全文获取类型
收费全文 | 1258篇 |
免费 | 122篇 |
国内免费 | 2篇 |
专业分类
化学 | 1146篇 |
晶体学 | 16篇 |
力学 | 11篇 |
数学 | 27篇 |
物理学 | 182篇 |
出版年
2023年 | 16篇 |
2022年 | 22篇 |
2021年 | 41篇 |
2020年 | 37篇 |
2019年 | 61篇 |
2018年 | 50篇 |
2017年 | 26篇 |
2016年 | 47篇 |
2015年 | 54篇 |
2014年 | 62篇 |
2013年 | 105篇 |
2012年 | 133篇 |
2011年 | 136篇 |
2010年 | 57篇 |
2009年 | 37篇 |
2008年 | 84篇 |
2007年 | 66篇 |
2006年 | 46篇 |
2005年 | 47篇 |
2004年 | 37篇 |
2003年 | 28篇 |
2002年 | 26篇 |
2001年 | 6篇 |
2000年 | 9篇 |
1999年 | 8篇 |
1998年 | 6篇 |
1997年 | 6篇 |
1995年 | 4篇 |
1994年 | 6篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1986年 | 4篇 |
1985年 | 6篇 |
1984年 | 4篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 9篇 |
1978年 | 8篇 |
1977年 | 11篇 |
1975年 | 10篇 |
1974年 | 6篇 |
1971年 | 3篇 |
1969年 | 3篇 |
1968年 | 3篇 |
1967年 | 5篇 |
1966年 | 3篇 |
排序方式: 共有1382条查询结果,搜索用时 601 毫秒
991.
Ryoichi Hirayama Yoshitaka Matsumoto Yuki Kase Miho Noguchi Koichi Ando Atsushi Ito Ryuichi Okayasu Yoshiya Furusawa 《Radiation Physics and Chemistry》2009,78(12):1175-1178
The contribution of OH radical-mediated indirect action by particle beams under hypoxic irradiation condition was investigated by using a radical scavenger. V79 cells were irradiated with 150 MeV/nucleon helium ions at an LET of 2.2 keV/μm in the presence or absence of DMSO, and their colony survivals were determined. The contribution of indirect action to cell killing under hypoxic condition was estimated to be 52±9%. We conclude that OH radical-mediated indirect action still has a half in total contribution on cell killing under hypoxic condition. 相似文献
992.
Yuko Okuyama Yuki Watanabe Mitsuhiro Takeshita Eunsang Kwon 《Tetrahedron letters》2009,50(2):193-5137
4-Hydroxy-prolinamide alcohol with different noncoordination sites as a molecule showed excellent asymmetric catalytic activity in both the Michael reaction (up to 98% ee) and the direct aldol reaction (up to >99% ee), and the catalyzing reactions with high enantioselectivity are supported by a DFT theoretical study of their transition state. 相似文献
993.
994.
We show that if a class K of finite relational structures is closed under quasi‐substructures, then there is no saturated K ‐generic structure that is superstable but not ω ‐stable (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
995.
996.
Synthesis of enantiopure 1-substituted, 1,2-disubstituted, and 1,4,5-trisubstituted imidazoles from 1,2-amino alcohols 总被引:1,自引:0,他引:1
A highly versatile method for the preparation of enantiopure 1-substituted, 1,2-disubstituted, and 1,4,5-trisubstituted imidazoles was developed by using the cyclocondensation reaction of a 1,2-dicarbonyl compound, an aldehyde, a 1,2-amino alcohol, and ammonium acetate. 相似文献
997.
Tomohiro Uchimura Satoshi Kawanabe Yuki Maeda Totaro Imasaka 《Analytical sciences》2006,22(10):1291-1295
An inverted microscope was combined with a compact dye laser with a pulse width of <190 ps and an intensified charge-coupled device (ICCD) camera with a minimum gate width of 200 ps. The resulting fluorescence lifetime imaging microscope, which has a temporal resolution of 340 ps, was used to measure the fluorescence lifetime of polymer microspherers. The results indicated a fluorescence lifetime of 0.9 ns. The present analytical instrument was also employed in an evaluation of biological cells after labeling them with SYTO 13, a fluorescent dye. 相似文献
998.
999.
Synthesis of π‐conjugated network polymers based on fluoroarene and fluorescent units via direct arylation polycondensation and their porosity and fluorescent properties
下载免费PDF全文
![点击此处可从《Journal of polymer science. Part A, Polymer chemistry》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Shotaro Hayashi Yuki Togawa Shin‐Ichi Yamamoto Toshio Koizumi Koji Nishi Atsushi Asano 《Journal of polymer science. Part A, Polymer chemistry》2017,55(23):3862-3867
In this study, we report the synthesis of π‐conjugated network polymers including unique fluorescent units via palladium‐catalyzed direct (C? H) arylation polycondensation of 1,2,4,5‐tetrafluorobenzene with tetrabromoarenes. The obtained polymers, including tetraphenylethene (TPE) or pyrene (PYR) units, had microporous structures with the specific Brunauer–Emmett–Teller (BET) surface areas at 508 and 824 m2 g?1, respectively. These polymers possessed narrow pore distributions (<15 nm). These analyses supported that π‐conjugated microporous polymers (CMPs) were synthesized by the direct arylation. Similar to the result of BET surface areas, carbon capture capacity of CMP based on PYR unit was higher than that of CMP based on TPE unit. Because the nitrogen capture capacity of these CMPs was low (≈ 0), selectivity of carbon dioxide adsorption was very high. TPE is a typical aggregation‐induced emission unit but PYR is an aggregation‐caused quenching (ACQ) molecule. The incorporation of TPE unit into the microporous polymer gave green‐colored fluorescence (Φ = 0.12). The polymer including PYR units also showed the green‐colored fluorescence (Φ = 0.05) even though the ACQ property. These synthesized CMPs exhibited characteristic solvatofluorochromism. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 3862–3867 相似文献
1000.