全文获取类型
收费全文 | 1309805篇 |
免费 | 25637篇 |
国内免费 | 7684篇 |
专业分类
化学 | 646712篇 |
晶体学 | 20229篇 |
力学 | 74125篇 |
综合类 | 102篇 |
数学 | 239621篇 |
物理学 | 362337篇 |
出版年
2021年 | 13466篇 |
2020年 | 15905篇 |
2019年 | 16036篇 |
2016年 | 27530篇 |
2015年 | 20646篇 |
2014年 | 30370篇 |
2013年 | 74239篇 |
2012年 | 36250篇 |
2011年 | 31709篇 |
2010年 | 36049篇 |
2009年 | 38700篇 |
2008年 | 31719篇 |
2007年 | 26831篇 |
2006年 | 33965篇 |
2005年 | 26054篇 |
2004年 | 27902篇 |
2003年 | 26722篇 |
2002年 | 27922篇 |
2001年 | 26619篇 |
2000年 | 23568篇 |
1999年 | 21915篇 |
1998年 | 20819篇 |
1997年 | 20814篇 |
1996年 | 21031篇 |
1995年 | 19107篇 |
1994年 | 18556篇 |
1993年 | 18093篇 |
1992年 | 17802篇 |
1991年 | 18122篇 |
1990年 | 17359篇 |
1989年 | 17395篇 |
1988年 | 16961篇 |
1987年 | 16979篇 |
1986年 | 15864篇 |
1985年 | 22307篇 |
1984年 | 23638篇 |
1983年 | 19911篇 |
1982年 | 21589篇 |
1981年 | 20827篇 |
1980年 | 20163篇 |
1979年 | 20258篇 |
1978年 | 21643篇 |
1977年 | 21195篇 |
1976年 | 20878篇 |
1975年 | 19584篇 |
1974年 | 19244篇 |
1973年 | 19711篇 |
1972年 | 14210篇 |
1968年 | 12070篇 |
1967年 | 12435篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
Giang Truong Nguyen Prof. Dr. Liviu Ungur 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(30):e202200227
Employing radical bridges between anisotropic metal ions has been a viable route to achieve high-performance single-molecule magnets (SMMs). While the bridges have been mainly considered for their ability to promote exchange interactions, the crystal-field effect arising from them has not been taken into account explicitly. This lack of consideration may distort the understanding and limit the development of the entire family. To shed light on this aspect, herein we report a theoretical investigation of a series of N -radical-bridged diterbium complexes. It is found that while promoting strong exchange coupling between the terbium ions, the N -radical induces a crystal field that interferes destructively with that of the outer ligands, and thus reduces the overall SMM behavior. Based on the theoretical results, we conclude that the SMM behavior in this series could be further maximized if the crystal field of the outer ligands is designed to be collinear with that of the radical bridge. This conclusion can be generalized to all exchange-coupled SMMs. 相似文献
2.
3.
4.
A liquid dewetting method for the determination of the viscoelastic properties of ultrathin polymer films has been extended to study thickness effects on the properties of ultrathin polycarbonate (PC) films. PC films with film thicknesses ranging from 4 to 299 nm were placed on glycerol at temperatures from below the macroscopic glass transition temperature (Tg) to above it with the dewetting responses being monitored. It is found that the isothermal creep results for films of the same thickness, but dewetted at different temperatures can be superposed into one master curve, which is consistent with the fact of PC being a thermorheologically simple material. Furthermore, the results show that the Tg of PC thin films is thickness dependent, but the dependence is weaker than the results for freely standing films and similar to literature data for PC films supported on rigid substrates. It was also found that the rubbery plateau region for the PC films stiffens dramatically, but still less than what has been observed for freely standing polycarbonate films. The rubbery stiffening is discussed in terms of a recently reported model that relates macroscopic segmental dynamics with the stiffening. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1559–1566 相似文献
5.
6.
Paired single residue‐transposed Lys‐N and Lys‐C digestions for label‐free identification of N‐terminal and C‐terminal MS/MS peptide product ions: ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry and tandem mass spectrometry for peptide de novo sequencing
下载免费PDF全文
![点击此处可从《Rapid communications in mass spectrometry : RCM》网站下载免费的PDF全文](/ch/ext_images/free.gif)
7.
The influence of different referencing methods on the accuracy of δ13C value measurement of ethanol fuel by gas chromatography/combustion/isotope ratio mass spectrometry
下载免费PDF全文
![点击此处可从《Rapid communications in mass spectrometry : RCM》网站下载免费的PDF全文](/ch/ext_images/free.gif)
8.
9.
10.
Chemical versus Electrochemical Synthesis of Carbon Nano‐onion/Polypyrrole Composites for Supercapacitor Electrodes
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Olena Mykhailiv Monika Imierska Martyna Petelczyc Prof. Dr. Luis Echegoyen Dr. Marta E. Plonska‐Brzezinska 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(15):5783-5793
The development of high‐surface‐area carbon electrodes with a defined pore size distribution and the incorporation of pseudo‐active materials to optimize the overall capacitance and conductivity without destroying the stability are at present important research areas. Composite electrodes of carbon nano‐onions (CNOs) and polypyrrole (Ppy) were fabricated to improve the specific capacitance of a supercapacitor. The carbon nanostructures were uniformly coated with Ppy by chemical polymerization or by electrochemical potentiostatic deposition to form homogenous composites or bilayers. The materials were characterized by transmission‐ and scanning electron microscopy, differential thermogravimetric analyses, FTIR spectroscopy, piezoelectric microgravimetry, and cyclic voltammetry. The composites show higher mechanical and electrochemical stabilities, with high specific capacitances of up to about 800 F g?1 for the CNOs/SDS/Ppy composites (chemical synthesis) and about 1300 F g?1 for the CNOs/Ppy bilayer (electrochemical deposition). 相似文献