全文获取类型
收费全文 | 7822篇 |
免费 | 236篇 |
国内免费 | 13篇 |
专业分类
化学 | 5119篇 |
晶体学 | 12篇 |
力学 | 148篇 |
数学 | 1371篇 |
物理学 | 1421篇 |
出版年
2020年 | 85篇 |
2019年 | 65篇 |
2018年 | 75篇 |
2017年 | 53篇 |
2016年 | 158篇 |
2015年 | 145篇 |
2014年 | 154篇 |
2013年 | 302篇 |
2012年 | 312篇 |
2011年 | 311篇 |
2010年 | 187篇 |
2009年 | 178篇 |
2008年 | 267篇 |
2007年 | 276篇 |
2006年 | 297篇 |
2005年 | 287篇 |
2004年 | 247篇 |
2003年 | 188篇 |
2002年 | 184篇 |
2001年 | 166篇 |
2000年 | 114篇 |
1999年 | 108篇 |
1998年 | 107篇 |
1997年 | 115篇 |
1996年 | 122篇 |
1995年 | 98篇 |
1994年 | 115篇 |
1993年 | 120篇 |
1992年 | 127篇 |
1991年 | 91篇 |
1990年 | 102篇 |
1989年 | 106篇 |
1988年 | 96篇 |
1987年 | 116篇 |
1986年 | 141篇 |
1985年 | 160篇 |
1984年 | 125篇 |
1983年 | 118篇 |
1982年 | 105篇 |
1981年 | 106篇 |
1980年 | 121篇 |
1979年 | 80篇 |
1978年 | 109篇 |
1977年 | 99篇 |
1976年 | 91篇 |
1975年 | 60篇 |
1974年 | 90篇 |
1973年 | 85篇 |
1972年 | 63篇 |
1970年 | 61篇 |
排序方式: 共有8071条查询结果,搜索用时 31 毫秒
1.
Cavitation erosion is caused in solids exposed to strong pressure waves developing in an adjacent fluid field. The knowledge of the transient distribution of stresses in the solid is important to understand the cause of damaging by comparisons with breaking points of the material. The modeling of this problem requires the coupling of the models for the fluid and the solid. For this purpose, we use a strategy based on the solution of coupled Riemann problems that has been originally developed for the coupling of 2 fluids. This concept is exemplified for the coupling of a linear elastic structure with an ideal gas. The coupling procedure relies on the solution of a nonlinear equation. Existence and uniqueness of the solution is proven. The coupling conditions are validated by means of quasi‐1D problems for which an explicit solution can be determined. For a more realistic scenario, a 2D application is considered where in a compressible single fluid, a hot gas bubble at low pressure collapses in a cold gas at high pressure near an adjacent structure. 相似文献
2.
3.
G. Grätzer 《Algebra Universalis》2015,74(3-4):351-359
4.
Yingchun Wu Haipeng Li Xuecheng Wu Gérard Gréhan Lutz Mädler Cyril Crua 《Proceedings of the Combustion Institute》2019,37(3):3211-3218
Droplet evaporation characterization, although of great significance, is still challenging. The recently developed phase rainbow refractometry (PRR) is proposed as an approach to measuring the droplet temperature, size as well as evaporation rate simultaneously, and is applied to a single flowing n-heptane droplet produced by a droplet-on-demand generator. The changes of droplet temperature and evaporation rate after a transient spark heating are reflected in the time-resolved PRR image. Results show that droplet evaporation rate increases with temperature, from ?1.28 m2/s at atmospheric 293 K to a range of (?1.5, ?8) m2/s when heated to (294, 315) K, agreeing well with the Maxwell and Stefan–Fuchs model predictions. Uncertainty analysis suggests that the main source is the indeterminate gradient inside droplet, resulting in an underestimation of droplet temperature and evaporation rate. With the demonstration on simultaneous measurements of droplet refractive index as well as droplet transient and local evaporation rate in this work, PRR is a promising tool to investigate single droplet evaporation in real engine conditions. 相似文献
5.
6.
7.
J. Gróh 《Colloid and polymer science》1941,94(1):1-10
Ohne Zusammenfassung
Die mitgeteilten Untersuchungen haben wir mit Unterstützung der Ungarischen wissenschaftlichen „Széchenyi“-Gesellschaft durchgeführt. 相似文献
8.
Wolfgang Gröbner 《Mathematische Annalen》1938,115(1):333-358
Ohne Zusammenfassung 相似文献
9.
Grégory Duby 《Archive for Mathematical Logic》2003,42(5):435-447
This paper generalizes results of F. K?rner from [4] where she established the existence of maximal automorphisms (i.e. automorphisms
moving all non-algebraic elements). An ω-maximal automorphism is an automorphism whose powers are maximal automorphisms. We
prove that any structure has an elementary extension with an ω-maximal automorphism. We also show the existence of ω-maximal
automorphisms in all countable arithmetically saturated structures. Further we describe the pairs of tuples (ˉa,ˉb) for which there is an ω-maximal automorphism mapping ˉa to ˉb.
Received: 12 December 2001 /
Published online: 10 October 2002
Supported by the ``Fonds pour la Formation à la Recherche dans l'Industrie et dans l'Agriculture'
Mathematics Subject Classification (2000): Primary: 03C50; Secondary: 03C57
Key words or phrases: Automorphism – Recursively saturated structure 相似文献
10.
Gerhard Rein 《Mathematical Methods in the Applied Sciences》1992,15(5):365-374
We consider a collisionless plasma, which consists of electrons and positively charged ions and is confined to a bounded domain in ?3. The distribution functions of the particles are assumed to satisfy specular reflections on the boundary of the domain and the boundary is assumed to be perfectly conducting. We establish the existence of stationary plasmas in the non-relativistic, electrostatic case described by the Vlasov–Poisson system as well as in the relativistic, electrodynamic case described by the relativistic Vlasov–Maxwell system. 相似文献