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101.
Kwang Ho Kim Soo Won Lee Dong Won Shin Chan Gyung Park 《Journal of the American Ceramic Society》1994,77(4):915-921
Antimony-doped tin oxide films were prepared on Corning glass substrate by chemical vapor deposition from a gas mixture of SnCl4 –SbCl5 –H2 O. The electrical conductivity and optical transmission of tin oxide films were studied with antimony doping. The film conductivity increased largely without losing optical transparency with a small addition of antimony. The increase of the conductivity was attributed mainly to more electrons donated by pentavalent Sb ions in the SnO2 lattice. Large additions of antimony, however, diminished the conductivity, optical transparency, and crystallinity of the film. The diminution was found to be caused by fine Sb2 O5 phases codeposited with SnO2 . 相似文献
102.
A numerical solution of the pseudo-steady state governing equations on the basis of the Langmuir-Hinshelwood type rate equation
was obtained by the approximate finite difference method in packed bed reactors for gas-solid reaction system. It was proved
that the numerical method has good accuracy compared with the strict solution in the special case that the reaction rate can
be represented by the first-order kinetics in terms of gaseous reactant and the effectiveness factor is unity druing the reaction.
The numerical method is proposed to predict the transient of exit-gas compositions of a packed bed reactor used for gas-solid
reaction systems. The exit-gas composition can be predicted from the conversion data of a single particle with varying reaction
time. The present method can be easily applied to the systems involving adsorptive gaseous reactants and complex reaction
behavior with structural changes of particles. 相似文献
103.
The effect of adsorptive species on non-isothermal gas-solid reactions is studied on the basis of Langmuir-Hinshelwood kinetics. The concept of an effectiveness factor provides good information to ascertain the effect of adsorptive species and the transition of the rate controlling regime, in connection with the parameters, generally used in the analysis of non-isothermal behavior. For highly exothermic reactions, the effectiveness factor-Thiele modulus curves with multiple solutions are presented with respect to the modified adsorption equilibrium constant. The variations of the rate-controlling regime by the effect of adsorptive species are also discussed. 相似文献
104.
A new characterization procedure for aqueous solutions with unknown composition was proposed based on the binomial distribution
of TOC (total organic carbon) fraction in terms of a characterizing variable, the Freundlich coefficient, k, so that the solution
in question can be described by a finite number of pseudo.species identified with a certain k value. The validity and computational
accuracy of this procedure has been demonstrated by characterizing three sets of experimental data chosen from different sources.
Predictions based on this procedure yielded acceptable results that agreed closely with experimental data. 相似文献
105.
A surface diffusion mocel with diffusional interference has been presented for the analysis of multicomponent adsorption of
phenols by activated carbon. Surface diffusion coefficients for multicomponent adsorptions were estimated from the relationship
between. the surface diffusion coefficient of each species and the surface coverage. The diffusional interference coefficients,
Wij, was determined from experimental counter-adsorption data. The numerical values of Wij were in the range of 0.4–0.9, which show that the introduction of diffusional interference is necessary to analyze multicomponent
counter-adsorptions properly. The proposed model successfully simulates the behaviour of phenols-activated carbon system in
a batch adsorber. 相似文献
106.
Mun-Soo Yun Ki-Young Jeong Eui-Wan Lee Bong-Soo Jin Seong-In Moon Chil-Hoon Doh 《Korean Journal of Chemical Engineering》2006,23(2):230-236
The aim of this paper is to study the electrochemical behavior of Si-C material synthesized by heating a mixture of silicon
and polyvinylidene fluoride (PVDF) in the ratios of 5, 20, and 50 wt%. The particle size of the synthesized material was found
to be increased with increase in the PVDF ratio. The coexistence of silicon with carbon was confirmed from the XRD analysis.
