全文获取类型
收费全文 | 66921篇 |
免费 | 6037篇 |
国内免费 | 5588篇 |
专业分类
电工技术 | 1471篇 |
综合类 | 3429篇 |
化学工业 | 9708篇 |
金属工艺 | 28179篇 |
机械仪表 | 3480篇 |
建筑科学 | 1009篇 |
矿业工程 | 1483篇 |
能源动力 | 1422篇 |
轻工业 | 1695篇 |
水利工程 | 115篇 |
石油天然气 | 1226篇 |
武器工业 | 906篇 |
无线电 | 2555篇 |
一般工业技术 | 11542篇 |
冶金工业 | 7310篇 |
原子能技术 | 870篇 |
自动化技术 | 2146篇 |
出版年
2024年 | 140篇 |
2023年 | 1114篇 |
2022年 | 1844篇 |
2021年 | 2155篇 |
2020年 | 2275篇 |
2019年 | 1841篇 |
2018年 | 1805篇 |
2017年 | 2354篇 |
2016年 | 2215篇 |
2015年 | 2302篇 |
2014年 | 3316篇 |
2013年 | 3546篇 |
2012年 | 4173篇 |
2011年 | 5145篇 |
2010年 | 3863篇 |
2009年 | 4148篇 |
2008年 | 3441篇 |
2007年 | 4639篇 |
2006年 | 4611篇 |
2005年 | 3639篇 |
2004年 | 3171篇 |
2003年 | 2799篇 |
2002年 | 2331篇 |
2001年 | 2073篇 |
2000年 | 1668篇 |
1999年 | 1423篇 |
1998年 | 1052篇 |
1997年 | 956篇 |
1996年 | 919篇 |
1995年 | 733篇 |
1994年 | 619篇 |
1993年 | 449篇 |
1992年 | 415篇 |
1991年 | 333篇 |
1990年 | 280篇 |
1989年 | 240篇 |
1988年 | 151篇 |
1987年 | 72篇 |
1986年 | 44篇 |
1985年 | 30篇 |
1984年 | 43篇 |
1983年 | 21篇 |
1982年 | 32篇 |
1981年 | 38篇 |
1980年 | 21篇 |
1979年 | 11篇 |
1978年 | 12篇 |
1977年 | 7篇 |
1975年 | 8篇 |
1951年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
1.
《International Journal of Hydrogen Energy》2022,47(67):29172-29183
To improve the safety of wet dust removal systems for processing magnesium-based alloys, a new method is proposed for preventing hydrogen generation. In this paper, hydrogen generation by Mg–Zn alloy dust was inhibited with six common metal corrosion inhibitors. The results showed that sodium dodecylbenzene sulfonate was the best hydrogen inhibitor, while CeCl3 enhanced hydrogen precipitation. The film-forming stability of sodium dodecylbenzene sulfonate was tested with different contents, temperatures, Cl? concentrations and perturbation rates. The results showed that this inhibitor formed stable protective films on the surfaces of Mg–Zn alloy particles, and adsorption followed the Langmuir adsorption model. 相似文献
2.
Liu Yang Pengfei Yu Wenyuan Li Fengliang Cao Xin Jin Sheng Xue Xianglong Zhang Tingwei Zhang Mingbo Wu Wenting Wu 《American Institute of Chemical Engineers》2022,68(9):e17760
Hydrogen peroxide (H2O2) has been listed as one of the 100 most important chemicals in the world. However, huge amount of residual H2O2 is hard to timely decomposed into O2 and H2O under acidic condition, easily resulting in explosion hazard. Here, we reported a core–shell structure catalyst, that is graphene with Co N structure encapsulated Co nanoparticles. Co N graphene shell serves as the active site for the H2O2 decomposition, and Co core further enhance this decomposition. Benefiting from it, the H2O2 decomposition were close to 100% after 6 cycles without pH adjustment, which increased 6 orders of magnitude compared with no catalyst. At the same time, the O2 generation reached 99.67% in 2 h with little metal leaching, and ·OH has been greatly inhibited to only 0.08%. This work can cleanly remove H2O2 with little deep oxidation and protect the process of H2O2 utilization to achieve a safer world. 相似文献
3.
