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951.
952.
David K. Hsu Kwang-Hee Im Young-Tae Cho Jae-Woung Park Jae-Ki Sim In-Young Yang 《Journal of Mechanical Science and Technology》2002,16(3):292-301
Ultrasound waves interact strongly with the orientation and sequence of the plies in a layup when propagating in the thickness direction of composite laminates. Also the layup orientation greatly influences its properties in a composite laminate. If the layup orientation of a ply is misaligned, it could result in the part being rejected and discarded. Now, most researchers cut a small coupon from the waste edge and use a microscope to optically verify the ply sequences on important parts. This may add a substantial cost to the production since the test is both labor intensive and performed after the part is cured. A nondestructive technique would be very beneficial, which could be used to test the part after curing and requires less time than the optical test. Therefore we have developed, reduced, and implemented a novel ply-by-ply vector decomposition model for composite laminates fabricated from unidirectional plies. This model decomposes the transmission of a linearly polarized ultrasound wave into orthogonal components through each ply of a laminate. High probability is found, by comparisons between the model and tests, in characterizing cured layups of the laminates by using the proposed method. 相似文献
953.
K. B. Jung J. Hong H. Cho J. R. Childress S. J. Pearton M. Jenson A. T. Hurst Jr. 《Journal of Electronic Materials》1998,27(8):972-978
Plasma chemistries based on chlorine, bromine, or iodine have been investigated for inductively coupled plasma etching of
NiFe and NiFeCo. There is clear evidence of a chemically enhanced etch mechanism with both Cl2- and I2- based mixtures, with no enhancement present for Br2 chemistries. Etch yields are typically low (≤0.25), emphasizing the need for high ion fluxes in order to achieve practical
material removal rates. 相似文献
954.
Jae-Young Cho Hyo-Jong Lee Hyoungbae Kim Jerzy A. Szpunar 《Journal of Electronic Materials》2005,34(5):506-514
Influence of annealing on the textural and microstructural transformation of Cu interconnects having various line widths is
investigated. Two types of annealing steps have been considered here: room temperature over 6 months and 200°C for 10 min.
The texture was determined by x-ray diffraction (XRD) of various cross-sectional profiles after electropolishing, and the
surface, microstructure, and grain boundary character distribution (GBCD) of Cu interconnects were characterized using electron
backscattered diffraction (EBSD) techniques. In order to analyze a relationship between the stress distribution and textural
evolution in the samples, microstresses were calculated with decreasing line widths at 200°C using finite element modeling
(FEM). In this investigation, it was found that the inhomogeneity of stress distribution in Cu interconnects is an important
factor, which is necessary for understanding textural transformation after annealing. A new interpretation of textural evolution
in damascene interconnects lines after annealing is suggested, based on the state of stress and the growth mechanisms of Cu
electrodeposits. 相似文献
955.
Young-Hee Cho Jeong-Jun Lee Il-Bum Park Chul-Sung Huh Young-Jin Baek Jiyong Park 《Journal of food science》2005,70(2):E148-E151
ABSTRACT: Two different emulsification methods involving multiple emulsification and heat gelation were used for preparation of whey protein-based microcapsules containing immunoglobulin in yolk (IgY). The residual activity of IgY during the emulsion preparation and the effects of microencapsulation on IgY stability under harsh conditions were investigated. The residual activity of IgY in an emulsion prepared with a membrane emulsifier was higher than for an emulsion using a homogenizer. Microencapsulated IgY showed remarkable stability against both pepsin and acid. Both microencapsulated IgY and nonencapsulated IgY were relatively stable in bile and artificial intestinal juice. Microencapsulated IgY retained 74% of initial activity during heat treatment. There were no significant differences in the residual activities of microencapsulated IgY under storage temperatures of 4, 25, and 37°C. 相似文献
956.
Cho T.B. Kang D. Chun-Huat Heng Bang Sup Song 《Solid-State Circuits, IEEE Journal of》2004,39(11):1916-1926
High-level integration of the Bluetooth and 802.11b WLAN radio systems in the 2.4-GHz ISM band is demonstrated in scaled CMOS. A dual-mode RF transceiver IC implements all transmit and receive functions including the low-noise amplifier (LNA), 0-dBm power amplifier, up/down mixers, synthesizers, channel filtering, and limiting/automatic gain control for both standards in a single chip without doubling the required silicon area to reduce the combined system cost. This is achieved by sharing the frequency up/down conversion circuits in the RF section and performing the required baseband channel filtering and gain functions with just one set of reconfigurable channel filter and amplifier for both modes. A chip implemented in 0.18-/spl mu/m CMOS occupies 4/spl times/4 mm/sup 2/ including pad and consumes 60 and 40 mA for RX and TX modes, respectively. The dual-mode receiver exhibits -80-dBm sensitivity at 0.1% BER in Bluetooth mode and at 12-dB SNR in WLAN mode. 相似文献
957.
