全文获取类型
收费全文 | 2442篇 |
免费 | 363篇 |
国内免费 | 260篇 |
专业分类
化学 | 465篇 |
晶体学 | 30篇 |
力学 | 733篇 |
综合类 | 10篇 |
数学 | 856篇 |
物理学 | 971篇 |
出版年
2024年 | 3篇 |
2023年 | 65篇 |
2022年 | 95篇 |
2021年 | 115篇 |
2020年 | 161篇 |
2019年 | 77篇 |
2018年 | 123篇 |
2017年 | 129篇 |
2016年 | 140篇 |
2015年 | 151篇 |
2014年 | 190篇 |
2013年 | 192篇 |
2012年 | 242篇 |
2011年 | 241篇 |
2010年 | 172篇 |
2009年 | 180篇 |
2008年 | 125篇 |
2007年 | 130篇 |
2006年 | 120篇 |
2005年 | 77篇 |
2004年 | 52篇 |
2003年 | 43篇 |
2002年 | 37篇 |
2001年 | 45篇 |
2000年 | 16篇 |
1999年 | 37篇 |
1998年 | 33篇 |
1997年 | 19篇 |
1996年 | 16篇 |
1995年 | 10篇 |
1994年 | 12篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1979年 | 2篇 |
1971年 | 2篇 |
1957年 | 1篇 |
排序方式: 共有3065条查询结果,搜索用时 187 毫秒
1.
The chiral phase transition and equation of state are studied within a novel self-consistent mean-field approximation of the two-flavor Nambu-Jona-Lasinio model. In this newly developed model, modifications to the chemical μ and chiral chemical \begin{document}$\mu_5$\end{document} ![]()
![]()
potentials are naturally included by introducing vector and axial-vector channels from Fierz-transformed Lagrangian to the standard Lagrangian. In the proper-time scheme, the chiral phase transition is a crossover in the \begin{document}$T-\mu$\end{document} ![]()
![]()
plane. However, when \begin{document}$\mu_5$\end{document} ![]()
![]()
is incorporated, our study demonstrates that a first order phase transition may emerge. Furthermore, the chiral imbalance will soften the equation of state of quark matter. The mass-radius relationship and tidal deformability of quark stars are calculated. The maximum mass and radius decrease as \begin{document}$\mu_5$\end{document} ![]()
![]()
increases. Our study also indicates that the vector and axial-vector channels exhibit an opposite influence on the equation of state. 相似文献
2.
为提高薄壁管结构耐撞性,以雀尾螳螂虾螯为仿生原型,结合仿生学设计方法,设计一种含正弦胞元的多胞薄壁管结构。以初始峰值载荷、比吸能和碰撞力效率为耐撞性指标,通过有限元数值模拟分析了不同碰撞角度(0o、10o、20o和30o)条件下,仿生胞元数对薄壁管耐撞性的影响,通过多目标的复杂比例评估法获取仿生薄壁管的最优胞元数。基于不同碰撞角度权重因子组合,设置了4种单一角度工况和3种多角度工况,采用多目标粒子群优化方法获取了不同工况下薄壁管结构最优胞元高宽比和壁厚。复杂比例评估结果表明,胞元数为4的薄壁管为最优晶胞数仿生薄壁管。优化结果表明,单一角度工况下,最优结构参数高宽比的范围为0.88~1.50,壁厚的范围为0.36~0.60 mm,碰撞角度为0o和10o的最优高宽比明显小于碰撞角度为20o和30o的;多角度工况下,最优高宽比范围为1.01~1.10,壁厚范围为0.49~0.57 mm。 相似文献
3.
Nonlinear Dynamics - This paper proposes an optimal parameter design of control scheme for mechanical systems by adopting the Stackelberg game theory. The goal of the control is to drive the... 相似文献
4.
Journal of Theoretical Probability - Consider the sample covariance matrices of form $$W=n^{-1}C C^{\top }$$ , where C is a $$k\times n$$ matrix with real-valued, independent and identically... 相似文献
5.
Yandong Guo 《中国物理 B》2022,31(12):127201-127201
Controlling the spin transport at the single-molecule level, especially without the use of ferromagnetic contacts, becomes a focus of research in spintronics. Inspired by the progress on atomic-level molecular synthesis, through first-principles calculations, we investigate the spin-dependent electronic transport of graphene nanoflakes with side-bonded functional groups, contacted by atomic carbon chain electrodes. It is found that, by rotating the functional group, the spin polarization of the transmission at the Fermi level could be switched between completely polarized and unpolarized states. Moreover, the transition between spin-up and spin-down polarized states can also be achieved, operating as a dual-spin filter. Further analysis shows that, it is the spin-dependent shift of density of states, caused by the rotation, that triggers the shift of transmission peaks, and then results in the variation of spin polarization. Such a feature is found to be robust to the length of the nanoflake and the electrode material, showing great application potential. Those findings may throw light on the development of spintronic devices. 相似文献
6.
In this paper, we propose a mechanism on how to construct long MDS self-dual codes from short ones. These codes are special types of generalized Reed-Solomon (GRS) codes or extended generalized Reed-Solomon codes. The main tool is utilizing additive structure or multiplicative structure on finite fields. By applying this method, more MDS self-dual codes can be constructed. 相似文献
7.
Nonlinear Dynamics - To describe the particular mechanical behaviors of beams with both uniform and non-uniform cross sections, such as the bidirectional bending, torsion-bending coupling, the... 相似文献
8.
9.
Nonlinear Dynamics - Aiming to isolate disturbance vibration for heavy machines with low frequency, a novel hydro-pneumatic vibration isolator with high-static and low-dynamic (HSLD) stiffness is... 相似文献
10.
In this paper, we present some necessary and sufficient conditions under which an irreducible polynomial is self-reciprocal (SR) or self-conjugate-reciprocal (SCR). By these characterizations, we obtain some enumeration formulas of SR and SCR irreducible factors of , , over , which are just open questions posed by Boripan et al. (2019). We also count the numbers of Euclidean and Hermitian LCD constacyclic codes and show some well-known results on Euclidean and Hermitian self-dual constacyclic codes in a simple and direct way. 相似文献