全文获取类型
收费全文 | 1674篇 |
免费 | 54篇 |
国内免费 | 11篇 |
专业分类
电工技术 | 283篇 |
综合类 | 33篇 |
化学工业 | 306篇 |
金属工艺 | 31篇 |
机械仪表 | 22篇 |
建筑科学 | 5篇 |
矿业工程 | 2篇 |
能源动力 | 962篇 |
石油天然气 | 5篇 |
无线电 | 9篇 |
一般工业技术 | 39篇 |
冶金工业 | 5篇 |
原子能技术 | 1篇 |
自动化技术 | 36篇 |
出版年
2024年 | 2篇 |
2023年 | 42篇 |
2022年 | 81篇 |
2021年 | 63篇 |
2020年 | 64篇 |
2019年 | 67篇 |
2018年 | 48篇 |
2017年 | 56篇 |
2016年 | 27篇 |
2015年 | 30篇 |
2014年 | 77篇 |
2013年 | 62篇 |
2012年 | 98篇 |
2011年 | 179篇 |
2010年 | 160篇 |
2009年 | 106篇 |
2008年 | 131篇 |
2007年 | 147篇 |
2006年 | 93篇 |
2005年 | 52篇 |
2004年 | 66篇 |
2003年 | 32篇 |
2002年 | 20篇 |
2001年 | 16篇 |
2000年 | 7篇 |
1999年 | 7篇 |
1998年 | 4篇 |
1996年 | 2篇 |
排序方式: 共有1739条查询结果,搜索用时 15 毫秒
41.
《International Journal of Hydrogen Energy》2021,46(56):28748-28759
Electric recreational vehicles represent a new challenge in terms of power supply systems compared to the current light-duty electric vehicles, which achieve high performance and long-range. The recreational vehicles need to heed the limited dimension requirements while assuring the high requested power. This paper proposes an integration of Lithium-Ion Capacitor (LIC) with Fuel Cell (FC) without any power electronic device for a three-wheel electric motorcycle. Unlike other hybrid power supply systems, the proposed FC-LIC passive configuration is lighter, compact, more efficient, and simpler to implement. Due to the different impedance of the components the system is self-management, in which FC supplies the average power component and LIC operates as a low-pass filter. In this respect, a simulator is built based on experimental tests to study the system performance in terms of hydrogen consumption and FC degradation. Subsequently, the system is tested under three standard motorcycle driving cycles at three different FC system lifespan stages. The obtained results demonstrate that a passive topology can supply the requested power along different FC stages of life and reported just an increment of 12% of hydrogen consumption at the oldest condition compared to the new condition. 相似文献
42.
Gerardo Valadez Huerta Johanan Álvarez Jordán Michael Dragon Keno Leites Stephan Kabelac 《International Journal of Hydrogen Energy》2018,43(34):16684-16693
Solid oxide fuel cell (SOFC) systems with anode off-gas recirculation (AGR) and diesel pre-reforming are advantageous because they can operate with the current fuel infrastructure. In the SchIBZ-project, the prototype of such a SOFC system for maritime applications has already been commissioned. In this first paper, we model the system devices to conduct an exergy analysis of this real SOFC plant and validate them with experimental values from experiments in laboratory scale. The results of our simulation agree well with the experimental values. The calculations with the validated results may be closer to the real thermodynamic behavior of such system components than previous literature. 相似文献
43.
This study proposes precise modeling for the proton exchange membrane fuel cells which present desirable advantages compared with other energy management systems. The presented model can be applied for the simulation of the actual behavior of the proton exchange membrane fuel cells such as the electrical, electrochemical, and mechanical. In the present literature, a newly presented optimizer namely Satin Bowerbird is implemented for the evaluation of the proton exchange membrane fuel cell performance criteria. The Satin Bowerbird optimizer is an evolutionary algorithm that imitates the mating process of the Bowerbirds in the mating season. The Satin Bowerbird optimizer is applied to the different commercial benchmark of proton exchange membrane fuel cell stack to assess the performance of the proposed algorithm. The statistical study is also carried out to show the superiority of the proposed method compared with other schemes. The standard deviation for the Satin Bowerbird optimizer is obtained 0.0941 which is the lowest value amongst the other well‐known approaches. Also, the lowest sum of squared error is calculated for the proposed algorithm. Moreover, the validation of the presented method is done with the experimental data which shows good agreement between the experimental and modeling data. 相似文献
44.
