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A semi-quantitative right coronary artery score (RCA score) was derived from the ratio of the number of the major left ventricular branches of the right coronary artery to the total of the right coronary and left circumflex arteries, to stratify the extent of perfusion in patients with right coronary artery dominance. Thirty-seven patients with one-vessel coronary disease involving a dominant right coronary artery proximal to the left ventricular branches were selected for study. Thallium scintigraphy was performed after right intracoronary injection in 11 patients, and 26 patients underwent conventional stress thallium scintigraphy (24 exercise thallium and two dipyridamole thallium scintigraphy). Thallium scores of perfusion region size after right intracoronary thallium injection and perfusion defect size in stress thallium studies were quantitated from planar thallium images. Both the RCA score and the regional thallium scores spanned over a wide range. The RCA score (range 0.23-0.85) correlated best with the posterior (70 degrees left anterior oblique view) plus lateral segment (40 degrees left anterior oblique view) thallium score (r = 0.88 and 0.53 for intracoronary and stress thallium studies respectively). It also correlated with the summed thallium scores in the posterior, lateral, apical and inferior segments (r = 0.73 and 0.54 respectively) but not with thallium scores in the apex or inferior segment alone. The proposed RCA score quantitates the variable posterolateral perfusion territory of the right coronary artery, and could stratify the area of myocardium at risk from coronary stenosis in the majority of patients with right coronary dominance.  相似文献   
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In this paper, we present a comparative analysis of artificial neural networks (ANNs) and Gaussian mixture models (GMMs) for design of voice conversion system using line spectral frequencies (LSFs) as feature vectors. Both the ANN and GMM based models are explored to capture nonlinear mapping functions for modifying the vocal tract characteristics of a source speaker according to a desired target speaker. The LSFs are used to represent the vocal tract transfer function of a particular speaker. Mapping of the intonation patterns (pitch contour) is carried out using a codebook based model at segmental level. The energy profile of the signal is modified using a fixed scaling factor defined between the source and target speakers at the segmental level. Two different methods for residual modification such as residual copying and residual selection methods are used to generate the target residual signal. The performance of ANN and GMM based voice conversion (VC) system are conducted using subjective and objective measures. The results indicate that the proposed ANN-based model using LSFs feature set may be used as an alternative to state-of-the-art GMM-based models used to design a voice conversion system.  相似文献   
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A simplified mathematical model leading to a closed form of solution is developed for estimation of nitric oxide emission from a coal fired circulating fluidized bed (CFB) furnace. The furnace is divided into two sections: a lower section below and an upper section above the secondary air injection level. Reactions in the cyclone and the return leg are neglected. Furnace dimensions, coal feed rate, coal composition and furnace temperature are inputs to the model which was validated against several pilot scale and commercial units. Experimental results from two pilot plants and two commercial power plants agree with model predictions. A sensitivity analysis was carried out using the model to examine the effect of different operating parameters and coal properties on the overall NO emission from the furnace. It was found that excess air and furnace temperature are most important factors influencing the NO emission level. The primary to secondary air ratio influences the NO emission level reasonably. Properties of coal are other factors which affect the NO emission to a large extent. The model, though it invovles some simplification, predicts the overall emission of NO with a level of accuracy accepted in commercial operation.  相似文献   
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A highly linear 5.5 GHz low noise amplifier (LNA) has been designed exploiting source inductive degeneration topology by using post distortion linearization techniques in 0.18 m CMOS technology. This technique improves the input third order intercept point \((IIP_{3})\) of a low noise amplifier. For enhancing the linearity, this technique used a diode connected MOSFET as IMD sinker and forward body biased which is done in cadence tool. The proposed low noise amplifier achieves high \(IIP_{3}\) by using two transistors, main and auxiliary transistors. Also source inductive degeneration topology is employed in the proposed LNA to optimize the noise figure (NF) and \(S_{11}\) at high frequency. In order to reduce power consumption and threshold voltage, Forward Body Biased technique was implemented. In this paper, the first section discusses the most widely used eight linearization techniques and in the second section, the proposed circuit is represented along with its employed topology, techniques and the simulated results. The proposed LNA achieves a simulated third order input intercept \((IIP_{3})\) of 9.20 dBm while consuming 10.8 mW from a power supply of 1.8 V. it also exhibits a measured gain of 11.34 dB and NF, NF of 2.33 dB.  相似文献   
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There is nearly unanimous consensus amongst scientists that increasing greenhouse gas emissions, including CO2 generated by human activity, are effecting the Earth’s climate. Increasing atmospheric CO2 emissions will likely increase the rates of carbonation in reinforced concrete structures. However, there is a lack of reliable models to predict the depth of carbonation as a function of time.To address this deficiency, a numerical model involving simultaneous solution of the transient diffusion and reaction equations of CO2 and Ca(OH)2 was developed. The model successfully includes the effects of variations in various properties such as porosity, humidity, temperature, atmospheric CO2 concentrations and chemical reaction rates.The applicability of the model was confirmed after calibration using data from accelerated carbonation experiments, and the model is used to evaluate the possible effects of climate change by inputting various future climate scenarios in Part 2.  相似文献   
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In order to study the mechanisms of heat and mass transfer at the gas–liquid interface, flows inside and around a rising inert bubble are considered and calculated using the numerical algorithm developed in a companion article. Studies of heat and mass transfer are carried out while special attention is paid to the effects of wake vortices. Recoveries of the Sherwood and Nusselt numbers are observed in the wake zone behind bubbles, and a physical explanation is proposed.  相似文献   
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Azobisisobutyronitlite (AIBN)-induced free radical polymerization of a methacrylate-based ionic liquid monomer, 1-(2-methacryloxyethyl)-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (Met-IL) was carried out in a common organic solvent, N,N-dimethylformamide (DMF), and an ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMImTFSI). The molecular weight of the obtained poly(Met-IL) was evaluated by transforming it to non-ionic poly(methyl methacrylate) with hydrolysis of the imidazolium-salt-substituted pendant ester groups and methyl esterification. Radical copolymerization with methyl methacrylate (MMA) was also carried out in both DMF and EMImTFSI. Analysis of copolymer composition revealed that the reactivity of Met-IL was lower than that of MMA in both DMF and EMImTFSI solutions.  相似文献   
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