全文获取类型
收费全文 | 97篇 |
免费 | 14篇 |
国内免费 | 7篇 |
专业分类
化学 | 98篇 |
晶体学 | 3篇 |
力学 | 1篇 |
物理学 | 16篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 7篇 |
2021年 | 10篇 |
2020年 | 23篇 |
2019年 | 3篇 |
2018年 | 5篇 |
2017年 | 4篇 |
2016年 | 4篇 |
2015年 | 4篇 |
2014年 | 2篇 |
2013年 | 6篇 |
2012年 | 6篇 |
2011年 | 7篇 |
2009年 | 8篇 |
2008年 | 5篇 |
2007年 | 3篇 |
2006年 | 5篇 |
2005年 | 2篇 |
2004年 | 2篇 |
2003年 | 2篇 |
2002年 | 2篇 |
2001年 | 1篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1995年 | 1篇 |
1992年 | 1篇 |
排序方式: 共有118条查询结果,搜索用时 140 毫秒
51.
Shelton Farai Kuchena Dr. Ying Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(62):15450-15459
Non-metal ammonium ( ) ions have recently been explored as effective charge carriers in battery systems due to their abundancy, light weight, small hydration shells in water. The research concerning the use of redox chemistry in batteries, particularly in flexible batteries, is still in its infancy. For the first time, we report a flexible full ion battery (AIB) composed of a concentrated hydrogel electrolyte sandwiched between NH4V3O8 ⋅ 2.9H2O nanobelts cathode and polyaniline (PANI) anode, for enhanced performance. The hydrogel electrolyte is simply synthesized by using ammonium sulfate, xanthan gum and water. As a reference, the AIB based on the liquid aqueous electrolyte is prepared first, which exhibits a capacity of 121 mAh g−1 and a capacity retention of 95 % after 400 cycles at a specific current of 0.1 A g−1. On the other hand, the simple synthesis of the hydrogel electrolyte allows us to facilely tune and optimize the salt contents in the electrolyte, to maximize the ionic conductivity, transport kinetics, mechanical characteristics, and consequently the battery performance. It is found that the flexible battery based on the hydrogel electrolyte prepared from 3 M ammonium sulfate solution shows the best electrochemical performance, i. e., a capacity of 60 mAh g−1 while maintaining a capacity retention of 88 % after 250 cycles at a specific current of 0.1 A g−1. Moreover, the flexible AIB retains excellent electrochemical performance when bent at different angles, demonstrating remarkable mechanical strength and flexibility. Therefore, this study sheds new light on the utilization of concentrated hydrogel electrolyte in the AIB chemistry, for developments of novel electrochemical energy storage technology with high safety and low cost. 相似文献
52.
Cyclic voltammetry and controlled-potential electrolysis have been employed to investigate the reduction of some mono-, di-, tri-, and tetrahalopyrimidines at mercury cathodes in acetonitrile containing tetramethylammonium tetrafluoroborate. Two irreversible cyclic voltammetric waves are observed for reduction of 2-bromo-, 5-bromo-, and 2-chloropyrimidine; the first wave is due to cleavage of the carbon---halogen bond, and the second wave is attributable to reduction of pyrimidine. Cyclic voltammograms for 2,4-dichloro- and 4,6-dichloropyrimidine exhibit three cathodic waves, whereas that for 2,4,6-trichloropyrimidine shows four cathodic waves, arising from sequential cleavage of carbon---chlorine bonds as well as the reduction of pyrimidine. For the reduction of 2,4,5,6-tetrachloropyrimidine, a cyclic voltammogram exhibits four major irreversible cathodic waves corresponding to the cleavage of carbon---chlorine bonds, but the wave for reduction of pyrimidine is poorly defined. Bulk electrolyses of halopyrimidines at potentials for different stages of reduction lead to products that are consistent with expectations based upon cyclic voltammetry. In addition, our findings agree well with theoretical calculations of the relative stabilities of the various reduction intermediates. Mechanistic aspects of the reduction of halopyrimidines are discussed and, using homogeneous redox catalysis, we have determined the lifetimes of the electrogenerated radical-anions of 2-bromo- and 2-chloropyrimidine. 相似文献
53.
