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51.
The amino acids L-glutamic and L-aspartic acids form the most widespread excitatory transmitter network in mammalian brain. The excitation produced by L-glutamic acid is important in the early development of the nervous system, synaptic plasticity and memory formation, seizures and neuronal degeneration. The receptors activated by L-glutamic acid are a target for therapeutic intervention in neurodegenerative diseases, brain ischaemia and epilepsy. There are two types of receptors for the excitatory amino acids, those that lead to the opening of cation-selective channels and those that activate phospholipase C (ref. 11). The receptors activating ion channels are NMDA (N-methyl-D-aspartate) and kainate/AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate)-sensitive receptors. The complementary DNAs for the kainate/AMPA receptor and for the metabotropic receptor have been cloned. We report here on the isolation and characterization of a protein complex of four major proteins that represents an intact complex of the NMDA receptor ion channel and on the cloning of the cDNA for one of the subunits of this receptor complex, the glutamate-binding protein. 相似文献
52.
Gelsolin inhibition of fast axonal transport indicates a requirement for actin microfilaments 总被引:2,自引:0,他引:2
The actions of actin-based microfilaments in cell motility suggest a possible role in the mechanism of fast axonal transport, but the pharmacological data evaluating their role in this process are equivocal. Moreover, microfilaments are difficult to preserve and identify in ultrastructural studies, so the organization and function of axonal actin has remained uncertain. We have now evaluated the role of actin microfilaments in intracellular transport of membranous organelles using video-enhanced contrast microscopy and gelsolin to analyse fast axonal transport directly in isolated axoplasm from the squid giant axon. With this preparation it is possible to perfuse axoplasm with large molecules that do not cross the plasmalemma, while controlling cation levels. The 90,000-molecular weight protein gelsolin depolymerizes actin microfilaments in micromolar Ca2+, but not in the absence of Ca2+. Axonal transport of membranous organelles has previously been shown to be unaffected by levels of Ca2+ up to 10 microM. In the presence of EGTA, gelsolin has no effect on the movement of membranous organelles, but in the presence of 10 microM Ca2+ it completely blocks transport of all membranous organelles. No changes in the organization of the axoplasm were detected. These results and results using other probes for actin are consistent with the hypothesis that actin-based microfilaments are involved in the movement of membranous organelles in the axon. 相似文献
53.
G. M. Vaughan J. P. Allen M. K. Vaughan T. M. Siler-Khodr 《Cellular and molecular life sciences : CMLS》1980,36(3):364-366
Summary Sensory deprivation produced by removing the eyes and olfactory bulbs in male rats allowed pinealectomy to markedly augment the post-adrenalectomy elevation of ACTH levels. Pineal removal or sensory deprivation separately did not have this effect. Thus, intact sensory input and an intact pineal gland are independently capable of restricting the post-adrenalectomy rise in ACTH levels.This work was supported in part by NIH Grant No. P30 HD 10202. We thank F. Lynd and R.J. Reiter for advice, P. Starr and J. Sackman for technical assistance, and Bess Mitchell for typing. 相似文献
54.
55.
Juan D. Delius Gillian Thompson Keith L. Allen Jacky Emmerton 《Cellular and molecular life sciences : CMLS》1972,28(10):1244-1246
Zusammenfassung Junggeschlüpfte Silber- und Heringsmöven zeigen beim Picken von kleinflächigen, beweglichen Reizen Spektralfarbbevorzugungen. Drei theoretische Modelle sind vorgeschlagen worden, die diese Bevorzugungen erklären sollen. Die Voraussagen dieser Modelle bezüglich der Bevorzugung von Mischfarben wurden experimentell geprüft und als nicht zutreffend befunden. Vielmehr legen die Ergebnisse die Vermutung nahe, dass die Bevorzugung nicht, wie bisher angenommen, auf einem afferenten sensorischen Filtermechanismus beruht, sondern auf einen mehr zentralen, postperzeptualen Prozess zurückzuführen ist. 相似文献
56.
57.
Non-random X chromosome expression in female mules and hinnies 总被引:3,自引:0,他引:3
58.
T Arendt Y Allen J Sinden M M Schugens R M Marchbanks P L Lantos J A Gray 《Nature》1988,332(6163):448-450
Alcohol-induced memory impairment in man has been attributed to deficiencies in subcortical noradrenergic and cholinergic systems, as well as to damage in midbrain structures. Korsakoff's psychosis, a disease in which alcohol poisoning causes apparently irreversible memory defects, is characterized by lesions in cholinergic and noradrenergic nuclei and by a decrease in the activity of choline acetyltransferase (ChAT) and the content of noradrenaline (NA) in forebrain areas such as cerebral cortex and hippocampus, innervated by these nuclei. Prolonged intake of ethanol in rodents similarly produces signs of noradrenergic and cholinergic deafferentation in the cortex and hippocampus, as well as persistent memory deficits. To test whether alcohol-induced memory impairments depend on cholinergic deafferentation, we transplanted cholinergic-rich fetal basal forebrain cell suspensions into the cortex and hippocampus of alcohol-treated rats. The substantial and persistent memory losses produced in our rats by ethanol intake were associated with an impairment of cholinergic function, and were reversed by cholinergic-rich transplants into cortex and hippocampus. 相似文献
59.
Phosphonopeptides, a new class of synthetic antibacterial agents 总被引:18,自引:0,他引:18
J G Allen F R Atherton M J Hall C H Hassall S W Holmes R W Lambert L J Nisbet P S Ringrose 《Nature》1978,272(5648):56-58
60.
J. J. Chart H. Sheppard M. J. Allen W. L. Bencze R. Gaunt 《Cellular and molecular life sciences : CMLS》1958,14(4):151-152
Zusammenfassung 2-Methyl-1,2-bis-(3-pyridyl)-1-propanon (Su 4885) hemmt beim Hund die Ausscheidung von 17-OH-Steroiden aus den Nebennieren und hemmtin vitro ähnlich wie Amphenon den ACTH-Effekt auf Ratten-, Meerschweinchen-und Hunde-Nebennieren.In situ bei der Ratte hat es jedoch keine Amphenon-Wirkung, von dem es sich auch sonst unterscheidet. 相似文献