全文获取类型
收费全文 | 6707篇 |
免费 | 1070篇 |
国内免费 | 678篇 |
专业分类
化学 | 4966篇 |
晶体学 | 57篇 |
力学 | 328篇 |
综合类 | 16篇 |
数学 | 719篇 |
物理学 | 2369篇 |
出版年
2024年 | 26篇 |
2023年 | 183篇 |
2022年 | 291篇 |
2021年 | 288篇 |
2020年 | 318篇 |
2019年 | 297篇 |
2018年 | 246篇 |
2017年 | 236篇 |
2016年 | 369篇 |
2015年 | 356篇 |
2014年 | 398篇 |
2013年 | 478篇 |
2012年 | 614篇 |
2011年 | 650篇 |
2010年 | 408篇 |
2009年 | 413篇 |
2008年 | 400篇 |
2007年 | 384篇 |
2006年 | 312篇 |
2005年 | 282篇 |
2004年 | 195篇 |
2003年 | 179篇 |
2002年 | 154篇 |
2001年 | 109篇 |
2000年 | 95篇 |
1999年 | 113篇 |
1998年 | 94篇 |
1997年 | 89篇 |
1996年 | 84篇 |
1995年 | 68篇 |
1994年 | 59篇 |
1993年 | 48篇 |
1992年 | 58篇 |
1991年 | 38篇 |
1990年 | 27篇 |
1989年 | 28篇 |
1988年 | 18篇 |
1987年 | 12篇 |
1986年 | 8篇 |
1985年 | 11篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1982年 | 6篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1957年 | 2篇 |
排序方式: 共有8455条查询结果,搜索用时 15 毫秒
121.
Based on our previous work about electrically conductive adhesives (ECAs), a flexibilizer named 1,3‐propanediol bis (4‐aminobenzoate) was used to fabricate flexible ECAs (FECAs). ECAs, FECAs, and electronic devices connected by them were carried out the hot and humid aging test under constant humidity level of 85% relative humidity at 85 °C for 600 h. After aging, the bulk resistance change of ECAs was about 26%, that of FECAs was a little higher, about 29%. The contact resistance change of devices connected by ECAs and FECAs was very great, about 450% and 410%, respectively. The bonding area at connection interface between colloids and devices had delamination, even cracks. The delamination of ECAs was calculated about 60%, the average shear strength of ECAs was reduced about 45%, and those of FECAs were about 50% and 30%, respectively, so FECAs had a higher bonding stability in hot and humid environment. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
122.
Target and non‐target identification of chemical components in Lamiophlomis rotata by liquid chromatography/quadrupole time‐of‐flight mass spectrometry using a three‐step protocol 下载免费PDF全文
123.
124.
Asymmetric Michael Addition of Aldimino Esters with Chalcones Catalyzed by Silver/Xing‐Phos: Mechanism‐Oriented Divergent Synthesis of Chiral Pyrrolines 下载免费PDF全文
Xing‐Feng Bai Dr. Li Li Dr. Zheng Xu Dr. Zhan‐Jiang Zheng Prof. Dr. Chun‐Gu Xia Dr. Yu‐Ming Cui Prof. Dr. Li‐Wen Xu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(30):10399-10404
The mechanism‐oriented reaction design for the divergent synthesis of chiral molecules from simple starting materials is highly desirable. In this work, aromatic amide‐derived nonbiarylatropisomer/silver (silver/Xing‐Phos) complex was used to catalyze the Michael addition of glycine aldimino esters to chalcones and successfully applied to the subsequent cyclocondensation to afford substituted cis‐Δ(1)‐pyrroline derivatives with up to 98 % ee. Besides the inherent performance of the chiral Ag/Xing‐Phos catalyst system, it was found that the workup of such reactions played an important role for the stereoselective construction of stereodivergent Δ(1)‐pyrrolines, in which an epimerization of the cis‐Δ(1)‐pyrrolines to the trans‐isomers during was revealed. 相似文献
125.
126.
127.
128.
Shan Jiang Yong-peng Zhao Yao Xie Miao Xu Huai-yu Cui Han Wu Yang Liu Qiang Xu Qi Wang 《Applied physics. B, Lasers and optics》2012,109(1):1-7
We demonstrated the lasing of Ne-like Ar 46.9?nm pumped by capillary discharge with the delay time between pre-pulse and main-pulse ranging from 2 to 130???s. Results show that the laser output reduced significantly when the delay time is much longer than 12???s. The temporal evolution of spontaneous radiation emitted from pre-ionized plasma implies that the observed reduction of the laser output is caused by the axial non-uniformity of pre-ionized plasma density and the decrease of pre-ionized plasma density. 相似文献
129.
130.