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41.
A high-performance, fully operational four-quadrant control scheme for the interior permanent magnet (PM) synchronous machine is described. The machine operates smoothly with full performance in the constant-torque region as well as in the flux-weakening constant-power region in both directions of motion. The transition between the constant-torque region and the constant-power region is very smooth at all conditions of operation. Control in the constant-torque region is based on the vector stator flux, while constant-power region control is implemented through the feedforward vector rotator. The control system is digitally implemented using a distributed microcomputer system, and all of the essential feedback signals such as torque, flux, etc. are estimated with precision. A 70 hp drive system using a neodymium-iron-boron (NeFeB) PM machine and transistor pulse width modulation inverter was designed and extensively tested in the laboratory on a dynamometer, and performance was found to be excellent 相似文献
42.
N. N. Rao Gaurav Bose Pradnya Khare S. N. Kaul 《Canadian Metallurgical Quarterly》2006,132(3):367-376
Oxidative treatment of H-acid (HA) and Reactive Black 5 (RB5) using Fenton reagent (Fe2+/H2O2) and the electro-Fenton (EF) method is reported. Optimization of doses of ferrous iron and hydrogen peroxide was carried out in each case using HA; and the oxidation of RB5 was also carried out under the optimized conditions. Approximately 71% chemical oxygen demand (COD) was removed in 2 h using the conventional Fenton method at optimized doses: Fe2+ = 0.3?g/L (5.37 mM), H2O2 = 6?mL/L (53.0 mM), H2O2/Fe2+ = 10. In contrast, more than 92% COD was removed in 15 min using the EF method with an optimized Fe2+ dose of 0.130?g/L (2.34 mM) and 8?ml/L (70.6 mM) of H2O2. The pseudo-first-order rate constants (k) for the Fenton reagent and EF method were 0.054 and 0.38?min?1. The COD removal through the EF method was seven times faster. The calculated energy requirement of the EF method was 0.82?kg?COD/kW?h at the minimum applied current (0.25 A) when approximately 92.5% COD was removed. In the case of RB5, about 67 and 87% COD was removed under optimized Fenton and electro-Fenton conditions, respectively. The higher efficiency of the EF method was attributed to incremental addition of Fe2+ and accompanying higher H2O2/Fe2+ molar ratio. The results are discussed in the light of the mechanism for Fenton’s oxidation. 相似文献
43.
A neural-network-based implementation of space-vector modulation (SVM) of a three-level voltage-fed inverter is proposed in this paper that fully covers the linear undermodulation region. A neural network has the advantage of very fast implementation of an SVM algorithm, particularly when a dedicated application-specific IC chip is used instead of a digital signal processor (DSP). A three-level inverter has a large number of switching states compared to a two-level inverter and, therefore, the SVM algorithm to be implemented in a neural network is considerably more complex. In the proposed scheme, a three-layer feedforward neural network receives the command voltage and angle information at the input and generates symmetrical pulsewidth modulation waves for the three phases with the help of a single timer and simple logic circuits. The artificial-neural-network (ANN)-based modulator distributes switching states such that neutral-point voltage is balanced in an open-loop manner. The frequency and voltage can be varied from zero to full value in the whole undermodulation range. A simulated DSP-based modulator generates the data which are used to train the network by a backpropagation algorithm in the MATLAB Neural Network Toolbox. The performance of an open-loop volts/Hz speed-controlled induction motor drive has been evaluated with the ANN-based modulator and compared with that of a conventional DSP-based modulator, and shows excellent performance. The modulator can be easily applied to a vector-controlled drive, and its performance can be extended to the overmodulation region 相似文献
44.
The heat capacity, thermal conductivity and coefficient of thermal expansion of MoSi2 and 18 vol % SiC whisker-reinforced MoSi2 were investigated as a function of temperature. The materials were prepared by hot isostatic pressing between 1650 and 1700 °C, the hold time at temperature being 4 h. The heat capacity of MoSi2 showed an increase from about 0.44 Wsg–11K–1 at room temperature to 0.53 at 700 °C. Whisker reinforcement increased heat capacity by about 10%. Thermal conductivity exhibited a decreasing trend from 0.63 Wcm–1 K–1 at room temperature to 0.28 Wem–1 K–1 at 1400°C. Whiskers reduced conductivity by about 10%. The thermal expansion coefficient increased from 7.42 °C–1 between room temperature and 200 °C to 9.13 °C–1 between room temperature and 1200 °C. There was a 10% decrease resulting from the whiskers. The measured data are compared with literature values. The trends in the data and their potential implications for high-temperature aerospace applications of MoSi2 are discussed. 相似文献
45.
A. Bose 《Materials and Manufacturing Processes》1992,7(3):469-472
46.
47.
In this paper, it is established that a necessary and sufficient condition for two monic polynomialsf(lambda) andg(lambda) to have a common root is thatdet [f(B)] = 0 ordet [g(A)] = 0 , whereA andB are, respectively, the companion matrices associated withf(lambda) andg(lambda) . The simplicity of this method is illustrated by examples. 相似文献
48.
This work reports the hole conductivity data of growing AgI film on silver both for the thicker (5500 to 30 000 Å) and thinner (<6000 Å) ranges at about room temperature. Hole conductivity has been estimated through tarnishing studies of silver in iodine atmosphere and estimation has been based on the fundamental equation of Wagner relating the rate constant and the conductivity of the film. It is revealed that the thinner films show a higher hole conductivity than that of the thicker films under similar temperature and iodine pressure. 相似文献
49.
N. K. Bose 《Multidimensional Systems and Signal Processing》2004,15(2):95-95
Editorial Commentary
Editorial 相似文献50.
Motivated by the study of sharp wave-associated ripples, high-frequency (approximately 200 Hz) extracellular field oscillations observed in the CA1 region of the rat hippocampus during slow-wave sleep and periods of behavioural immobility, we consider a single inhibitory neuron synapsing onto a network of uncoupled, excitatory neurons. The inhibitory synapse is depressing and has a small synaptic delay. Each excitatory cell provides instantaneous, positive feedback to the inhibitory cell. We show that the interneuron can rapidly synchronize the action potentials of the pyramidal cells if the frequency of inhibitory input is increased in a ramp-like manner as occurs during the ripple. We show that the basin of attraction of the synchronous solution is larger when the inhibition frequency is gradually increased as opposed to remaining constant. 相似文献