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31.
采用了一种HMM(隐马尔可夫模型 )的方法用于G蛋白偶联受体超家族层次各类别之间进行识别 ,具体考虑了ACDE与B类超家族 ,以及BCDE与A类超家族的分辨 ,取得了不错的效果 ,类之间的识别准确率可以达到10 0 % .研究过程中 ,考虑了G蛋白偶联受体一级结构信息和数据自身特性 ,合理地利用了G蛋白偶联受体一级结构序列的不等长特性 ,同时在模型的预测方面采用了双模型的预测机制 . 相似文献
32.
Excitatory effect of histamine on neuronal activity of rat cerebellar fastigial nucleus in vitro 总被引:1,自引:0,他引:1
TANG Biao ZHANG Jun LI HongZhao ZHU JingNing & WANG JianJun Department of Biological Science Technology/State Key Laboratory of Pharmaceutical Biotechnology School of Life Sciences Nanjing University Nanjing China Jiangsu Key Laboratory for Bioresource Technology School of Life Sciences Nanjing Normal University Nanjing China 《科学通报(英文版)》2007,52(4):497-503
The cerebellar fastigial nucleus (FN) holds an important role in motor control and body balance. Previous studies have revealed that the nucleus is innervated by direct hypothalamocerebellar histaminergic fibers. However, the functional role of histaminergic projection in cerebellar FN has never been established. In this study, we investigated the effect of histamine on neuronal firing of cerebellar FN by using slice preparations. Sixty-five FN cells were recorded from 47 cerebellar slices, and a vast majority of the cells responded to histamine stimulation with an excitatory response (58/65, 89.2%). Perfusing slices with low-Ca2 /high-Mg2 medium did not block the histamine-induced excitation (n=10), supporting a direct postsynaptic action of histamine on the cells. Furthermore, the excitatory effect of histamine on FN neurons was not blocked by selective histamine H1 receptor antagonist triprolidine (n=15) or chlorpheniramine (n=10), but was effectively suppressed by ranitidine (n=15), a highly selective histamine H2 receptor antagonist. On the other hand, highly selective histamine H2 receptor agonist dimaprit (n=20) instead of histamine H1 receptor agonist 2-pyridylethylamine (n=16) mimicked the ex- citatory effect of histamine on FN neurons. The dimaprit-induced FN neuronal excitation was effectively antagonized by selective histamine H2 receptor antagonist ranitidine (n=13) but not influenced by se- lective histamine H1 receptor antagonist triprolidine (n=15). These results demonstrate that histamine excites cerebellar FN cells via the histamine H2 receptor mechanism and suggest that the hypotha- lamocerebellar histaminergic fibers may modulate cerebellar FN-mediated sensorimotor integration through their excitatory innervations on FN neurons. 相似文献
33.
34.
谷氨酸及其受体与运动 总被引:2,自引:0,他引:2
谷氨酸是中枢神经系统中主要的兴奋性神经递质,它的变化与运动性中枢疲劳的产生有密切的联系.谷氨酸是通过谷氨酸受体传递兴奋性信息的,谷氨酸受体是中枢神经系统主要的兴奋性神经受体,分为离子型受体与代谢型受体.谷氨酸受体在学习.记忆的形成、脑缺氧.缺血导致的病变及其它神经系统功能中扮演着重要的角色. 相似文献
35.
On day 3 of gestation ,one uterine horn of female pregnant mouse was injected intraluminally with 5 μL 0.1μg/mL lactacystin,a specific inhibitor of ubiquitin-pro-teasome pathway (UPP),while the contralateral horn served as control ,Animals were sacrificed by cervical dislocation on day 5,6,7 of gestation ,respectively,Then the number of implanted embryos in each uterine horn was calcuated,and the expression of VEGF and its receptors was examined,The data showed that the number of implanted embryos was decreased significantly after treatment with lactacystin ,The results of RT-PCR and Western blot indicated that expression of VEGF and its receptors at mRNA and protein levels was significantly decreased in the treated uterus,menawhile,the expression of HIF-1α(the α subunit of HIF ,a transcrip-tional factor of VEGF) was reduced at both mRNA and protein levels,These data suggested that the effect of UPP on VEGF expression was realized through regulating HIF-1α expression .In addition ,UPP is likely to take part in the modulation of VEGF receptors expression ,These changes may be one of the reasons for the reduction of implanted embryos. 相似文献
36.
Molecular mechanisms of nitrosative stress-mediated protein misfolding in neurodegenerative diseases
Nitrosative and oxidative stress, associated with the generation of excessive reactive oxygen or nitrogen species, are thought
to contribute to neurodegenerative disorders. Many such diseases are characterized by conformational changes in proteins that
result in their misfolding and aggregation. Accumulating evidence implies that at least two pathways affect protein folding:
the ubiquitin-proteasome system (UPS) and molecular chaperones. Normal protein degradation by the UPS can prevent accumulation
of aberrantly folded proteins. Molecular chaperones – such as protein-disulfide isomerase, glucose-regulated protein 78, and
heat shock proteins – can provide neuroprotection from aberrant proteins by facilitating proper folding and thus preventing
their aggregation. Our recent studies have linked nitrosative stress to protein misfolding and neuronal cell death. Here,
we present evidence for the hypothesis that nitric oxide contributes to degenerative conditions by S-nitrosylating specific chaperones or UPS proteins that would otherwise prevent accumulation of misfolded proteins.
