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131.
混酸插层制备膨胀石墨研究 总被引:1,自引:1,他引:0
对采用H2SO4-HNO3-KMnO4-H2O2混酸氧化插层体系制备膨胀石墨进行了研究,采用扫描电镜(SEM)、X射线衍射(XRD)、红外光谱(IR)和热重一差热法(TG-DTA)分析产物,并提出了氧化插层过程和机理。分析表明:插入剂的插入破坏了原有鳞片石墨层的紧密结构,使碳层间距增大,高温膨胀后,膨胀石墨呈蠕虫状或手风琴状蓬松结构,一个石墨蠕虫由许多微胞连接在一起组成,微胞之间呈现较大的狭缝裂开。氧化插层破坏了鳞片石墨原有的晶体结构,但是未破坏石墨的C—C键,20=29.5。处的特征峰是由石墨插层物结晶区引起的。可膨胀石墨片层。间存在SO4^2-、NO2阴离子插层物。可膨胀石墨在500℃之前的热失重和267℃附近较小的放热峰,均是由石墨插层物的气化、分解所致。 相似文献
132.
《Journal of the European Ceramic Society》2023,43(10):4443-4450
Na3Zr2Si2PO12 (NZSP) solid-state electrolyte is considered one of the most promising solid-state electrolyte because of their excellent electrochemical and thermal stability. Even though, the low conductivity of NZSP solid-state electrolytes hinders practical application. Therefore, an anions/cations co-assisting strategy is proposed by introducing the Zn2+ and F−. The influence of adding different amounts of Zn2+ and F− on the Na+ conductivity of NZSP was investigated computationally and experimentally. The Zn2+/F− co-assisting (Na3.3Zr1.85Zn0.15Si2PO12) solid-state electrolyte exhibits the ionic conductivity of 0.722 mS cm−1 at 30 °C, and the activation energy of ∼0.237 eV. Its applicability in a solid-state battery is tested, and the assembled Na/Na3V2(PO4)3 (NVP) battery exhibits an outstanding electrochemical performance of 98.4% capacity retention after being cycled at 0.5 C. Moreover, DFT calculations also have been used to demonstrate the effect of doping on the crystal structure and space migration energy barrier. This research provides new ideas for improving the electrochemical properties of inorganic solid electrolytes. 相似文献
133.
Chuan Lai Xueming Li Daixiong Zhang Zhen Xiang Wenjing Yang Xiaogang Guo 《Materials Chemistry and Physics》2014
The corrosion behavior of fresh porous silicon (f-PS) in sodium hydroxide (NaOH) solution in the presence and absence of ethanol was studied by weight loss measurements and scanning electron microscope (SEM) technique. The phenomena and progress of f-PS corrosion in 1.0 M NaOH at 318 K was obtained and described. Weight loss measurements show that the corrosion rate increases with increasing temperature and concentration of NaOH solution. Meanwhile, the corrosion rate first increases with increasing volume ratio of ethanol in 1.0 M NaOH, and then decreases. Additionally, the thermodynamic and kinetic parameters (Ea, A, ΔHa and ΔSa) for f-PS corrosion were obtained and discussed. And the effect factors (T, c and v) of f-PS corrosion in NaOH solution were studied in this paper. 相似文献
134.
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136.
采用失重法、自腐蚀电位法研究了钼酸钠对AZ61镁合金在磷酸介质中的缓蚀作用及温度的影响,并对相关腐蚀动力学数据进行了计算.结果表明:钼酸钠对镁合金在磷酸介质中的溶解有一定的抑制作用,在试验缓蚀剂浓度范围(0~0.10mol/L)内,缓蚀效率与缓蚀剂浓度之间很好地符合线性关系;缓蚀机理属于阴极型被膜缓蚀作用;镁合金在不含和含0.10mol/L钼酸钠的0.50mol/L磷酸介质中反应的表观活化能分别为1092 J/mol和2499 J/mol;升高温度不能提高钼酸钠的缓蚀效率,但却有助于其较快发挥缓蚀作用. 相似文献
137.
电解锰渣是电解金属锰生产过程中产生的固体滤渣,含有锰化合物、铵盐等物质。随着电解锰行业的快速发展,电解锰渣引发了严重的环境问题。实验采用XRD、TGA-DTA和SEM等手段对电解锰渣中化学成分、物相组成和矿物形貌进行分析。结果表明:电解锰渣含有大量Si、Ca、S、Al、Fe组成的化合物,主要物相包括SiO2、FeS2、CaSO4及CaSO4·nH2O。矿物颗粒之间交错堆积,发现柱状晶体颗粒。锰渣中可溶性锰离子主要以(NH4)2Mn2(SO4)3化合物存在。 相似文献
138.
《Ceramics International》2016,42(10):12005-12009
The effects of small amounts of lithium fluoride sintering aid on the microstructure and dielectric properties of CaCu3Ti4O12 (CCTO) ceramics were investigated. CCTO polycrystalline ceramics with 0.5 and 1.0 mol% LiF, and without additive were prepared by solid state synthesis. Good densification (>90% of the theoretical density) was obtained for all prepared materials. Specimens without the sintering aid and sintered at 1090 °C exhibit secondary phases as an outcome of the decomposition reaction. The mean grain size is controlled by the amount of LiF in specimens containing the additive. Impedance spectroscopy measurements on CaCu3Ti4O12 ceramics evidence the electrically heterogeneous nature of this material consisting of semiconductor grains along with insulating grain boundaries. The activation energy for grain boundary conduction is lower for specimens prepared with the additive, and the electric permittivity reached 53,000 for 0.5 mol% LiF containing CCTO. 相似文献
139.
《Ceramics International》2016,42(10):11851-11857
Low-cost dynamic materials for Faradaic redox reactions are needed for high-energy storage supercapacitors. A simple and cost-effective hydrothermal process was employed to synthesize amaryllis-like NiCo2S4 nanoflowers. The sample was characterized by X-ray powder diffraction, Brunauer–Emmett–Teller method, scanning electron microscopy, and transmission electron microscopy. NiCo2S4 nanoflowers were coated onto carbon fiber fabric and used as a binder-free electrode to fabricate a solid-state supercapacitor compact device. The solid-state supercapacitor exhibited excellent electrochemical performance, including high specific capacitance of 360 F g−1 at scan rate of 5 mV s−1 and high energy density of 25 W h kg−1 at power density of 168 W kg−1. In addition, the supercapacitor possessed high flexibility and good stability by retaining 90% capacitance after 5000 cycles. The high conductivity and Faradic-redox activity of NiCo2S4 nanoflowers resulted in high specific energy and power. Thus, NiCo2S4 nanoflowers are promising pseudocapacitive materials for low-cost and lightweight solid-state supercapacitors. 相似文献
140.
《International Journal of Hydrogen Energy》2023,48(71):27441-27449
The development of cheap, high-efficiency, and stable oxygen evolution reaction (OER) electrocatalysts is a current research hotspot. In this work, reduced graphene oxide (rGO) composite Ni3S2 microspheres grown directly on nickel foam (Ni3S2-rGO/NF) were prepared by tube furnace calcination and hydrothermal method. The Ni3S2-rGO/NF had excellent OER catalytic activity and stability with an overpotential of 303 mV at the current density of 100 mA cm−2, which was 100 mV lower than that of Ni3S2/NF, and its Tafel slope was as low as 23 mV·dec−1. The main reason for enhancing OER activity of the Ni3S2-rGO/NF is due to synergistic effect of Ni3S2 microspheres and rGO, which inhibited the production of NiS and refined the micron size of Ni3S2. This work offers a new method for developing stable and efficient OER catalysts. 相似文献