全文获取类型
收费全文 | 10911篇 |
免费 | 1072篇 |
国内免费 | 756篇 |
专业分类
化学 | 1502篇 |
晶体学 | 23篇 |
力学 | 752篇 |
综合类 | 132篇 |
数学 | 8620篇 |
物理学 | 1710篇 |
出版年
2024年 | 8篇 |
2023年 | 89篇 |
2022年 | 103篇 |
2021年 | 172篇 |
2020年 | 294篇 |
2019年 | 311篇 |
2018年 | 282篇 |
2017年 | 298篇 |
2016年 | 345篇 |
2015年 | 272篇 |
2014年 | 504篇 |
2013年 | 1028篇 |
2012年 | 538篇 |
2011年 | 598篇 |
2010年 | 500篇 |
2009年 | 687篇 |
2008年 | 630篇 |
2007年 | 724篇 |
2006年 | 651篇 |
2005年 | 541篇 |
2004年 | 506篇 |
2003年 | 469篇 |
2002年 | 456篇 |
2001年 | 362篇 |
2000年 | 358篇 |
1999年 | 321篇 |
1998年 | 265篇 |
1997年 | 266篇 |
1996年 | 170篇 |
1995年 | 132篇 |
1994年 | 111篇 |
1993年 | 66篇 |
1992年 | 94篇 |
1991年 | 46篇 |
1990年 | 51篇 |
1989年 | 37篇 |
1988年 | 31篇 |
1987年 | 26篇 |
1986年 | 33篇 |
1985年 | 47篇 |
1984年 | 57篇 |
1983年 | 25篇 |
1982年 | 40篇 |
1981年 | 38篇 |
1980年 | 37篇 |
1979年 | 38篇 |
1978年 | 18篇 |
1977年 | 24篇 |
1976年 | 23篇 |
1975年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
13.
14.
In this paper, we derive the non-singular Green’s functions for the unbounded Poisson equation in one, two and three dimensions using a spectral cut-off function approach to impose a minimum length scale in the homogeneous solution. The resulting non-singular Green’s functions are relevant to applications which are restricted to a minimum resolved length scale (e.g. a mesh size ) and thus cannot handle the singular Green’s function of the continuous Poisson equation. We furthermore derive the gradient vector of the non-singular Green’s function, as this is useful in applications where the Poisson equation represents potential functions of a vector field. 相似文献
15.
《Physics letters. A》2019,383(20):2370-2375
We consider a bosonic Josephson junction in the Bose-Hubbard two-mode approximation where some of the parameters are corrupted by physically meaningful noise processes and study the corresponding relaxation dynamics towards its equilibrium state. We show with numerical simulations that this model can essentially capture all the important features observed in a recent experiment regarding the relaxation dynamics in one-dimensional bosonic Josephson junctions, namely the damped oscillations of the population imbalance and the relative phase, as well as the large final coherence factor. We expect that this work will further motivate research about the origin of relaxation mechanism in these systems. 相似文献
16.
Due to their intrinsic link with nonlinear Fokker-Planck equations and many other applications, distribution dependent stochastic differential equations (DDSDEs) have been intensively investigated. In this paper, we summarize some recent progresses in the study of DDSDEs, which include the correspondence of weak solutions and nonlinear Fokker-Planck equations, the well-posedness, regularity estimates, exponential ergodicity, long time large deviations, and comparison theorems. 相似文献
17.
Isochronicity and linearizability of two-dimensional polynomial Hamiltonian systems are revisited and new results are presented. We give a new computational procedure to obtain the necessary and sufficient conditions for the linearization of a polynomial system. Using computer algebra systems we provide necessary and sufficient conditions for linearizability of Hamiltonian systems with homogeneous non-linearities of degrees 5, 6 and 7. We also present some sufficient conditions for systems with nonhomogeneous nonlinearities of degrees two, three and five. 相似文献
18.
Li Song Jiaxiang Lin Yang He Jingqing Li Jing Sheng Shichun Jiang Dinghai Huang 《Journal of Polymer Science.Polymer Physics》2019,57(3):142-151
Time‐dependent demixing enthalpy recovery behavior of aqueous poly(vinyl methyl ether) (PVME) solutions exhibits distinct recovery characteristics in three concentration regions. The absence of recovery behavior below a water concentration of 38.3 wt % indicates that the PVME coil is in a globular state. The typically sigmoidal recovery behavior of demixing enthalpy above 38.3 wt % is ascribed to the reswelling of the collapsed polymer coils induced by the entropic effect. The increase in difference between the upper and lower limits indicates the continued swelling of the PVME coils. Above 65 wt %, a dominant diluting effect can be observed, and a much longer phase separation time is needed to reach the expected lower limit. In contrast, the recovery of demixing enthalpy in a wide range of water concentration (from 38.3 to 90 wt %) exhibits the same feature. The infrared spectroscopy results are in agreement with the above macroscopic differential scanning calorimetry results. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 142–151 相似文献
19.
20.
《Mathematische Nachrichten》2018,291(10):1470-1485
In this paper we study a class of second order coefficient operators differential equation with general (possibly non local) boundary conditions. We obtain new results extending those given in a previous paper 1 . Existence, uniqueness and optimal regularity of the strict solution are proved in UMD spaces, using the well‐known Dore–Venni theorem. 相似文献