Received 5 December 2006; received after revision 7 February 2007; accepted 15 March 2007 相似文献
37.
Purine and pyrimidine receptors 总被引:17,自引:0,他引:17
Burnstock G 《Cellular and molecular life sciences : CMLS》2007,64(12):1471-1483
Adenosine 5′-triphosphate (ATP), in addition to its intracellular roles, acts as an extracellular signalling molecule via
a rich array of receptors, which have been cloned and characterised. P1 receptors are selective for adenosine, a breakdown
product of ATP, produced after degradation by ectonucleotidases. Four subtypes have been identified, A1, A2A, A2B and A3 receptors. P2 receptors are activated by purines and some subtypes also by pyrimidines. P2X receptors are ligand-gated ion
channel receptors and seven subunits have been identified, which form both homomultimers and heteromultimers. P2Y receptors
are G protein-coupled receptors, and eight subtypes have been cloned and characterised to date.
Received 22 November 2006; received after revision 11 January 2007; accepted 27 February 2007 相似文献
38.
Taste perception and coding in the periphery 总被引:5,自引:0,他引:5
Sugita M 《Cellular and molecular life sciences : CMLS》2006,63(17):2000-2015
Recent identification of taste receptors and their downstream signaling molecules, expressed in taste receptor cells, led
to the understanding of taste coding in the periphery. Ion channels appear to mediate detection of salty and sour taste. The
sensations of sweet, umami and bitter taste are initiated by the interaction of sapid molecules with the G-protein-coupled
receptors T1Rs and T2Rs. Mice lacking either PLCβ2 or TRPM5 diminish behavioral and nerve responses to sweet, umami and bitter
taste stimuli, suggesting that both receptor families converge on a common signaling pathway in the taste receptor cells.
Nevertheless, separate populations of taste cells appear to be uniquely tuned to sweet, umami and bitter taste. Since PLCβ2-deficient
mice still respond to sour and salty stimuli, sour and salty taste are perceived independent of bitter, umami and sweet taste.
In this review, the recent characterization of the cellular mechanisms underlying taste reception and perception, and of taste
coding in the periphery will be discussed.
Received 5 March 2006; received after revision 2 May 2006; accepted 10 June 2006 相似文献
39.
Maldonado-Celisa ME Roussia S Foltzer-Jourdainne C Gossé F Lobstein A Habold C Roessner A Schneider-Stock R Raul F 《Cellular and molecular life sciences : CMLS》2008,65(9):1425-1434
We showed previously that inhibition of polyamine catabolism with the polyamine oxidase inhibitor MDL 72527 (MDL) potentiates
the apoptotic effects of apple procyanidins (Pcy) in SW620 cells. Here we report that Pcy caused an activation of the intrinsic
apoptotic pathway through enhanced polyamine catabolism and mitochondrial membrane depolarization. MDL in the presence of
Pcy caused a profound intracellular depletion of polyamines and exerted a protective effect on mitochondrial functions. MDL
potentiation of Pcy-triggered apoptosis was reversed by addition of exogenous polyamines. In addition, MDL in combination
with Pcy activated the extrinsic apoptotic pathway through enhanced TRAIL-death receptor (DR4/DR5) expression. Potentiation
of Pcy-triggered apoptosis by MDL was inhibited when cells were exposed to specific inhibitors of DR4/DR5. These data indicate
that the depletion of intracellular polyamines by MDL in the presence of Pcy caused a switch from intrinsic to extrinsic apoptotic
pathways in human colon cancer-derived metastatic cells.
Received 15 January 2008; received after revision 19 February 2008; accepted 7 March 2008 相似文献
40.
Caltabiano G Campillo M De Leener A Smits G Vassart G Costagliola S Pardo L 《Cellular and molecular life sciences : CMLS》2008,65(16):2484-2492
The glycoprotein hormone receptor family is peculiar because, in contrast to other G protein-coupled receptors, a large N-terminal extracellular ectodomain is responsible for hormone recognition. Hormone-receptor pairs have evolved in such a manner that a limited number of positions both at the 'seat-belt' domain of the hormone and the leucine-rich repeats of the receptor, play attractive and repulsive interactions for binding and specificity, respectively. Surprisingly, the constitutive activity of the receptor, mostly modulated by highly conserved amino acids within the heptahelical domain of the receptor (i.e., outside the hormone binding region), also regulates effectiveness of hormone recognition by the extracellular part. In this review we analyze, at the molecular level, these important discriminating determinants for selective binding of glycoprotein hormones to their receptors, as well as natural mutations, observed in patients with gestational hyperthyroidism or ovarian hyperstimulation syndrome, that modify the selectivity of binding. 相似文献