Guishang Pei Junyi Xiang Qingyun Huang Xuewei Lv 《Journal of the American Ceramic Society》2022,105(10):6359-6369
A double pyrovanadate CaMgV2O7 sample was synthesized via a facile solid-state route under an air atmosphere. The nonequilibrium formation pathways of the CaMgV2O7 were investigated via powder X-ray diffraction. A multistep reactions path (metavanadates–pyrovanadates–double pyrovanadate CaMgV2O7) was proposed to describe the formation of the CaMgV2O7 considering the thermodynamic and kinetic factors. The cell unit parameters of the CaMgV2O7 sample indicated the crystallization according to a monoclinic system with space group P12/c1(14), and the lattice parameters of a = 6.756 Å, b = 14.495 Å, c = 11.253 Å, β = 99.12, and V = 108.806 Å3. X-ray photoelectron spectroscopy also confirmed the +5 oxidation state vanadium in CaMgV2O7. The endothermic effects at 1033 and 1143 K were related to the incongruent melting and liquidus temperatures of CaMgV2O7, respectively. The comprehensive thermodynamic properties of CaMgV2O7 were established in both low- and high-temperature regions, utilizing a physical property measurement system and multi-high-temperature calorimetry (96 lines). The heat capacity (200 J mol K−1) and entropy (198 J mol K−1) at 298.15 K were computed based on the low-temperature heat capacity values, and the enthalpy of formation at 298.15 K was also estimated. The fitted high-temperature capacity can be used to obtain the changes in the enthalpy, entropy, and Gibbs free energy. This study is part of building a reliable thermodynamic database of the CaO–MgO–V2O5 system. 相似文献
4.
《International Journal of Hydrogen Energy》2022,47(42):18496-18503
Methanol crossover is one of the main challenges for direct methanol fuel cells (DMFCs). Depositing a metal barrier on Nafion can reduce the crossover but usually faces the metal cracking issues. This study presents a new composite membrane in which an anodic aluminum oxide (AAO) substrate is impregnated with a Nafion solution and then coated with a layer of Au. The AAO/Nafion/Au composite membrane shows an ideal metal crack-free surface. Higher and more stable voltage has been achieved for the cell with the membrane, indicating an effectively suppressed methanol-crossover. Results reveal that there is a tradeoff between suppressing the methanol crossover and increasing the ion transmission. By optimizing the membrane, it can not only suppress the methanol crossover but also enhance the output performance of DMFCs. The current density and power density of the cells can be enhanced by 59% and 52.85%, respectively, compared to the cell with a commercial Nafion 117. Overall, this work provides a new approach to designing crack-free membranes for DMFCs. 相似文献
5.
《International Journal of Hydrogen Energy》2022,47(52):22165-22179
Aluminum alloy bipolar plates have unique application potential in proton exchange membrane fuel cell (PEMFC) due to the characteristics of lightweight and low cost. However, extreme susceptibility to corrosion in PEMFC operation condition limits the application. To promote the corrosion resistance of aluminum alloy bipolar plates, a Ni–P/TiNO coating was prepared by electroless plating and closed field unbalanced magnetron sputter ion plating (CFUMSIP) technology on the 6061 Al substrate. The research results show that Ni–P interlayer improves the deposition effect of TiNO outer layer and increase the content of TiN and TiOxNy phases. Compared to Ni–P and TiNO single-layer coatings, the Ni–P/TiNO coating samples exhibited the lowest current density value of (1.10 ± 0.02) × 10?6 A·cm?2 in simulated PEMFC cathode environment. Additionally, potential cyclic polarization measurements were carried out aiming to evaluate the durability of the aluminum alloy bipolar plate during the PEMFC start-up/shut-up process. The results illustrate that the Ni–P/TiNO coating samples exhibit excellent stability and corrosion resistance. 相似文献
6.
《International Journal of Hydrogen Energy》2022,47(5):3063-3074
Non-noble metal catalyst with high catalytic activity and stability towards oxygen reduction reaction (ORR) is critical for durable bioelectricity generation in air-cathode microbial fuel cells (MFCs). Herein, nitrogen-doped (iron-cobalt alloy)/cobalt/cobalt phosphide/partly-graphitized carbon ((FeCo)/Co/Co2P/NPGC) catalysts are prepared by using cornstalks via a facile method. Carbonization temperature exerts a great effect on catalyst structure and ORR activity. FeCo alloys are in-situ formed in the catalysts above 900 °C, which are considered as the highly-active component in catalyzing ORR. AC-MFC with FeCo/Co/Co2P/NPGC (950 °C) cathode shows the highest power density of 997.74 ± 5 mW m?2, which only declines 8.65% after 90 d operation. The highest Coulombic efficiency (23.3%) and the lowest charge transfer resistance (22.89 Ω) are obtained by FeCo/Co/Co2P/NPGC (950 °C) cathode, indicating that it has a high bio-electrons recycling rate. Highly porous structure (539.50 m2 g?1) can provide the interconnected channels to facilitate the transport of O2. FeCo alloys promote charge transfer and catalytic decomposition of H2O2 to ?OH and ?O2?, which inhibits cathodic biofilm growth to improve ORR durability. Synergies between metallic components (FeCo/Co/Co2P) and N-doped carbon energetically improve the ORR catalytic activity of (FeCo)/Co/Co2P/NPGC catalysts, which have the potential to be widely used as catalysts in MFCs. 相似文献
7.
