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排序方式: 共有124条查询结果,搜索用时 31 毫秒
31.
Circadian Activity Rhythms and Phase‐Shifting of Cultured Neurons of the Rat Suprachiasmatic Nucleus
The mammalian suprachiasmatic nucleus (SCN) is the major endogenous pacemaker that coordinates various daily rhythms including locomotor activity and autonomous and endocrine responses, through a neuronal and humoral influence. In the present study we examined the behavior of dispersed individual SCN neurons obtained from 1‐ to 3‐day‐old rats cultured on multi‐microelectrode arrays (MEAs). SCN neurons were identified by immunolabeling for the neuropeptides arginine‐vasopressin (AVP) and vasoactive intestinal polypeptide (VIP). Single SCN neurons cultured at low density onto an MEA can express firing rate patterns with different circadian phases. In these cultures we observed rarely synchronized firing patterns on adjacent electrodes. This suggests that, in cultures of low cell densities, SCN neurons function as independent pacemakers. To investigate whether individual pacemakers can be influenced independently by phase‐shifting stimuli, we applied melatonin (10 pM to 100 nM) for 30 min at different circadian phases and continuously monitored the firing rate rhythms. Melatonin could elicit phase‐shifting responses in individual clock cells which had no measurable input from other neurons. In several neurons, phase‐shifts occurred with a long delay in the second or third cycle after melatonin treatment, but not in the first cycle. Phase‐shifts of isolated SCN neurons were also observed at times when the SCN showed no sensitivity to these phase‐shifting stimuli in recordings from brain slices. This finding suggests that the neuronal network plays an essential role in the control of phase‐shifts. 相似文献
32.
《Molecular membrane biology》2013,30(1):9-25
AbstractThe icosahedral Polio virus capsid consists of 60 copies of each of the coat proteins VP1, VP2, VP3 and myristolyated VP4 (myrVP4). Catalyzed by the host cell receptor the Polio virus enters the host cell via externalization of myrVP4 and the N terminal part of VP1. There are several assumptions about the individual role of both of the proteins in the mechanism of membrane attachment and genome injection. We use the first 32 N terminal amino acids of VP1 and applied molecular dynamics simulations to assess its mechanism of function when attached and inserted into hydrated lipid membranes (POPC). Helical models are placed in various positions in regard to the lipid membrane to start with. As a comparison, the first 33 amino acids of the fusion peptide of gp41 of HIV-1 are simulated under identical conditions. Computational data support the idea that VP1 is not penetrating into the membrane to form a pore; it rather lays on the membrane surface and only perturbs the membrane. Furthermore, this idea is strengthened by channel recordings of both peptides showing irregular openings. 相似文献
33.
《Cell》2021,184(18):4626-4639.e13
34.
35.
Role of P2 purinergic receptors in synaptic transmission under normoxic and ischaemic conditions in the CA1 region of rat hippocampal slices 总被引:3,自引:3,他引:0
The role of ATP and its stable analogue ATPγS [adenosine-5′-o-(3-thio)triphosphate] was studied in rat hippocampal neurotransmission
under normoxic conditions and during oxygen and glucose deprivation (OGD). Field excitatory postsynaptic potentials (fEPSPs)
from the dendritic layer or population spikes (PSs) from the soma were extracellularly recorded in the CA1 area of the rat
hippocampus. Exogenous application of ATP or ATPγS reduced fEPSP and PS amplitudes. In both cases the inhibitory effect was
blocked by the selective A1 adenosine receptor antagonist DPCPX (8-cyclopentyl-1,3-dipropylxanthine) and was potentiated by different ecto-ATPase inhibitors:
ARL 67156 (6-N,N-diethyl-D-β,γ-dibromomethylene), BGO 136 (1-hydroxynaphthalene-3,6-disulfonate) and PV4 [hexapotassium dihydrogen monotitanoundecatungstocobaltate(II)
tridecahydrate, K6H2[TiW11CoO40]·13H2O]. ATPγS-mediated inhibition was reduced by the P2 antagonist suramin [8-(3-benzamido-4-methylbenzamido)naphthalene-1,3,5-trisulfonate]
at the somatic level and by other P2 blockers, PPADS (pyridoxalphosphate-6-azophenyl-2′,4′-disulfonate) and MRS 2179 (2′-deoxy-N
6-methyladenosine 3′,5′-bisphosphate), at the dendritic level. After removal of both P2 agonists, a persistent increase in
