全文获取类型
收费全文 | 15747篇 |
免费 | 3188篇 |
国内免费 | 2033篇 |
专业分类
化学 | 11848篇 |
晶体学 | 232篇 |
力学 | 869篇 |
综合类 | 133篇 |
数学 | 1731篇 |
物理学 | 6155篇 |
出版年
2024年 | 44篇 |
2023年 | 438篇 |
2022年 | 526篇 |
2021年 | 748篇 |
2020年 | 871篇 |
2019年 | 814篇 |
2018年 | 667篇 |
2017年 | 629篇 |
2016年 | 873篇 |
2015年 | 961篇 |
2014年 | 1063篇 |
2013年 | 1269篇 |
2012年 | 1573篇 |
2011年 | 1576篇 |
2010年 | 1051篇 |
2009年 | 1087篇 |
2008年 | 1117篇 |
2007年 | 959篇 |
2006年 | 844篇 |
2005年 | 689篇 |
2004年 | 497篇 |
2003年 | 392篇 |
2002年 | 361篇 |
2001年 | 263篇 |
2000年 | 235篇 |
1999年 | 225篇 |
1998年 | 188篇 |
1997年 | 159篇 |
1996年 | 145篇 |
1995年 | 113篇 |
1994年 | 98篇 |
1993年 | 89篇 |
1992年 | 91篇 |
1991年 | 54篇 |
1990年 | 46篇 |
1989年 | 47篇 |
1988年 | 32篇 |
1987年 | 28篇 |
1986年 | 27篇 |
1985年 | 26篇 |
1984年 | 15篇 |
1983年 | 6篇 |
1982年 | 8篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1976年 | 2篇 |
1971年 | 2篇 |
1966年 | 2篇 |
1957年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
Wu Shang-Zhuo Yu Qiang Li Yue-Hua Cui Guang-Hua 《Research on Chemical Intermediates》2021,47(2):835-851
Research on Chemical Intermediates - Combination of three aromatic carboxylic acids (5-nitroisophthalic acid (H2nip), 2,6-naphthalenedicarboxylic acid (H2ndc), tetrabromoterephthalic acid (H2tbta))... 相似文献
13.
14.
In the view of substrate availability, atomic efficiency and cost, directly using arenols as coupling partners in cross‐coupling, would be one of the most attractive goals. Up to date, many efforts have been made to activate the C—O bond of phenols with different strategies, for example, through in‐situ formed intermediates, through a catalytic reductive dearomatization‐condensation‐rearomatization sequence or catalytic deoxygenation. In this review, we summarized recent advances in cross‐couplings of arenols as the electrophiles via C—O activation. 相似文献
15.
16.
Tuning the Basicity of Cyano‐Containing Ionic Liquids to Improve SO2 Capture through Cyano–Sulfur Interactions 下载免费PDF全文
Dr. Guokai Cui Fengtao Zhang Xiuyuan Zhou Prof. Haoran Li Prof. Jianji Wang Prof. Congmin Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(14):5632-5639
A new approach has been developed to improve SO2 sorption by cyano‐containing ionic liquids (ILs) through tuning the basicity of ILs and cyano–sulfur interaction. Several kinds of cyano‐containing ILs with different basicity were designed, prepared, and used for SO2 capture. The interaction between these cyano‐containing ILs and SO2 was investigated by FTIR and NMR methods. Spectroscopic investigations and quantum chemical calculations showed that dramatic effects on SO2 capacity originate from the basicity of the ILs and enhanced cyano–sulfur interaction. Furthermore, the captured SO2 was easy to release by heating or bubbling N2 through the ILs. This efficient and reversible process, achieved by tuning the basicity of ILs, is an excellent alternative to current technologies for SO2 capture. 相似文献
17.
Hierarchical motion planning at the acceleration level based on task priority matrix for space robot
Nonlinear Dynamics - A capacitive micromachined ultrasonic transducer (CMUT) due to many benefits is being considered as an imaging and therapeutic technology recently. The critical challenge is to... 相似文献
18.
Nonlinear Dynamics - Conventional tuned liquid column dampers (TLCDs) are deficient in multidirectionality. In contrast, toroidal TLCDs are designed to extend the application to multidirectional... 相似文献
19.
20.
We demonstrate a harmonically pumped femtosecond optical parametric oscillator(OPO)laser using a frequency-doubled mode-locked Yb:KGW laser at a repetition rate of 75.5 MHz as the pump laser.Based on a bismuth borate nonlinear crystal,repetition rates up to 1.13 GHz are realized,which is 15 times that of the pump laser.The signal wavelength is tunable from 700 nm to 887 nm.The maximum power of the signal is 207 m W at the central wavelength of 750 nm and the shortest pulse duration is 117 fs at 780 nm.The beam quality(M^2 factor)in the horizontal and vertical directions of the output beam are 1.077 and 1.141,respectively. 相似文献