全文获取类型
收费全文 | 1685篇 |
免费 | 261篇 |
国内免费 | 331篇 |
专业分类
化学 | 730篇 |
晶体学 | 6篇 |
力学 | 65篇 |
综合类 | 29篇 |
数学 | 745篇 |
物理学 | 702篇 |
出版年
2024年 | 8篇 |
2023年 | 56篇 |
2022年 | 67篇 |
2021年 | 91篇 |
2020年 | 78篇 |
2019年 | 44篇 |
2018年 | 50篇 |
2017年 | 43篇 |
2016年 | 45篇 |
2015年 | 48篇 |
2014年 | 109篇 |
2013年 | 182篇 |
2012年 | 210篇 |
2011年 | 197篇 |
2010年 | 162篇 |
2009年 | 170篇 |
2008年 | 119篇 |
2007年 | 127篇 |
2006年 | 109篇 |
2005年 | 87篇 |
2004年 | 53篇 |
2003年 | 48篇 |
2002年 | 41篇 |
2001年 | 37篇 |
2000年 | 27篇 |
1999年 | 13篇 |
1998年 | 15篇 |
1997年 | 14篇 |
1996年 | 3篇 |
1995年 | 11篇 |
1994年 | 7篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1985年 | 1篇 |
1957年 | 2篇 |
排序方式: 共有2277条查询结果,搜索用时 842 毫秒
1.
In this paper we study the Cauchy problem of the incompressible fractional Navier-Stokes equations in critical variable exponent Fourier-Besov-Morrey space F Ns(·)p(·),h(·),q(R3)with s(·)=4-2α-3/p(·).We prove global well-posedness result with small initial data belonging to FN4-2α-3/p(·)p(·),h(·)q(R3).The result of this paper extends some recent work. 相似文献
2.
Shi-Tao Han Hong-Ying Duan Lan-Yun Chen Dr. Tian-Guang Zhan Dr. Li-Juan Liu Li-Chun Kong Prof. Kang-Da Zhang 《化学:亚洲杂志》2021,16(23):3886-3889
A photo-switchable hetero-complementary quadruple H-bonding array, which consists of an azobenzene-derived ureidopyrimidinone (UPy) module ( Azo-UPy ) and a nonphotoactive diamidonaphthyridine (DAN) derivative ( Napy-1 ), is constructed based on a reversible photo-locking approach. Upon UV (390 nm)/Vis (460 nm) light irradiations, photo-switchable quadruple H-bonded dimerization between Azo-UPy and Napy-1 can be achieved with exhibiting 4.8×104-fold differences in binding strength (ON/OFF ratios). Furthermore, smart polymeric gels with unique photo-controlled macroscopic self-assembly behavior can be fabricated by introducing such quadruple H-bonding array as photo-regulable noncovalent interfacial connections. 相似文献
3.
4.
WANG Yue-Yue ZHANG Jie-Fang 《理论物理通讯》2006,46(8)
In this paper, the cylindrical KP-Burgers equation with variable coefficient for two-temperature ions in unmagnified dusty plasma with dissipative effects and transverse perturbations in cylindrical geometry is derived by using the standard reductive perturbation technique. With the help of variable-coefficient generalized projected Ricatti equation expansion method, the cylindrical KP-Burgers equation is solved and shock wave solution is obtained. The effects of some important parameters to the shock wave solution are illustrated from the wave evolution figures. The effects caused by dissipation and transverse perturbations are also discussed. 相似文献
5.
《Chaos, solitons, and fractals》2006,27(2):413-425
Degasperis and Procesi applied the method of asymptotic integrability and obtain Degasperis–Procesi equation. They showed that it has peakon solutions, which has a discontinuous first derivative at the wave peak, but they did not explain the reason that the peakon solution arises. In this paper, we study these non-smooth solutions of the generalized Degasperis–Procesi equation ut − utxx + (b + 1)uux = buxuxx + uuxxx, show the reason that the non-smooth travelling wave arise and investigate global dynamical behavior and obtain the parameter condition under which peakon, compacton and another travelling wave solutions engender. Under some parameter condition, this equation has infinitely many compacton solutions. Finally, we give some explicit expression of peakon and compacton solutions. 相似文献
6.
《Communications in Nonlinear Science & Numerical Simulation》2007,12(5):784-793
We consider the dynamical behavior of the strongly damped wave equations under homogeneous Neumann boundary condition. By the property of limit set of asymptotic autonomous differential equations, we prove that in certain parameter region, the system has a one-dimensional global attractor, which is a periodic horizontal curve. 相似文献
7.
《Communications in Nonlinear Science & Numerical Simulation》2007,12(3):243-253
Navier–Stokes equations (NS) admit transformations which transform a solution to another solution (galilean transformation, scaling transformation, …). They also admit viscosity dependent transformations which transform a solution to a solution of another NS with different viscosity. These particular transformations are called symmetries of NS. Each of them has a physical role (such as conservation laws, …). A consistent turbulence model should then remain invariant under these symmetry transformations. Unfortunately, this is not the case of several models.In this article, a class of subgrid-scale models preserving the symmetries of NS is built. This class is then refined such that the models respect the second law of thermodynamics. One of the simplest models of the class is tested to the flow in a ventilated room. Better results than those provided by Smagorinsky and dynamic models are obtained. 相似文献
8.
9.
10.
Backlund transformation and variable separation solutions for the generalized Nozhnik—Novikov—Veselov equation 下载免费PDF全文
Using the extended homogeneous balance method, the B?cklund transformation for a (2+1)-dimensional integrable model, the generalized Nizhnik-Novikov-Veselov (GNNV) equation, is first obtained. Also, making use of the B?cklund transformation, the GNNV equation is changed into three equations: linear, bilinear and trilinear form equations. Starting from these three equations, a rather general variable separation solution of the model is constructed. The abundant localized coherent structures of the model can be induced by the entrance of two variable-separated arbitrary functions. 相似文献