全文获取类型
收费全文 | 22124篇 |
免费 | 3613篇 |
国内免费 | 3634篇 |
专业分类
化学 | 16294篇 |
晶体学 | 397篇 |
力学 | 1583篇 |
综合类 | 308篇 |
数学 | 2771篇 |
物理学 | 8018篇 |
出版年
2024年 | 51篇 |
2023年 | 344篇 |
2022年 | 607篇 |
2021年 | 700篇 |
2020年 | 765篇 |
2019年 | 827篇 |
2018年 | 689篇 |
2017年 | 756篇 |
2016年 | 1069篇 |
2015年 | 1061篇 |
2014年 | 1230篇 |
2013年 | 1633篇 |
2012年 | 1931篇 |
2011年 | 1915篇 |
2010年 | 1468篇 |
2009年 | 1452篇 |
2008年 | 1578篇 |
2007年 | 1422篇 |
2006年 | 1372篇 |
2005年 | 1151篇 |
2004年 | 1034篇 |
2003年 | 889篇 |
2002年 | 1036篇 |
2001年 | 930篇 |
2000年 | 633篇 |
1999年 | 554篇 |
1998年 | 385篇 |
1997年 | 299篇 |
1996年 | 307篇 |
1995年 | 246篇 |
1994年 | 214篇 |
1993年 | 183篇 |
1992年 | 119篇 |
1991年 | 113篇 |
1990年 | 82篇 |
1989年 | 65篇 |
1988年 | 58篇 |
1987年 | 40篇 |
1986年 | 47篇 |
1985年 | 37篇 |
1984年 | 15篇 |
1983年 | 18篇 |
1982年 | 11篇 |
1981年 | 12篇 |
1980年 | 6篇 |
1979年 | 4篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1957年 | 4篇 |
1936年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 573 毫秒
1.
2.
Interactions of the vector breathers for the coupled Hirota system with $$4\times 4$$ 4 × 4 Lax pair
Nonlinear Dynamics - In this paper, we investigate the interactions of the vector breathers for the coupled Hirota system with $$4\times 4$$ Lax pair. Firstly, we give the first-order breather... 相似文献
3.
Analysis and pharmacokinetic study of polyphyllin H in beagle dog plasma after oral administration of Rhizoma Paridis Extracts by LC‐MS/MS 下载免费PDF全文
4.
5.
6.
We investigate terahertz radiation(T-rays) from a pentacene organic diode at room temperature. The quantum chemistry calculation for frequency-related Huang–Rhys factor of pentacene is also carried out. The results demonstrate that the T-rays can come from a bending vibration of pentacene skeleton after the energy of pentacene exciton transferring to the vibrational excited state via electron–phonon coupling. Frequency and natural bond orbital analytics of pentacene and its derivatives are performed in order to explain the result and develop new materials to get higher emission. This work provides a new way to produce T-rays with a simple device at room temperature. 相似文献
7.
8.
9.
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
10.
Hui Li Jian Liu Juan Zhao Huiting He Dr. Dabo Jiang Prof. Steven Robert Kirk Prof. Qiong Xu Dr. Xianxiang Liu Prof. Dulin Yin 《ChemistryOpen》2021,10(4):477-485
A series of tetraimidazolium salts with different anions was prepared and applied in the isomerization of β-pinene oxide. After examining the activity of different catalysts, a remarkable enhancement of the selectivity of perillyl alcohol (47 %) was obtained over [PEimi][HNO3]4 under mild reaction conditions and using DMSO as the solvent. Furthermore, noncovalent interactions between solvent molecules and the catalyst were found by FT-IR spectroscopy and confirmed by computational chemistry. The homogeneous catalyst showed excellent stability and was reused up to six times without significant loss. 相似文献