evoked synaptic responses was recorded both at the dendritic and somatic levels. This effect was prevented in the presence
of different P2 antagonists. A 7-min OGD induced tissue anoxic depolarization and was invariably followed by irreversible
loss of fEPSP. PPADS, suramin, MRS2179 or BBG (brilliant blue G) significantly prevented the irreversible failure of neurotransmission
induced by 7-min OGD. Furthermore, in the presence of these P2 antagonists, the development of anoxic depolarization was blocked
or significantly delayed. Our results indicate that P2 receptors modulate CA1 synaptic transmission under normoxic conditions
by eliciting both inhibitory and excitatory effects. In the same brain region, P2 receptor stimulation plays a deleterious
role during a severe OGD insult. 相似文献
36.
Circadian Activity Rhythms and Phase-Shifting of Cultured Neurons of the Rat Suprachiasmatic Nucleus
The mammalian suprachiasmatic nucleus (SCN) is the major endogenous pacemaker that coordinates various daily rhythms including locomotor activity and autonomous and endocrine responses, through a neuronal and humoral influence. In the present study we examined the behavior of dispersed individual SCN neurons obtained from 1- to 3-day-old rats cultured on multi-microelectrode arrays (MEAs). SCN neurons were identified by immunolabeling for the neuropeptides arginine-vasopressin (AVP) and vasoactive intestinal polypeptide (VIP). Single SCN neurons cultured at low density onto an MEA can express firing rate patterns with different circadian phases. In these cultures we observed rarely synchronized firing patterns on adjacent electrodes. This suggests that, in cultures of low cell densities, SCN neurons function as independent pacemakers. To investigate whether individual pacemakers can be influenced independently by phase-shifting stimuli, we applied melatonin (10 pM to 100 nM) for 30 min at different circadian phases and continuously monitored the firing rate rhythms. Melatonin could elicit phase-shifting responses in individual clock cells which had no measurable input from other neurons. In several neurons, phase-shifts occurred with a long delay in the second or third cycle after melatonin treatment, but not in the first cycle. Phase-shifts of isolated SCN neurons were also observed at times when the SCN showed no sensitivity to these phase-shifting stimuli in recordings from brain slices. This finding suggests that the neuronal network plays an essential role in the control of phase-shifts. 相似文献
37.
Christophe Py Mike W. Denhoff Marzia Martina Robert Monette Tanya Comas Tarun Ahuja Dolores Martinez Simon Wingar Juan Caballero Sylvain Laframboise John Mielke Alexei Bogdanov Collin Luk Naweed Syed Geoff Mealing 《Biotechnology and bioengineering》2010,107(4):593-600
We report on a simple and high‐yield manufacturing process for silicon planar patch‐clamp chips, which allow low capacitance and series resistance from individually identified cultured neurons. Apertures are etched in a high‐quality silicon nitride film on a silicon wafer; wells are opened on the backside of the wafer by wet etching and passivated by a thick deposited silicon dioxide film to reduce the capacitance of the chip and to facilitate the formation of a high‐impedance cell to aperture seal. The chip surface is suitable for culture of neurons over a small orifice in the substrate with minimal leak current. Collectively, these features enable high‐fidelity electrophysiological recording of transmembrane currents resulting from ion channel activity in cultured neurons. Using cultured Lymnaea neurons we demonstrate whole‐cell current recordings obtained from a voltage‐clamp stimulation protocol, and in current‐clamp mode we report action potentials stimulated by membrane depolarization steps. Despite the relatively large size of these neurons, good temporal and spatial control of cell membrane voltage was evident. To our knowledge this is the first report of recording of ion channel activity and action potentials from neurons cultured directly on a planar patch‐clamp chip. This interrogation platform has enormous potential as a novel tool to readily provide high‐information content during pharmaceutical assays to investigate in vitro models of disease, as well as neuronal physiology and synaptic plasticity. Biotechnol. Bioeng. 2010;107:593–600. © 2010 Wiley Periodicals, Inc. 相似文献
38.
