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51.
Mahshid Fardadi Dustin F. McLartyJacob Brouwer Faryar Jabbari 《International Journal of Hydrogen Energy》2014
We study a counter-flow solid oxide fuel cell system and consider the challenges faced in minimizing thermal variations from the nominal operating conditions for a reasonable range of power tracking. Blower dynamics, reformer transport delays, spatial distribution of the heat generated and the resulting thermal response are among the issues considered. A novel approach, relying on partial internal reformation of the feedstock is proposed as a remedy to maintain a strong level of power tracking with minimal thermal stress to the fuel cell. 相似文献
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X-ray fluorescence (XRF) is a commonly used analytical method to quantify lead (Pb), a toxic element, in atmospheric aerosol. The commercially available reference materials used for calibrating XRF do not mimic the concentrations and filter materials of particulate matter (PM) monitoring networks. In this study, we described an aerosol deposition method to generate Pb reference materials (RMs) over a range of concentrations to serve several purposes for the US Environmental Protection Agency (EPA) and Interagency Monitoring of PROtected Visual Environments (IMPROVE) monitoring networks including laboratory auditing, federal equivalency method evaluation, and calibration and quality control of XRF instruments. The RMs were generated using a laboratory-built aerosol chamber equipped with a federal reference sampler at concentration levels ranging from 0.0125 to 0.70 μg/m3. XRF analysis at UC Davis was demonstrated to be equivalent to a US and EU reference method, inductively coupled plasma—mass spectrometry (ICP-MS), for measuring Pb on RMs following a methodology described in the United States and international standards. The Pb concentrations on subsets of the RMs were verified by three other XRF laboratories with different analyzers and/or quantification methods and were shown to be equivalent to the UC Davis XRF analysis. The generated RMs were demonstrated to have short and long-term stability, satisfying an additional requirement of reference materials.
Copyright © 2016 American Association for Aerosol Research 相似文献
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Amirhosein Ramazanpour Esfahani Saeid Hojati Amin Azimi Leila Alidokht Alireza Khataee Meysam Farzadian 《Korean Journal of Chemical Engineering》2014,31(4):630-638
We studied the optimization of hexavalent chromium (Cr(VI)) removal from aqueous solution using the synthesized zero-valent iron nanoparticles stabilized with sepiolite clay (S-ZVIN), under various parameters such as reaction time (min), initial solution pH and concentration of S-ZVIN (g·L?1) using response surface methodology (RSM). The kinetic study of Cr(VI) was conducted using three types of the most commonly used kinetic models including pseudo zero-order, pseudo first-order, and pseudo second-order models. The rate of reduction reaction showed the best fit with the pseudo first-order kinetic model. The process optimization results revealed a high agreement between the experimental and the predicted data (R2=0.945, Adj-R2=0.890). The results of statistical analyses showed that reaction time was the most impressive factor influencing the efficiency of removal process. The optimum conditions for maximum response (98.15%) were achieved at the initial pH of 4.7, S-ZVIN concentration of 1.3 g·L?1 and the reaction time of 75 min. 相似文献
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Sevda Dehghani Ahad Hanifpour Mehdi Nekoomanesh-Haghighi Samahe Sadjadi Seyed Amin Mirmohammadi Ali Farhadi Naeimeh Bahri-Laleh 《应用聚合物科学杂志》2020,137(22):49018
The main aim of this research is to decrease the amount of AlCl3 content that is very corrosive and hazardous in the catalytic system, required for the α-olefin oligomerization without substantial change of final oil features. This was successfully achieved by supporting AlCl3 on different carriers. More precisely, a series of supported bimetallic catalysts was synthesized by immobilization of AlCl3 and TiCl4 onto Al2O3, SiO2, and mixed supports, that is, Al2O3/FeCl3 and SiO2/FeCl3. It was found that silica and alumina-based catalysts had higher catalytic activities compared to support free AlCl3; however, this enhancement for silica-based supports was more significant. According to gel permeation chromatography (GPC) results, the use of single supports, that is, Al2O3 and SiO2, increased oligomer's molecular weight, while the application of mixed supports resulted in the decrease of molecular weight of the oligomers. Viscosity characteristics of the synthesized oligomers have also been studied at two different temperatures of 40 and 100°C (KV40 and KV100). The viscosity index (VI) values, derived from KV40 and KV100, of the prepared oligomers were in the range of 126–145. The molecular weight and termination mechanisms of the oligomers were studied by 1H-NMR spectroscopy. The obtained results disclosed that the employed reaction conditions led to the production of oligomer chains with various structures including vinylidene (Vd), and di and three-substituted vinylene (2Vn, 3Vn) structures. 相似文献
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Elchin Jafariyeh-Yazdi Akram Tavakoli Farhang Abbasi Mohammad Javad Parnian Amin Heidari 《应用聚合物科学杂志》2020,137(15):48553
Bi-supported Ziegler–Natta catalysts (TiCl4/MCM-41/MgCl2 (ethoxide type)) were synthesized to improve the morphology and the properties of polyethylene. The morphology control is a crucial issue in polymerization process, while tailoring the properties of polymers is needed for specific applications. The catalysts were synthesized in different ratios of two supports with impregnation method. The polymerization process was carried out in atmospheric slurry reactor. The catalysts were characterized with scanning electron microscopy - energy dispersive X-ray spectroscopy (SEM–EDX), inductively coupled plasma, Fourier transform infrared spectrometry (FTIR), and Brunauer-Emmett-Teller (BET) methods. The polymers were analyzed with scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry, FTIR, and tensile-strength analyses. Ubbelohde viscometer and frequency sweep measurements showed that the synthesized polymers are ultra-high-molecular-weight polyethylene. Mechanical properties of polymers showed higher Young's modulus in samples containing MCM-41, having higher thermal stability supported by TGA analysis. SEM images of bi-supported catalyst showed a controlled spherical morphology with uniform size distribution. SEM analysis support that the polymers replicate their morphology from catalyst, improving their morphology comparing to MgCl2-supported catalyst. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48553. 相似文献
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Basaleh A. S. Amin M. S. Mahmoud M. H. H. 《Journal of Inorganic and Organometallic Polymers and Materials》2021,31(9):3829-3841
Journal of Inorganic and Organometallic Polymers and Materials - The present work offers beneficial method for Hg (II) elimination from aqueous solution. ZnIn2S4/g-C3N4 nanocomposites were... 相似文献