全文获取类型
收费全文 | 22096篇 |
免费 | 3596篇 |
国内免费 | 3071篇 |
专业分类
化学 | 16385篇 |
晶体学 | 256篇 |
力学 | 1437篇 |
综合类 | 231篇 |
数学 | 2917篇 |
物理学 | 7537篇 |
出版年
2024年 | 50篇 |
2023年 | 456篇 |
2022年 | 500篇 |
2021年 | 683篇 |
2020年 | 884篇 |
2019年 | 849篇 |
2018年 | 667篇 |
2017年 | 594篇 |
2016年 | 1042篇 |
2015年 | 962篇 |
2014年 | 1207篇 |
2013年 | 1597篇 |
2012年 | 1915篇 |
2011年 | 1918篇 |
2010年 | 1456篇 |
2009年 | 1241篇 |
2008年 | 1406篇 |
2007年 | 1295篇 |
2006年 | 1211篇 |
2005年 | 1127篇 |
2004年 | 867篇 |
2003年 | 789篇 |
2002年 | 868篇 |
2001年 | 773篇 |
2000年 | 542篇 |
1999年 | 543篇 |
1998年 | 445篇 |
1997年 | 406篇 |
1996年 | 429篇 |
1995年 | 345篇 |
1994年 | 322篇 |
1993年 | 260篇 |
1992年 | 205篇 |
1991年 | 195篇 |
1990年 | 132篇 |
1989年 | 120篇 |
1988年 | 98篇 |
1987年 | 60篇 |
1986年 | 61篇 |
1985年 | 64篇 |
1984年 | 53篇 |
1983年 | 36篇 |
1982年 | 29篇 |
1981年 | 22篇 |
1980年 | 17篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1957年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 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.
14.
15.
16.
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
17.
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
18.
Yongjie Zhou Yuqi Mei Tian Luo Wenxue Chen Qiuping Zhong Haiming Chen Weijun Chen 《Molecules (Basel, Switzerland)》2021,26(9)
The contribution of rheological properties and viscoelasticity of the interfacial adsorbed layer to the emulsification mechanism of enzymatic modified sugar beet pectin (SBP) was studied. The component content of each enzymatic modified pectin was lower than that of untreated SBP. Protein and ferulic acid decreased from 5.52% and 1.08% to 0.54% and 0.13%, respectively, resulting in a decrease in thermal stability, apparent viscosity, and molecular weight (Mw). The dynamic interfacial rheological properties showed that the interfacial pressure and modulus (E) decreased significantly with the decrease of functional groups (especially proteins), which also led to the bimodal distribution of particle size. These results indicated that the superior emulsification property of SBP is mainly determined by proteins, followed by ferulic acid, and the existence of other functional groups also promotes the emulsification property of SBP. 相似文献
19.
20.
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