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991.
《Analytical letters》2012,45(13):2471-2484
Abstract A procedure is described for simultaneous determination of Ca, Mg and P in small amounts (a few mg) of tissues by use of Direct Current Plasma-Atomic Emission Spectrometry. The samples were analyzed by using matrix matched standards. The necessity to use high-purity acids for decomposition of samples is demonstrated. The method was tested on four different reference samples. The accuracies for the elements were satisfactory (93–103%). The within-run and between-run precisions were 0.9–6.8 and 0.9–8.6%, respectively. The method may be used for determination of other elements. 相似文献
992.
993.
In this paper the realization of nth order (n ≥ 3) fully-differential current-mode filters using Current Differencing Current Conveyors (CDCC) has been presented which results in circuits employing all grounded passive elements. In contrast to earlier known realizations of fully-differential filters which invariably require more than one capacitors per pole, the proposed realization employs only one capacitor per pole. The cut-off frequency of the realized filter can be electronically tuned when all the grounded resistors associated with the integrators are implemented by identical CMOS grounded voltage-controlled-resistors (VCR) driven by a common control voltage. The methodology has been illustrated by realizing a fifth order Butterworth filter as a specific example whose workability has been verified using SPICE simulations in 0.18 µm TSMC technology. A reduced-component-version of the designed fifth order Butterworth filter has also been presented which also employs all grounded RC components but does not have electronic-tunability. Some representative simulation results have been included. 相似文献
994.
Si1−xGex bulk crystals (0.2<x<0.85) with various B doping levels were grown by the traveling liquidus zone (TLZ) method for fabricating substrates of high mobility electronic devices. Large single crystals with a diameter ranging from 30 to 50 mm were achieved. Si1−xGex crystals were characterized by measuring concentration profile along and perpendicular to the growth axis, indicating good compositional homogeneity. High crystalline quality was evaluated by electron backscatter spectroscopy and X-ray diffraction. Measured hole mobility was higher than the previously reported data for the similar dopant concentration and Ge content, suggesting smaller alloy scattering effects and high crystalline nature in the TLZ-grown Si1−xGex bulk crystals. 相似文献
995.
This paper presents second order band-pass filter with high quality factor. Its high quality factor is provided by feedback circuit. The used second order filter is modified so that filters outputs through capacitor can be obtained to high impedance output. Thereby, there is no need the extra active element to obtain filter outputs. Also, the output stage of current differencing transconductance amplifier have only X− terminals instead of X+ and X− terminals. Furthermore, the quality factor of the band-pass filter with feedback circuit is increased by feedback gain consisting of only four transistors. Besides, to examine effects of parasitic elements, non-ideal and sensitivity, the overall structure is investigated deeply. Working conditions and boundaries of the overall structure is also defined. The simulation demonstrates good agreement between the theoretical expectations and simulation results. 相似文献
996.
We report a fabrication method of controlling the doped concentration of phosphorescent dye to induce the trap-site in an emitting layer (EML) for an efficient near-infrared (NIR) organic upconversion device (OUD). Such an OUD was used as a device configuration of ITO/mixed layer of chloroaluminum phthalocyanine and C60/1,1-bis(di-4-tolylaminophenyl) cyclohexane/4,4′ -Bis(N-carbazolyl)-1,1′ -biphenyl doped with fac-tris (2-phenylpyridine) iridium (III) [Ir(ppy)3]/4,7-diphenyl-l,10-phenanthroline/CS2CO3/Ag to provide a green emission under NIR illumination. Our optimized OUD with a high Ir(ppy)3 doped concentration of ∼13 wt% exhibited a higher electroluminescent efficiency in the display unit and was suitable for inducing a large amount of trap-sites in the EML, which effectively blocked the hole and electron carrier in the EML. To induce the trap-site in the EML by the doping process, we used a hole- and electron-only device to examine the OUD with a lower dark current density. As a result, an optimal OUD with a current gain as high as 21,300 (defined as the light current density divided by dark current density) at a driving voltage of 3 V was successfully achieved. 相似文献
997.
We demonstrate that the open-circuit voltage (VOC) of organic photovoltaic (OPV) devices composed of rubrene and C60 can be considerably different when the anode and active layer are changed. Two types of anodes and active layers were compared. In plasma-treated indium-tin-oxide (ITO) OPV devices, the parameter VOC exhibits an improvement from 0.68 V to 0.76 V when the device structure is varied from a bilayer to a mixed structure. However, in the OPV devices that use ITO/MoO3 as the anode, a similar VOC is observed regardless of the device structure. A series of temperature-dependent measurements are conducted to investigate these results. The calculation of barrier height at the rubrene/C60 (or rubrene:C60) interface yields the prediction of VOC, suggesting that an excess energetic loss occurs in the mixed structures. The electroluminescent (EL) spectra of these devices show that the mixed structure can completely quench the EL of rubrene single layer. A broad band of the charge transfer (CT) emission is observed clearly. A temperature-dependent measurement for the extracting injection barrier is conducted and shows that the mixed structure is favorable for the hole current injection. The CT properties are obtained using the external quantum efficiency and EL spectra of the OPV devices. We find that the nonradiative recombination loss is highly correlated with the injected current; the lower the injection barrier induced the less the nonradiative recombination loss. Therefore, the parameter VOC can be improved when the injected current is increased. 相似文献
998.
《AEUE-International Journal of Electronics and Communications》2014,68(6):496-503
This paper proposes an enhanced variant of the particle swarm optimization technique PSO-2S, and its application to analogue circuit performance optimization. For comparison reasons, we focus on performance optimization of a second generation CMOS current conveyor, for different bias current values. It is worth noting that the approach can be easily adapted to deal with other types of circuits. The paper shows that PSO-2S achieves better results than three other well-known optimization techniques, namely bacterial foraging optimization technique (BFO), PSO and differential evolution (DE). 相似文献
999.
This paper presents a novel approach to model the interaction of electromagnetic waves with the magnetized plasma medium based on the Transmission Line Matrix (TLM) method. Anisotropic and dispersive characters of magnetized plasma are modeled by voltage sources, where the formulation is developed using the Current Density Recursive Convolution (CDRC) technique. Computational examples illustrate not only the improved accuracy, but also significant CPU time saving in comparison with TLM Constant Recursive Convolution (CRC-TLM) approach. 相似文献
1000.
The dynamics of an optical phase locked loop (OPLL) with first order loop filter having inherent loop time delay is investigated. In the presence of delay, the system is modeled as a third order autonomous system. In the out of lock condition or during the process of locking, the dynamics of the system is highly nonlinear and different nonlinear phenomena, like limit cycle oscillation, period doubling, chaotic oscillations etc., may be observed with the variation of design parameters. Applying the techniques of the nonlinear dynamics, we have calculated the effects of the inherent loop time delay in determining the state of the loop. The analytical results predicting the parameter values for stable and unstable region of operation are obtained using the quasi-linear Routh–Hurwitz method. The parameter range required for the onset of chaotic oscillations is estimated by Melnikov's global perturbation method. The predicted results are in agreement with those obtained by numerical integration of system equations. 相似文献