全文获取类型
收费全文 | 19955篇 |
免费 | 3338篇 |
国内免费 | 2590篇 |
专业分类
化学 | 14468篇 |
晶体学 | 216篇 |
力学 | 1216篇 |
综合类 | 171篇 |
数学 | 2577篇 |
物理学 | 7235篇 |
出版年
2024年 | 42篇 |
2023年 | 429篇 |
2022年 | 461篇 |
2021年 | 612篇 |
2020年 | 792篇 |
2019年 | 794篇 |
2018年 | 618篇 |
2017年 | 538篇 |
2016年 | 893篇 |
2015年 | 921篇 |
2014年 | 1084篇 |
2013年 | 1382篇 |
2012年 | 1756篇 |
2011年 | 1842篇 |
2010年 | 1309篇 |
2009年 | 1096篇 |
2008年 | 1305篇 |
2007年 | 1226篇 |
2006年 | 1134篇 |
2005年 | 1024篇 |
2004年 | 789篇 |
2003年 | 650篇 |
2002年 | 665篇 |
2001年 | 572篇 |
2000年 | 413篇 |
1999年 | 443篇 |
1998年 | 374篇 |
1997年 | 352篇 |
1996年 | 371篇 |
1995年 | 321篇 |
1994年 | 273篇 |
1993年 | 233篇 |
1992年 | 190篇 |
1991年 | 189篇 |
1990年 | 156篇 |
1989年 | 145篇 |
1988年 | 105篇 |
1987年 | 68篇 |
1986年 | 67篇 |
1985年 | 70篇 |
1984年 | 57篇 |
1983年 | 31篇 |
1982年 | 31篇 |
1981年 | 18篇 |
1980年 | 18篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1957年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
11.
In the paper, the authors establish several integral representations for the generating functions of the large and little Schröder numbers and for the large and little Schröder numbers. 相似文献
12.
13.
In the view of substrate availability, atomic efficiency and cost, directly using arenols as coupling partners in cross‐coupling, would be one of the most attractive goals. Up to date, many efforts have been made to activate the C—O bond of phenols with different strategies, for example, through in‐situ formed intermediates, through a catalytic reductive dearomatization‐condensation‐rearomatization sequence or catalytic deoxygenation. In this review, we summarized recent advances in cross‐couplings of arenols as the electrophiles via C—O activation. 相似文献
14.
Polypyrrole Shell@3D‐Ni Metal Core Structured Electrodes for High‐Performance Supercapacitors
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)
Gao‐Feng Chen Yu‐Zhi Su Pan‐Yong Kuang Zhao‐Qing Liu Dao‐Yi Chen Xu Wu Nan Li Prof. Shi‐Zhang Qiao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(12):4614-4621
Three‐dimensional (3D) nanometal films serving as current collectors have attracted much interest recently owing to their promising application in high‐performance supercapacitors. In the process of the electrochemical reaction, the 3D structure can provide a short diffusion path for fast ion transport, and the highly conductive nanometal may serve as a backbone for facile electron transfer. In this work, a novel polypyrrole (PPy) shell@3D‐Ni‐core composite is developed to enhance the electrochemical performance of conventional PPy. With the introduction of a Ni metal core, the as‐prepared material exhibits a high specific capacitance (726 F g?1 at a charge/discharge rate of 1 A g?1), good rate capability (a decay of 33 % in Csp with charge/discharge rates increasing from 1 to 20 A g?1), and high cycle stability (only a small decrease of 4.2 % in Csp after 1000 cycles at a scan rate of 100 mV s?1). Furthermore, an aqueous symmetric supercapacitor device is fabricated by using the as‐prepared composite as electrodes; the device demonstrates a high energy density (≈21.2 Wh kg?1) and superior long‐term cycle ability (only 4.4 % and 18.6 % loss in Csp after 2000 and 5000 cycles, respectively). 相似文献
15.
16.
Guo Yan Li Zhuang Wei Yuxi Zhang Xinxu Shi Kexin 《Journal of Solid State Electrochemistry》2022,26(4):1051-1065
Journal of Solid State Electrochemistry - Polyvinylpyrrolidone (PVP) and graphene (G)-modified iron oxides (Fe2O3-PVP-G) are prepared by a simple hydrothermal reaction. Their morphology and... 相似文献
17.
18.
19.
20.
Cuixia Cui Yong Gao Dr. Jun Li Chao Yang Meng Liu Prof. Dr. Huile Jin Prof. Dr. Zhenhai Xia Prof. Dr. Liming Dai Prof. Dr. Yong Lei Prof. Dr. Jichang Wang Prof. Dr. Shun Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(20):8002-8007
Although tremendous efforts have been devoted to understanding the origin of boosted charge storage on heteroatom-doped carbons, none of the present studies has shown a whole landscape. Herein, by both experimental evidence and theoretical simulation, it is demonstrated that heteroatom doping not only results in a broadened operating voltage, but also successfully promotes the specific capacitance in aqueous supercapacitors. In particular, the electrolyte cations adsorbed on heteroatom-doped carbon can effectively inhibit hydrogen evolution reaction, a key step of water decomposition during the charging process, which broadens the voltage window of aqueous electrolytes even beyond the thermodynamic limit of water (1.23 V). Furthermore, the reduced adsorption energy of heteroatom-doped carbon consequently leads to more stored cations on the heteroatom-doped carbon surface, thus yielding a boosted charge storage performance. 相似文献