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31.
CAO Ning GUO JingYu BOUKHERROUB Rabah SHAO QingGuo ZANG XiaoBei LI Jin LIN XueQiang JU Hong LIU EnYang ZHOU ChaoFan LI HuiPing 《中国科学:技术科学(英文版)》2019,(9)
In recent years, graphene oxide(GO), prepared by the modified Hummers' method, and its derivatives have become a focus of research owing to their outstanding physical and chemical properties and low cost. Drawing inspiration from the mussel protein,a facile and environmentally-friendly method was employed to fabricate superhydrophobic/superoleophilic reduced graphene oxide(rGO) derivative. The preparation comprises two steps: coating GO nanosheets with polydopamine(PDA) and subsequent reaction with 1H,1H,2H,2H-perfluorodecanethiol. Due to the excellent adhesive ability of PDA, the resulting f PDA modified rGO nanosheets(rGO-f PDA) were firmly immobilized onto polyurethane(PU) sponge skeleton by a simple drop-coating method. The as-prepared rGO-f PDA functionalized sponge exhibited superhydrophobic behavior with a water contact angle of 162°±2°, high organic adsorption capacity, recyclability and stable oil/water separation behavior under different acidic/alkaline conditions. Due to its facile fabrication technique and outstanding properties, the superhydrophobic-superoleophilic PU-rGOf PDA sponge holds great promise as an oil adsorbent for cleaning up large-scale pollution of oil and organic solvents, and dehydrating crude oil. 相似文献
32.
Faults prognosis using partially observed stochastic Petri-nets: an incremental approach 总被引:1,自引:0,他引:1
Rabah Ammour Edouard Leclercq Eric Sanlaville Dimitri Lefebvre 《Discrete Event Dynamic Systems》2018,28(2):247-267
This article deals with the problem of fault prognosis in stochastic discrete event systems. For that purpose, partially observed stochastic Petri nets are considered to model the system with its sensors. The model represents both healthy and faulty behaviors of the system. Our goal is, based on a timed measurement trajectory issued from the sensors, to compute the probability that a fault will occur in a future time interval. To this end, a procedure based on an incremental algorithm is proposed to compute the set of consistent behaviors of the system. Based on the measurement dates, the probabilities of the consistent trajectories are evaluated and a state estimation is obtained as a consequence. From the set of possible current states and their probabilities, a method to evaluate the probability of future faults is developed using a probabilistic model. An example is presented to illustrate the results. 相似文献
33.
Ahmed Saber Ahmed Emam Rabah Amer 《IEEJ Transactions on Electrical and Electronic Engineering》2016,11(1):43-48
This paper presents a scheme for classification of faults on double circuit parallel transmission lines using combination of discrete wavelet transform and support vector machine (SVM). Only one cycle post fault of the phase currents was employed to predict the fault type. Two features for each phase current were extracted using discrete wavelet transform. Thus, a total of 12 features were extracted for the six phase currents. The training data were collected, and SVM was employed to establish the fault classification unit. After that, the fault classification unit was tested for different fault states. The power system simulation was conducted using the MATLAB/Simulink program. The proposed technique took into account the mutual coupling between the parallel transmission lines and the randomness of the faults on transmission line considering time of occurrence, fault location, fault type, fault resistance, and loading conditions. The results show that the proposed technique can classify all the faults on the parallel transmission lines correctly. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献
34.
Kaminska I Das MR Coffinier Y Niedziolka-Jonsson J Sobczak J Woisel P Lyskawa J Opallo M Boukherroub R Szunerits S 《ACS applied materials & interfaces》2012,4(2):1016-1020
An easy and environmentally friendly chemical method for the simultaneous reduction and noncovalent functionalization of graphene oxide (GO) using dopamine derivatives is described. The reaction takes place at room temperature under ultrasonication of an aqueous suspension of GO and a dopamine derivative. X-ray photoelectron spectroscopy, FT-IR spectroscopy, and cyclic voltammetry characterizations revealed that the resulting material consists of graphene functionalized with the dopamine derivative. This one-step protocol is applied for simultaneous reduction and functionalization of graphene oxide with a dopamine derivative bearing an azide function. The chemical reactivity of the azide function was demonstrated by a postfunctionalization with ethynylferrocene using the Cu(I) catalyzed 1,3-dipolar cyloaddition. 相似文献
35.
André JM Benbalagh R Barchewitz R Ravet MF Raynal A Delmotte F Bridou F Julié G Bosseboeuf A Laval R Soullié G Rémond C Fialin M 《Applied optics》2002,41(1):239-244
An x-ray multilayer monochromator with improved resolution and a low specular background is presented. The monochromator consists of a lamellar multilayer amplitude grating with appropriate parameters used at the zeroth diffraction order. The device is fabricated by means of combining deposition of thin films on a nanometer scale, UV lithography, and reactive ion etching. The performance of this new monochromator at photon energies near 1500 eV is shown. 相似文献
36.