The durability of a niobium (Nb) thin film deposited on AISI 316L by magnetron sputtering was investigated in simulated polymer electrolyte membrane fuel cell (PEMFC) environments. The result of a potentiostatic test in a simulated corrosion environment showed that the current densities of the cathode and anode were 1.56 × 10−7 and -7.2 × 10−7 A/cm2, respectively.Before and after the potentiostatic test, the value of the interfacial contact resistance (ICR) increased 40.1 mΩ cm2 at 1.5 MPa. The cell performance observed with the Nb-bipolar plate (BP) was slightly decreased compared to the commercial graphite-BP over this test period. After a 300 h durability test, cell performance of the Nb-BP unit cell was slightly decreased by 5.4% at a current density of 400 mA/cm2. 相似文献
45.
Effect of the doping time of the 1‐butyl‐3‐methylimidazolium ionic liquid cation on the Nafion membrane proprieties 下载免费PDF全文
Letícia G. da Trindade Letícia Zanchet Katiúscia M.N. Borba Josiane C. Souza Edson R. Leite Emilse M.A. Martini 《国际能源研究杂志》2018,42(11):3535-3543
Nafion membranes were prepared by incorporating in the polymer matrix the 1‐butyl‐3‐methylimidazolium (BMI+) ionic liquid cation at different doping levels. Increasing the doping time of the membranes with the ionic liquid results in increased incorporation of the BMI+ cation but a decrease in the bulk conductivity. The thermogravimetric analysis shows that the BMI+ cation incorporation increases the thermal stability of the membranes. The higher discharge efficiency of the fuel cell at 80°C was obtained by using Nafion membrane after 15 minutes of doping in the ionic liquid solution. 相似文献
46.
W.Y. Wong W.R.W. Daud A.B. Mohamad A.A.H. Kadhum K.S. Loh E.H. Majlan 《International Journal of Hydrogen Energy》2013
Nitrogen-doped carbon nanotubes (NCNTs) as noble-metal free catalysts were synthesised via chemical vapour deposition using iron (II) phthalocyanine as a metal catalyst for growth of the nanotubes. The synthesis process was performed in one step in a tube furnace using different chemical precursors (aniline, diethylamine and ethylenediamine) as nitrogen sources. The NCNT samples were physically characterised using scanning electron microscopy, transmission electronic microscopy and X-ray photoelectron spectroscopy. Cyclic voltammetry measurements were conducted to investigate the oxygen reduction reaction (ORR), and they showed that the electrocatalytic activities depend on the structural and morphological changes in the NCNTs. The results showed that NCNTs synthesised from ethylenediamine precursors exhibit an ORR scheme proceed via indirect four electron transfer process in acidic media, which implies that these NCNTs are a candidate for serving as the cathodic catalyst in PEMFCs. The highly active NCNTs possess unique characteristics, including a high concentration of surface defects with high pyridinic-N and pyridinic-N-oxides configurations that serve as active sites for ORR activity in acidic media. 相似文献
47.
由于氢能具有无污染、安全度高等特点,随着能源供需及国际高油价情势的演变,已被国际能源总署(IEA)规划为未来主要的能源利用形态。基于对降低温室气体排放与空气污染,台湾因具机车与电子产品生产优势,在推动燃料电池应用方面,亦积极投入小型质子交换膜燃料电池发电系统之研发,目前已建立1kW移动式燃料电池发电系统、3kW及5kW多重进料重组器之热电共生燃料电池发电系统;在3C电子产品DMFC应用方面也有很好的成果。 相似文献
48.
Ahmad FadelBiao Zhou 《Journal of power sources》2011,196(6):3271-3279
The implementation of fuel cell vehicles requires a supervisory control strategy that manages the power distribution between the fuel cell and the energy storage device. Some of the current problems with power management strategies are: fuel efficiency optimization methods require prior knowledge of the driving cycle before they can be implemented, the impact on the fuel cell and battery life cycle are not considered and finally, there are no standardized measures to evaluate the performance of different control methods. In addition to that, the performances of different control methods for power management have not been directly compared using the same mathematical models. The proposed work will present a different optimization approach that uses fuel mass flow rate instead of fuel mass consumption as the cost function and thus, it can be done instantaneously and does not require knowledge of the driving cycle ahead of time. Also this study presents an experimental approach to validate the mathematical simulation results. 相似文献
49.
50.