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991.
The hyperbranched aliphatic poly(amide ester) (HAPAE) was synthesized based on 4‐N,N‐di(2‐hydroxy ethyl)‐4‐ketobutyric acid prepared by the reaction of succinic anhydride with diethanol amine, as an AB2 monomer (repeating unit), and with 2‐ethyl‐2‐(hydroxymethyl)‐1,3‐propanediol, as a core molecule, using acid catalysis. The second generation of the product was characterized by measuring dynamic viscosity, which decreased sharply with the increase in frequency. The product exhibits relative thermal stability as analyzed by thermogravimetry in a nitrogen atmosphere. The glass transition temperature, determined by differential scanning calorimetry, is ?27 °C. The molar mass was measured by vapor pressure osmometry. The polydispersity, measured by size exclusion chromatography, is 2.16. Dynamic mechanical thermal analyses were performed to characterize the thermal properties of the ultraviolet‐cured films of the acrylate‐modified HAPAE. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1630–1636, 2001 相似文献
992.
Philippe Nika Yannick Bailly Michel De Labachelerie Jean Claude Jeannot Jacques De Lallee 《Nanoscale and Microscale Thermophysical Engineering》2013,17(4):301-325
The miniaturization of refrigerating systems represents a very current scientific and technical challenge to improve the performances of numerous electronic components. This work presents a global approach to the problem and suggests studying the cooling by means of small channels filled with an oscillating gas: the double inlet pulse tube refrigerator (DIPTR). A great level of miniaturization based on the technology of carving silicon is exposed. This study proposes to apply an electric analogy for modeling both hydrodynamic and thermal phenomena. Considering the complexity of the theoretical problem including mechanical, thermal, thermodynamical, and acoustic considerations, the authors take care to summarize the main governing equations in a particular form so any scientific engineer could understand the DIPTR principle. 相似文献
993.
994.
元强 《武汉理工大学学报(材料科学英文版)》2013,28(3):548-556
Chloride binding is often described by chloride binding isotherm, which is closely related to the service life of concrete structures in chloride environments. Many methods have been proposed to determine chloride binding isotherm. Compared to other methods, chloride binding isotherms obtained directly from nonsteady-state diffusion tests seem closer to the reality. We studied the chloride binding isotherm from both nonsteady-state electrical-accelerated migration and diffusion tests at different temperatures. Twelve concrete mixes with different supplementary cementing materials and water-to-binder ratios of 0.35, 0.48 and 0.6 were cast for study. The specimens after diffusion (or migration) tests were sliced layer by layer, and acid-soluble and free chloride contents of each layer were measured. A chloride binding isotherm was obtained from one specimen. Experimental results indicated that electrical voltage had a slight effect on the chloride binding isotherm of concrete. Temperature had a positive effect on chloride binding. The higher the water-to-binder ratio was, the higher the chloride binding was. 相似文献
995.
This paper presents a novel system for production of pure oxygen based on the integration of a solid oxide fuel cell (SOFC) and a solid oxide electrolyzer (SOEC). In the proposed arrangement, the SOFC provides electricity, heat and H2O in vapour phase to the SOEC which carries out the inverse reactions of the SOFC, that is the separation of H2O into H2 (used as a fuel for the SOFC) and O2 (representing the yield of the system). Simulations carried out in different operating conditions show that when the integrated SOFC–SOEC device runs at low current densities (less than 1000 A m−2), pure oxygen can be generated with an electric consumption comparable to mid-size cryogenic air separation units, and significantly lower than small scale systems based on the PSA technology. 相似文献
996.
W. Habchi C. Matta L. Joly-Pottuz M. I. De Barros J. M. Martin P. Vergne 《Tribology Letters》2011,42(3):351-358
In this article, the lubricating properties of pure glycerol are investigated under both mild and severe EHL regimes. Amazingly
low friction coefficients (about 0.01) are reported by experiments in thick film regimes compared to traditional base oils.
EHL calculations of film thickness and friction (including thermal effects) predict friction coefficients that are twice those
actually found for glycerol. Chemical analysis of glycerol before and after the friction tests were performed by NMR and Karl
Fischer methods, and they reveal that water is produced by tribochemical reaction as well as other species like aldehydes.
This finding is in agreement with a corrosion pattern observed inside the wear scars of the steel samples. This study provides
an explanation to the anomalously low friction observed in the thick film regime. In fact, water produced in the lubricant
decreases traction forces due to the drastic decrease of the viscosity of glycerol with water addition. 相似文献
997.
In the SPIDER experiment a ITER-like full size plasma source will be realized with the target to extract a Dˉ beam of 70 A and then to accelerate it to 100 keV energy. The reduction of the effects due to the frequent breakdowns between the accelerating grids is needed, because of grids damage due to energy deposition by arcing and strong electromagnetic noise (EMI) emission. The solution proposed is a comprehensive design of the circuit. Two passive components are installed: a Damping Resistor and an Output Filter in series to the Power Supplies. Then a doubled screened structure will be adopted for the 30 m long – 100 kV Transmission Line TL, which connects the Ion Source and Acceleration Power Supplies to their loads: the Inner Screen will be connected to the reference ground (the vessel) by a resistive link, the Outer Screen acting as a low-impedance ground. Finally, a Distributed Core Snubber DCS (magnetic snubber) will be installed onto the TL, aimed to increase the damping of the oscillations due to the stray inductances and capacitances. The DCS is composed of 10 magnetic alloy cores and is equipped by a biasing circuit to enhance the flux swing in unsaturated condition during the breakdown. A detailed model of the circuit is developed to evaluate the passive components parameters for protection against breakdown, in which all the magnetic and capacitive couplings between components are modeled as well as the magnetic core snubber saturation. 相似文献
998.
K. Channa R. De SilvaBrian J. Kaseman David J. Bayless 《International Journal of Hydrogen Energy》2011,36(1):779-786
Planar electrolyte supported solid oxide fuel cells were operated at 900 °C with humidified H2 for 200 h using silver mesh and paste for cathode current collection. Continuous potentiostatic tests at 0.7 V appeared to induce migration of Ag towards electrode-electrolyte interphase, while continuous OCV tests caused no mass transport. Similar SOFCs fueled by coal syngas at 850 °C using Ag for both anode and cathode current collection indicated little, if any, Ag migration; providing the possibility of employing Ag for 100 h laboratory scale tests using coal-derived syngas. Use of high temperature steam, carbon dioxide and carbon monoxide did not result in the formation of silver carbonates. 相似文献
999.
Rafael Vargas‐Bernal Carlos A. De la Cruz Blas Cristina Gómez‐Polo 《International Journal of Circuit Theory and Applications》2015,43(12):2072-2080
Nowadays, the design of magneto‐impedance (MI) sensors requires the development of lumped circuit models that can be simulated through equivalent impedance circuits relied on Bessel functions. A new impedance model based on Senani's equivalent using the zeros of Bessel functions is developed in this paper. The model allows to describe the impedance as a transfer function that can be easily synthesized by means of current conveyor circuits and passive elements. The mathematical representation was verified under simulation of transfer functions involving different number of poles and zeros. Moreover, the model has been verified using SPICE simulations and measurement results from a fabricated prototype demonstrating its scope and validity. Finally, a study of finite tracking errors of CCIIs used in the implementation of magneto‐impedance sensor has been realized. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
1000.
Sensors: Detection Beyond Debye's Length with an Electrolyte‐Gated Organic Field‐Effect Transistor (Adv. Mater. 5/2015)
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