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81.
Chandra Smita Prasad Neeli Rashmi Lindgren Peter Prasad Ramjee 《Wireless Personal Communications》2022,125(4):3787-3800
Wireless Personal Communications - Internet of things (IoTs) has been the smartest technology proven worldwide these days. The application products of IoTs are Mobile ad hoc network (MANET) and... 相似文献
82.
Pillai S. Vijayan Santhanakrishnan T. Kumar N. Suresh Rajesh R. 《Multidimensional Systems and Signal Processing》2022,33(3):879-898
Multidimensional Systems and Signal Processing - High-performance sonar systems mostly combine a large sensor array and an efficient beamformer for enhancing the overall detection capabilities and... 相似文献
83.
Ramesh Chandra Gupta S. P. Singh 《Journal of Infrared, Millimeter and Terahertz Waves》2006,27(2):273-291
A 4×4 planar array of modified box-horns as a microwave hyperthermia applicator is theoretically studied to characterize power deposition (SAR) in heating tissue (muscle) at 2450 MHz. A modified box-horn is a novel improved version of conventional box-horn in which horn exciting the box waveguide is flared in both E-and H-planes. Modified box-horn supports TE10 and TE30 modes. The amplitude distribution over the H-plane of the box-horn aperture is a closer approximation to the uniform distribution. It is proposed that the interior of the box-horn be filled with water to provide a better impedance match to biological tissue. By applying Fresnel-Kirchhoff scalar diffraction field theory, the expression for electric field in heating region is derived and distribution of specific absorption rate (SAR) in that region due to planar array of modified box-horns as direct contact applicator is evaluated at 2450 MHz. The results of modified box-horn array are compared with those of a single modified box-horn operating at the same frequency. Results demonstrate that planar array of modified box-horns offers improvement in SAR distribution and penetration depth. It is shown that by changing the phase and amplitude of excitation of the modified box-horns of the array, the relative amplitude and position of the hot spot can be changed. The present analysis is validated through the results obtained by plane wave spectral technique. 相似文献
84.
Nidhi Sharma Chandra Mohan Singh Negi Ajay Singh Verma Saral K. Gupta 《Journal of Electronic Materials》2018,47(12):7023-7033
We have investigated the effect of C60 concentration on the performance of poly[2-methoxy-5-(2′-ethylhexoxy-p-phenylene vinylene] (MEH-PPV):C60 blend-based Schottky barrier-based devices. Incorporation of C60 in MEH-PPV leads to a red shift and the reduction of intensity in MEH-PPV absorption spectra. The appearance of a C60 characteristic band in the Raman spectra of the composites indicates the presence of C60 in the blends. A FESEM study reveals that the addition of C60 significantly modifies the surface morphology of the blend films. However, higher concentrations (>?5 wt.%) results in agglomeration of C60 particles. Dark I–V measurements allow us to extract various diode parameters including barrier height, ideality factor, and saturation current. Profound variations have been observed in the dominant charge carrier transport mechanism for different C60 concentrations. A photoresponse study demonstrates the enhancement in the photocurrent with the increase in the C60 concentration up to 5 wt.%. Beyond this concentration, agglomeration impedes exciton dissociation and charge transport, which results in a decrease in the photocurrent. Finally, an impedance spectroscopy analysis has been extensively carried out to estimate the internal device parameters, such as junction resistance, capacitance and carrier lifetime. The correlation between these parameters and I–V curves has been established. 相似文献
85.
This paper deals with a new control scheme for a parallel 3-phase active filter to eliminate harmonics and to compensate the reactive power of the nonlinear loads. A 3-phase voltage source inverter bridge with a DC bus capacitor is used as an active filter (AF). A hysteresis based carrierless PWM current control is employed to derive the switching signals to the AF. Source reference currents are derived using load currents, DC bus voltage and source voltage. The command currents of the AF are derived using source reference and load currents. A 3-phase diode rectifier with capacitive loading is employed as the nonlinear load. The AF is found effective to meet IEEE-519 standard recommendations on the harmonics level 相似文献
86.
