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1.
The water activities of the mixed aqueous electrolyte NaCl–BaCl2(aq) are measured at total molalities from 0.25 mol kg−1 to about saturation for different ionic strength fractions (y) of NaCl with y=0.33,0.50,0.67. The results allow the deduction of osmotic coefficients. The experimental results are compared with the predictions of the Zdanovskii, Stokes, and Robinson (ZSR), Kusik and Meissner (KM), Robinson and Stokes (RS), Lietzke and Stoughton (LSII), Reilly, Wood, and Robinson (RWR), and Pitzer models. From these measurements, the Pitzer mixing ionic parameters are determined and used to predict the solute activity coefficients in the mixture. The excess Gibbs energy is also determined. 相似文献
2.
The cooling power of aqueous solutions of ethylene oxide-propylene oxide copolymers are studied with a silver standard sample by using two apparatuses quench with injection and quench with agitation. For temperature T>400°C, the viscosity plays the predominant role; for T<400°C, the cooling is controlled by the polymer precipitation and the cooling rate decreases by lowering the cloud point of the polymer solution. This work demonstrates the possibility of adjusting the cooling curves by taking into account the thermodynamical properties of the polymer. 相似文献
3.
This paper deals with the problem of piecewise auto regressive systems with exogenous input(PWARX) model identification based on clustering solution. This problem involves both the estimation of the parameters of the affine sub-models and the hyper planes defining the partitions of the state-input regression. The existing identification methods present three main drawbacks which limit its effectiveness. First, most of them may converge to local minima in the case of poor initializations because they are based on the optimization using nonlinear criteria. Second, they use simple and ineffective techniques to remove outliers. Third, most of them assume that the number of sub-models is known a priori. To overcome these drawbacks, we suggest the use of the density-based spatial clustering of applications with noise(DBSCAN) algorithm. The results presented in this paper illustrate the performance of our methods in comparison with the existing approach. An application of the developed approach to an olive oil esterification reactor is also proposed in order to validate the simulation results. 相似文献
4.
Mohammed Alaeddine Abderrahim Mohammed Dib Mohammed El-Amine Abderrahim Mohammed Amine Chikh 《International Journal of Speech Technology》2016,19(2):229-236
As part of information retrieval systems (IRS) and in the context of the use of ontologies for documents and queries indexing, we propose and evaluate in this paper the contribution of this approach applied to Arabic texts. To do this we indexed a corpus of Arabic text using Arabic WordNet. The disambiguation of words was performed by applying the Lesk algorithm. The results obtained by our experiment allowed us to deduct the contribution of this approach in IRS for Arabic texts. 相似文献
5.
Numerical simulation has been performed to improve the performance of Cu2ZnSnS4 (CZTS) solar cells by replacing CdS with Zn1–xSnxO buffer layer. The influences of thickness, donor concentration and defect density of buffer layers on the performance of CZTS solar cells were investigated. It has been found that Zn1–xSnxO buffer layer for Sn content of 0.20 is better for CZTS solar cell. A higher efficiency can be achieved with thinner buffer layer. The optimized solar cell demonstrated a maximum power conversion efficiency of 13%. 相似文献
6.
Fatima Zahra Chafi Abderrahim Jabar Lahoucine Bahmad Najem Hassanain Boubker Fares Ahmed Mzerd 《Journal of Superconductivity and Novel Magnetism》2017,30(8):2123-2128
Using Monte Carlo simulations, we are studying the magnetic properties of Fe-doped CuO thin films. The total magnetizations and the susceptibilities are studied as a function of the effect doping, external magnetic field, and exchange coupling. The critical temperature is discussed as a function of the effect of iron concentration. On the other hand, we investigate the effect of increasing temperatures on the coercive field for a constant value of exchange coupling and a fixed concentration. The coercive magnetic field is found to decrease with increasing temperature values until reaching its null value. The effect of increasing the exchange coupling amount on the saturation magnetic field H s is illustrated. A linear growth of the saturation magnetic field is found as a function of the exchange coupling interaction. To complete this study, we presented and discussed the magnetic hysteresis cycle loops. 相似文献
7.
Two newly synthesised Sr0.50SbFe(PO4)3 [Sr0.5.] and SrSb0.50Fe1.50(PO4)3 [Sr.] phases were obtained by conventional solid-state reaction techniques at 1000 °C in air atmosphere. Their crystallographic
structures were determined at room temperature from X-ray powder diffraction (XRPD) data using the Rietveld analysis. Both
compounds belong to the Nasicon structural family. [Sr0.5.] and [Sr.] crystallise in rhombohedral system with
\textR[`3] {\text{R}}\overline{3} and
\textR[`3] \textc {\text{R}}\overline{3} {\text{c}} space group, respectively. Hexagonal cell parameters for [Sr0.5.] and [Sr.] are: a = 8.227(1) ?, c = 22.767(2) ? and a = 8.339(1) ?, c = 22.704(2) ?, respectively. Sr2+ and vacancies in {[Sr0.50]3a[□0.50]3b}M1SbFe(PO4)3 are practically ordered within the two positions, 3a and 3b, of M1 sites. Structure refinements show also an ordered distribution
of Sb5+ and Fe3+ ions within the Nasicon framework. Within the structure, each Sr(3a)O6 octahedron shares two faces with two Fe3+O6 octahedra and each vacancy (□(3b)O6) site is located between two Sb5+O6 octahedra. In [Sr]M1Sb0.50Fe1.50(PO4)3 compound, all M1 sites are occupied by Sr2+ and the Sb5+ and Fe3+ ions are randomly distributed within the Nasicon framework. A Raman and infrared spectroscopic study was used to obtain further
structural information about the nature of bonding in both selected compositions. 相似文献
8.
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10.
Synthesis and photovoltaic properties of mono-substituted quaterthiophenes bearing strong electron-withdrawing group 总被引:1,自引:0,他引:1
Abderrahim Yassar Christine Videlot Abdelhafid. Jaafari 《Solar Energy Materials & Solar Cells》2006,90(7-8):916-922
We report here on the synthesis and properties of a monosubstituted quaterthiophene derivative asymmetrically functionalized by an electron-withdrawing group using the palladium-catalyzed Stille's coupling reaction. The UV–vis absorption spectrum evidences a strong intramolecular charge transfer transition. Thus oligothiophenes act as electron donors and substituent group as acceptor. The diodes in which monosubstituted quaterthiophenes behave as organic semiconductors, exhibit a rectifying behavior. Photovoltaic measurements show moderate power conversion efficiency. 相似文献