全文获取类型
收费全文 | 3744篇 |
免费 | 78篇 |
国内免费 | 19篇 |
专业分类
化学 | 2562篇 |
晶体学 | 25篇 |
力学 | 66篇 |
数学 | 531篇 |
物理学 | 657篇 |
出版年
2022年 | 27篇 |
2021年 | 54篇 |
2020年 | 34篇 |
2019年 | 49篇 |
2018年 | 30篇 |
2017年 | 31篇 |
2016年 | 82篇 |
2015年 | 84篇 |
2014年 | 92篇 |
2013年 | 128篇 |
2012年 | 161篇 |
2011年 | 168篇 |
2010年 | 105篇 |
2009年 | 93篇 |
2008年 | 133篇 |
2007年 | 184篇 |
2006年 | 132篇 |
2005年 | 137篇 |
2004年 | 145篇 |
2003年 | 106篇 |
2002年 | 110篇 |
2001年 | 48篇 |
2000年 | 56篇 |
1999年 | 46篇 |
1998年 | 31篇 |
1997年 | 34篇 |
1996年 | 42篇 |
1995年 | 37篇 |
1994年 | 34篇 |
1993年 | 28篇 |
1992年 | 36篇 |
1991年 | 22篇 |
1988年 | 26篇 |
1987年 | 29篇 |
1986年 | 27篇 |
1985年 | 34篇 |
1983年 | 23篇 |
1982年 | 30篇 |
1981年 | 38篇 |
1980年 | 26篇 |
1978年 | 25篇 |
1974年 | 20篇 |
1965年 | 41篇 |
1964年 | 91篇 |
1963年 | 126篇 |
1962年 | 160篇 |
1961年 | 142篇 |
1960年 | 145篇 |
1959年 | 25篇 |
1958年 | 45篇 |
排序方式: 共有3841条查询结果,搜索用时 15 毫秒
131.
Felix Becker Klaus Zimmermann Tatiana Volkova Vladimir T. Minchenya 《Regular and Chaotic Dynamics》2013,18(1-2):63-74
This article concerns microrobots for solid and liquid environments. A short overview of microrobotics, suitable actuators and energy systems is given. The principles of terrestrial and aquatic locomotion are discussed and illustrated with examples from the literature on robotics. The state of the art with a focus on piezo microrobots for solid and liquid environments is presented. Furthermore, we report an amphibious prototype, which can move on flat solid ground and on the free surface of water. The design, characteristic parameters and experiments on locomotion are described. The robot is characterized by a light and simple design and can perform twodimensional locomotion in different environments with a speed up to 30 mm/s. An analytical model to predict the maximum carrying capacity of the robot on water is solved numerically. 相似文献
132.
Dr. Peter Wick Dr. Anna E. Louw‐Gaume Dr. Melanie Kucki Prof. Harald F. Krug Prof. Kostas Kostarelos Prof. Bengt Fadeel Prof. Kenneth A. Dawson Dr. Anna Salvati Prof. Ester Vázquez Dr. Laura Ballerini Dr. Mauro Tretiach Dr. Fabio Benfenati Dr. Emmanuel Flahaut Dr. Laury Gauthier Prof. Maurizio Prato Dr. Alberto Bianco 《Angewandte Chemie (International ed. in English)》2014,53(30):7714-7718
133.
134.
135.
Abstract The physical properties of Pb2+ impurities in the perovskite-like lattice of KMgF3 are very similar to those of (ns)2 ions in alkali halides. The impurity inhomogeneous distribution leads to high dopant levels in the bottom region of the crystals, with a segregation coefficient equal to 0. 020. The optical features of the 336 nm emission support its attribution to luminescence of Pb2+ ions from the relaxed excited B state. 相似文献
136.
137.
The impact of blood on liver metabolite profiling – a combined metabolomic and proteomic approach 下载免费PDF全文
Saray Ly‐Verdú Alexander Schaefer Melanie Kahle Thomas Groeger Susanne Neschen Jose M. Arteaga‐Salas Marius Ueffing Martin Hrabe de Angelis Ralf Zimmermann 《Biomedical chromatography : BMC》2014,28(2):231-240
Metabolomics has entered the well‐established omic sciences as it is an indispensable information resource to achieve a global picture of biological systems. The aim of the present study was to estimate the influence of blood removal from mice liver as part of sample preparation for metabolomic and proteomic studies. For this purpose, perfused mice liver tissue (i.e. with blood removed) and unperfused mice liver tissue (i.e. containing blood) were compared by two‐dimensional gas chromatography time of flight mass spectrometry (GC × GC‐TOFMS) for the metabolomic part, and by liquid chromatography tandem mass spectrometry (LC‐MS/MS) for the proteomic part. Our data showed significant differences between the unperfused and perfused liver tissue samples. Furthermore, we also observed an overlap of blood and tissue metabolite profiles in our data, suggesting that the perfusion of liver tissue prior to analysis is beneficial for an accurate metabolic profile of this organ. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
138.
Eva Lucaccini Matteo Briganti Dr. Mauro Perfetti Dr. Laure Vendier Dr. Jean‐Pierre Costes Dr. Federico Totti Prof. Dr. Roberta Sessoli Prof. Dr. Lorenzo Sorace 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(16):5552-5562
The magnetic behaviour of a Dy(LH)3 complex (LH? is the anion of 2‐hydroxy‐N′‐[(E)‐(2‐hydroxy‐3‐methoxyphenyl)methylidene]benzhydrazide) was analysed in depth from both theoretical and experimental points of view. Cantilever torque magnetometry indicated that the complex has Ising‐type anisotropy, and provided two possible directions for the easy axis of anisotropy due to the presence of two magnetically non‐equivalent molecules in the crystal. Ab initio calculations confirmed the strong Ising‐type anisotropy and disentangled the two possible orientations. The computed results obtained by using ab initio calculations were then used to rationalise the composite dynamic behaviour observed for both pure DyIII phase and YIII diluted phase, which showed two different relaxation channels in zero and non‐zero static magnetic fields. In particular, we showed that the relaxation behaviour at the higher temperature range can be correctly reproduced by using a master matrix approach, which suggests that Orbach relaxation is occurring through a second excited doublet. 相似文献
139.
Jose Gracia Mauro Fianchini Chiara Biz Victor Polo Roberto Gómez 《Current Opinion in Electrochemistry》2021
Strongly correlated catalysts can be understood from precise quantum approximations. Incorporating properly electronic correlations thus let’s define Spin rules in catalysis, opening a new door towards optimum compositions for the most important reactions for a sustainable future. 相似文献
140.
Computational Management Science - In this paper, we consider a random vector $$X=\left( X_1,X_2\right) $$ following a multivariate Skew Normal distribution and we provide an explicit formula for... 相似文献