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991.
《International Journal of Hydrogen Energy》2020,45(53):28272-28284
Anion exchange membrane water electrolysis (AEMWE) has acquired substantial consideration as a cost-effective hydrogen production technology. The anion ionomer content in the catalyst layers during hydrogen and oxygen evolution reaction (HER and OER) is of ultimate significance. Herein, an in-situ half-cell analysis with reference electrodes was carried out for simultaneous potential measurements and identification of the influence of the anion exchange ionomer (AEI) content on anode and cathode performance. The measured half-cell potentials proved the influence of AEI content on the catalytic activity of HER and OER, which was supported by the rotating disk electrode (RDE) measurements. Cathode overpotential of Ni/C was not negligible and more affected by the AEI content than anode with the optimized AEI content of 10 wt% while NiO anode OER overpotential was independent of the AEI content. For the same AEI content, PGM catalysts showed higher electroactivity than Ni-based catalysts for HER and OER and the cathode catalyst's intrinsic activity is of high importance in the AEM electrolysis operation. Post-mortem analysis by SEM mapping of both AEI and catalyst distributions on the electrode surface showed the effect of AEI loading on the catalyst morphology, which could be related to the electrode performance. 相似文献
992.
Supporting Information for this article is available on the WWW under http://www.wiley‐vch.de/home/asc Cyclopropanation of trisubstituted alkenes with diazoacetates can be achieved with remarkabe syn‐selectivity when the polymeric ruthenium(I) complex [Ru2(CO)4(μ‐OAc)2]n is used as catalyst. 相似文献
993.
Oxidation of primary and secondary aliphatic and secondary benzylic alcohols into their corresponding aldehydes and ketones was achieved in good yields with palladium catalysts using air as the reoxidant of palladium. The use of palladacycle 1 resulted in higher yields and a faster reaction than the use of Pd(OAc)2 as the palladium source. 相似文献
994.
通过对镍基稀土改性催化剂TPR的研究,结果表明稀土氧化物La2O3添加到Ni/a-Al2O3中改变了镍铝的相互作用,添加CeO2、MgO助剂能够有效地提高活性组份镍的分散度。 相似文献
995.
Xue Han Yafei Wang Yan zhang Yunbo Yu Hong He 《International Journal of Hydrogen Energy》2017,42(16):11177-11186
The Ce1?xLaxO2?δ solid solution (CL) supported Ir (nIr/CL, n = 2, 5 and 10 wt.%) catalysts are studied for H2 production from ethanol oxidative steam reforming (OSR). The Ir dispersion, surface area, oxygen vacancy density and carbon deposition resistance of nIr/CL catalysts are greatly enhanced compared with Ir/CeO2. Among the tested catalysts, 5%Ir/CL shows the best catalytic performance, exhibiting >99.9% ethanol conversion at 400 °C with H2 yield rate of 323 μmol·gcata?1·s?1 and no obvious carbon deposition after used. The 5%Ir/CL catalyst contains the highest amount of reducible interface Ce4+, leading to a strong interaction with surface Ir species at the metal-support interface during the OSR reaction. The strong interaction induces Ir to be well dispersed on the CL support, and is associated with more redox-active sites (interface Ce4+/Ce3+), to guarantee high activity. 相似文献
996.
Prangtip Kaewpengkrow Duangduen Atong Viboon Sricharoenchaikul 《International Journal of Hydrogen Energy》2017,42(31):19629-19640
Rapid catalytic thermal conversion of Physic nut (Jatropha curcas) residues for upgrading the released vapors was performed using analytical pyrolyzer-gas chromatography/mass spectrometry at 873 K. Conditioning of the evolved vapor product is required since the main vapor products formed without catalysts typically contained around 60% fatty acids, while the total hydrocarbon yields were only 12%. Catalysts tested were alumina (Al2O3) alone and modified by 5 wt% impregnation with various transition metal salts and then calcined to metal oxides. A significant decrease in the proportion of oxygenated compounds (including acids) from 73% without a catalyst to less than 10% with, and an increased conversion to hydrocarbons of more than 70% was obtained with the metal/Al2O3 catalysts at a Jatropha:catalyst (J:C) ratio of 1:10. The product selectivity was greatly increased as the J:C ratio was increased from 1:1 to 1:10. The total hydrocarbon selectivity of the metal/Al2O3 catalysts was increased in the order of Pd > Ni > Ce > Ru > La > none > Co > Mo, with the highest proportion of total hydrocarbons obtained being 75%. In addition, only a low yield (<2%) of polycyclic aromatic hydrocarbons was obtained from the conversion of Jatropha curcas residues. However, these catalysts adversely promoted N-containing compounds, suggesting that a further denitrogenation process is necessary. Nevertheless, the overall performance of these transition metal/Al2O3 catalysts is acceptable and they can be considered as good candidates for bio-oil upgrading. 相似文献
997.
