全文获取类型
收费全文 | 12685篇 |
免费 | 1108篇 |
国内免费 | 1598篇 |
专业分类
化学 | 884篇 |
晶体学 | 18篇 |
力学 | 679篇 |
综合类 | 298篇 |
数学 | 9446篇 |
物理学 | 4066篇 |
出版年
2024年 | 23篇 |
2023年 | 145篇 |
2022年 | 208篇 |
2021年 | 267篇 |
2020年 | 267篇 |
2019年 | 298篇 |
2018年 | 267篇 |
2017年 | 309篇 |
2016年 | 362篇 |
2015年 | 287篇 |
2014年 | 588篇 |
2013年 | 832篇 |
2012年 | 525篇 |
2011年 | 783篇 |
2010年 | 685篇 |
2009年 | 903篇 |
2008年 | 955篇 |
2007年 | 1035篇 |
2006年 | 837篇 |
2005年 | 773篇 |
2004年 | 598篇 |
2003年 | 673篇 |
2002年 | 585篇 |
2001年 | 459篇 |
2000年 | 503篇 |
1999年 | 430篇 |
1998年 | 402篇 |
1997年 | 309篇 |
1996年 | 226篇 |
1995年 | 126篇 |
1994年 | 128篇 |
1993年 | 81篇 |
1992年 | 61篇 |
1991年 | 58篇 |
1990年 | 48篇 |
1989年 | 27篇 |
1988年 | 34篇 |
1987年 | 18篇 |
1986年 | 16篇 |
1985年 | 42篇 |
1984年 | 36篇 |
1983年 | 17篇 |
1982年 | 34篇 |
1981年 | 16篇 |
1980年 | 24篇 |
1979年 | 22篇 |
1978年 | 13篇 |
1977年 | 14篇 |
1976年 | 9篇 |
1974年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
一类广义非线性隐拟变分包含 总被引:5,自引:0,他引:5
引入和研究了一类新的涉及集值极大单调映象的广义非线性隐拟变分包含.对此类变分包含在没有紧性假设下证明了解的存在定理.为寻求此类变分包含的近似解,建议和分析了一个新的迭代算法.给出了由新算法产生的迭代序列的收敛性.作为特殊情形,也讨论了在此领域内的某些已知结果. 相似文献
82.
The nonlinear wavelet estimator of regression function with random design is constructed. The optimal uniform convergence
rate of the estimator in a ball of Besov spaceB
3
p,q
is proved under quite general assumpations. The adaptive nonlinear wavelet estimator with near-optimal convergence rate in
a wide range of smoothness function classes is also constructed. The properties of the nonlinear wavelet estimator given for
random design regression and only with bounded third order moment of the error can be compared with those of nonlinear wavelet
estimator given in literature for equal-spaced fixed design regression with i.i.d. Gauss error.
Project supported by Doctoral Programme Foundation, the National Natural Science Foundation of China (Grant No. 19871003)
and Natural Science Fundation of Heilongjiang Province, China. 相似文献
83.
为研究双温电子等离子体中束流不稳定性的演化过程,用二维粒子模拟(PIC)代码对双温电子束流不稳定性进行了模拟,其中泊松方程用松弛迭代法求解,代码满足电荷守恒、动量守恒和能量守恒条件。在电子双流不稳定性的非线性演化过程中,得到相空间的空洞结构,实空间也相应出现了电子空洞。给出了不稳定性增长率以及相应色散关系。 相似文献
84.
The fundamental equation of the thermodynamic system gives the relation between the internal energy, entropy and volume of two adjacent equilibrium states. Taking a higher-dimensional charged Gauss–Bonnet black hole in de Sitter space as a thermodynamic system, the state parameters have to meet the fundamental equation of thermodynamics. We introduce the effective thermodynamic quantities to describe the black hole in de Sitter space. Considering that in the lukewarm case the temperature of the black hole horizon is equal to that of the cosmological horizon, we conjecture that the effective temperature has the same value. In this way, we can obtain the entropy formula of spacetime by solving the differential equation. We find that the total entropy contains an extra term besides the sum of the entropies of the two horizons. The corrected term of the entropy is a function of the ratio of the black hole horizon radius to the cosmological horizon radius, and is independent of the charge of the spacetime. 相似文献
85.
This paper presents a new parameter and state estimation algorithm for single-input single-output systems based on canonical state space models from the given input–output data. Difficulties of identification for state space models lie in that there exist unknown noise terms in the formation vector and unknown state variables. By means of the hierarchical identification principle, those noise terms in the information vector are replaced with the estimated residuals and a new least squares algorithm is proposed for parameter estimation and the system states are computed by using the estimated parameters. Finally, an example is provided. 相似文献
86.
In this paper, we consider the Cauchy problems for compressible Euler equations with damping. In terms of the Littlewood–Paley decomposition and Bony's para‐product formula, we prove the global existence, uniqueness and asymptotic behavior of the solution in the critical Besov space comparing with previous results. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
87.
88.
89.
J. Prost J.-B. Manneville R. Bruinsma 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,1(4):465-480
Membranes in thermal equilibrium are well known to exhibit Brownian motion type shape fluctuations. Membranes containing active
force centers -- such as chemically active membrane proteins -- suffer additional non-equilibrium shape fluctuations due to
the activity of these force centers. We demonstrate, using scaling arguments, that non-equilibrium shape fluctuations are
in general greatly amplified by the presence of a nearby wall or membrane due to the absence of a fluctuation-dissipation
theorem. For adhesive membranes, this fluctuation magnification effect may facilitate the establishment of bonding. For non-adhesive
membranes, fluctuation magnification produces a long-range repulsive pressure which can exceed the well known Helfrich repulsion
due to purely thermal fluctuations.
Received: 1 September 1997 / Accepted: 3 December 1997 相似文献
90.
Professor Peter V.E. McClintock 《Contemporary Physics》2013,54(6):551-552
The arrival of the first hard X-ray free electron laser facilities promises new advances in structural dynamics and nanoscale imaging that will have impact across the sciences. This introductory review is intended to cover the basic physics behind this potential and illustrate the current state-of-the-art by discussing a number of recent findings from the LCLS facility at the Stanford Linear Accelerator Centre (SLAC). We concentrate on the new science using these light sources rather than the new light source technology itself, although a brief introduction to the operation of LCLS is given. Emphasis is placed upon the new regime of high intensity X-ray matter interaction physics with ultrashort X-ray pulses. We discuss how the unique combination of X-ray parameters will open new opportunities for time resolved structural studies and how the high brightness enables a new class of coherent diffraction X-ray imaging. The potential importance of this new imaging method in the study of nanostructures and biological systems at the sub-cellular and molecular level will be outlined. 相似文献