全文获取类型
收费全文 | 4780篇 |
免费 | 202篇 |
国内免费 | 34篇 |
专业分类
化学 | 3511篇 |
晶体学 | 31篇 |
力学 | 131篇 |
数学 | 555篇 |
物理学 | 788篇 |
出版年
2023年 | 39篇 |
2022年 | 58篇 |
2021年 | 79篇 |
2020年 | 103篇 |
2019年 | 104篇 |
2018年 | 74篇 |
2017年 | 59篇 |
2016年 | 140篇 |
2015年 | 123篇 |
2014年 | 157篇 |
2013年 | 249篇 |
2012年 | 308篇 |
2011年 | 383篇 |
2010年 | 176篇 |
2009年 | 140篇 |
2008年 | 342篇 |
2007年 | 334篇 |
2006年 | 320篇 |
2005年 | 273篇 |
2004年 | 241篇 |
2003年 | 202篇 |
2002年 | 167篇 |
2001年 | 48篇 |
2000年 | 46篇 |
1999年 | 46篇 |
1998年 | 47篇 |
1997年 | 44篇 |
1996年 | 67篇 |
1995年 | 40篇 |
1994年 | 39篇 |
1993年 | 34篇 |
1992年 | 31篇 |
1991年 | 36篇 |
1990年 | 34篇 |
1989年 | 20篇 |
1988年 | 19篇 |
1987年 | 20篇 |
1986年 | 14篇 |
1985年 | 50篇 |
1984年 | 42篇 |
1983年 | 18篇 |
1982年 | 25篇 |
1981年 | 20篇 |
1980年 | 28篇 |
1979年 | 19篇 |
1978年 | 25篇 |
1977年 | 18篇 |
1976年 | 23篇 |
1975年 | 21篇 |
1974年 | 21篇 |
排序方式: 共有5016条查询结果,搜索用时 31 毫秒
21.
Kevin Hisler 《Tetrahedron letters》2006,47(35):6293-6295
Aldehydes are prepared in excellent yield by Wittig reactions of phosphoranes on the Weinreb amide of formic acid followed by in situ hydrolysis. 相似文献
22.
23.
24.
25.
Kevin S. Peters 《Angewandte Chemie (International ed. in English)》1994,33(3):294-302
Why have molecules only been seen but not heard? For over a century chemists have probed reactions with various spectroscopic methods to learn about structures, dynamics, and reactivities of their molecules. What they have not done is to listen to their molecules react. Although the photoacoustic phenomenon has been known since 1880, it is only in the last twenty years that technology has developed to the point where sound waves produced by reacting molecules can be time resolved and the information contained within the waves deciphered. The information content within the photoacoustic wave is indeed rich, for one can learn about the dynamics and the magnitude of enthalpy changes associated with the reaction as well as the changes in molecular volume. This review article chronicles the development of time-resolved photoacoustic calorimetry and its application to a variety of reactions encountered in organic and organometallic chemistry and biochemistry. 相似文献
26.
27.
28.
29.
Kevin Welford 《Optical and Quantum Electronics》1991,23(1):1-27
Surface plasmon-polaritons have been experimentally and theoretically studied for many years but in recent years interest has grown substantially due to their possible use in novel device applications. The aim of this review is to introduce the concept of surface plasmon-polaritons so that the reader will be able to appreciate the physics they can probe, and the device applications in which they may be utilized. 相似文献
30.
Utilizing forward recoil spectrometry (FRES), we have determined the segregation isotherm which describes the interfacial excess zi* of diblock copolymers of poly (d8-styrene-b-2-vinylpyridine) (dPS-PVP) at the interface between the homopolymers PS and PVP as a function of ?∞, the volume fraction of diblock copolymer remaining in the host homopolymer. All the samples were analyzed after annealing at temperatures and times sufficient to achieve equilibrium segregation. The effect of the degree of polymerization of both the diblock copolymers and the host homopolymers on the segregation isotherm is investigated. When the degree of polymerization of the homopolymer is much larger than that of the diblock copolymer, the normalized interfacial excess (zi*/Rg), where Rg is the radius of gyration of an isolated block copolymer chain, is a universal function of that portion of the block copolymer chemical potential due to chain stretching. The existence of such a universal function is predicted by theory and its form is in good agreement with self-consistent mean field calculations. Using these results, one can predict important aspects of the block copolymer segregation (e.g., the saturation interfacial excess) without recourse to the time-consuming numerical calculations. © 1994 John Wiley & Sons, Inc. 相似文献