | 1篇 |
2012年 | 4篇 |
2011年 | 6篇 |
2010年 | 3篇 |
2009年 | 3篇 |
2008年 | 4篇 |
2007年 | 7篇 |
2006年 | 4篇 |
2005年 | 13篇 |
2004年 | 3篇 |
2003年 | 6篇 |
2002年 | 1篇 |
2001年 | 4篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 16篇 |
1990年 | 5篇 |
1989年 | 8篇 |
1988年 | 14篇 |
1987年 | 5篇 |
1986年 | 8篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1976年 | 5篇 |
1975年 | 5篇 |
1974年 | 3篇 |
1973年 | 5篇 |
1972年 | 4篇 |
1970年 | 2篇 |
1966年 | 1篇 |
1965年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有202条查询结果,搜索用时 140 毫秒
111.
112.
113.
114.
115.
New reversible blockers for the β-adrenergic receptor have been synthesized. All the compunds possess free amine(s) residues which have been bromoacetylated. The N-bromoacetyl derivatives were also found to be potent β-blockers. One of these bromoacetyl derivatives: N-(2-hydroxy-3-naphthoxypropyl)-N′-bromoacetyl-ethylenediamine is shown to inhibit irreversibly 1-epinephrine-dependent adenylate cyclase from turkey erythrocytes, whereas it has no effect on the fluoride-dependent activity of the enzyme. This compound also eliminates the specific [3H]-propranolol binding to the β-receptors. These findings suggest that the compound N-(2-hydroxy-3-naphthoxypropyl)-N′-bromoacetyl-ethylenediamine is a potent β-receptor-directed affinity label. 相似文献
116.
Daphne Atlas 《Cellular signalling》2010,22(11):1597-1603
Voltage-gated calcium channels (VGCC) are involved in a large variety of cellular Ca2+ signaling processes, including exocytosis, a Ca2+ dependent release of neurotransmitters and hormones.Great progress has been made in understanding the mode of action of VGCC in exocytosis, a process distinguished by two sequential yet independent Ca2+ binding reactions. First, Ca2+ binds at the selectivity filter, the EEEE motif of the VGCC, and second, subsequent to a brief and intense Ca2+ inflow to synaptotagmin, a vesicular protein. Inquiry into the functional and physical interactions of the channels with synaptic proteins has demonstrated that exocytosis is triggered during the initial Ca2+ binding at the channel pore, prior to Ca2+ entry. Accordingly, a cycle of secretion begins by an incoming stimulus that releases vesicles from a releasable pool upon Ca2+ binding at the pore, and at the same time, the transient increase in [Ca2+]i primes a fresh set of non-releasable vesicles, to be fused by the next incoming stimulus.We propose a model, in which the Ca2+ binding at the EEEE motif and the consequent conformational changes in the channel are the primary event in triggering secretion, while synaptotagmin acts as a vesicle docking protein. Thus, the channel serves as the molecular On/Off signaling switch, where the predominance of a conformational change in Ca2+-bound channel provides for the fast secretory process. 相似文献
117.
118.
Clonidine and several analogues of clonidine are shown to be useful probes for alpha 2-adrenergic receptors in a comparative study of ligand binding and inhibition of adenylate cyclase. The alpha-adrenergic properties of a new potential probe, N-(4-hydroxyphenacetyl)-4-aminoclonidine hydrochloride, are described. [3H]Clonidine binds to alpha-receptors of NG108-15 neuroblastoma X glioma hybrid cell membranes with Kd values of 1.7 and 33 nM for putative high-affinity and low-affinity sites, respectively. p-Aminoclonidine and hydroxyphenacetyl aminoclonidine displace [3H]clonidine from the high-affinity sites with Kd values of 2.3 and 5.8 nM, respectively. Rat brain alpha 2-receptors also exhibit high affinity toward clonidine, p-aminoclonidine, and hydroxyphenacetyl aminoclonidine, as determined by displacement of specifically bound [3H]clonidine. Clonidine, p-amino-clonidine, and hydroxyphenacetyl aminoclonidine elicit modest inhibition (up to 24%) of NG108-125 adenylate cyclase by interaction with alpha 2-receptors (Kd,app 300, 30, and 130 nM, respectively); these compounds also partially reverse the inhibition elicited by (--)-norepinephrine. Components of the adenylate cyclase assay mixture, particularly ATP, GTP, sodium ions, and a nucleoside-triphosphate-regenerating system, decrease the high-affinity [3H]clonidine binding to NG108-15 membranes; in the presence of these components, alpha-receptors possess only low affinity (Kd 43 nM) for [3H]clonidine. The results are consistent with the concept that certain components required for the receptor-mediated inhibition of adenylate cyclase convert alpha 2-receptors from a high-affinity inactive state to a low-affinity active state. 相似文献
119.
Biodegradation of petroleum in seawater at low temperatures 总被引:9,自引:0,他引:9
120.