全文获取类型
收费全文 | 455篇 |
免费 | 150篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 9篇 |
综合类 | 2篇 |
化学工业 | 49篇 |
金属工艺 | 5篇 |
能源动力 | 113篇 |
石油天然气 | 1篇 |
无线电 | 138篇 |
一般工业技术 | 292篇 |
冶金工业 | 1篇 |
出版年
2024年 | 1篇 |
2023年 | 101篇 |
2022年 | 26篇 |
2021年 | 44篇 |
2020年 | 78篇 |
2019年 | 79篇 |
2018年 | 66篇 |
2017年 | 57篇 |
2016年 | 27篇 |
2015年 | 16篇 |
2014年 | 19篇 |
2013年 | 15篇 |
2012年 | 11篇 |
2011年 | 12篇 |
2010年 | 11篇 |
2009年 | 5篇 |
2008年 | 8篇 |
2007年 | 9篇 |
2006年 | 3篇 |
2005年 | 6篇 |
2004年 | 3篇 |
2001年 | 2篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1994年 | 1篇 |
排序方式: 共有610条查询结果,搜索用时 0 毫秒
21.
《International Journal of Hydrogen Energy》2019,44(3):1610-1619
Spinel CoFe2O4 supported on three dimensional graphene (3DG) is prepared by hydrothermal reaction, which is denoted as CoFe2O4/3DG. The 3DG is prepared by the templated method, where coal tar pitch (CTP) and MgO are used as the carbon source and the template, respectively. The microstructure and composition of the resultant have been investigated by X-ray diffraction as well as X-ray photoelectron spectroscopy indicating the formation of spinel CoFe2O4 and composite of CoFe2O4/3DG. The multilayer structure of 3DG and CoFe2O4/3DG is also examined by the Raman spectra. Electrochemically, CoFe2O4/3DG shows high-performance half-wave potential is 0.80 V vs. RHE in O2-saturated 0.1 M KOH, which is compared to 20 wt% Pt/C. When evaluated for OER activity, CoFe2O4/3DG obtains a low overpotential 1.63 V vs. RHE (at j = 10 mA cm−2), which is 180 mV better than 20 wt% Pt/C. Moreover, it possesses excellent durability superior to 20 wt% Pt/C. 相似文献
22.
《International Journal of Hydrogen Energy》2019,44(26):13195-13204
It has been being an interesting challenge to develop novel electrocatalysts with advantageous nanostructures and thereby-improved catalytic performance for hydrogen evolution reaction (HER) over the past years. Herein, we report on the flower-like clusters of CoNiP nanofoils thickly grown on the randomly-interconnected reduced graphene oxide (rGO) nanosheets (CoNiP-NF/rGO) of 3-dimensional framework architecture, which has been successfully achieved via an optimized solvothermal process with Ni-doped ZIF-67 (Ni-ZIF-67) dodecahedral particles as the precursor and graphene oxide (GO) nanosheets as the substrate for the in-situ growth of flower-like CoNi-hydroxides nanofoils, as well as a following topotactic transformation in a controlled phosphorization. Benefiting from its distinctly advantageous nanostructures featured with extremely high specific surface area, enriched catalytic active sites and enhanced electronic transportation, the as-prepared CoNiP-NF/rGO exhibits an excellent electrocatalytic performance of HER with an onset overpotential of 33 mV, an overpotential of 82 mV at 10 mA cm−2, a Tafel slope of 37 mV dec−1 and a high chemical stability in acidic solutions. Such an advantageous nanostructure and its positive influences on the electrocatalytic performance are useful for the preparation of other nonprecious metal electrocatalysts. 相似文献
23.
Chia‐Che Chang Sin‐Ren Li Hung‐Lung Chou Yi‐Cheng Lee Shivaraj Patil Ying‐Sheng Lin Chun‐Chih Chang Yuan Jay Chang Di‐Yan Wang 《Small (Weinheim an der Bergstrasse, Germany)》2019,15(49)
The generation of ammonia, hydrogen production, and nitrogen purification are considered as energy intensive processes accompanied with large amounts of CO2 emission. An electrochemical method assisted by photoenergy is widely utilized for the chemical energy conversion. In this work, earth‐abundant iron pyrite (FeS2) nanocrystals grown on carbon fiber paper (FeS2/CFP) are found to be an electrochemical and photoactive catalyst for nitrogen reduction reaction under ambient temperature and pressure. The electrochemical results reveal that FeS2/CFP achieves a high Faradaic efficiency (FE) of ≈14.14% and NH3 yield rate of ≈0.096 µg min?1 at ?0.6 V versus RHE electrode in 0.25 m LiClO4. During the electrochemical catalytic reaction, the crystal structure of FeS2/CFP remains in the cubic pyrite phase, as analyzed by in situ X‐ray diffraction measurements. With near‐infrared laser irradiation (808 nm), the NH3 yield rate of the FeS2/CFP catalyst can be slightly improved to 0.1 µg min?1 with high FE of 14.57%. Furthermore, density functional theory calculations demonstrate that the N2 molecule has strong chemical adsorption energy on the iron atom of FeS2. Overall, iron pyrite‐based materials have proven to be a potential electrocatalyst with photoactive behavior for ammonia production in practical applications. 相似文献
24.
25.