为了提高固体氧化物燃料电池阴极的电化学性能和热循环性能,避免La0.7Sr0.3MnO3-σ(LSM)在制备及工作温度下与氧化钇稳定的氧化锆(YSZ)电解质发生反应,增大电化学反应电阻,降低SOFC的性能,采用喷涂法在YSZ电解质片的表面制备了LSM-YSZ的多层复合阴极。从电解质表面开始,各层LSM所占比例依次为40%、70%和100%(质量分数)。结果表明:复合阴极材料的热膨胀系数随着LSM含量的增加而增大,仍与YSZ电解质的热膨胀系数比较接近。阴极极化曲线的测量结果表明,多层复合阴极LSM-YSZ与单层LSM阴极比较,具有更好的电化学性能和更加稳定的热循环性能。 相似文献
54.
Dr. Jie Gao Michael A. Lowe Sean Conte Stephen E. Burkhardt Prof. Héctor D. Abruña 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(27):8521-8526
Organosulfur compounds with multiple thiol groups are promising for high gravimetric energy density electrochemical energy storage. We have synthesized a poly(2,5‐dimercapto‐1,3,4‐thiadiazole) (PDMcT)/poly(3,4‐ethylenedioxythiophene) (PEDOT) composite cathode for lithium‐ion batteries with a new method and investigated its electrochemical behavior by charge/discharge cycles and cyclic voltammetry (CV) in an ether‐based electrolyte. Based on a comparison of the electrochemical performance with a carbonate‐based electrolyte, we found a much higher discharge capacity, but also a very attractive cycling performance of PDMcT by using a tetra(ethylene glycol) dimethyl ether (TEGDME)‐based electrolyte. The first discharge capacity of the as‐synthesized PDMcT/PEDOT composite approached 210 mAh g?1 in the TEGDME‐based electrolyte. CV results clearly show that the redox reactions of PDMcT are highly reversible in this TEGDME‐based electrolyte. The reversible capacity remained around 120 mAh g?1 after 20 charge/discharge cycles. With improved cycling performance and very low cost, PDMcT could become a very promising cathode material when combined with a TEGDME‐based electrolyte. The poor capacity in the carbonate‐based electrolyte is a consequence of the irreversible reaction of the DMcT monomer and dimer with the solvent, emphasizing the importance of electrolyte chemistry when studying molecular‐based battery materials. 相似文献
55.
It is shown that, for the electrodes of fuel cells with solid polymer electrolyte, the dependence of overall current on the active layer thickness contains an extremum. There is an optimum thickness of active layer, at which the overall current reaches its maximum possible value. The nature of this dependence is explained. The character of the distribution of electrochemical process intensity over the depth of active layer of cathode with solid polymer electrolyte is analyzed. The optimum thicknesses of active layers of oxygen and air cathodes of fuel cells with Nafion and platinum and the corresponding overall currents and contents of catalyst in the active layer are calculated. In the calculations, the temperature of fuel cell, the pressure in the cathode gas chamber, and the cathodic potential were varied. The optimization of active layer thickness of cathode with solid polymer electrolyte can reduce the platinum consumption, i.e. its amount per 1 kW of power produced in a membrane-electrode assembly. 相似文献
56.
Thermal analysis of a pierce type electron gun using the FEM software ANSYS and its experimental validation are presented in this paper. Thermal analysis of the electron gun structure has been carried out to find out the effect of heater power on steady state temperature and warm-up time. The thermal drain of the supporting structure has also been analyzed for different materials. These results were experimentally verified in an electron gun. The experimental results closely match the ANSYS results. 相似文献
57.
Enhancing the Electrochemical Performance of the LiMn2O4 Hollow Microsphere Cathode with a LiNi0.5Mn1.5O4 Coated Layer
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Wei Liu Dr. Jun Liu Kunfeng Chen Dr. Shaomin Ji Yanling Wan Prof. Dr. Yichun Zhou Prof. Dr. Dongfeng Xue Prof. Dr. Peter Hodgson Dr. Yuncang Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(3):824-830
Spinel cathode materials consisting of LiMn2O4@LiNi0.5Mn1.5O4 hollow microspheres have been synthesized by a facile solution‐phase coating and subsequent solid‐phase lithiation route in an atmosphere of air. When used as the cathode of lithium‐ion batteries, the double‐shell LiMn2O4@LiNi0.5Mn1.5O4 hollow microspheres thus obtained show a high specific capacity of 120 mA h g?1 at 1 C rate, and excellent rate capability (90 mAhg?1 at 10 C) over the range of 3.5–5 V versus Li/Li+ with a retention of 95 % over 500 cycles. 相似文献
58.