Iris Recognition Using Wavelet Features 总被引:3,自引:0,他引:3
Jaemin Kim Seongwon Cho Jinsu Choi Robert J. Marks II 《The Journal of VLSI Signal Processing》2004,38(2):147-156
The traditional iris recognition systems require equal high quality human iris images. A cheap image acquisition system has difficulty in capturing equal high quality iris images. This paper describes a new feature representation method for iris recognition robust to noises. The disc-shaped iris image is first convolved with a low pass filter along the radial direction. Then, the radially smoothed iris image is decomposed in the angular direction using a one-dimensional continuous wavelet transform. Each decomposed one-dimensional waveform is approximated by an optimal piecewise linear curve connecting a small set of node points. The set of node points is used as a feature vector. The optimal approximation procedure reduces the feature vector size while maintaining recognition accuracy. The similarity between two iris images is measured by the normalized cross-correlation coefficients between optimal curves. The similarity between two iris images is estimated using mid-frequency bands. The rotation of one-dimensional signals due to the head tilt is estimated using the lowest frequency component. Experimentally we show the proposed method produces superb performance in iris recognition. 相似文献
958.
Jun-Young Lee Jin-Sung Kim Nam-Sung Jung Bo-Hyung Cho 《Industrial Electronics, IEEE Transactions on》2004,51(3):615-624
A new concept of energy recovery for a plasma display panel (PDP) is proposed. Different from conventional LC resonant sustaining drivers, the current built up before inverting the polarity of the panel electrodes is utilized to change the panel polarity together with energy previously charged in panel capacitance. This operation provides zero-voltage switching of switches and reduction of electromagnetic interference by rejecting the surge current when the sustain switches are turned on. The buildup current helps to reduce the transition time of the panel polarity and may produce more stable light waveforms. This method is suitable for a PDP sustaining driver requiring stable light emission characteristic while it maintains low circuit loss like the series-resonant-type energy recovery circuit which is known to be a very effective method. 相似文献
959.
The sequentially combined carbon (SCC) of methanol and acetic acid was used for the biological nutrient removal (BNR). Its BNR performance was compared with methanol or acetic acid as a sole carbon substrate. Compared to the sole carbon substrate, the use of SCC demonstrated the highest overall TIN removal of 98.3% at a COD ratio of 30 mg COD/l of methanol/50 mg CDO/l of acetic acid. Furthermore, denitrification was more enhanced when methanol was used as one of the SCC, rather than as a sole carbon source. Complete phosphorus removal was accomplished with a non-detectable o-P concentration when SCC was added. This research also showed that aerobic denitrifiers appear to prefer acetic acid to methanol, and the amount of poly-beta-hydroxybutyrate (PHB) stored by P accumulating organisms (PAOs) using acetic acid in the anoxic zone could be another important factor in improving the aerobic denitrification. The SCC was a very favorable carbon source for the aerobic denitrification since acetic acid was utilized more efficiently for P-release in accordance with increase of PHB stored in the cell of PAOs by removing nitrogen first using methanol. 相似文献
960.
The fundamental performance of a bio-electrochemical reactor for the direct treatment of metal pickling wastewater was investigated experimentally. In the reactor, carbon anode and cathode were installed. On the cathode, denitrifying microorganisms were immobilized. Continuous experiments were carried out by feeding a synthetic wastewater containing nitrate and binary heavy metal ions, copper and lead, under different operating conditions. Acetate as well as the electric current was supplied at the minimum amount for stoichiometry of the dissimilatory denitrification reaction. The results indicated that the dissolved copper and lead removal, denitrification and neutralization could be achieved simultaneously in a single bio-electrochemical reactor. The dissolved heavy metals were removed by electrochemical deposition on cathode and by the other phenomena such as the formation of insoluble suspensions and the sorption on suspended bacterial sludge. Denitrification proceeded effectively with the utilization of both added acetate and hydrogen gas generated by electrolysis of water. The pH value increased up to around neutral due to the occurrence of denitrification in the reactor, although the influent pH was less than 3. The removal efficiencies of heavy metals and nitrate increased with increasing the current density. The applied electric current was indispensable for sustaining the stable treatment in the reactor. 相似文献