全文获取类型
收费全文 | 1773篇 |
免费 | 129篇 |
国内免费 | 32篇 |
专业分类
化学 | 1225篇 |
晶体学 | 20篇 |
力学 | 52篇 |
综合类 | 3篇 |
数学 | 184篇 |
物理学 | 450篇 |
出版年
2023年 | 12篇 |
2022年 | 15篇 |
2021年 | 30篇 |
2020年 | 29篇 |
2019年 | 37篇 |
2018年 | 23篇 |
2017年 | 21篇 |
2016年 | 54篇 |
2015年 | 55篇 |
2014年 | 85篇 |
2013年 | 85篇 |
2012年 | 145篇 |
2011年 | 157篇 |
2010年 | 87篇 |
2009年 | 104篇 |
2008年 | 138篇 |
2007年 | 125篇 |
2006年 | 80篇 |
2005年 | 92篇 |
2004年 | 58篇 |
2003年 | 46篇 |
2002年 | 41篇 |
2001年 | 38篇 |
2000年 | 37篇 |
1999年 | 10篇 |
1998年 | 12篇 |
1997年 | 12篇 |
1996年 | 12篇 |
1995年 | 14篇 |
1994年 | 11篇 |
1993年 | 28篇 |
1992年 | 13篇 |
1991年 | 17篇 |
1990年 | 8篇 |
1989年 | 7篇 |
1988年 | 11篇 |
1987年 | 9篇 |
1986年 | 10篇 |
1985年 | 22篇 |
1984年 | 15篇 |
1983年 | 10篇 |
1982年 | 12篇 |
1980年 | 12篇 |
1979年 | 11篇 |
1978年 | 10篇 |
1977年 | 10篇 |
1976年 | 12篇 |
1975年 | 9篇 |
1973年 | 9篇 |
1971年 | 5篇 |
排序方式: 共有1934条查询结果,搜索用时 15 毫秒
1.
Fan Wang Zicheng Zuo Liang Li Kuo Li Feng He Zhongqing Jiang Yuliang Li 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(42):15152-15157
A two‐dimensional (2D) carbon nanofilm with uniform artificial nanopores is an ideal material to ultimately suppress the fuel permeation in the proton exchange membrane fuel cells. Graphdiyne has great mechanical strength, high dimensional stability, and controllable nanopores, and has good prospects to play this crucial role. It is found that graphdiyne nanofilm with amino groups and natural nanopores can be easily prepared with high integrity. The aminated graphdiyne has good compatibility with the Nafion matrix owing to the acid–base interaction between them. The excellent comprehensive properties of graphdiyne in selectivity, dimensional stability, and integrity effectively improve the power performance and stability of fuel cells at wide temperature. Our results can be developed into a universal method that can easily realize the selective separation of ions and small molecules, and open a new way for the emerging applications in green energy. 相似文献
2.
Ling-Yang Hsu Qiumin Liang Zhiheng Wang Hsin-Hung Kuo Wun-Shan Tai Shi-Jian Su Xiuwen Zhou Yi Yuan Yun Chi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(67):15375-15386
Iridium complexes bearing chelating cyclometalates are popular choices as dopant emitters in the fabrication of organic light-emitting diodes (OLEDs). In this contribution, we report a series of blue-emitting, bis-tridentate IrIII complexes bearing chelates with two fused five-six-membered metallacycles, which are in sharp contrast to the traditional designs of tridentate chelates that form the alternative, fused five-five metallacycles. Five IrIII complexes, Px-21 – 23 , Cz-4 , and Cz-5 , have been synthesized that contain a coordinated dicarbene pincer chelate incorporating a methylene spacer and a dianionic chromophoric chelate possessing either a phenoxy or carbazolyl appendage to tune the coordination arrangement. All these tridentate chelates afford peripheral ligand–metal–ligand bite angles of 166–170°, which are larger than the typical bite angle of 153–155° observed for their five-five-coordinated tridentate counterparts, thereby leading to reduced geometrical distortion in the octahedral frameworks. Photophysical measurements and TD-DFT studies verified the inherent transition characteristics that give rise to high emission efficiency, and photodegradation experiments confirmed the improved stability in comparison with the benchmark fac-[Ir(ppy)3] in degassed toluene at room temperature. Phosphorescent OLED devices were also fabricated, among which the carbazolyl-functionalized emitter Cz-5 exhibited the best performance among all the studied bis-tridentate phosphors, showing a maximum external quantum efficiency (EQEmax) of 18.7 % and CIEx,y coordinates of (0.145, 0.218), with a slightly reduced EQE of 13.7 % at 100 cd m−2 due to efficiency roll-off. 相似文献
3.
Emily J. Hopkins Dr. Yurii Prots Dr. Ulrich Burkhardt Dr. Yves Watier Dr. Zhiwei Hu Dr. Chang‐Yang Kuo Dr. Jen‐Che Chiang Dr. Tun‐Wen Pi Dr. Arata Tanaka Prof. Liu Hao Tjeng Dr. Martin Valldor 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(21):7938-7943
Through a solid‐state reaction, a practically phase pure powder of Ba3V2S4O3 was obtained. The crystal structure was confirmed by X‐ray single‐crystal and synchrotron X‐ray powder diffraction (P63, a=10.1620(2), c=5.93212(1) Å). X‐ray absorption spectroscopy, in conjunction with multiplet calculations, clearly describes the vanadium in charge‐disproportionated VIIIS6 and VVSO3 coordinations. The compound is shown to be a strongly correlated Mott insulator, which contradicts previous predictions. Magnetic and specific heat measurements suggest dominant antiferromagnetic spin interactions concomitant with a weak residual ferromagnetic component, and that intrinsic geometric frustration prevents long‐range order from evolving. 相似文献
4.
Daoyong Zhu Zhiwei Jiao Yonggui Robin Chi Tho P. Gonalves Kuo‐Wei Huang Jianrong Steve Zhou 《Angewandte Chemie (International ed. in English)》2020,59(13):5341-5345
Substituted cyclohexylamines are becoming increasingly important in drug discovery. Asymmetric Heck insertion/amination of nonconjugated cyclodienes proceeds to give 5‐aryl cyclohexenylamines with good enantioselectivity and exclusive trans configurations. Primary and secondary anilines, indoline, and benzylamines are suitable amines. The weakly donating diphosphite Kelliphite forms a deep unsymmetrical pocket, which is essential for stereoselective anti attack of amines. 相似文献
5.
6.
7.
8.
Yang T. L. Kao C. L. Kuo C. E. Yeh H. C. Li W. J. Li H. T. Chen C. Y. 《Chemistry of Natural Compounds》2022,58(5):825-827
Chemistry of Natural Compounds - A novel bibenzyl derivative, hydrangchinenin (1), was isolated from the stems of Hydrangea chinensis Maxim. (Hydrangeaceae). Its structure was determined on the... 相似文献
9.
10.
Chen C. Y. Kao C. L. Kuo C. E. Li H. T. Wu M. D. Cheng M. J. 《Chemistry of Natural Compounds》2022,58(4):644-646
Chemistry of Natural Compounds - A new 24-crown 8-ether, namely mahoniafortunin (1) was isolated from the leaves of Mahonia fortunei (Lindl.) Fedde (Berberidaceae). The structure of the new crown... 相似文献