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排序方式: 共有64条查询结果,搜索用时 484 毫秒
1.
Gillespie J.K. Fitch R.C. Sewell J. Dettmer R. Via G.D. Crespo A. Jenkins T.J. Luo B. Mehandru R. Kim J. Ren F. Gila B.P. Onstine A.H. Abernathy C.R. Pearton S.J. 《Electron Device Letters, IEEE》2002,23(9):505-507
The low temperature (100°C) deposition of Sc2O3 or MgO layers is found to significantly increase the output power of AlGaN/GaN HEMTs. At 4 GHz, there was a better than 3 dB increase in output power of 0.5×100 μm2 HEMTs for both types of oxide passivation layers. Both Sc2 O3 and MgO produced larger output power increases at 4 GHz than conventional plasma-enhanced chemical vapor deposited (PECVD) SiNx passivation which typically showed ⩽2 dB increase on the same types of devices. The HEMT gain also in general remained linear over a wider input power range with the Sc2O3 or MgO passivation. These films appear promising for reducing the effects of surface states on the DC and RF performance of AlGaN/GaN HEMTs 相似文献
2.
Derek Hodson Gila Hanna Jacques Désautels 《Canadian Journal of Science, Mathematics, & Technology Education》2013,13(1):1-4
Abstract This article investigates some of the specific features involved in accommodating the idea of actual infinity as it appears in set theory. It focuses on the conceptions of two individuals with sophisticated mathematics background, as manifested in their engagement with variations of a well-known paradox: the ping-pong ball conundrum. The APOS theory is used as a framework to interpret participants’ efforts to resolve the paradoxes. The cases discussed focus on how transfinite subtraction may be conceptualized, and they suggest that there is more to accommodating the idea of actual infinity than the ability to act on a completed object—rather, it is the manner in which objects are acted upon that is also significant. 相似文献
3.
Dworkin Robert H.; Hartstein Gila; Rosner Howard L.; Walther Robert R.; Sweeney Eugene W.; Brand Leonard 《Canadian Metallurgical Quarterly》1992,101(1):200
Although patients with chronic pain (CP) are often psychologically distressed, it has been difficult to determine whether this distress is an antecedent of CP or whether it is caused by the experience of living with CP. This investigation aimed to develop a method that would allow individuals who are at risk for the development of CP to be studied before the pain has become chronic. Patients with acute herpes zoster (HZ) were assessed with demographic, medical, pain, and psychosocial measures. Pain was assessed in follow-up interviews at 6 wks and 3, 5, 8, and 12 mo after these initial assessments. There were no significant differences between Ss who developed short-term HZ pain and Ss who did not develop short-term pain for any of the measures at the initial assessment, except for 1 measure of pain intensity. Ss who developed HZ CP, however, had significantly greater pain intensity, higher state and trait anxiety, greater depression, lower life satisfaction, and greater disease conviction at the initial assessment than Ss who did not develop CP. In discriminant analyses, disease conviction, pain intensity, and state anxiety each made a unique contribution to discriminating Ss who did and did not develop CP. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
4.
Foreign body aspiration (FBA) is a leading cause of accidental death in children less than one year old and is the cause of death in 7% of children less than four. Food items, especially peanuts, are the most common items aspirated in infants and toddlers, whereas older children are more likely to aspirate non-food items such as pen caps, pins, and paper clips. A high degree of suspicion is required to diagnose FBA. A history of a witnessed choking episode is most important in early diagnosis. An asymptomatic period is common after aspiration and contributes to a delay in diagnosis of greater than one week in 12% to 26% of patients. This delay in diagnosis causes increased morbidity from bronchial inflammation, obstruction, and pneumonia which is resistant to treatment. Prompt endoscopic removal of the foreign body with an open rigid bronchoscope under general anesthesia is the mainstay of therapy. 相似文献
5.
J.S. Wright L. Stafford B.P. Gila D.P. Norton S.J. Pearton Hung-Ta Wang F. Ren 《Journal of Electronic Materials》2007,36(4):488-493
The effect of cryogenic temperatures during metal deposition on the contact properties of Pd, Pt, Ti, and Ni on bulk single-crystal
n-type ZnO has been investigated. Deposition at both room and low temperature produced contacts with Ohmic characteristics
for Ti and Ni metallizations. By sharp contrast, both Pd and Pt contacts showed rectifying characteristics after deposition
with barrier heights between 0.37 eV and 0.69 eV. Changes in contact behavior were measured on Pd to anneal temperatures of
∼300 °C, showing an increase in barrier height along with a decrease in ideality factor with increasing annealing temperature.
This difference with annealing temperature is in sharp contrast to previous results for Au contacts to ZnO. There were no
differences in near-surface stoichiometry for the different deposition temperatures; however, low temperature contacts demonstrated
some peeling/cracking for Pt and Pd. 相似文献
6.
