全文获取类型
收费全文 | 15045篇 |
免费 | 326篇 |
国内免费 | 77篇 |
专业分类
化学 | 8673篇 |
晶体学 | 91篇 |
力学 | 514篇 |
数学 | 2091篇 |
物理学 | 4079篇 |
出版年
2023年 | 68篇 |
2021年 | 122篇 |
2020年 | 177篇 |
2019年 | 116篇 |
2018年 | 127篇 |
2017年 | 94篇 |
2016年 | 230篇 |
2015年 | 229篇 |
2014年 | 276篇 |
2013年 | 561篇 |
2012年 | 628篇 |
2011年 | 788篇 |
2010年 | 441篇 |
2009年 | 394篇 |
2008年 | 658篇 |
2007年 | 723篇 |
2006年 | 724篇 |
2005年 | 744篇 |
2004年 | 606篇 |
2003年 | 475篇 |
2002年 | 441篇 |
2001年 | 414篇 |
2000年 | 384篇 |
1999年 | 228篇 |
1998年 | 210篇 |
1997年 | 192篇 |
1996年 | 236篇 |
1995年 | 218篇 |
1994年 | 211篇 |
1993年 | 251篇 |
1992年 | 240篇 |
1991年 | 218篇 |
1990年 | 172篇 |
1989年 | 179篇 |
1988年 | 203篇 |
1987年 | 184篇 |
1986年 | 142篇 |
1985年 | 191篇 |
1984年 | 182篇 |
1983年 | 139篇 |
1982年 | 175篇 |
1981年 | 155篇 |
1980年 | 152篇 |
1979年 | 158篇 |
1978年 | 160篇 |
1977年 | 121篇 |
1976年 | 139篇 |
1975年 | 102篇 |
1974年 | 121篇 |
1973年 | 98篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
1.
Reza Kordnezhadian Bing-Yu Li Armir Zogu Dr. Joachim Demaerel Prof. Dr. Wim M. De Borggraeve Dr. Ermal Ismalaj 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(60):e202201491
Pentafluorosulfanyl (SF5)-containing compounds and corresponding analogs are a highly valuable class of fluorine-containing building blocks owing to their unique properties. The reason for that is the set of peculiar and tremendously beneficial characteristics they can impart on molecules once introduced onto them. Despite this, their application in distinct scientific fields remains modest, given the extremely harsh reaction conditions needed to access such compounds. The recent synthetic approaches via S−F, and C−SF5 bond formation as well as the use of SF5-containing building blocks embody a “stairway-to-heaven” loophole in the synthesis of otherwise-inaccessible chemical scaffolds only a few years ago. Herein, we report and evaluate the properties of the SF5 group and analogs, by summarizing synthetic methodologies available to access them as well as following applications in material science and medicinal chemistry since 2015. 相似文献
2.
3.
Vsevolod Khikhlovskyi Albert J. J. M. van Breemen Jasper J. Michels René A. J. Janssen Gerwin H. Gelinck Martijn Kemerink 《Journal of Polymer Science.Polymer Physics》2015,53(17):1231-1237
In many organic electronic devices functionality is achieved by blending two or more materials, typically polymers or molecules, with distinctly different optical or electrical properties in a single film. The local scale morphology of such blends is vital for the device performance. Here, a simple approach to study the full 3D morphology of phase‐separated blends, taking advantage of the possibility to selectively dissolve the different components is introduced. This method is applied in combination with AFM to investigate a blend of a semiconducting and ferroelectric polymer typically used as active layer in organic ferroelectric resistive switches. It is found that the blend consists of a ferroelectric matrix with three types of embedded semiconductor domains and a thin wetting layer at the bottom electrode. Statistical analysis of the obtained images excludes the presence of a fourth type of domains. The criteria for the applicability of the presented technique are discussed. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1231–1237 相似文献
4.
5.
6.
Claudia Poloni Marc C. A. Stuart Pieter van der Meulen Wiktor Szymanski Ben L. Feringa 《Chemical science》2015,6(12):7311-7318
The external photocontrol over peptide folding, by the incorporation of molecular photoswitches into their structure, provides a powerful tool to study biological processes. However, it is limited so far to switches that exhibit only a rather limited geometrical change upon photoisomerization and that show thermal instability of the photoisomer. Here we describe the use of an overcrowded alkene photoswitch to control a model β-hairpin peptide. This photoresponsive unit undergoes a large conformational change and has two thermally stable isomers which has major influence on the secondary structure and the aggregation of the peptide, permitting the phototriggered formation of amyloid-like fibrils. 相似文献
7.
8.
9.
Ieva
Dauickait Amos S. Lawless Jennifer A. Scott Peter Jan van Leeuwen 《Numerical Linear Algebra with Applications》2020,27(5)
We consider the large sparse symmetric linear systems of equations that arise in the solution of weak constraint four‐dimensional variational data assimilation, a method of high interest for numerical weather prediction. These systems can be written as saddle point systems with a 3 × 3 block structure but block eliminations can be performed to reduce them to saddle point systems with a 2 × 2 block structure, or further to symmetric positive definite systems. In this article, we analyse how sensitive the spectra of these matrices are to the number of observations of the underlying dynamical system. We also obtain bounds on the eigenvalues of the matrices. Numerical experiments are used to confirm the theoretical analysis and bounds. 相似文献
10.