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111.
Processing of global and local properties——An analysis with event-related brain potentials 总被引:3,自引:1,他引:2
The different processing of global and local properties of compound visual stimuli was studied with event-related brain potentials (ERPs) in the present experiment. It was found that, compared with the identification of global properties, the discrimination of local properties elicited longer RTs, lower accuracies, increased amplitudes of P1, decreased amplitudes of N1, and longer latencies of N2 and P3. The conflict of global and local properties increased the amplitudes of P2, decreased the amplitudes of P3, and prolonged latencies of N2 and P3. These results indicated that the advantage of global processing occurs at an early perceptual stage, and the attentional mechanisms for global and local processing may be different. 相似文献
112.
We compared the pattern of 3-phosphorylated phosphoinositides produced by confluent 3T3-L1 preadipose cells upon exposure to growth factors that either induce differentiation (insulin, insulin-like growth factor-1) or do not (platelet-derived growth factor). Following addition of insulin or insulin-like growth factor-1, PI(3,4,5)P3 rapidly rose, on average, to levels tenfold over basal. PI(3,4)P2 either did not change (after insulin) or slightly increased (1.5 fold). Time course studies with insulin demonstrated that the rise in PI(3,4,5)P3 peaked by 1 minute, and levels then remained steady over 30 minutes. Dose-response experiments showed that insulin at a concentration of 1 nM was sufficient for the PI(3,4,5)P3 response. Insulin failed to increase PI(3,4)P2 at any of the time points or at any of the doses used. In contrast, after addition of platelet-derived growth factor, both PI(3,4)P2 and PI(3,4,5)P3 rose concurrently and to comparable extents. These data suggest that one possible mechanism contributing to insulin/insulin-like growth factor-1-induced 3T3-L1 preadipose cell differentiation is a distinct pattern of 3-phosphorylated phosphoinositide accumulation, defined by a prominent increase in PI(3,4,5)P3 with no (in the case of insulin), or a minimal (in the case of IGF-1), rise in PI(3,4)P2. 相似文献
113.
第四纪甲虫的研究在国外已开展多年,形成了一套完整的方法,而在我国几乎为一空白。第四纪甲虫研究方法一般包括如下几个步骤:野外采样,实验室分离,标本保存,标本鉴定,结果分析。第四纪甲虫研究的意义主要表现在如下三个方面:重建古气候、恢复昆虫地理史和第四纪考古。 相似文献
114.
115.
盐或低温胁迫对花生幼苗下胚轴ATP酶和质膜中PIP2含量的影响 总被引:2,自引:0,他引:2
经6%-12%Dextran T70密度梯度离心,获得了纯度较高的7d龄花生幼苗下胚轴质膜和液泡膜制剂。150mmol/L NaCl或10℃低温处理花生幼苗24h,其下胚轴质膜上的Mg^2+激活的ATPase活性分别提高了37.6%和17.2%;Ca^2+-ATPase活性分别提高45.8%和33.6%。上述盐或低温处理也提高了液泡膜上Mg^2+激活的ATPase活性,分别为对照的141.2%和1 相似文献
116.
国家自然科学基金评审程序剖析──1993年和1994年植物学科面上基金项目分析陈峰,朱大保(中国科学院武汉植物研究所武汉430074)(国家自然科学基金委员会生命科学部北京100083)关键词基金,评审,科研立项,学科ANALYSLSFORJUDGE... 相似文献
117.
Chang WC Shyu WJ Shi GY Lin MT Jen CJ Wing LY Tang MJ Wu HL 《Journal of biomedical science》1996,3(1):59-66
Treatment of cultured bovine carotid artery endothelial cells with 0.1 µM human plasmin has been reported to induce a receptor-mediated short burst of arachidonate release, which is a pertussis toxin-sensitive and extracellular calcium-dependent reaction. Plasmin-induced calcium influx in cells was significantly inhibited by pretreatment with pertussis toxin, indicating that the former was coupled with a pertussis toxin-sensitive guanosine 5-triphosphate (GTP)-binding protein. Plasmin significantly induced the formation of lysophosphatidylcholine but not lysophosphatidylethanolamine. A cellular phospholipase A2 with an arachidonyl specificity at the sn-2 position of phosphatidylcholine, which required submicromolar calcium, was identified as a cytosolic phospholipase A2 by immunoblot analysis. By a cell-free enzyme activity assay and immunoblot analysis, plasmin was found to induce a translocation of the cytosolic phospholipase A2 from the cytosol to the membrane. Taken together, the results suggest that plasmin bound to its putative receptor and activated a GTP-binding protein coupled to calcium influx channel, followed by translocation and activation of cytosolic phospholipase A2 in endothelial cells. 相似文献
118.
Blackfoot disease is a peripheral vascular disease resulting in gangrene of the lower extremities. Although extensive epidemiological
study has implicated high arsenic content in artesian well water of the endemic area bears some important connection with
the disease, the etiology of the disease is still not clarified. In this study, attention is paid to chemical speciation of
arsenic in order to find out whether the concentrations of arsenic species in urine of Blackfoot disease patients are different
from those of controls. Experimental results indicate that the total arsenic, inorganic arsenic, monomethylarsonic acid, and
other forms of arsenic in the urine of patients are significantly higher than those of the contols. The possible connection
of those arsenic species with the etiology of the disease is discussed. 相似文献
119.
Virtual electrodes in cardiac tissue: a common mechanism for anodal and cathodal stimulation. 总被引:6,自引:0,他引:6 下载免费PDF全文
Traditional cable analyses cannot explain complex patterns of excitation in cardiac tissue with unipolar, extracellular anodal, or cathodal stimuli. Epifluorescence imaging of the transmembrane potential during and after stimulation of both refractory and excitable tissue shows distinctive regions of simultaneous depolarization and hyperpolarization during stimulation that act as virtual cathodes and anodes. The results confirm bidomain model predictions that the onset (make) of a stimulus induces propagation from the virtual cathode, whereas stimulus termination (break) induces it from the virtual anode. In make stimulation, the virtual anode can delay activation of the underlying tissue, whereas in break stimulation this occurs under the virtual cathode. Thus make and break stimulations in cardiac tissue have a common mechanism that is the result of differences in the electrical anisotropy of the intracellular and extracellular spaces and provides clear proof of the validity of the bidomain model. 相似文献