全文获取类型
收费全文 | 113610篇 |
免费 | 6803篇 |
国内免费 | 4694篇 |
专业分类
化学 | 49161篇 |
晶体学 | 1289篇 |
力学 | 8991篇 |
综合类 | 287篇 |
数学 | 35976篇 |
物理学 | 29403篇 |
出版年
2024年 | 93篇 |
2023年 | 762篇 |
2022年 | 1090篇 |
2021年 | 1250篇 |
2020年 | 1477篇 |
2019年 | 1388篇 |
2018年 | 11338篇 |
2017年 | 11092篇 |
2016年 | 7619篇 |
2015年 | 2507篇 |
2014年 | 2355篇 |
2013年 | 2922篇 |
2012年 | 6875篇 |
2011年 | 13700篇 |
2010年 | 7838篇 |
2009年 | 8183篇 |
2008年 | 8943篇 |
2007年 | 10807篇 |
2006年 | 2356篇 |
2005年 | 2937篇 |
2004年 | 2818篇 |
2003年 | 3044篇 |
2002年 | 2033篇 |
2001年 | 1072篇 |
2000年 | 1164篇 |
1999年 | 985篇 |
1998年 | 926篇 |
1997年 | 837篇 |
1996年 | 902篇 |
1995年 | 742篇 |
1994年 | 616篇 |
1993年 | 525篇 |
1992年 | 480篇 |
1991年 | 399篇 |
1990年 | 357篇 |
1989年 | 299篇 |
1988年 | 263篇 |
1987年 | 229篇 |
1986年 | 215篇 |
1985年 | 201篇 |
1984年 | 146篇 |
1983年 | 107篇 |
1982年 | 102篇 |
1981年 | 75篇 |
1980年 | 62篇 |
1979年 | 54篇 |
1914年 | 45篇 |
1912年 | 40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 250 毫秒
21.
22.
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
23.
24.
Xiaoxia Yang Hongyan Xie Zhiguang Xu Jiabing Feng Qiwei Fu Haidong Li Yongtang Jia 《Journal of polymer science. Part A, Polymer chemistry》2021,59(9):813-823
An efficient, atom-economic, oxygen-tolerant, and water-tolerant strategy has been established to synthesize cyano-rich polyesters. Four kinds of organic bases, 1,1,3,3-tetramethylguanidine (TMG), 4-dimethylaminopyridine, triethylamine, and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) were explored for accelerating Michael addition polymerization of malononitrile and 1,4-butandiol diacrylate. TMG can promote the polymerization efficiently under mild conditions to quantitatively afford polyester with high-molecular weight and moderate polydispersity. The comparison of the kinetic studies of TMG and TBD reveals that TMG shows better catalytic performance, while the catalysis of TBD brings about oligomers in spite of the higher efficiency at early age of the polymerization. Moreover, other diacrylate compounds could also be quantitatively polymerized to afford polyesters with high molecular weight. When dimethacrylate is chose as the monomer, the polymerization becomes sluggish. All the afforded polyesters display programmable thermal and mechanical properties that are closely related to their chemical structures. 相似文献
25.
We present the fabrication of core-shell-satellite Au@SiO2-Pt nanostructures and demonstrate that LSPR excitation of the core Au nanoparticle can induce plasmon coupling effect to initiate photocatalytic hydrogen generation from decomposition of formic acid. Further studies suggest that the plasmon coupling effect induces a strong local electric field between the Au core and Pt nanoparticles on the SiO2 shell, which enables creation of hot electrons on the non-plasmonic-active Pt nanoparticles to participate hydrogen evolution reaction on the Pt surface. In addition, small SiO2 shell thickness is required in order to obtain a strong plamon coupling effect and achieve efficient photocatalytic activities for hydrogen generation. 相似文献
26.
The research progress of a novel traffic solution,a submerged floating tunnel(SFT),is reviewed in terms of a study approach and loading scenario.Among existing publications,the buoyancy-weight ratio(BWR) is usually predefined.However,BWR is a critical structural parameter that tremendously affects the dynamic behaviour of not only the tunnel tube itself but also the cable system.In the context of a SFT prototype(SFTP) project in Qiandao Lake(Zhejiang Province,China),the importance of BWR is illustrated by finite element analysis and subsequently,an optimized BWR is proposed within a reasonable range in the present study.In the numerical model,structural damping is identified to be of importance.Rayleigh damping and the corresponding Rayleigh coefficients are attained through a sensitivity study,which shows that the adopted damping ratios are fairly suitable for SFTP.Lastly,the human sense of security is considered by quantifying the comfort index,which helps further optimize BWR in the SFTP structural parameter design. 相似文献
27.
28.
29.
30.