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排序方式: 共有1067条查询结果,搜索用时 31 毫秒
71.
T Aoe E Cukierman A Lee D Cassel PJ Peters VW Hsu 《Canadian Metallurgical Quarterly》1997,16(24):7305-7316
The small GTPase ADP-ribosylation factor 1 (ARF1) is a key regulator of intracellular membrane traffic. Regulators of ARF1, its GTPase-activating protein (GAP) and its guanine nucleotide exchange factor have been identified recently. However, it remains uncertain whether these regulators drive the GTPase cycle of ARF1 autonomously or whether their activities can be regulated by other proteins. Here, we demonstrate that the intracellular KDEL receptor, ERD2, self-oligomerizes and interacts with ARF1 GAP, and thereby regulates the recruitment of cytosolic ARF1 GAP to membranes. Because ERD2 overexpression enhances the recruitment of GAP to membranes and results in a phenotype that reflects ARF1 inactivation, our findings suggest that ERD2 regulates ARF1 GAP, and thus regulates ARF1-mediated transport. 相似文献
72.
A bolometric method of calibrating low-level microwave power measuring devices is currently employed at the National Bureau of Standards in Boulder, Colo. The technique is one of direct comparison between the standard and the unknown, and utilizes NBS working standard bolometer units and self-balancing dc bridges. In general, the unknown is calibrated to an accuracy of one per cent. The following quantities are defined and the associated errors are discussed: 1) Calibration factor of a bolometer unit in combination with a directional coupler, 2) Calibration factor of a bolometer unit, and 3) Effective efficiency of a bolometer unit. 相似文献
73.
The predominant early childhood education philosophy in the United States views formal academic instruction as inappropriate and harmful to the social development of young children. Chinese American immigrants to the United States, however, have been found to teach their young children in more formal ways, to be more directive, and to structure their children's use of time to a greater degree (C. S. Huntsinger, P. E. Jose, F.-R. Liaw, & W.-D. Ching, 1997). Forty European American (20 boys, 20 girls) and 36 2nd-generation Chinese American (18 boys, 18 girls) 1st- and 2nd-grade children and their mothers, fathers, and teachers participated in the Time 2 data collection of this longitudinal study to assess whether the formal academic environment provided by Chinese American parents is linked to poorer social adjustment in their children. Regressions showed that parents' work-oriented methods influenced academic performance but not social adjustment of their children. 相似文献
74.
Microelectromechanical wavelength tuning is demonstrated for the first time in a resonant-cavity light-emitting diode. The device utilizes a deformable-membrane top mirror suspended by an air gap above a diode-active region and bottom mirror. Applied membrane-substrate bias produces an electrostatic force which reduces the air-gap thickness, and therefore, the resonant wavelength. We report broad tunability of nearly 40 nm and spectral linewidths as narrow as 1.9 nm (2.6 meV) for operation near 950 nm 相似文献
75.
RN Gunn PA Sargent CJ Bench EA Rabiner S Osman VW Pike SP Hume PM Grasby AA Lammertsma 《Canadian Metallurgical Quarterly》1998,8(4):426-440
[Carbonyl-11C]WAY-100635 is a promising PET radioligand for the 5-HT1A receptor, having demonstrated more favorable characteristics for in vivo imaging than the previously available [O-methyl-11C]WAY-100635. The current study evaluates different tracer kinetic modelling strategies for the quantification of 5-HT1A receptor binding in human brain. Mathematical modelling of the carbonyl-labeled radiotracer is investigated using compartmental structures, including both plasma input and reference tissue approaches. Furthermore, the application of basis function methods allows for the investigation of parametric imaging, providing functional maps of both delivery and binding of the radioligand. Parameter estimates of binding from normal volunteers indicate a low intra- versus a high intersubject variability. It is concluded that a simplified reference tissue approach may be used to quantify 5-HT1A binding either in terms of ROI data or as parametric images. 相似文献
76.
Fritze M. Chen C.L. Calawa S. Yost D. Wheeler B. Wyatt P. Keast C.L. Snyder J. Larson J. 《Electron Device Letters, IEEE》2004,25(4):220-222
High-speed results on sub-30-nm gate length pMOSFETs with platinum silicide Schottky-barrier source and drain are reported. With inherently low series resistance and high drive current, these deeply scaled transistors are promising for high-speed analog applications. The fabrication process simplicity is compelling with no implants required. A sub-30-nm gate length pMOSFET exhibited a cutoff frequency of 280 GHz, which is the highest reported to date for a silicon MOS transistor. Off-state leakage current can be easily controlled by augmenting the Schottky barrier height with an optional blanket As implant. Using this approach, good digital performance was also demonstrated. 相似文献
77.
Air-water counter-current flow limit experiments were conducted in thin rectangular channels at atmospheric pressure. The parameters were: narrow channel width, either 1.1 mm or 2.2 mm; inlet water temperature, ranging from 294 K to 330 K; channel surface condition, either clean aluminum, aluminum oxide, or acrylic; location and geometry of the air inlet; method of forcing air through the channel; and liquid head above the channel. Experimental results for each set of parameters can be linearly correlated using the square root of the non-dimensional superficial velocities. Channel surface wetting and location and geometry of the air injection had the greatest effect. Narrow channel width, water temperature, method used to force air through the channel, and liquid head above the channel had little effect on the flooding characteristics. 相似文献
78.
Paulter N.G. Smith A.J.A. Larson D.R. Souders T.M. Roddie A.G. 《IEEE transactions on instrumentation and measurement》2003,52(6):1825-1833
A comparison of the pulse parameter values obtained from the pulse measurement services of the National Institute of Standards and Technology, USA, and the National Physical Laboratory, U.K., was performed. The comparison was based on the pulse parameters of amplitude, transition duration, overshoot, and undershoot (preshoot). The parameter comparison was applied to raw (measured) waveforms, corrected waveforms (if applicable), and reconstructed waveforms. The results of the comparison show that the pulse parameter values for both national laboratories are within published uncertainties. 相似文献
79.
VW Rusch 《Canadian Metallurgical Quarterly》1996,111(2):293-295
Occupational asthma is one of the commonest occupational lung diseases. This is a case of asthma related to arc-welding in a shipyard. Serial peak expiratory flow rate readings were taken with and without exposure to the welding process. The results showed that the patient had occupational asthma from welding. This case report serves to remind us of the need to ask every adult with asthma for their occupational history. It emphasises the need for early diagnosis and removal from the cause of asthma. A delay in diagnosis may lead to non-specific bronchial reactivity and persistence of symptoms. 相似文献
80.
VW Rahlfs 《Canadian Metallurgical Quarterly》1995,45(2):205-210
Differences between conventional statistical methods and more useful, modern methods are demonstrated using a statistical analysis of data from therapeutic research in rheumatology. The conventional methods, t-test and graphs of mean values and the boxplot, detect almost no differences between treatment groups. A more recent procedure for analysing group differences is the Wilcoxon-Mann-Whitney test. The associated graphs are based on the cumulative distribution function of the two treatment groups and the synthetic Receiver Operating Characteristic (ROC). Special differences, namely baseline dependencies, can be visualized in this way. 相似文献