全文获取类型
收费全文 | 159篇 |
免费 | 13篇 |
国内免费 | 22篇 |
专业分类
化学 | 124篇 |
晶体学 | 3篇 |
力学 | 11篇 |
综合类 | 1篇 |
数学 | 10篇 |
物理学 | 45篇 |
出版年
2023年 | 11篇 |
2022年 | 22篇 |
2021年 | 13篇 |
2020年 | 17篇 |
2019年 | 8篇 |
2018年 | 10篇 |
2017年 | 4篇 |
2016年 | 12篇 |
2015年 | 5篇 |
2014年 | 9篇 |
2013年 | 7篇 |
2012年 | 21篇 |
2011年 | 11篇 |
2010年 | 2篇 |
2009年 | 7篇 |
2008年 | 5篇 |
2007年 | 12篇 |
2006年 | 4篇 |
2005年 | 8篇 |
2004年 | 2篇 |
1998年 | 2篇 |
1991年 | 1篇 |
1979年 | 1篇 |
排序方式: 共有194条查询结果,搜索用时 12 毫秒
41.
42.
Tingting Lv Dr. Guoyin Zhu Dr. Shengyang Dong Prof. Qingquan Kong Yi Peng Shu Jiang Guangxun Zhang Zilin Yang Prof. Shengyang Yang Prof. Xiaochen Dong Prof. Huan Pang Prof. Yizhou Zhang 《Angewandte Chemie (International ed. in English)》2023,62(5):e202216089
Vanadium-based oxides with high theoretical specific capacities and open crystal structures are promising cathodes for aqueous zinc-ion batteries (AZIBs). In this work, the confined synthesis can insert metal ions into the interlayer spacing of layered vanadium oxide nanobelts without changing the original morphology. Furthermore, we obtain a series of nanomaterials based on metal-confined nanobelts, and describe the effect of interlayer spacing on the electrochemical performance. The electrochemical properties of the obtained Al2.65V6O13 ⋅ 2.07H2O as cathodes for AZIBs are remarkably improved with a high initial capacity of 571.7 mAh ⋅ g−1 at 1.0 A g−1. Even at a high current density of 5.0 A g−1, the initial capacity can still reach 205.7 mAh g−1, with a high capacity retention of 89.2 % after 2000 cycles. This study demonstrates that nanobelts confined with metal ions can significantly improve energy storage applications, revealing new avenues for enhancing the electrochemical performance of AZIBs. 相似文献
43.
To comprehensively control the corner separation and mid-span boundary layer (BL) separation, this study proposed and evaluated two new flow control configurations. One is a slotted configuration composed of blade-end and whole-span slots, and the other is a combined configuration with end-wall BL suction and whole-span slot. Additionally, the adaptability of the combined configuration to the lower blade solidity (c/t) condition was verified. The results indicate that both the slotted configuration and combined configuration can eliminate the mid-span BL separation, but a better reduction in the corner separation can be observed in the combined configuration. The two configurations can remove the concentrated shedding vortex and reduce the passage vortex (PV) for the datum cascade, but the wall vortex (WV) will be generated. By contrast, the combined configuration has weaker WV and PV than the slotted configuration, which contributes to further reducing the corner separation. In the combined configuration with a c/t of 1.66 and 1.36, the total pressure loss is reduced by 38.4% and 42.1%, respectively, on average, while the averaged static pressure rise coefficient is increased by 16.2% and 17.6%, respectively. This is advantageous for enhancing the working stability and pressure diffusion capacity for compressors. Besides this, the combined configuration with lower c/t can achieve a stronger pressure diffusion capacity and smaller loss than the higher c/t datum cascade. Therefore, the combined configuration is advantageous to the improvement of the aero-engine thrust-to-weight ratio through decreasing the compressor single-stage blade number. 相似文献
44.
厚度微米级热界面材料的热物性参数,可通过相敏瞬态热反射测量法拟合得出。本文对该方法的原理进行了发展研究:基于数据测量过程中,不同调制频率区间对应在样品中的热穿透深度不同(高频区间内热穿透深度小,低频区间内热穿透深度大),提出针对多层材料,分频率段依次对各层热参数拟合的方法。本方法的途径是通过不同频率区间的选择,沿着热穿透方向依次对各层参数进行拟合,从而减少后层材料未知参数对当前层参数拟合的影响,同时减少对已知参数条件的要求,提高了拟合结果的质量。用本文方法对四层材料样品做了测量及拟合数据对比,结果表明拟合结果相对误差保持在±8%之内,同时对界面热导的信号敏感度进行了分析,发现拟合参数的信号敏感度依赖于频率的选择。 相似文献
45.