Dipak Rana Hak Lim Kim Hanjin Kwag Jangweon Rhee Kyucheol Cho Taewoo Woo Byung H. Lee Soonja Choe 《应用聚合物科学杂志》2000,76(13):1950-1964
The rheological and morphological behaviors of commercially available three binary blends of ethylene 1‐octene copolymer (EOC) regarding the melt index (MI), density and comonomer contents, one component made by the Ziegler–Natta and the other by the metallocene catalysts, were investigated to elucidate miscibility and phase behavior. Miscibility of the EOCs blend in a melt state was related to the value of the MI, density, and comonomer content. If the comonomer contents are similar, then the melt viscosity is weight average value, otherwise it is positively or negatively deviated. The microtomed surface prepared by two different cooling processes—one is fast cooling and the other is slow cooling—indicated that all the blends were not homogenous regardless the density, MI, and comonomer content. The Ziegler–Natta catalyzed EOCs exhibited bigger spherulitic diameter and larger ring space than those of the metallocene EOCs prepared by a cooling process. The blends consisting of similar MI showed banded spherulites with different diameter, whereas the blend consisting of different MI and density takes place of explicit phase separation and phase inversion at 1 : 1 blend composition. The melt rheology appeared to influence the mechanical and film properties in the solid state. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1950–1964, 2000 相似文献
998.
Shiyuah Cheng Zushun Xu Jianjun Yuan Peijun Ji Jian Xu Meiling Ye Lianghe Shi 《应用聚合物科学杂志》2000,77(13):2882-2888
Well‐defined polystyrene (PS)‐b‐poly(ethylene oxide) (PEO)‐b‐PS triblock copolymers were synthesized by atom‐transfer radical polymerization (ATRP), using C—X‐end‐group PEO as macroinitiators. The triblock copolymers were characterized by infrared spectroscopy, nuclear magnetic resonance spectroscopy, and gel permeation chromatography. The experimental results showed that the polymerization was controlled/living. It was found that when the number‐average molecular weight of the macroinititors increased from 2000 to 10,000, the molecular weight distribution of the triblock copolymers decreased roughly from 1.49 to 1.07 and the rate of polymerization became much slower. The possible polymerization mechanism is discussed. According to the Cu content measured with atomic absorption spectrometry, the removal of catalysts, with CHCl3 as the solvent and kaolin as the in situ absorption agent, was effective. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2882–2888, 2000 相似文献
999.
The drop‐in of metallocene catalysts (MCs) in existing industrial polymerization plants is the current goal of most polymer producers. However, the narrow molecular weight distribution (MWD) of the polymers produced by MCs prevent them of moving into commodities market dominated by conventional Ziegler–Natta catalysts, where ease of processing is an essential property. Broader MWDs may be obtained through mixing of different MCs or blending of different resins, but resin‐compatibility problems and complex undesirable catalyst interactions pose technological problems that have yet to be solved. For these reasons, modern olefin polymerization plants have to work with both catalysts to respond to market demands, resulting in costly operations of grade/catalyst change. In this article, we describe how periodic control of short residence‐time reactors operating with an MC (Me2Si(2‐Me‐Benz[e]Ind)2ZrCl2/MAO) can lead to polymers with broad MWD and, consequently, to high processability. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 437–452, 2000 相似文献
1000.
Abd El‐Aziz A Said Kamal MS Khalil 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2000,75(3):196-204
Different ratios of vanadium pentoxide supported on aluminum phosphate (1–30 mol%) have been prepared by an impregnation method. The original and calcined samples were characterized by TG, DTG, DSC, X‐ray diffraction, IR spectra, N2 adsorption and electrical conductivity measurements. The catalytic decomposition of ethanol has been carried out at 210 °C in a flow system at 1 atm using air as a carrier gas. The results indicate that the catalysts calcined at 400 °C were active and selective towards ethene formation whereas the samples calcined at 600 °C showed a drastic reduction in both activity and selectivity. © 2000 Society of Chemical Industry 相似文献