过渡金属-氮共掺杂炭材料是一类高效的CO2电还原催化剂。以热解聚合物制备的氮掺杂炭材料为载体,浸渍镍源,经红外灯光照2 h,利用光化学法制备了高分散的镍-氮-碳催化剂(Ni/NC)。采用扫描电镜(SEM)、物理吸附、粉末X射线衍射(XRD)、X射线光电子能谱(XPS)等手段对催化剂的形貌、结构、物相和组成进行了分析,并评价了催化剂的CO2电还原反应性能。电化学性能测试结果表明,在0.5 mol/L的KHCO3电解液中,镍的负载量为2 %(质量分数)时催化性能最好,CO分电流密度得到有效提升,塔菲尔斜率为492 mV/dec,起始过电位为286 mV;在-0.6 V(vs.RHE)下,CO的法拉第效率为78%,在-1.0 ~-0.5 V(vs.RHE)内,n(CO)/n(H2)=0.5~3.6。 相似文献
26.
Platinum surface atom (or site) concentrations for a series of commercially available 10, 20, and 40 wt% Pt/C electrocatalysts have been determined using X-ray diffraction (XRD), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), selective chemisorption, and cyclic voltammetry (CV) methods. Each method of analysis was repeated for a sufficient number of times to determine reproducibility and standard deviation limits. Comparison of the results shows that XRD and STEM methods give Pt surface site concentrations much higher than for chemisorption analysis due to assumptions regarding Pt particle shapes and particle size distributions. The results from CV analysis agree reasonably well with those from chemisorption if the sample amounts and methods of sample deposition preceding CV analysis can be well-controlled and there is no loss of surface exposure by the Nafion over-layer. Because both chemisorption and CV analyses more directly measure actual site concentrations with fewer assumptions, these methods should be considered superior to XRD and STEM analyses. Further, since chemisorption uses substantially larger sample sizes (up to 0.25 g) compared to CV (<0.01 g), reliability of chemisorption data is much more reliable and should be considered as the metric for surface Pt site determination. 相似文献
27.
Co nanoparticles (Co NPs) and nanoscale tungsten carbide (WC) are successfully synthesized simultaneously with mesoporous structured carbon black (C) using an innovative simple method, which is known as solution plasma processing (SPP), and NPs are also loaded onto carbon black at the same time by SPP. The introduction of Co NPs led to not only superior oxygen reduction reaction (ORR) activity in terms of onset potential and peak potential, but also to a more efficient electron transfer process compared to that of pure WC. Co-WC/C also showed durability for long-term operation better than that of commercial Pt/C. These results clearly demonstrate that the presence of Co NPs significantly enhanced the ORR and charge transfer number of neighboring WC NPs in ORR activities. In addition, it was proved that SPP is a simple method (from synthesis of NPs and carbon black to loading on carbon black) for the large-scale synthesis of NP-carbon composite. Therefore, SPP holds great potential as a candidate for next-generation synthetic methods for the production of NP-carbon composites. 相似文献
28.
29.
Huanran Zheng Shibin Wang Shoujie Liu Jiao Wu Jianping Guan Qian Li Yuchao Wang Yu Tao Shouyao Hu Yu Bai Jinxian Wang Xiang Xiong Yu Xiong Yongpeng Lei 《Advanced functional materials》2023,33(40):2300815
The rational design and construction of efficient and inexpensive bifunctional oxygen electrocatalysts are highly desirable for the development of rechargeable Zn–air batteries (ZABs). Although single-atom Fe sites anchored on N-doped carbon catalysts (Fe1/NC) ensure high oxygen reduction reaction activity, their unitary atomically dispersed active center faces difficult condition in catalyzing oxygen evolution reaction simultaneously. Herein, a composite catalyst containing heterointerface between Fe1/NC and selenides ((Fe,Co)Se2) is constructed. The obtained (Fe,Co)Se2@Fe1/NC exhibits extremely narrow potential gap of 0.616 V and remarkable stability in alkaline media, outperforming the benchmark catalysts (Pt/C+RuO2: 0.720 V). Experimental results and density functional theory calculations reveal that heterointerface between Fe1/NC and (Fe,Co)Se2 accelerates the electron transfer and provides more moderate adsorption sites, which endow (Fe,Co)Se2@Fe1/NC with extremely high bifunctional oxygen catalytic activity. This study not only provides a superior bifunctional catalyst for ZABs, but also enriches the application of single-atom catalysts in multifunctional energy storage and conversion devices. 相似文献
30.
Kun Guo Zhimin He Song Lu Pengjun Zhang Ning Li Lipiao Bao Zhixin Yu Li Song Xing Lu 《Advanced functional materials》2023,33(29):2302100
Carbon nano-onions (CNOs) as a novel form of carbon materials hold peculiar structural features but their electrocatalytic applications are largely discouraged by the demanding synthesis conditions (e.g., ≥1500 °C and vacuum). Using C60 fullerene molecules as the sacrificial seeds and melamine as the main feedstock, herein, a novel strategy for the facile construction of CNOs nanoparticles is presented with ultrafine sizes (≈5 nm) at relatively low temperatures (≤900 °C) and atmospheric pressure. During the calcination, in-depth characterizations reveal that C60 can retain the melamine-derived graphitic carbon nitride from complete sublimation at high temperatures (≥700 °C). Owing to the N removal and subsequent pentagon generation, severely deformed graphitic fragments together with the disintegrated C60 molecules merge into larger sized nanosheets with high curvature, eventually leading to the formation of N-doped defect-rich CNOs. Owing to the integration of multiple favorable structural features of pentagons, edges, and N dopants, the CNOs obtained at 900 °C present superior oxygen reduction half-wave potential (0.853 VRHE) and zinc–air cathode performance to the commercial Pt/C (0.838 VRHE). Density functional theory calculation further uncovers that the carbon atoms adjacent to the N-doped edged pentagons are turned into the ORR-active sites with O2 protonation as the rate-determining step. 相似文献