Propylene polymerization was carried out with MCM-41 supported rac-Et(Ind)2ZrCl2 catalysts, in the presence and absence of beta-cyclodextrin. The resultant PP was studied by X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, and differential scanning calorimetry. Through comparison of the results, it was found that the channels of MCM-41 could act as a nanoreactor of propylene polymerization and the polypropylene (PP) contained in the channels had noncrystal structure. However, the PP could grow out of the channels and form some crystals after the active sites on the surface of MCM-41 were destroyed. This showed that the channels of MCM-41 had great confinement effects on propylene polymerization. 相似文献
46.
Wu Xiaochen Yang Qi Huang Wenlong Na Ren Yu Yu Liu Huitian Liu Xu Liu Yuansheng Cao Yuhao Shan Zhongqiang 《Journal of Solid State Electrochemistry》2022,26(5):1201-1210
Journal of Solid State Electrochemistry - Physical confinement through particular nanostructures is inadequate to avoid the shuttle effect in the lithium–sulfur batteries. Electrocatalysts... 相似文献
47.
Polycyclic naphthalenediimide-based nanoparticles for NIR-Ⅱ fluorescence imaging guided phototherapy
Tang Chuanchao Song Chuanhui Wei Zheng Liang Chen Ran Jianchuan Cai Yu Dong Xiaochen Han Wei 《中国科学:化学(英文版)》2020,63(7):946-956
Optical imaging and phototherapy in the second near-infrared window(NIR-Ⅱ, 900–1700 nm) can reduce tissue auto-fluorescence and photon scattering, which facilitates higher spatial resolution and deeper tissue penetration depth for solid tumor theranostics. Herein, a polycyclic naphthalenediimide(NDI) based chromophore 13-amino-4,5-dibromo-2,7-di(dodecan-6-yl)-1 H-isoquinolino[4,5,6-fgh]naphtho[1,8-bc][1,9]phenanthroline-1,3,6,8(2H,7H,9H)-tetraone(NDI-NA) was designed and synthesized. With large polycyclic π-systems, NDI-NA molecule possesses broad near-infrared(NIR) absorption(maximum at777 nm) and emission(maximum at 921 nm). By nanoprecipitation, NDI-NA nanoparticles(NPs) were formed in aqueous solution with J-aggregative state, which showed huge red-shift in both absorption spectrum(maximum at 904 nm) and emission spectrum(maximum at 1,020 nm), endowing NDI-NA NPs efficient NIR-Ⅱ fluorescence imaging capability. Besides, the NPs present effective tumor-targeting capability in vivo based on the enhanced permeation and retention(EPR) effect. More importantly, NDI-NA NPs simultaneously have high photothermal conversion efficiency(30.8%) and efficient reactive oxygen species generation ability, making them remarkably phototoxic to cancer cells. The polycyclic chromophore based multifunctional NDI-NA NPs as NIR-Ⅱ phototheranostic agents possess bright future for clinical NIR-Ⅱ imaging-guided cancer phototherapy. 相似文献
48.
The ruthenium complex Ru(terpyridine)(2,6‐pyridinedicarboxylate) was successfully grafted onto MCM‐41 using a multi‐step grafting method. The immobilized ruthenium complex was characterized thoroughly using Fourier transform infrared, Raman, UV–visible diffuse reflectance and energy‐dispersive X‐ray spectroscopies, X‐ray diffraction, N2 adsorption, scanning electron microscopy, thermogravimetric analysis and inductively coupled plasma analysis. This immobilized ruthenium complex showed excellent performance in the oxidation of various secondary alcohols to their corresponding ketones with tert‐butyl hydroperoxide as oxidant under solvent‐free conditions, and had the advantages of easy recovery and good reusability. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
49.
Dr. Yun Wu Dr. Wei Wang Dr. Lingli Liu Dr. Sane Zhu Dr. Xiaochen Wang Dr. Enzhu Hu Dr. Kunhong Hu 《ChemistryOpen》2019,8(3):333-338
The use of metal complex immobilized/decorated porous materials as catalysts has found various applications. As such, finding a new and mild method for synthesis of metal complex immobilized over porous material is of great interest. Immobilized porous materials for styrene oxidation were reported in this work. Immobilized porous material of Cu-Schiff base complex @MIL-101 were described, in which immobilized Cu-Schiff base complex within super cage of a metal-organic framework (MOF)-based porous material, chromium (III) terephthalate MIL-101. They were systematically characterized by using elemental analysis, powder X-ray diffraction, fourier transform infrared spectroscopy, N2 absorption-desorption, and so on, also used as catalyst for the selective oxidation of styrene to benzaldehyde. Comparatively, the immobilized heterogeneous catalyst of Cu-Schiff base complex@MIL-101 acted as an efficient heterostructure catalyst in the oxidation of styrene to benzaldehyde up to six cycles, and showed superior activity for styrene oxidation over MIL-101. 相似文献