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81.
Processing of High‐Density Magnesia Spinel Electro‐Conducting Ceramic Composite and its Oxidation at 1400°C 下载免费PDF全文
Zaki Zaki Nasser Mostafa Yasser Ahmed Emad Ewais Mohamed Rashad 《International Journal of Applied Ceramic Technology》2016,13(4):662-669
Dense conductive ceramic composites of MgAl2O4 and MoSi2 were processed using combustion synthesis under‐load methodology. The starting reactants were blends of MoO3, SiO2, MgO, and Al powders. The study revealed that to obtain dense composite with homogeneous microstructure, 30 wt. % of MoSi2, 18.5 μm Al average particle size, and 175 MPa load are required. The produced dense composite was found to have a low apparent porosity (<1.0 vol. %), moderate density 4.61 g/cm3, and low electrical resistivity 0.3 Ωcm. The dense composite exhibited excellent thermodynamic stability between its phases at 1400°C in open atmosphere. 相似文献
82.
Mohammad Maududul Huq Md. Robiur Rahman Masnun Naher Mohammad Mizanur Rahman Khan Mostafa Kamal Masud Golam Mohammad Golzar Hossain Nianyong Zhu Yih Hsing Lo Muhammad Younus Wai-Yeung Wong 《Journal of Inorganic and Organometallic Polymers and Materials》2016,26(6):1243-1252
Two palladium(II) nitroaryl complexes trans-[bromo(p-nitrophenyl)bis(triphenylphosphine)palladium(II)] 1 and trans-[bromo(2,4-dinitrophenyl)bis(triphenylphosphine)palladium(II)] 2 have been synthesized. The complexes were characterized by FTIR and NMR (1H, 13C and 31P) spectroscopy and elemental analysis. The molecular structure of complex 2, as confirmed by X-ray crystallography, reveals that the Pd atom and its neighboring groups (two PPh3, Br and phenylene group) lie in a slightly distorted square plane. In the UV–Vis spectra of the complexes 1 and 2, the palladium to aryl charge transfer bands were observed. The emission peaks from the singlet excited states (S1 → S0) were observed in the photoluminescence spectra of the complexes. The thermal stability of the complexes has been studied by thermal gravimetric analysis (TGA). TGA data showed that both complexes are thermally stable up to 200 °C, and complex 1 is more stable than 2. The catalytic efficiency of the new palladium(II) complexes was studied as demonstrated using the Sonogashira coupling reactions with good yields. The experimental results suggest that the Sonogashira coupling reactions can be performed at moderate temperature (50 °C) using these new palladium(II) complexes as catalysts. 相似文献
83.
Jaber Gharib Mostafa Keshavarz MoravejiReza Davarnejad Mohamad Ebrahim Malool 《Chemical Engineering Research and Design》2013
Gas holdup and gas–liquid mass transfer coefficient were considered in an external airlift reactor. Air was sparged through some aliphatic alcohols (methanol, ethanol, n-propanol, and n-butanol) with different concentrations (0–1%, v/v). It was observed that gas holdup and mass transfer coefficient increased with increasing the number of carbons in alcohols. Furthermore, an increment in alcohols concentration increased gas holdup and mass transfer coefficient. The same behavior was observed in external and internal loop airlift reactors although gas holdup and mass transfer coefficient values were less than those of internal airlift reactor. According to the experiments, two correlations for gas holdup and mass transfer were developed. 相似文献
84.
85.
Radial heat transfer in laminar pipe flow is characterized by a wide temperature distribution over the pipe cross‐section. We use a validated Computational Fluid Dynamics (CFD) model to show that the superimposition of a transverse vibration on the steady laminar flow of a Newtonian fluid moving in a pipe with an isothermal wall, generates considerable chaotic flow and radial mixing which result in a large enhancement in wall heat transfer as well as a considerably more uniform radial temperature field. Transverse vibration also causes the temperature profile to develop very rapidly in the axial direction reducing the thermal entrance length by a large factor. These effects are dependent on vibration amplitude and frequency, and fluid viscosity. © 2010 American Institute of Chemical Engineers AIChE J, 2011 相似文献
86.
