全文获取类型
收费全文 | 14895篇 |
免费 | 1519篇 |
国内免费 | 1476篇 |
专业分类
化学 | 3426篇 |
晶体学 | 207篇 |
力学 | 1986篇 |
综合类 | 260篇 |
数学 | 9510篇 |
物理学 | 2501篇 |
出版年
2024年 | 21篇 |
2023年 | 142篇 |
2022年 | 153篇 |
2021年 | 246篇 |
2020年 | 380篇 |
2019年 | 343篇 |
2018年 | 322篇 |
2017年 | 392篇 |
2016年 | 437篇 |
2015年 | 321篇 |
2014年 | 612篇 |
2013年 | 1055篇 |
2012年 | 771篇 |
2011年 | 885篇 |
2010年 | 886篇 |
2009年 | 955篇 |
2008年 | 1014篇 |
2007年 | 1095篇 |
2006年 | 908篇 |
2005年 | 837篇 |
2004年 | 751篇 |
2003年 | 792篇 |
2002年 | 646篇 |
2001年 | 511篇 |
2000年 | 451篇 |
1999年 | 412篇 |
1998年 | 380篇 |
1997年 | 310篇 |
1996年 | 270篇 |
1995年 | 248篇 |
1994年 | 208篇 |
1993年 | 149篇 |
1992年 | 141篇 |
1991年 | 112篇 |
1990年 | 94篇 |
1989年 | 74篇 |
1988年 | 70篇 |
1987年 | 60篇 |
1986年 | 59篇 |
1985年 | 66篇 |
1984年 | 53篇 |
1983年 | 25篇 |
1982年 | 61篇 |
1981年 | 45篇 |
1980年 | 32篇 |
1979年 | 25篇 |
1978年 | 19篇 |
1977年 | 10篇 |
1976年 | 13篇 |
1972年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 171 毫秒
21.
22.
23.
Tomoyuki Nakatsuka 《Mathematische Nachrichten》2021,294(1):98-117
We study the existence of a time‐periodic solution with pointwise decay properties to the Navier–Stokes equation in the whole space. We show that if the time‐periodic external force is sufficiently small in an appropriate sense, then there exists a time‐periodic solution of the Navier–Stokes equation such that and uniformly in as . Our solution decays faster than the time‐periodic Stokes fundamental solution and the faster decay of its spatial derivatives of higher order is also described. 相似文献
24.
Effect of external electric field on the terahertz transmission characteristics of electrolyte solutions 下载免费PDF全文
Jia-Hui Wang 《中国物理 B》2021,30(11):110204-110204
We fabricated a microfluidic chip with simple structure and good sealing performance, and studied the influence of the electric field on THz absorption intensity of liquid samples treated at different times by using THz time domain spectroscopy system. The tested liquids were deionised water and CuSO4, CuCl2, NaHCO3, Na2CO3 and NaCl solutions. The transmission intensity of the THz wave increases as the standing time of the electrolyte solution in the electric field increases. The applied electric field alters the dipole moment of water molecules in the electrolyte solution, which affects the vibration and rotation of the whole water molecules, breaks the hydrogen bonds in the water, increases the number of single water molecules and leads to the enhancement of the THz transmission spectrum. 相似文献
25.
《Mathematical Methods in the Applied Sciences》2018,41(9):3294-3306
In this article, we consider the asymptotic behavior of the classical solution to the 3‐dimensional Vlasov‐Poisson plasma interacting repulsively with N point charges. The large time behavior in terms of diameters of its velocity‐spatial supports is improved to O(t2/3+ϵ) for any ϵ>0. 相似文献
26.
The flow behavior in non-parallel walls is an important factor of any physical model including cavity flow and canals, which is applicable for diverging/converging channel. The present communication explains that the flow of the hybrid nanomaterial subjected to the convergent/divergent channel has non-parallel walls. It is assumed that the hybrid nanomaterial movement is in the porous region. A Darcy-Forchheimer medium of porosity is considered to interpret the porosity features. A useful similarity function is adopted to get the strong ordinary coupled equations. Numerical solutions are achieved through the Runge-Kutta-Fehlberg(RKF) fourth-fifth order method, and they are validated with the existing results. Physical nature of the involving constraints is reported with the help of plots. It is explored that the velocity of divergent channel decreases, and convergent channel enhances for the higher solid volume faction. Further, the presence of inertia coefficient and porosity parameter amplifies the velocity at the wall. 相似文献
27.
The(3+1)-dimensional Burgers equation, which describes nonlinear waves in turbulence and the interface dynamics,is considered. Two types of semi-rational solutions, namely, the lump–kink solution and the lump–two kinks solution, are constructed from the quadratic function ansatz. Some interesting features of interactions between lumps and other solitons are revealed analytically and shown graphically, such as fusion and fission processes. 相似文献
28.
29.
目前,悬链线在竖向集中力和均布荷载共同作用下的构形分析和受力计算的理论仍不完善。针对这一问题,通过引入悬链线的几何约束方程、力平衡方程和超越方程,建立了竖向集中力与均布荷载共同作用下的非线性方程组。采用牛顿迭代法求解方程组,得到了悬链线的构形和受力情况。为了验证理论计算的正确性,进行了算例和试验验证。结果表明,算例的计算结果与文献结论保持一致,试验测得的构形和水平张力大小与理论计算的构形和水平张力大小吻合较好。本文的理论计算可以更加简单精确地计算出悬链线在竖向集中力和均布荷载共同作用下的构形和受力情况,为实际工程提供重要的理论指导。 相似文献
30.
In this article, we study the existence of nonoscillatory solutions of higher order differential and delay differential equations with forcing term. Some new sufficient conditions are given. We use the Schauder’s fixed point theorem to prove our results. 相似文献