全文获取类型
收费全文 | 74612篇 |
免费 | 4492篇 |
国内免费 | 2526篇 |
专业分类
化学 | 39137篇 |
晶体学 | 1062篇 |
力学 | 4205篇 |
综合类 | 111篇 |
数学 | 9339篇 |
物理学 | 27776篇 |
出版年
2023年 | 586篇 |
2022年 | 1228篇 |
2021年 | 1255篇 |
2020年 | 1313篇 |
2019年 | 1300篇 |
2018年 | 2338篇 |
2017年 | 2290篇 |
2016年 | 2344篇 |
2015年 | 1839篇 |
2014年 | 2230篇 |
2013年 | 3596篇 |
2012年 | 4686篇 |
2011年 | 4654篇 |
2010年 | 3173篇 |
2009年 | 3173篇 |
2008年 | 3186篇 |
2007年 | 2997篇 |
2006年 | 2740篇 |
2005年 | 5372篇 |
2004年 | 4971篇 |
2003年 | 3235篇 |
2002年 | 1588篇 |
2001年 | 1753篇 |
2000年 | 1386篇 |
1999年 | 1293篇 |
1998年 | 1023篇 |
1997年 | 1004篇 |
1996年 | 944篇 |
1995年 | 822篇 |
1994年 | 738篇 |
1993年 | 617篇 |
1992年 | 689篇 |
1991年 | 663篇 |
1990年 | 626篇 |
1989年 | 562篇 |
1988年 | 537篇 |
1987年 | 533篇 |
1986年 | 461篇 |
1985年 | 522篇 |
1984年 | 517篇 |
1983年 | 386篇 |
1982年 | 420篇 |
1981年 | 393篇 |
1980年 | 329篇 |
1979年 | 410篇 |
1978年 | 384篇 |
1977年 | 397篇 |
1976年 | 399篇 |
1975年 | 353篇 |
1973年 | 342篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
We study the full counting statistics of transport electrons through a semiconductor two-level quantum dot with Rashba spin–orbit (SO) coupling, which acts as a nonabelian gauge field and thus induces the electron transition between two levels along with the spin flip. By means of the quantum master equation approach, shot noise and skewness are obtained at finite temperature with two-body Coulomb interaction. We particularly demonstrate the crucial effect of SO coupling on the super-Poissonian fluctuation of transport electrons, in terms of which the SO coupling can be probed by the zero-frequency cumulants. While the charge currents are not sensitive to the SO coupling. 相似文献
2.
Simultaneous determination of cinnamaldehyde and its metabolite in rat tissues by gas chromatography–mass spectrometry 下载免费PDF全文
Hang Zhao Qian Yang Yanhua Xie Jiyuan Sun Honghai Tu Wei Cao Siwang Wang 《Biomedical chromatography : BMC》2015,29(2):182-187
Cinnamaldehyde (CA), an active ingredient isolated from the traditional Chinese medicine Cortex Cinnamomi, has a wide range of bioactivities. To clarify the distribution characteristics of CA, a selective and sensitive method utilizing gas chromatography–mass spetrometry was initially developed for simultaneously determining the concentration of CA and its metabolite cinnamyl alcohol in rat tissues. Selected ion masses of m/z 131, 105 and 92 were chosen, and separation of the analytes was performed on a DB‐5 ms (30 m × 0.25 mm, 0.25 µm, thickness) capillary column by gas chromatography–mass spectrometry. The calibration curves demonstrated good linearity and reproducibility over the range of 20–2000 and 20–4000 ng/mL for various tissue samples. Recoveries ranged from 86.8 to 107.5%, while intra‐ and interday relative standard deviations were all <11.3%. The analysis method was successfully applied in tissue distribution studies for CA and cinnamyl alcohol. As CA and cinnamyl alcohol may inter‐convert to one another, simultaneous determination of both analytes provides a comparative and accurate data for tissue study. The concentrations of CA and cinnamyl alcohol remaining in spleen were the highest among the main organs, including heart, liver, spleen, lung, kidney and brain. In addition, there was no long‐term accumulation of CA in rat tissues. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
3.
S. Q. Hou W. Wang Z. Y. Wang Z. W. Hu K. Liu 《Journal of Applied Mechanics and Technical Physics》2018,59(1):153-162
In order to investigate the characteristics of force chains in a granular flow system, a parallel plate shear cell is constructed to simulate the shear movement of an infinite parallel plate and observe variations in relevant parameters. The shear dilatancy process is divided into three stages, namely, plastic strain, macroscopic failure, and granular recombination. The stickslip phenomenon is highly connected with the evolution of force chains during the shear dilatancy process. The load–distribution rate curves and patterns of the force chains are utilized to describe the load-carrying behaviors and morphologic changes of force chains separately. Force chains, namely, “diagonal gridding,” “tadpole-shaped,” and “pinnate” are defined according to the form of the force chains in the corresponding three stages. 相似文献
4.
5.
Valiullina Z. R. Ivanova N. A. Shitikova O. V. Miftakhov M. S. 《Russian Journal of Organic Chemistry》2019,55(8):1131-1135
Russian Journal of Organic Chemistry - Methyl (Z)-3-[(2R,3R,4S,5S)-5-(2-methoxy-2-oxoethyl)-3,4-(isopropylidenedioxy)tetrahydrofuran-2-yl]-prop-2-enoate was synthesized, and its intramolecular... 相似文献
6.
7.
Saleh Z. M. Nasser H. Özkol E. Günöven M. Abak K. Canli S. Bek A. Turan R. 《Journal of nanoparticle research》2015,17(10):1-12
Journal of Nanoparticle Research - Plasmonic interfaces consisting of silver nanoparticles of different sizes (50–100&;nbsp;nm) have been processed by the self-assembled dewetting... 相似文献
8.
9.
10.