A field emission scanning electron microscope (FESEM) study performed with the material proved the improvement in coating
efficiency with increase in the PVDF ratio. Coin cells of the type 2025 were made by using the synthesized material, and the
electrochemical properties were studied. An electrode was prepared by using the developed Si-C material. Si-C|Li cells were
made with this electrode. A charge|discharge test was performed for 20 cycles at 0.1 C hour rate. Initial charge and discharge
capacities of Si-C material derived from 20 wt% of PVDF was found to be 1,830 and 526 mAh|g, respectively. Initial charge/discharge
characteristics of the electrode were analyzed. The level of reversible specific capacity was about 216mAh/g at Si-C material
derived from 20 wt% of PVDF, initial intercalation efficiency (IIE), intercalation efficiency at initial charge/discharge,
was 68%. Surface irreversible specific capacity was 31 mAh/g, and average specific resistance was 2.6 ohm * g. 相似文献
107.
Highly Efficient Overall Water Splitting Through Optimization of Preparation and Operation Conditions of Layered Perovskite Photocatalysts 总被引:1,自引:0,他引:1
Jindo Kim Dong Won Hwang Hyun Gyu Kim Sang Won Bae Jae Sung Lee Wei Li Se Hyuk Oh 《Topics in Catalysis》2005,35(3-4):295-303
The layered perovskite materials were found to give the high photocatalytic activity in water splitting reaction under UV
irradiation, where the electronic structure of perovskite slab constructing the layered structure (the total cation valency)
was the most crucial factor to the high photocatalytic activity. Both the excessive cation valency and the layered structure
were required for active photocatalysts, while the slab thickness of layered perovskites had an insignificant effect on water-splitting
activity. In order to identify key variables that affected photocatalytic activity and to optimize the performance of (110)
layered perovskite, La2Ti2O7 was modified by various methods. The optimum amount of loaded nickel had a great effect and the amount depended on the surface
area of the perovskite phase. When an alkaline-earth element such as Ba, Sr, and Ca was doped on La2Ti2O7, the photocatalytic activity was enhanced markedly. Introduction of an alkaline hydroxide into the reaction system as an
external additive enhanced the activity further showing extremely high quantum yields close to 50%. 相似文献
108.
Concepts for the effective MWCO of tight-UF membranes, and apparent diffusion coefficients for NOM, were introduced to determine the mechanisms influencing NOM removal and to explain the various behaviors of NOM removal by UF membranes with different hydrophobicities, permeability, and surface charges. Colloidal NOM (COM) and non-colloidal hydrophobic NOM (NCD HP) constituents were chosen for the evaluation of two different UF membranes. For a relatively hydrophobic, relatively high permeability, and less negatively charged UF membrane, the hydrophobic fractions of COM were preferentially removed and were also removed by a size exclusion mechanism (i.e., both hydrophobic interaction and size exclusion mechanisms). The NCD HP exhibited no such preferential removal of the hydrophobic fractions, but could be removed by a size exclusion mechanism (i.e., only size exclusion mechanism). With a relatively hydrophilic, relatively low permeability, and more negatively charged UF membrane, COM exhibited no preferential removal of the hydrophobic fractions, but could be removed by a size exclusion mechanism (i.e., only size exclusion mechanism). Whereas the hydrophobic fractions of the NCD HP were preferentially removed, these could not be removed by a size exclusion mechanism (i.e., only hydrophobic interaction mechanism). The apparent diffusion coefficients of NOM, as determined from NOM diffusion experiments using a diffusion cell equipped with a regenerated cellulose membrane, were much lower than those calculated by the Stokes-Einstein relation. The diffusion coefficient of NOM is expected to be used to predict and explain NOM transport behaviors in tight-UF membranes. 相似文献
109.
110.
Defect detection is an important technology for the quality control in the production process of wafer, TFT-LCD and PCB. Inspection is performed using the finished product’s image. The images are classified into two different groups—images with a repetitive pattern on a regular cycle and images without a repetitive pattern. A standard object for comparison is required, because manual defect detection is not possible for areas without repetitive patterns. In such areas, defect detection occurs through contrasting a reference pattern to the pattern being inspected. Methods of inspection using reference image have been researched but have limitations due to their requirement of precise alignment of the images. This paper proposes a method of defect detection to overcome such limitation using feature point matching. Feature points are extracted using a corner detector and detects defect by finding a correspondence between two feature point sets. Performance of the proposed method is evaluated by using Wafer SEM images and compared with conventional methods. Experiment results demonstrate the proposed method achieves higher detection accuracy than conventional methods and is less sensitive to alignment error and noise. 相似文献