全文获取类型
收费全文 | 203134篇 |
免费 | 6455篇 |
国内免费 | 3566篇 |
专业分类
化学 | 99508篇 |
晶体学 | 2308篇 |
力学 | 8165篇 |
综合类 | 116篇 |
数学 | 18167篇 |
物理学 | 57523篇 |
无线电 | 27368篇 |
出版年
2022年 | 1820篇 |
2021年 | 2298篇 |
2020年 | 2433篇 |
2019年 | 2418篇 |
2018年 | 2576篇 |
2017年 | 2491篇 |
2016年 | 4016篇 |
2015年 | 3032篇 |
2014年 | 4267篇 |
2013年 | 8814篇 |
2012年 | 7924篇 |
2011年 | 9294篇 |
2010年 | 6513篇 |
2009年 | 6716篇 |
2008年 | 8467篇 |
2007年 | 8492篇 |
2006年 | 7913篇 |
2005年 | 7373篇 |
2004年 | 6311篇 |
2003年 | 5456篇 |
2002年 | 5426篇 |
2001年 | 5697篇 |
2000年 | 4672篇 |
1999年 | 4007篇 |
1998年 | 3539篇 |
1997年 | 3439篇 |
1996年 | 3182篇 |
1995年 | 2972篇 |
1994年 | 2850篇 |
1993年 | 2548篇 |
1992年 | 2777篇 |
1991年 | 2839篇 |
1990年 | 2564篇 |
1989年 | 2501篇 |
1988年 | 2373篇 |
1987年 | 2056篇 |
1986年 | 1999篇 |
1985年 | 2472篇 |
1984年 | 2544篇 |
1983年 | 2129篇 |
1982年 | 2268篇 |
1981年 | 2140篇 |
1980年 | 2057篇 |
1979年 | 2157篇 |
1978年 | 2308篇 |
1977年 | 2185篇 |
1976年 | 2232篇 |
1975年 | 2126篇 |
1974年 | 2158篇 |
1973年 | 2156篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Kazakova E. F. Dmitrieva N. E. Zvereva N. L. 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2020,94(2):341-344
Russian Journal of Physical Chemistry A - Rapidly quenched alloys of aluminum with cobalt and zirconium are investigated using a combination of means of physicochemical analysis to study the... 相似文献
32.
Bankov S. E. Vesnik M. V. Kravchenko V. F. 《Journal of Communications Technology and Electronics》2020,65(4):398-405
Journal of Communications Technology and Electronics - Abstract—The article presents a rigorous numerical solution, using the Wiener–Hopf method, to the problem of plane wave... 相似文献
33.
34.
Simultaneous determination of cinnamaldehyde and its metabolite in rat tissues by gas chromatography–mass spectrometry
下载免费PDF全文
![点击此处可从《Biomedical chromatography : BMC》网站下载免费的PDF全文](/ch/ext_images/free.gif)
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
35.
Wireless Personal Communications - The existing long term evolution networks originally designed for human-to-human communications are hard to tackle numerous and bursty random access requests from... 相似文献
36.
37.
38.
39.
40.
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