A theoretical treatment to determine the natural flow rate through a flat plate collector having heat losses is made. The governing equations have been expressed in terms of Grashof and Prandtl numbers and a dimensionless heat loss parameter. The method predicts the optimum tilt of the flat plate collector for the maximum draught for a given latitude and insolation. The experimental verification of the theoretical results shows a fair agreement.
A method to calibrate the hot wire anemometer at the desired temperature is evolved for the range of velocities encountered in practice for the flat plate solar collector. 相似文献
87.
The DX-center-related short-pulse threshold voltage shifts (SPTVS) in AlxGa1-xAs-based MODFETs is modeled using CBAND, a simulator that solves Poisson equations self-consistently with Schrodinger equations and donor statistics. Using values given in the literature for the DX energy level in AlxGa1-xAs this technique gives good agreement between measured and simulated SPTVS for Al0.3Ga0.7As/GaAs and Al0.3Ga0.7As/In0.2Ga0.8As MODFETs. Both simulation and experiment show that the use of Al0.2 Ga0.8As in the donor layer reduces the SPTVS relative to the structures using Al0.3Ga0.7As. However, the measured shifts at this composition are considerably lower than the simulated values, indicating a DX energy level that may be higher than the value extrapolated from the literature, possibly due to the existence of multiple trap levels. Despite this discrepancy, these results support the use of strained-channel layers and lower Alx Ga1-xAs compositions in MODFETs for digital and other large-signal applications requiring good threshold stability 相似文献
88.
89.
Suresh Kumar Dhungel Jinsu Yoo Kyunghae Kim Somnath Ghosh Sungwook Jung Junsin Yi 《Renewable Energy》2008,33(2):282
Back surface passivation becomes a key issue for the silicon solar cells made with thin wafers. The high surface recombination due to the metal contacts can be lowered by reducing the back contact area and forming local back surface field (LBSF) in conjunction with the passivation with dielectric layer. About 3×10-7 m thick porous silicon (PS) layer with pore diameter mostly of 1×10-8–5×10-8 m was formed by chemical etching of silicon using the acidic solution containing hydrofluoric acid (HF), nitric acid (HNO3) and De-ionized water in the volume ratio 1:3:5 at 298 K for which etching time was kept constant for 360 s. Electrical properties of oxidized PS was studied through the current–voltage (I–V) and capacitance–voltage (C–V) characteristics of the metal–insulator–semiconductor (MIS) device in which the oxidized PS was used as an insulating layer and the results were further analyzed. The C–V curves of all the studies MIS devices showed the negative flatband voltage varying from -2 to , confirming that the oxidized layer of PS has fixed positive charge. 相似文献
90.
Rotating ring-disc electrode (RRDE) voltammetry is applied for the in situ determination of hydroxy borohydride (BH3(OH)−) formation during borohydride (BH4−) electro-oxidation on a gold (Au) electrode in 6.0 M NaOH solution. The BH3(OH)− is detected at the ring electrode due to its further oxidation to BH2(OH)2− by maintaining its potential in the range of −0.800 to −0.600 V vs. normal hydrogen electrode (NHE) while oxidizing BH4− on the disc electrode. The study reveals that the generation of BH3(OH)− increases if the anodic polarization of the disc electrode is increased. The RRDE ring-shielding experiments show that the electro-oxidation of BH4− occurs over a wide potential range of −0.500 to 0.400 V on the Au electrode under hydrodynamic conditions. Chronoamperometry is also used to study the BH3(OH)− oxidation in the potential range of −0.800 to −0.600 V with 0.33 M NaBH4 in three different buffer solutions of pH 10.2, 11.0 and 11.70, respectively. The chronoamperometric studies indicate that the formation and stability of BH3(OH)− depends on the pH value. 相似文献