A. Y. Polyakov N. B. Smirnov A. V. Govorkov Jihyun Kim F. Ren G. T. Thaler R. M. Frazier B. P. Gila C. R. Abernathy S. J. Pearton I. A. Buyanova G. Y. Rudko W. M. Chen C. -C. Pan G. -T. Chen J. -I. Chyi J. M. Zavada 《Journal of Electronic Materials》2004,33(3):241-247
Electrical and electroluminescent properties were studied for GaN/InGaN light-emitting diodes (LEDs) with the n-GaN layer
up and with the top portion of the n layer made of undoped GaMnN to allow polarization modulation by applying an external
magnetic field (so-called “spin-LEDs”). The contact annealing temperature was kept to 750°C, which is the thermal stability
limit for retaining room-temperature magnetic ordering in the GaMnN layer. Measurable electroluminescence (EL) was obtained
in these structures at threshold voltages of ∼15 V, with a lower EL signal compared to control LEDs without Mn. This is related
to the existence of two parasitic junctions between the metal and the lower contact p-type layer and between the GaMnN and
the n-GaN in the top contact layer. 相似文献
7.
8.
Guillermo Gómez Graciano Martínez José L. Gálvez Raúl Gila Raquel Cuevas Jesús Maellas Emilio Bueno 《International Journal of Hydrogen Energy》2009
Hydrogen is considered as the optimal carrier for the surplus energy storage from renewable resources. Although hydrogen and its application in fuel cell is considered as a high-cost energy system, some cost-efficient solutions have been found for their use in stand-alone applications, which usually depend on the variability of renewable sources that have to be oversized in order to reduce their dependence on external energy sources. This paper shows the results from the simulation of several alternatives of introducing hydrogen technologies to increase the independence of a remote-telecom application fed by photovoltaic panels. Hydrogen is obtained by electrolysis and it is used in a fuel cell when the renewable energy source is not enough to maintain the stand-alone application. TRNSYS simulation environment has been used for evaluating the proposed alternatives. The results show that the best configuration option is that considering the use of hydrogen as a way to storage the surplus of radiation and the management system can vary the number of photovoltaic panels assigned to feed the hydrogen generation, the batteries or the telecom application. 相似文献
9.
J Medina L Baud C Garcia Escribano JA Gila D Rodriguez Puyol M Rodriguez Puyol 《Canadian Metallurgical Quarterly》1993,122(2):164-172
The role of tumor necrosis factor alpha in the regulation of renal function, particularly glomerular filtration rate, has not been completely defined. This study was designed to assess the intrinsic role of this cytokine on glomerular filtration rate by analyzing its short-term effect on the degree of contraction in cultured rat mesangial cells, not only directly but also in the presence of angiotensin II. Contraction was evaluated both morphologically--by measuring planar cell surface area of cultured rat mesangial cells and glomerular cross-sectional area of isolated rat glomeruli--and biochemically--by analyzing myosin light-chain phosphorylation in cells. Tumor necrosis factor alpha significantly decreased planar cell surface area in a dose-dependent and time-dependent manner, an effect completely abolished by preincubation of the cells with platelet-activating factor receptor antagonists BN 52021 and alprazolam. This effect was also observed in the presence of angiotensin II, whether tumor necrosis factor alpha was added before or after angiotensin II, increasing the reduction in planar cell surface area induced by angiotensin II in both cases. Changes in planar cell surface area were evident not only when the absolute values of this parameter were considered but also when the percentage of contracted cells (cells with a planar cell surface area reduction > 10%) was analyzed. Tumor necrosis factor alpha also induced a significant reduction of glomerular cross-sectional area in isolated rat glomeruli. The results of the morphologic studies were supported by myosin light-chain phosphorylation experiments.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
10.
B. P. Gila J. Kim B. Luo A. Onstine W. Johnson F. Ren C. R. Abernathy S. J. Pearton 《Solid-state electronics》2003,47(12):2139
MgO and Sc2O3 were deposited by gas source molecular beam epitaxy on GaN. MgO was found to produce lower interface state densities than Sc2O3, 2–3 × 1011 vs. 9–11 × 1011 eV−1 cm−2. The good electrical quality of the interface is believed to be due to the presence of a single crystal epitaxial layer at the GaN surface. By contrast, the MgO was found to be more sensitive to environmental and thermal degradation than the Sc2O3. The environmental degradation is believed to be due to interaction with water vapor in the air and was suppressed by capping of the MgO. Annealing at the temperatures needed for implant activation in GaN produced significant roughening of the MgO/GaN interface and an order of magnitude increase in the interface state density. This sensitivity to thermal degradation will require changes in the processing sequence presently envisioned for e-mode devices in order to avoid damaging the interface and increasing the gate leakage in the device. 相似文献