《Advanced Powder Technology》2022,33(3):103450
In the present investigation, systematic grinding experiments were conducted in a laboratory ball mill to determine the breakage properties of low-grade PGE bearing chromite ore. The population balance modeling technique was used to study the breakage parameters such as primary breakage distribution (Bi, j) and the specific rates of breakage (Si). The breakage and selection function values were determined for six feed sizes. The results stated that the breakage follows the first-order grinding kinetics for all the feed sizes. It was observed that the coarser feed sizes exhibit higher selection function values than the finer feed size. Further, an artificial neural network was used to predict breakage characteristics of low-grade PGE bearing chromite ore. The predicted results obtained from the neural network modeling were close to the experimental results with a correlation of determination R2 = 0.99 for both product size and selection function. 相似文献
8.
《International Journal of Hydrogen Energy》2022,47(59):24796-24806
Developing inexpensive and efficient electrocatalysts for hydrogen evolution reaction (HER) in both acidic and alkaline mediums is of great significance to the hydrogen energy industry. Hereby, we prepared a mixture of precursors with homogeneous composition by using the chelating ability of soybean protein isolate (C and N source) and phytic acid (dopant and phosphating agent) with cobalt ions, and achieved one-step synthesis and construction of Co2P/N–P co-doped porous carbon composite by carbonization at 800 °C. The as-synthesized Co2P/NPPC-800 electrocatalyst exhibits low HER overpotentials of 121 and 125 mV at 10 mA cm?2 in 0.5 M H2SO4 and 1.0 M KOH, which are close to those of the commercial Pt/C catalyst. Additionally, the NPPC substrate surrounding the Co2P could diminish the corrosion during the HER, and Co2P/NPPC-800 displays good stability and durability. Furthermore, this work offers a convenient synthesis strategy for phosphide/doped porous carbon composites in other electrochemical energy technologies. 相似文献
9.
《International Journal of Hydrogen Energy》2022,47(47):20617-20631
Morphology of carbon nanofibers significantly effects Pt nanoparticles dispersion and specific interaction with the support, which is an important aspect in the fuel cell performance of the electrocatalysts. This study emphasizes, the defects creation and structural evolution comprised due to N–F co-doping on graphitic carbon nanofibers (GNFs) of different morphologies, viz. GNF-linearly aligned platelets (L), antlers (A), herringbone (H), and their specific interaction with Pt nanoparticle in enhancing the oxygen reduction reaction (ORR). GNFs–NF–Pt catalysts exhibit better ORR electrocatalytic activity, superior durability that is solely ascribed to the morphological evolution and the doped N–F heteroatoms, prompting the charge density variations in the resultant carbon fiber matrices. Amongst, H–NF–Pt catalyst performed outstanding ORR activity with exceptional electrochemical stability, which shows only 20 mV loss in the half-wave potential whilst 100 mV loss for Pt/C catalyst on 20,000 potential cycling. The PEMFC comprising H–NF–Pt as cathode catalyst with minimum loading of 0.10 mg cm?2, delivers power density of 0.942 W cm?2 at current density of 2.50 A cm?2 without backpressures in H2–O2 feeds. The H–NF–Pt catalyst owing to its hierarchical architectures, performs well in PEMFC at the minimized catalyst loading with outstanding stability that can significantly decrease total price for the fuel cell. 相似文献
10.
《International Journal of Hydrogen Energy》2022,47(73):31330-31341
A class of ruthenium-nickel alloy catalysts featured with nanoporous nanowires (NPNWs) were synthesized by a strategy combining rapid solidification with two-step dealloying. RuNi NPNWs exhibit excellent electrocatalytic activity and stability for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in which the RuNi-2500 NPNWs catalyst shows an OER overpotential of 327 mV to deliver a current density of 10 mA cm?2 and the RuNi-0 NPNWs catalyst requires the overpotential of 69 mV at 10 mA cm?2 showing the best HER activity in alkaline media. Moreover, the RuNi-1500 NPNWs catalyst was used as the bifunctional electrocatalyst in a two-electrode alkaline electrolyzer for water splitting, which exhibits a low cell voltage of 1.553 V and a long-term stability of 24 h at 10 mA cm?2, demonstrating that the RuNi NPNWs catalysts can be considered as promising bifunctional alkaline electrocatalysts. 相似文献