全文获取类型
收费全文 | 27944篇 |
免费 | 5182篇 |
国内免费 | 4374篇 |
专业分类
化学 | 21007篇 |
晶体学 | 461篇 |
力学 | 1552篇 |
综合类 | 304篇 |
数学 | 3149篇 |
物理学 | 11027篇 |
出版年
2024年 | 64篇 |
2023年 | 572篇 |
2022年 | 873篇 |
2021年 | 1144篇 |
2020年 | 1308篇 |
2019年 | 1372篇 |
2018年 | 1083篇 |
2017年 | 1078篇 |
2016年 | 1446篇 |
2015年 | 1534篇 |
2014年 | 1871篇 |
2013年 | 2330篇 |
2012年 | 2715篇 |
2011年 | 2797篇 |
2010年 | 2011篇 |
2009年 | 1926篇 |
2008年 | 2082篇 |
2007年 | 1710篇 |
2006年 | 1546篇 |
2005年 | 1216篇 |
2004年 | 1009篇 |
2003年 | 764篇 |
2002年 | 772篇 |
2001年 | 598篇 |
2000年 | 509篇 |
1999年 | 503篇 |
1998年 | 379篇 |
1997年 | 315篇 |
1996年 | 317篇 |
1995年 | 248篇 |
1994年 | 221篇 |
1993年 | 223篇 |
1992年 | 153篇 |
1991年 | 150篇 |
1990年 | 114篇 |
1989年 | 113篇 |
1988年 | 89篇 |
1987年 | 55篇 |
1986年 | 66篇 |
1985年 | 65篇 |
1984年 | 32篇 |
1983年 | 22篇 |
1982年 | 28篇 |
1981年 | 13篇 |
1979年 | 8篇 |
1978年 | 7篇 |
1977年 | 6篇 |
1976年 | 5篇 |
1972年 | 4篇 |
1957年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
11.
Nonlinear Dynamics - Epilepsy is the second largest neurological disease which seriously threatens human life and health. The one important reason of inducing epileptic seizures is ischemic stroke... 相似文献
12.
13.
Lei Chen Hui-Qing Yang Cheng-Yu Jin Zhao-Xu Chen 《International journal of quantum chemistry》2020,120(22):e26366
We studied the ring opening of propylene oxide (PO) by salen-M coordinated OH− group [M = Al(III), Sc(III), Cr(III), Mn(III), Fe(III), Co(II), Co(III), Ni(II), Cu(II), Zn(II), Ru(III) and Rh(III)]. The results show that the ring-opening energy barriers for M(II) complexes are much lower than those with M(III) complexes in the gas phase, and the barriers correlate linearly with the negative charges on the OH− group and the Fukui function condensed on the OH− group. The nucleophilicity ordering in the gas phase can be rationalized by the ratio of formal positive charges/radius of M cations. Solvent effect greatly increases the barriers of M(II) complexes but slightly changes the results of M(III) ones, making the barriers similar. Analysis indicates that the reaction heats are linearly proportional to the reverse reaction barriers. The relationships established here can be used to estimate the ring-opening barriers and to screen epoxide ring-opening catalysts. 相似文献
14.
Paired single residue‐transposed Lys‐N and Lys‐C digestions for label‐free identification of N‐terminal and C‐terminal MS/MS peptide product ions: ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry and tandem mass spectrometry for peptide de novo sequencing
下载免费PDF全文
![点击此处可从《Rapid communications in mass spectrometry : RCM》网站下载免费的PDF全文](/ch/ext_images/free.gif)
15.
Annals of the Institute of Statistical Mathematics - To obtain M-estimators of a response variable when the data are missing at random, we can construct three bias-corrected nonparametric... 相似文献
16.
Jie Lu Ju-Kang Wu Yao Jiang Dr. Peng Tan Lin Zhang Yu Lei Prof. Xiao-Qin Liu Prof. Lin-Bing Sun 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(16):6490-6496
Hierarchically porous metal–organic frameworks (HP-MOFs) are promising in various applications. Most reported HP-MOFs are prepared based on the generation of mesopores in microporous frameworks, and the formed mesopores are connected by microporous channels, limiting the accessibility of mesopores for bulky molecules. A hierarchical structure is formed by constructing microporous MOFs in uninterrupted mesoporous tunnels. Using the confined space in as-prepared mesoporous silica, highly dispersed metal precursors for MOFs are coated on the internal surface of mesoporous tunnels. Ligand vapor-induced crystallization is employed to enable quantitative formation of MOFs in situ, in which sublimated ligands diffuse into mesoporous tunnels and react with metal precursors. The obtained hierarchically porous composites exhibit record-high adsorption capacity for the bulky molecule trypsin. The thermal and storage stability of trypsin is improved upon immobilization on the composites. 相似文献
17.
Xinyi Yuan 《Mathematische Zeitschrift》2015,280(3-4):1075-1084
18.
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
19.
Yao Yuan Chen Ying Chen Jianyong Gong Yulie 《Journal of Thermal Analysis and Calorimetry》2021,144(6):2357-2367
Journal of Thermal Analysis and Calorimetry - Based on innovative design, a liquid–vapor separation plate condenser with excellent heat transfer performance is invented. It takes less time to... 相似文献
20.