全文获取类型
收费全文 | 28026篇 |
免费 | 5319篇 |
国内免费 | 4048篇 |
专业分类
化学 | 20390篇 |
晶体学 | 393篇 |
力学 | 1736篇 |
综合类 | 355篇 |
数学 | 3671篇 |
物理学 | 10848篇 |
出版年
2024年 | 28篇 |
2023年 | 521篇 |
2022年 | 646篇 |
2021年 | 843篇 |
2020年 | 1164篇 |
2019年 | 1129篇 |
2018年 | 975篇 |
2017年 | 954篇 |
2016年 | 1379篇 |
2015年 | 1422篇 |
2014年 | 1770篇 |
2013年 | 2126篇 |
2012年 | 2616篇 |
2011年 | 2775篇 |
2010年 | 1963篇 |
2009年 | 1927篇 |
2008年 | 2079篇 |
2007年 | 1769篇 |
2006年 | 1706篇 |
2005年 | 1454篇 |
2004年 | 1220篇 |
2003年 | 904篇 |
2002年 | 872篇 |
2001年 | 756篇 |
2000年 | 563篇 |
1999年 | 581篇 |
1998年 | 429篇 |
1997年 | 400篇 |
1996年 | 379篇 |
1995年 | 347篇 |
1994年 | 312篇 |
1993年 | 214篇 |
1992年 | 161篇 |
1991年 | 183篇 |
1990年 | 172篇 |
1989年 | 118篇 |
1988年 | 102篇 |
1987年 | 86篇 |
1986年 | 74篇 |
1985年 | 47篇 |
1984年 | 43篇 |
1983年 | 42篇 |
1982年 | 35篇 |
1981年 | 27篇 |
1980年 | 18篇 |
1979年 | 9篇 |
1976年 | 8篇 |
1975年 | 10篇 |
1971年 | 4篇 |
1959年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 390 毫秒
81.
A Pronounced Halogen Effect on the Organogelation Properties of Peripherally Halogen Functionalized Poly(benzyl ether) Dendrons 下载免费PDF全文
Prof. Dr. Yu Feng Hui Chen Zhi‐Xiong Liu Yan‐Mei He Prof. Dr. Qing‐Hua Fan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(14):4980-4990
An interesting halogen‐substituent effect on the organogelation properties of poly(benzyl ether) dendrons is reported. A new class of poly(benzyl ether) dendrons with halo substituents decorating their periphery was synthesized and fully characterized. A systematic study on the gelation abilities, thermotropic behaviors, aggregated microstructures, and mechanical properties of self‐assembled organogels was performed to elucidate the halogen‐substituent effects on their organogelation propensity. It was found that the exact halogen substitutions on the periphery of dendrons exert a profound effect on the organogelation propensity, and dendrons G n ‐Cl (n=2, 3) and G2‐I proved to be highly efficient organogelators. The cooperation of multiple π–π, dispersive halogen, CH–π, and weak C?H ??? X hydrogen‐bonding interactions were found to be the key contributor to forming the self‐assembled gels. Dendritic organogels formed from G n ‐Cl (n=2, 3) in 1,2‐dichloroethane exhibited thixotropic‐responsive properties, and such thixotropic organogels are promising materials for future research and applications. 相似文献
82.
83.
84.
85.
86.
Qing-Long Bai Chun-Hua Zhang Juan-Juan Song Jing-Hai Liu Yan-Chun Feng Li-Mei Duan Chuan-Hui Cheng 《中国化学快报》2016,27(5):764-768
A metal-free purple H2Pc single crystal was synthesized by a facile solvothermal method, and its solubility and near-infrared (NIR) optical properties were also investigated due to its potential applications as a light-emitting layer for OLEDs. The H2Pc single crystal is insoluble in 1-chlorine naphthalene and other organic solvents. It gives a wide absorption in the range from 620 nm to 679 nm and a wide emission in near 922 nm. As an active light-emitting layer, H2Pc was employed to fabricate electroluminescent (EL) devices with a structure of ITO/NPB (30 nm)/Alq3:H2Pc (30 nm)/BCP (20 nm)/Alq3 (20 nm)/Al. The emission center is at 936 nm when the H2Pc doping concentration is 20 wt%. The doping concentration strongly governs the emission intensity. When doping concentration decreases from 10 wt% to 1 wt%, the emission intensity remarkably fades, and simultaneously the emission center undergoes a blue shift. 相似文献
87.
Results in Mathematics - In the paper, the authors establish some asymptotic formulas and double inequalities for the factorial n! and the gamma function Γ in terms of the tri-gamma function... 相似文献
88.
89.
Ann Feng Dr. Wei Cheng Dr. Jennifer Holter Dr. Neil Young Prof. Dr. Richard G. Compton 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(20):6981-6986
The charging and controlled oxidative doping of single organometallic ferrocene nanoparticles is reported in aqueous sodium tetrafluoroborate using the nano‐impacts method. It is shown that ferrocene nanoparticles of approximately 105 nm diameter are essentially quantitatively oxidatively doped with the uptake of one tetrafluoroborate anion per ferrocene molecule at suitably high overpotentials. By using lower potentials, it is possible to achieve low doping levels of single nanoparticles in a controlled manner. 相似文献
90.