Kinetic and prediction studies of ascorbic acid degradation in normal and concentrate local lemon juice during storage 总被引:2,自引:0,他引:2
Kinetics of the loss of ascorbic acid (AA) in local lemon juice of 9° and 50° Brix stored at 25, 35, and 45 °C for 4 months have been investigated. The results indicate that increases of concentrations and temperatures increase the rate of AA degradation. The calculated values of activation energies (E≠) and frequency factors (A) at different Brix imply that the concentration of juice does not change the mechanism of degradation. Thermodynamic functions of activation (ΔG≠, ΔH≠, ΔS≠ and K≠) have been determined and considered briefly. A direct equation for estimation of the shelf life of stored juice with respect to first-order losses of AA, at any specific temperature and degradation ratio, has been derived and programmed successfully. 相似文献
37.
Mohammed Yacine Ferroukhi Rabah Djedjig Karim Limam Rafik Belarbi 《Building Simulation》2016,9(5):501-512
High levels of humidity in buildings lead to building pathologies. Moisture also has an impact on the indoor air quality and the hygrothermal comfort of the building’s occupants. To better assess these pathologies, it is necessary to take into account the heat and moisture transfer between the building envelope and its indoor ambience. In this work, a new methodology was developed to predict the overall behavior of buildings, which combines two simulation tools: COMSOL Multiphysics© and TRNSYS. The first software is used for the modeling of heat, air and moisture transfer in multilayer porous walls (HAM model: Heat, Air and Moisture transfer), and the second is used to simulate the hygrothermal behavior of the building (BES model: Building Energy Simulation). The combined software applications dynamically solve the mass and energy conservation equations of the two physical models. The HAM-BES coupling efficiency was verified. In this paper, the use of a coupled (HAM-BES) co-simulation for the prediction of the hygrothermal behavior of building envelopes is discussed. Furthermore, the effect of the 2D HAM modeling on relative humidity variations within the building ambience is shown. The results confirm the importance of the HAM modeling in the envelope on the hygrothermal behavior and energy demand of buildings. 相似文献
38.
H. Rached D. Rached S. Benalia A.H. Reshak M. Rabah R. Khenata S. Bin Omran 《Materials Chemistry and Physics》2013
The structural stabilities, elastic and electronic properties of 5d transition metal mononitrides (TMNs) XN with (X = Ir, Os, Re, W and Ta) and 5d transition metal monocarbides (TMCs) XC with (X = Ir, Os, Re and Ta) were investigated using the full-potential linear muffin-tin orbital (FP-LMTO) method, in the framework of the density functional theory (DFT) within the local density approximation (LDA) for the exchange correlation functional. The ground state quantities such as the lattice parameter, bulks modulus and its pressure derivatives for the six considered crystal structures, Rock-salt (B1), CsCl (B2), zinc-blend (B3), Wurtzite (B4), NiAs (B81) and the tungsten carbides (Bh) are calculated. The elastic constants of TMNs and TMCs compounds in its different stable phases are determined by using the total energy variation with strain technique. The elastic modulus for polycrystalline materials, shear modulus (G), Young's modulus (E), and Poisson's ratio (ν) are calculated. The Debye temperature (θD) and sound velocities (vm) were also derived from the obtained elastic modulus. The analysis of the hardness of the herein studied compounds classifies OsN – (B4 et B81), ReN – (B81), WN – (B81) and OsC – (B81) as superhard materials. Our results for the band structure and densities of states (DOS), show that TMNs and TMCs compounds in theirs energetically and mechanically stable phase has metallic characteristic with strong covalent nature Metal–Nonmetal elements. 相似文献
39.
In the present work, we focus to study numerically the natural convection cooling process from two identical electronic components located on the bottom wall of a two-dimensional cavity. Each electronic component is covered by a porous medium with finite thickness. The conservation equations governing the problem are discretized using the finite volume method and the SIMPLER algorithm is used to handle the nonlinear character of conservation equations. Calculations were carried out for the following control parameters: the porous/fluid thermal conductivity ratio (1 ≤ RkP1 ≤ 100), the Darcy and Rayleigh numbers (10−1 ≤ Da ≤ 10−6, 103 ≤ Ra ≤ 106), the first porous-cover thickness (0.05 ≤ e1 ≤ 0.3), and the separation distance between components (0.2 ≤ S ≤ 1) to highlight their influence on the cooling process. The results show that under specific values of the Darcy and Rayleigh numbers and in the limiting case of a high value of the porous/fluid thermal conductivity ratio (RkP1 = 100), a decrease in the maximum components temperature, up to 95%, is observed by increasing the porous-cover thickness from 0.05 to 0.3. In addition, by increasing the permeability, the Rayleigh number or the separation distance, an improvement in the cooling process of the two components greater than or equal to 22% is achieved. 相似文献
40.
Saravanan Rajendran Tuan K.A. Hoang Rabah Boukherroub D.E. Diaz-Droguett F. Gracia M.A. Gracia-Pinilla A. Akbari-Fakhrabadi Vinod Kumar Gupta 《International Journal of Hydrogen Energy》2018,43(5):2861-2868
In this work, we present the synthesis of Ag doped TiO2 materials. The products are characterized by powder X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, nitrogen adsorption, and hydrogen adsorption. The Ag/TiO2 materials exhibit 3.65 times higher in hydrogen adsorption capability compared with the non-doped TiO2 materials thank to the existence of Ti3+ species, which are Kubas-type hydrogen adsorption centers, and the Ag nanoparticles which provide spillover effects. We believe that this is the first time that both Kubas-type adsorption and spillover are exploited in the design of novel hydrogen storage materials. 相似文献