全文获取类型
收费全文 | 37418篇 |
免费 | 1215篇 |
国内免费 | 288篇 |
专业分类
化学 | 25532篇 |
晶体学 | 221篇 |
力学 | 927篇 |
综合类 | 1篇 |
数学 | 6184篇 |
物理学 | 6056篇 |
出版年
2022年 | 290篇 |
2021年 | 500篇 |
2020年 | 521篇 |
2019年 | 485篇 |
2018年 | 447篇 |
2017年 | 435篇 |
2016年 | 895篇 |
2015年 | 887篇 |
2014年 | 1012篇 |
2013年 | 1997篇 |
2012年 | 2142篇 |
2011年 | 2523篇 |
2010年 | 1420篇 |
2009年 | 1199篇 |
2008年 | 2078篇 |
2007年 | 2040篇 |
2006年 | 2059篇 |
2005年 | 1861篇 |
2004年 | 1729篇 |
2003年 | 1421篇 |
2002年 | 1369篇 |
2001年 | 668篇 |
2000年 | 584篇 |
1999年 | 522篇 |
1998年 | 451篇 |
1997年 | 511篇 |
1996年 | 492篇 |
1995年 | 440篇 |
1994年 | 466篇 |
1993年 | 401篇 |
1992年 | 379篇 |
1991年 | 366篇 |
1990年 | 329篇 |
1989年 | 313篇 |
1988年 | 286篇 |
1987年 | 230篇 |
1986年 | 255篇 |
1985年 | 387篇 |
1984年 | 388篇 |
1983年 | 332篇 |
1982年 | 366篇 |
1981年 | 332篇 |
1980年 | 350篇 |
1979年 | 283篇 |
1978年 | 316篇 |
1977年 | 289篇 |
1976年 | 236篇 |
1975年 | 200篇 |
1974年 | 198篇 |
1973年 | 174篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Backstepping design is proposed for synchronization of Genesio chaotic system. Firstly, the control problem for the chaos synchronization of nominal Genesio systems without unknown parameters is considered. Next, an adaptive backstepping control law is derived to make the error signals between drive Genesio system and response Genesio system with an uncertain parameter asymptotically synchronized. Finally, the approach is extended to the synchronization problem for the system with three unknown parameters. The stability analysis in this article is proved by using a well-known Lyapunov stability theorem. Note that the approach provided here needs only a single controller to realize the synchronization. Two numerical simulations are presented to show the effectiveness of the proposed chaos synchronization scheme. 相似文献
102.
T. Kasahara H.S. Park D. Shindo H. Yoshikawa T. Sato K. Kondo 《Journal of magnetism and magnetic materials》2006
Domain wall motion in Mn–Zn and Ni–Zn ferrites with applied magnetic fields is investigated by in situ observations with Lorentz microscopy and electron holography. It is found that both Mn–Zn and Ni–Zn ferrites have a mean grain size of approximately 10 μm and several pores with sizes ranging from 0.2 to 1.1 μm. In situ observations by Lorentz microscopy with an applied magnetic field reveals that in Mn–Zn ferrite, the domain walls move easily across the grain boundary, while in Ni–Zn ferrite, the domain walls move along the grain boundary but are pinned at the grain boundary and pores. From in situ observations of Ni–Zn ferrite by electron holography, it is clarified that domain wall pinning at the grain boundary retards a sensitive increase in magnetic flux parallel to the applied field direction, which is considered to result in high hysteresis loss. 相似文献
103.
104.
Peter Šimon 《Journal of Thermal Analysis and Calorimetry》2006,83(3):521-522
This
issue of Journal of Thermal Analysis and Calorimetry contains selected papers
based on presentations in the field of thermal characteristics of advanced
polymer systems presented at the 8th International
Symposium on Polymers for Advanced Technologies (PAT 2005) held in Budapest,
September 2005.
Guest Editors 相似文献
105.
106.
In this paper, we analyze the manufacturing lead time in a production system with BMAP (Batch Markovian Arrival process) input and post-operation operated under the N-policy. We use the factorization principle to derive the waiting time distribution (hence the manufacturing lead time) and the mean performance measures. A numerical example is provided. 相似文献
107.
In this paper, the possibility of using the gradients of the temperature and of the internal parameters as additional state variables in Continuum Thermodynamics is considered. The expressions of the two principles are discussed and Clausius–Duhem inequality is derived under an appropriate statement of the internal entropy production. Several formulations are proposed and compared to existing results in the literature. To cite this article: P. Ireman, Q.S. Nguyen, C. R. Mecanique 332 (2004). 相似文献
108.
Monodisperse polyaniline nanoparticles (PAPSSA) were synthesized from an oxidative dispersion polymerization using poly(sodium 4-styrenesulfonate) (PSSA) as both a polymeric stabilizer and a dopant agent due to its acidity. The nanoparticles were being stabilized with two different molecular weight of PSSA. Size effect of PAPSSA particles were examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and dynamic light scattering (DLS). The d.c. electrical conductivity of composite films on the glass substrate was measured by a four-probe method. It was found that the electrical properties of the composite films are affected by the content of nano-sized polyaniline and different molecular weights of stabilizer in the poly(vinyl alcohol) (PVA) matrix. 相似文献
109.
110.
A new parallel storm surge model, the Parallel Environmental Model (PEM), is developed and tested by comparisons with analytic solutions. The PEM is a 2‐D vertically averaged, wetting and drying numerical model and can be operated in explicit, semi‐implicit and fully implicit modes. In the implicit mode, the propagation, Coriolis and bottom friction terms can all be treated implicitly. The advection and diffusion terms are solved with a parallel Eulerian–Lagrangian scheme developed for this study. The model is developed specifically for use on parallel computer systems and will function accordingly in either explicit of implicit modes. Storm boundary conditions are based on a simple exponential decay of pressure from the centre of a storm. The simulated flooding caused by a major Category 5 hurricane making landfall in the Indian River Lagoon, Florida is then presented as an example application of the PEM. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献