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61.
Thanit Tangcharoen Jiraroj T-Thienprasert Chanapa Kongmark 《International Journal of Applied Ceramic Technology》2021,18(4):1125-1143
Using the sol–gel auto combustion method with diethanolamine (DEA) as fuel, a sequence of iron-substituted zinc aluminates, ZnFexAl2-xO4 powders, including variable Fe3+ ion concentrations (0 ≤ x ≤ 2) were effectively prepared. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), the Brunauer–Emmett–Teller (BET) method, UV–visible diffuse reflectance spectroscopy (UV-DRS), and vibrating sample magnetometer (VSM) were employed to examine the structures, chemical bonds, morphologies, composition, surface area, and optical properties as well as the magnetic behavior of the obtained samples. A single-phase spinel structure was obtained for the calcined aluminate powders with different interplanar spacing and crystallite sizes, as revealed by the classification results. The bandgap energy (Eg) of adapted aluminates was in the range of 2.04-3.14 eV, identified as being much lower compared to the pure sample (5.60 eV). Thus, Fe3+-substituted ZnAl2O4 samples could be successfully photoexcited using both ultraviolet and visible light, as suggested by the results. Examination of how the four main pollutant types decay when irradiated by sunlight was carried out to assess the samples and establish photocatalytic activity. These contaminants included rhodamine B (RhB), methylene blue (MB), methyl orange (MO), and methyl red (MR). The performance of photocatalytic degradation reached 98% after 150 min for all optimal samples of organic dyes. Besides, each of the altered photocatalysts could be recycled and displayed high stability. The S-shaped curve of ferrimagnetism can result in those samples as found by the magnetic measurements, though pure ZnAl2O4 displays diamagnetic characteristics. The adapted samples show intense improvement in the remanent magnetization (Mr) when compared to pure ZnAl2O4, signifying that magnetic photocatalyst recovery by applying an external magnetic field is easy. Thus, these results offer a convincing sign that ZnAl2O4 powders replaced by Fe3+ could provide the ability to aid in the ecologically friendly collection of solar energy. 相似文献
62.
综述了近年来国内外铂系低碳烷烃脱氢催化剂的技术现状与研究进展。首先从热力学角度论述了低碳烷烃脱氢反应与相关副反应的反应机理,随后分别从活性位点性能与催化脱氢的关系,氧化铝、分子筛等载体的作用,以及锡、碱金属、碱土金属、过渡金属等助剂改性对催化剂的影响等3个方面分析了铂系低碳烷烃脱氢催化剂的优势与存在的问题,进而探究了铂系脱氢催化剂的失活原因。最后对铂系脱氢催化剂的研究前景做了展望,提出该系列催化剂的主要发展方向包括降低贵金属铂的负载量、提高催化剂的稳定性、减少积炭副反应等。 相似文献
63.
采用水热法制备GRQD-NiCo2O4复合物,利用XRD、SEM及TEM分析其微结构,并探讨其作为DMFC阳极催化剂使用时的电化学性能。微结构分析表明所得GRQD-NiCo2O4复合物皆为具NiCo2O4单一相的尖晶石结构,且GRQD质量浓度高于0.25 g/mL后表面形貌将转变GRQD与NiCo2O4相互结合的状态。电化学分析表明添加GRQD可有效增强NiCo2O4的导电性并提升其电化学稳定性,其中GRQD质量浓度为0.25 g/mL时所得样品经500次循环测试后电流密度约为77.5 A/g,与循环5次后相比其电流密度剩余量最大(约为69.7%),该样品作为DMFC阳极催化剂使用时性价比最佳。 相似文献
64.
简要介绍了日本围绕燃气轮机用关键超高温金属结构材料所展开的研究开发工作,包括Ni基超合金、耐热金属间化合物、Nb基超合金及其复合材料。Ni基超合金仍是当前燃气轮机用超高温结构的主要材料,但其使用温度的上升潜力已经不多,用新的超高温材料替代Ni基超合金是燃气轮机用材的发展趋势,金属材料中耐热金属间化合物和Nb基复合材料是今后关注的焦点。 相似文献
65.
66.
The electrocatalysis of the oxygen reduction reaction (ORR) on carbon supported Pt:V 1:1 catalyst in polymer electrolyte fuel cells (PEFC) was investigated. At an oxygen pressure of 1 atm results indicate a lower electrocatalytic activity for the ORR in the presence of vanadium. However, at an O2 pressure ≥2 atm an enhanced electrocatalytic property of PtV/C compared with Pt/C is revealed. This result indicates the occurrence of a different electrocatalytic mechanism for the ORR on Pt/C and PtV/C. An increase of mass transport overpotentials is observed for the PtV/C catalyst, and this was related to the presence of vanadium oxide. Indeed, XRD analysis revealed that only about 30% of V present in the catalyst is alloyed with Pt, forming a face centred cubic (fcc) Pt3V solid solution. A thermal treatment at 850 °C under reducing atmosphere leads to the formation of an ordered fcc Pt2V phase. After this, the ORR activity of PtV/C at O2 pressure 1 atm is higher than that of Pt/C. 相似文献
67.
Catalytic dehydrogenative coupling of methane on active carbon. Effect of metal supported on active carbon 总被引:3,自引:0,他引:3
Ethane, ethene, ethyne and hydrogen are obtained in good yields via dehydrogenative coupling of methane in the presence of active carbon as a catalyst. The product yield is increased by supporting metal on active carbon. 相似文献
68.
An anomalous rate enhancement with increasing conversion has been observed during the liquid phase hydrogenation of nitrobenzene and crotonaldehyde over Ge/Pd/C catalysts at ambient temperature and atmospheric pressure. Inductive coupled plasma atomic emission spectroscopy and electrochemical measurement of the oxidation state of catalysts during reaction revealed that the bimetallic particles were partially oxidized by the reactants, which resulted in Ge-dissolution and increased exposure of Pd on the surface. It is proposed that the surface and bulk composition of Ge/Pd catalysts are a function of their oxidation state. This behaviour is due to the unusually high mobility of Ge in the Pd lattice and to the good solubility of GeO2 in polar solvents. The influence of hydrogen transport on the corrosion process and the stability of other X/Pd type bimetallic catalysts during liquid phase hydrogenation are also discussed. 相似文献
69.
P. Da Costa C. Potvin J.-M. Manoli M. Breysse G. Djega-Mariadassou 《Catalysis Letters》2003,86(1-3):133-138
Hydrodesulfurization (HDS) of 4,6-dimethyldibenzothiophene on alumina-supported Mo2C has been studied. These catalysts are stable and active under deep HDS conditions (0-250 wt ppm S). However, although they are well known to have hydrogenation properties, they lead preferentially to a non-hydrogenated product of the HDS reaction: dimethylbiphenyl. For the same reaction, supported platinum and sulfided molybdenum oxide lead to the hydrogenated products dimethyldicyclohexyl and methylcyclohexyltoluene, respectively. The ranking of HDS activity is as follows: MoS2/Al2O3 < Mo2C/Al2O3 < Pt/SiO2. 相似文献
70.
A chitosan (CTN)/silica‐supported nanosized palladium catalyst was obtained from a silica‐supported chitosan palladium complex through a complex transition method. An adsorption model was employed to simplify the structure of the di‐supporter. It was indicated that when the polymer coil adsorbed on the silica surface with even a monolayer the catalytic activity would reach an optimum value, and different situations of the, nanosized palladium particles would cause a different catalysis. The molar ratio of the chitosan structure unit to the palladium would affect the metal's size, which therefore influenced its catalytic activity. The experimental results corresponded with the inferences. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 989–994, 2002 相似文献