全文获取类型
收费全文 | 2460篇 |
免费 | 48篇 |
国内免费 | 6篇 |
专业分类
化学 | 1691篇 |
晶体学 | 11篇 |
力学 | 31篇 |
数学 | 380篇 |
物理学 | 401篇 |
出版年
2020年 | 21篇 |
2019年 | 26篇 |
2018年 | 20篇 |
2017年 | 20篇 |
2016年 | 41篇 |
2015年 | 50篇 |
2014年 | 43篇 |
2013年 | 109篇 |
2012年 | 95篇 |
2011年 | 97篇 |
2010年 | 72篇 |
2009年 | 84篇 |
2008年 | 94篇 |
2007年 | 111篇 |
2006年 | 79篇 |
2005年 | 98篇 |
2004年 | 91篇 |
2003年 | 59篇 |
2002年 | 66篇 |
2001年 | 33篇 |
2000年 | 54篇 |
1999年 | 62篇 |
1998年 | 55篇 |
1997年 | 53篇 |
1996年 | 44篇 |
1995年 | 28篇 |
1994年 | 47篇 |
1993年 | 53篇 |
1992年 | 49篇 |
1991年 | 37篇 |
1990年 | 25篇 |
1989年 | 28篇 |
1988年 | 29篇 |
1987年 | 41篇 |
1986年 | 45篇 |
1985年 | 45篇 |
1984年 | 43篇 |
1983年 | 35篇 |
1982年 | 51篇 |
1981年 | 33篇 |
1980年 | 53篇 |
1979年 | 31篇 |
1978年 | 34篇 |
1977年 | 24篇 |
1976年 | 34篇 |
1975年 | 28篇 |
1974年 | 19篇 |
1973年 | 14篇 |
1972年 | 17篇 |
1971年 | 14篇 |
排序方式: 共有2514条查询结果,搜索用时 15 毫秒
241.
Determination of Soot Particle Size in a Premixed Flame: a Static and Dynamic Light Scattering Study
Gert Kroner Heribert Fuchs Reinhard Tatschl Otto Glatter 《Particle & Particle Systems Characterization》2003,20(2):111-123
In this contribution we report upon our static and dynamic light scattering experiments to characterize soot particles in flames. We studied sooting laminar premixed flame with acetylene as fuel mixed with air as oxidizer. The air equivalence ratio of the combustion was larger than one. We used a Kaskan type burner with circular geometry and a stabilizing flow of nitrogen around the flame. We focused on the determination of the size of the soot particles in the center of the flame as a function of height above burner. In addition we investigated the influence of the mixing ratio of the gases on the size of the particles. Our results show that static light scattering is better suited than dynamic light scattering for a fast and reliable characterization of soot particles in flames. The latter needs detailed a priori information about the flame to allow the unique determination of sizes from the diffusion measurements. The soot particles grow monotonously with height above burner and with decreasing air equivalence ratio. The aggregates have a fractal dimension lower than two. 相似文献
242.
Christoph H. DIETRICH Steffen NOEHTE Reinhard MANNER Kurt K. SCHWARTZ 《Optical Review》1994,1(1):36-38
Amorphous As2S3 films are real-time photographic materials for phase holograms. This work focuses on the phase shift in As2S3 films as a function of the exposure. A method for measuring the phase shift response and the exposure simultaneously is presented. A relative displacement determination of interferometric patterns allows precise measurements insensitive to changes of experimental conditions. The phase shift dependence on the intensity of the writing beam is evaluated for two different films. As a result, a linear phase shift response is obtained with a dynamic range of nearly n. It is independent of the intensity over four orders of magnitude. The results are proofed by diffraction efficiency measurements. 相似文献
243.
244.
The visible surgery theory of M. Weiss is used to complete the topological classification of four-dimensionals-cobordisms between three-dimensional spherical spaceforms. Applications to various questions concerning pseudo-isotopies of 3-manifolds, computations of the simple Wall groups of finite periodic groups, and inductive detection of self-homeomorphisms of manifolds are also discussed.The first named author was partially supported by a grant from the Louisiana Board of Regents and National Science Foundation Grants DMS 89-01583 and 91-01575, and the second named author was partially supported by National Science Foundation Grants DMS 86-02543, 89-02622 and 91-02711. 相似文献
245.
246.
247.
248.
249.
250.