Keivan Navi Razieh Farazkish Samira Sayedsalehi Mostafa Rahimi Azghadi 《Microelectronics Journal》2010,41(12):820-826
A novel expandable five-input majority gate for quantum-dot cellular automata and a new full-adder cell are presented. Quantum-dot cellular automata (QCA) is an emerging technology and a possible alternative for semiconductor transistor based technologies. A novel QCA majority-logic gate is proposed. This component is suitable for designing QCA circuits. The gate is simple in structure and powerful in terms of implementing digital functions. By applying these kinds of gates, the hardware requirement for a QCA design can be reduced and circuits can be simpler in level, gate counts and clock phases. In order to verify the functionality of the proposed device, some physical proofs are provided. The proper functionality of the FA is checked by means of computer simulations using QCADesigner tool. Both simulation results and physical relations confirm our claims and its usefulness in designing every digital circuit. 相似文献
87.
An exact three-dimensional analysis based on the linear potential theory and the elaborated method of eigenfunction expansion in elliptic coordinates are presented to study the free coupled elasto-hyrodynamic characteristics of an upright non-deformable cylindrical container of elliptical planform with a flexible bottom plate, filled to an arbitrary depth with an inviscid incompressible liquid. Extensive numerical data are presented in an orderly fashion for the first few symmetric/anti-symmetric coupled hydroelastic natural frequencies as a function of fluid depth parameter for two plate aspect ratios. Also, selected hydrodynamic and structural deformation modes shapes are presented in graphical form. The effects of liquid level, bottom plate elasticity, and cross sectional aspect ratio on the sloshing frequencies and hydrodynamic pressure modes are examined. The validity of the results is examined through computations using a commercial finite element package as well as by comparison with the data available in literature. 相似文献
88.
Mohamed Shaban Mostafa R. Abukhadra Ahmed Hamd 《Clean Technologies and Environmental Policy》2018,20(1):13-28
Glass was successfully recycled in the synthesis of mesoporous silica MCM-48 which was used as catalyst support for nickel oxide photocatalyst. The resulted products were evaluated using X-ray diffraction, scanning electron microscope and UV–Vis spectrophotometer. The precipitated nickel oxide is of Ni2O3 form and loading of it onto MCM-48 resulted in a reduction in the band gap energy from about 3.66 eV to about 2.4 eV. The role of MCM-48 as catalyst support for Ni2O3 in enhancing the adsorption capacity and photocatalytic properties of nickel oxide was evaluated through series of equilibrium studies and photocatalytic degradation of Congo red dye under visible light. Using of glass-based MCM-48 as catalyst support for Ni2O3 showed enhancing the adsorption capacity by 31.3 and 14.8% higher than the adsorption capacity of Ni2O3 and MCM-48, respectively. Also, the photocatalytic degradation percentage increased by about 67.3% relative to the Ni2O3 degradation percentage. The nature of MCM-48/Ni2O3 adsorption mechanism is chemisorption and occurs in multilayer form throughout the heterogeneous surface of the composite. The using of MCM-48 as support for Ni2O3 photocatalyst enhanced the adsorption capacity through increasing the total surface area. The loading process resulted in fixing of the Ni2O3 particles throughout the porous structure which producing more exposed active photocatalyst sites and active adsorption sites for the incident photons as well as preventing the nickel oxide particles from agglomeration. Based on the obtained results, supporting of Ni2O3 particles onto MCM-48 is promising active centers for the degradation of Congo red dye molecules. 相似文献
89.
Mohamed M. Mostafa 《Expert systems with applications》2009,36(8):11030-11038
This study uses self-organizing maps (SOM) to examine the effect of various psychographic and cognitive factors on green consumption in Kuwait. SOM is a machine learning method that can be used to explore patterns in large and complex datasets for linear and non-linear patterns. The results show that major variables affecting green consumption are related to altruistic values, environmental concern, environmental knowledge, skepticism towards environmental claims, attitudes toward green consumption, and intention to buy green products. The study also shows that SOM models are capable of improving clustering quality while extracting valuable information from multidimensional data. 相似文献
90.
Mostafa Sadooni 《Petroleum Science and Technology》2013,31(4):422-429
In gas condensate reservoirs, after a decrease in pressure below the dew point pressure, condensate formation would occur. One of the common and practical methods for prohibiting the rapid pressure drop in the reservoir and reduction of liquid dropout is gas injection. In this study, experimental measurement, the full field reservoir model and an economical evaluation have been performed to investigate the effect of nitrogen injection on an Iranian Southwestern gas condensate reservoir. At first, swelling and CVD tests were carried out to determine the swelling factor and changing the saturation pressure by nitrogen. Then, the full field simulation (history matching and prediction) was performed and finally an economical evaluation has been made. The results show that injecting more volumes of nitrogen cause to decrease the liquid dropout, increase the dew point pressure, and condensate ultimate recovery, but this process is not an economical project. 相似文献