Chen Zhao Gui‐Liang Xu Tianshou Zhao Khalil Amine 《Angewandte Chemie (International ed. in English)》2020,59(40):17634-17640
Electrolyte modulation simultaneously suppresses polysulfide the shuttle effect and lithium dendrite formation of lithium–sulfur (Li‐S) batteries. However, the sluggish S redox kinetics, especially under high S loading and lean electrolyte operation, has been ignored, which dramatically limits the cycle life and energy density of practical Li‐S pouch cells. Herein, we demonstrate that a rational combination of selenium doping, core–shell hollow host structure, and fluorinated ether electrolytes enables ultrastable Li stripping/plating and essentially no polysulfide shuttle as well as fast redox kinetics. Thus, high areal capacity (>4 mAh cm?2) with excellent cycle stability and Coulombic efficiency were both demonstrated in Li metal anode and thick S cathode (4.5 mg cm?2) with a low electrolyte/sulfur ratio (10 μL mg?1). This research further demonstrates a durable Li‐Se/S pouch cell with high specific capacity, validating the potential practical applications. 相似文献
59.
Dr. Anqiang Pan Ting Zhu Hao Bin Wu Prof. Xiong Wen Lou 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(2):494-500
Nanosheet‐assembled hierarchical V2O5 hollow microspheres are successfully obtained from V‐glycolate precursor hollow microspheres, which in turn are synthesized by a simple template‐free solvothermal method. The structural evolution of the V‐glycolate hollow microspheres has been studied and explained by the inside‐out Ostwald‐ripening mechanism. The surface morphologies of the hollow microspheres can be controlled by varying the mixture solution and the solvothermal reaction time. After calcination in air, hierarchical V2O5 hollow microspheres with a high surface area of 70 m2 g?1 can be obtained and the structure is well preserved. When evaluated as cathode materials for lithium‐ion batteries, the as‐prepared hierarchical V2O5 hollow spheres deliver a specific discharge capacity of 144 mA h g?1 at a current density of 100 mA g?1, which is very close to the theoretical capacity (147 mA h g?1) for one Li+ insertion per V2O5. In addition, excellent rate capability and cycling stability are observed, suggesting their promising use in lithium‐ion batteries. 相似文献
60.
Jie Li Bo Peng Yapeng Li Lai Yu Gongrui Wang Dr. Liang Shi Prof. Genqiang Zhang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(57):13094-13098
Sodium-ion batteries have attracted tremendous attention due to their much lower cost and similar working principle compared with lithium-ion batteries, which have been invited great expectation as energy storage devices in grid-level applications. The sodium superionic conductor Na3V2(PO4)3 has been considered as a promising cathode candidate; however, its intrinsic low electronic conductivity results in poor rate performance and unsatisfactory cycling performance, which severely impedes its potential for practical applications. Herein, we developed a facile one-pot strategy to construct dual carbon-protected hybrid structure composed of carbon coated Na3V2(PO4)3 nanoparticles embedded with carbon matrix with excellent rate performance, superior cycling stability and ultralong lifespan. Specifically, it can deliver an outstanding rate performance with a 51.5 % capacity retention from 0.5 to 100 C and extraordinary cycling stability of 80.86 % capacity retention after 6000 cycles at the high rate of 20 C. The possible reasons for the enhanced performance could be understood as the synergistic effects of the strengthened robust structure, facilitated charge transfer kinetics, and the mesoporous nature of the Na3V2(PO4)3 hybrid structure. This work provides a cost-effective strategy to effectively optimize the electrochemical performance of a Na3V2(PO4)3 cathode, which could contribute to push forward the advance of its practical applications. 相似文献