During the 1970s, the multiunit reactivity of the olfactory bulb to food odor was extensively shown to increase before their usual meal in rats habituated to having a single 2 h daily meal compared to the same rats recorded after their usual meal. More recently, we reported dramatic modifications of mitral cell single-unit reactivity in adult rats following a simple a manipulation of the olfactory environment--exposure to an odor. The present study aimed at testing the hypothesis that a simple behavioral change such as habituation to chronic food restriction may induce profound changes in olfactory bulb responsiveness compared to occasional fasting. We compared mitral cell reactivity in non-fasted rats, in rats fasted during 22 h for the very first time, and in rats habituated during 15 days to a chronic 22 h food restriction. Mitral cell single-unit reactivity was found to increase less in rats habituated to fasting than in newly fasted rats. Indeed, the proportion of mitral cell responses to food and non-food odors was significantly higher in rats habituated to fasting than in non-fasted rats, but lower than in newly fasted rats. The proportion of simple unsynchronized and synchronized responses of 1b and 2b types was also lower in habituated rats whereas the proportion of complex synchronized responses of 4b type increased. This decreased responsiveness in habituated rats, similar to that observed in rats repeatedly exposed for 20 min per day to an odor during six consecutive days in our previous studies, is discussed with respect to olfactory bulb plasticity. 相似文献
39.
B. Pophof 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1998,183(2):153-164
Three volatile alkyl-thio-trifluoro propanones inhibiting the esterase in olfactory sensilla of the silkmoths Antheraea polyphemus and A. pernyi were used to test the hypothesis that enzymatic pheromone degradation is responsible for the decline of the receptor potential
after pheromone stimulation. Test stimuli were the pheromone components (E,Z)-6,11-hexadecadienyl acetate, a substrate for the sensillar esterase, and (E,Z)-6,11-hexadecadienal, not degraded by the esterase. Each compound acts on a separate type of receptor cell. In both receptor
cell types the trifluoro propanones caused a partially reversible reduction of sensitivity as indicated by smaller receptor
potential amplitudes and lower nerve impulse frequencies. Since application of the esterase inhibitors did not prolong the
decline of the receptor potential of the acetate cell, the esterase is not responsible for the rapid pheromone deactivation.
When the trifluoro propanones were applied after the pheromone at high concentrations, they rapidly inhibited (repolarized)
both receptor cell types. Experiments with local application of trifluoro propanones revealed that the inhibitory effect spreads
within seconds along the length of the sensillum. The inhibition of the electrophysiological responses might be due to an
antagonistic action of the trifluoro propanones at the pheromone-binding sites, either at the receptor molecules or at the
pheromone-binding protein.
Accepted: 4 February 1998 相似文献
40.
By definition, electrical resonance of excitable biomembranes reflects their remarkable ability to select input signals with preferential frequencies as ones that will pass through the chain of information exchange within a coordinated organism. This feature is known to be caused and regulated by the voltage-dependent kinetics of transmembrane ion channels. Knowledge about the resonant behavior of excitable cells may prove crucial toward better underpinning those essential properties of neurons which make them to function as a highly coordinated network. In this work we present novel experimental evidence which strongly supports the paradigm of selective communication between excitable cells, by no more than efficient transfer of energy which takes place when the frequency of subthreshold presynaptic pulses matches the natural, resonant frequency of a target excitable tissue. As a possible direct application, our novel experimental results prove the functional importance of bursting activity of pre-synaptic neurons as an effective physiological mechanism for discriminatory communication between neurons. 相似文献