全文获取类型
收费全文 | 102954篇 |
免费 | 4909篇 |
国内免费 | 4742篇 |
专业分类
化学 | 42661篇 |
晶体学 | 1195篇 |
力学 | 8255篇 |
综合类 | 384篇 |
数学 | 34941篇 |
物理学 | 25169篇 |
出版年
2024年 | 51篇 |
2023年 | 388篇 |
2022年 | 676篇 |
2021年 | 818篇 |
2020年 | 999篇 |
2019年 | 1032篇 |
2018年 | 11157篇 |
2017年 | 11001篇 |
2016年 | 7219篇 |
2015年 | 2143篇 |
2014年 | 1915篇 |
2013年 | 2330篇 |
2012年 | 6077篇 |
2011年 | 12896篇 |
2010年 | 7494篇 |
2009年 | 7919篇 |
2008年 | 8645篇 |
2007年 | 10527篇 |
2006年 | 1912篇 |
2005年 | 2744篇 |
2004年 | 2665篇 |
2003年 | 2876篇 |
2002年 | 2051篇 |
2001年 | 1034篇 |
2000年 | 949篇 |
1999年 | 645篇 |
1998年 | 527篇 |
1997年 | 403篇 |
1996年 | 435篇 |
1995年 | 289篇 |
1994年 | 245篇 |
1993年 | 218篇 |
1992年 | 177篇 |
1991年 | 168篇 |
1990年 | 143篇 |
1989年 | 137篇 |
1988年 | 122篇 |
1987年 | 94篇 |
1986年 | 93篇 |
1985年 | 89篇 |
1984年 | 69篇 |
1983年 | 58篇 |
1982年 | 56篇 |
1981年 | 48篇 |
1980年 | 55篇 |
1979年 | 51篇 |
1978年 | 49篇 |
1914年 | 45篇 |
1909年 | 41篇 |
1908年 | 40篇 |
排序方式: 共有10000条查询结果,搜索用时 343 毫秒
11.
Mesoscopic modeling at the pore scale offers great promise in exploring the underlying structure transport performance of flow through porous media. The present work studies the fluid flow subjected to capillarity-induced resonance in porous media characterized by different porous structure and wettability. The effects of porosity and wettability on the displacement behavior of the fluid flow through porous media are discussed. The results are presented in the form of temporal evolution of percentage saturation and displacement of the fluid front through porous media. The present study reveals that the vibration in the form of acoustic excitation could be significant in the mobilization of fluid through the porous media. The dependence of displacement of the fluid on physicochemical parameters like wettability of the surface, frequency along with the porosity is analyzed. It was observed that the mean displacement of the fluid is more in the case of invading fluid with wetting phase where the driving force strength is not so dominant. 相似文献
12.
13.
Sarah Peluse 《Israel Journal of Mathematics》2018,227(1):379-396
We prove that the group of diffeomorphisms of the interval [0, 1] contains surface groups whose action on (0, 1) has no global fix point and such that only countably many points of the interval (0, 1) have non-trivial stabiliser. 相似文献
14.
Dr. Qing Xu Dr. Shanshan Tao Dr. Qiuhong Jiang Prof. Donglin Jiang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(11):4587-4593
A strategy based on covalent organic frameworks for ultrafast ion transport involves designing an ionic interface to mediate ion motion. Electrolyte chains were integrated onto the walls of one-dimensional channels to construct ionic frameworks via pore surface engineering, so that the ionic interface can be systematically tuned at the desired composition and density. This strategy enables a quantitative correlation between interface and ion transport and unveils a full picture of managing ionic interface to achieve high-rate ion transport. Moreover, the effect of interfaces was scaled on ion transport; ion mobility is increased in an exponential mode with the ionic interface. This strategy not only sets a benchmark system but also offers a general guidance for designing ionic interface that is key to systems for energy conversion and storage. 相似文献
15.
Yi Han Zibo Xue Dr. Guangwu Li Dr. Yanwei Gu Dr. Yong Ni Dr. Shaoqiang Dong Prof. Chunyan Chi 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(23):9111-9116
Incorporation of a non-hexagonal ring into a nanographene framework can lead to new electronic properties. During the attempted synthesis of naphthalene-bridged double [6]helicene and heptagon-containing nanographene by the Scholl reaction, an unexpected azulene-embedded nanographene and its triflyloxylated product were obtained, as confirmed by X-ray crystallographic analysis and 2D NMR spectroscopy. A 5/7/7/5 ring-fused substructure containing two formal azulene units is formed, but only one of them shows an azulene-like electronic structure. The formation of this unique structure is explained by arenium ion mediated 1,2-phenyl migration and a naphthalene to azulene rearrangement reaction according to an in-silico study. This report represents the first experimental example of the thermodynamically unfavorable naphthalene to azulene rearrangement and may lead to new azulene-based molecular materials. 相似文献
16.
17.
18.
19.
20.
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