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排序方式: 共有415条查询结果,搜索用时 15 毫秒
101.
102.
This work investigates the significance of higher-order terms on the modal behavior of a large, stressed power system's transient response. Second-order analysis indicates that many more frequencies of oscillation may have significant influence on the power system response. These additional frequencies result from second-order interactions of the linear modes and cannot be studied using linear analysis. A methodology based on the normal-form method is developed and utilized to describe the stressed, nonlinear system response. This methodology is used to extend linear concepts, such as eigenvectors and mode-state participation, to include second-order modal affects on power system performance. Data from the 50-generator IEEE test system is used in this investigation 相似文献
103.
As a result of modifications of BET model assumptions a new equation for sorption/desorption isotherms containing three constants was obtained. The proposed equation was verified successfully by means of measurements of sorption and desorption isotherms of water vapour for 29 substances and low-temperature adsorption of argon on 10 materials. Our own equation fits better, sometimes even much better, to the experimental points than the relations proposed by Harkins and Jura. Kühn, Halsey, Henderson, and Brunauer. Emmett and Teller (n = ∞). 相似文献
104.
Fouad S. S. Parditka B. Nabil M. Baradács E. Negm S. Erdélyi Zoltán 《Journal of Materials Science: Materials in Electronics》2022,33(26):20594-20603
Journal of Materials Science: Materials in Electronics - In this paper, we focused our attention on the tailoring of structure and optical analysis as a function of Cu interlayer between the ZnO... 相似文献
105.
H. K. Seo Farheen S. A. Ansari Nazish Parveen Shabeena Qadir H. Fouad H. S. Shin Moo Hwan Cho S. G. Ansari Z. A. Ansari 《Journal of Materials Science: Materials in Electronics》2017,28(4):3210-3216
Extensive research have been made in improving the dye sensitized solar cells (DSSC) performance by designing, tailoring and enhancing the photoconversion properties of the matrix. The approaches used are material synthesis, dye permutation combinations, use of natural extracts or using several sensitizers. The polymers are also being explored in this regards in their pristine or composite forms. Therefore, in this study an attempt is made to synthesize a mesoporous polyaniline–titanium dioxide (PANI–TiO2) nanocomposites with one pot synthesis approach at different concentrations of PANI (0.3–0.7 ml). Titanium isopropoxide was used as precursor for TiO2 with aniline and the material was synthesized at ice bath temperature. Morphological observations showed that the composite is a mesoporous material with tubular structure where TiO2 particles are seen entrapped in the polymer matrix and found that intercalation can be tailored with PANI concentration. Structural, functional and optical characterization indicate anatase phase of TiO2, with several functional bands that can help in dye interaction and broad absorption bands within visible region. The photocurrent-voltage response was measured with simulated light and source-meter. It is interesting to note that increasing PANI concentration enhances the mesoporous structure and hence increases the dye loading capacity and photoconductivity of the material. The efficiency increased by about 22 % with addition of 0.5 ml of PANI from 0.3 ml. The proposed study has indicated that such material have the potential to be used for DSSC fabrication with which the device performance can further be increased to a better levels. 相似文献
106.
The transient energy function method 总被引:4,自引:0,他引:4
A. A. Fouad V. Vittal 《International Journal of Electrical Power & Energy Systems》1988,10(4):233-246
The status of the transient energy function (TEF) method of direct analysis of transient stability of power systems is reviewed. The mathematical model is presented; an elementary theoretical basis of the method is introduced; the procedure for using the method in assessing power system transient stability is outlined; and the present condition of the technique and the available computer program is given. The outstanding issues, current development work and new applications are then summarized. 相似文献
107.
Evaluation of flow maldistribution in air-cooled heat exchangers 总被引:1,自引:0,他引:1
Investigation of the evaluation of flow maldistribution in air-cooled heat exchangers is presented. The flow field in the inlet and return headers was obtained through the numerical solution of the governing partial differential equations including the conservation equations of mass and momentum in addition to the equations of the turbulence model. The effects of the number of nozzles, nozzle location, nozzle geometry, nozzle diameter, inlet flow velocity and the incorporation of a second header on the flow maldistribution inside the tubes of an air-cooled heat exchanger were investigated using a 3-D computational method. The results are presented in terms of the standard deviations of the mass flow rate and static pressure in addition to the distributions in the static pressure inside the inlet header of the air-cooled heat exchanger. The results indicate that reducing the nozzle diameter results in an increase in the flow maldistribution. 25% increase is obtained in the standard deviation as a result of decreasing the diameter by 25%. Increasing the number of nozzles has a significant influence on the flow maldistribution. A reduction of 62.5% in the standard deviation of the mass flow rate inside the tubes is achieved by increasing the number of nozzles from 2 to 4. The results indicate that incorporating a second header results in a significant reduction in the flow maldistribution. Fifty percent decrease in the standard deviation is achieved as a result of incorporation of a second header of 7 holes. The results indicate that the mass flow rate and the static pressure distributions become uniform at the inlet of the second pass. 相似文献
108.
109.
An iterative process based on the wave concept is presented. This technique enables the rigorous treatment of radiating structures modeled by the finite element method (FEM) while preserving its computational efficiency. The coupling of the FEM model with the open region modeled by the integral equation technique is solved iteratively. © 2001 John Wiley & Sons, Inc. Int J RF and Microwave CAE 11: 194–201, 2001. 相似文献
110.
Yin Zhou Kai Liu Rafael E. Carrillo Kenneth E. Barner Fouad Kiamilev 《Pattern recognition》2013,46(12):3208-3222
In this paper, we propose a novel sparse representation based framework for classifying complicated human gestures captured as multi-variate time series (MTS). The novel feature extraction strategy, CovSVDK, can overcome the problem of inconsistent lengths among MTS data and is robust to the large variability within human gestures. Compared with PCA and LDA, the CovSVDK features are more effective in preserving discriminative information and are more efficient to compute over large-scale MTS datasets. In addition, we propose a new approach to kernelize sparse representation. Through kernelization, realized dictionary atoms are more separable for sparse coding algorithms and nonlinear relationships among data are conveniently transformed into linear relationships in the kernel space, which leads to more effective classification. Finally, the superiority of the proposed framework is demonstrated through extensive experiments. 相似文献