全文获取类型
收费全文 | 10352篇 |
免费 | 532篇 |
国内免费 | 599篇 |
专业分类
化学 | 1473篇 |
晶体学 | 24篇 |
力学 | 342篇 |
综合类 | 62篇 |
数学 | 2717篇 |
物理学 | 1182篇 |
综合类 | 5683篇 |
出版年
2024年 | 18篇 |
2023年 | 69篇 |
2022年 | 91篇 |
2021年 | 136篇 |
2020年 | 168篇 |
2019年 | 172篇 |
2018年 | 146篇 |
2017年 | 211篇 |
2016年 | 199篇 |
2015年 | 212篇 |
2014年 | 455篇 |
2013年 | 548篇 |
2012年 | 486篇 |
2011年 | 595篇 |
2010年 | 512篇 |
2009年 | 629篇 |
2008年 | 608篇 |
2007年 | 730篇 |
2006年 | 715篇 |
2005年 | 587篇 |
2004年 | 514篇 |
2003年 | 537篇 |
2002年 | 433篇 |
2001年 | 440篇 |
2000年 | 361篇 |
1999年 | 283篇 |
1998年 | 252篇 |
1997年 | 194篇 |
1996年 | 155篇 |
1995年 | 143篇 |
1994年 | 134篇 |
1993年 | 110篇 |
1992年 | 92篇 |
1991年 | 77篇 |
1990年 | 62篇 |
1989年 | 57篇 |
1988年 | 68篇 |
1987年 | 45篇 |
1986年 | 29篇 |
1985年 | 25篇 |
1984年 | 28篇 |
1983年 | 15篇 |
1982年 | 23篇 |
1981年 | 16篇 |
1980年 | 24篇 |
1979年 | 26篇 |
1978年 | 10篇 |
1977年 | 11篇 |
1973年 | 4篇 |
1955年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
S. Mancini D. Vitali V. Giovannetti P. Tombesi 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,22(3):417-422
We show that the optomechanical coupling between an optical cavity mode and two movable cavity mirrors is able to entangle
two different macroscopic oscillation modes of the mirrors. This continuous variable entanglement is maintained by the light
bouncing between the mirrors and is robust against thermal noise. In fact, it could be experimentally demonstrated using present
technology.
Received 2 September 2002 / Received in final form 10 October 2002 Published online 7 January 2003 相似文献
42.
Shuichi Ishida Keiki Takeda Atsushi Okamoto Ichiro Shibasaki 《Physica E: Low-dimensional Systems and Nanostructures》2004,20(3-4):255
Magnetoresistance (MR) effects have been investigated in perpendicular and parallel magnetic fields at 300, 80 K and liquid He temperatures for undoped InSb thin films 0.1–2.3 μm thick grown on GaAs(1 0 0) substrates by MBE. At high temperatures, the intrinsic carriers show the parabolic negative MR observable only in magnetic fields parallel to the film. The skipping-orbit effect due to surface boundary scattering in the classical orbits in the plane vertical to the film has been argued to be responsible for the negative MR. At low temperatures (T=80 K), the transport is dominated by the two-dimensional (2D) electrons in the accumulation layers at the InSb/GaAs(1 0 0) hetero interface; MR is positive and shows a logarithmic increase with anisotropy between parallel and perpendicular field orientation, arising from the 2D weak anti-localization (WAL) that reflects the interplay between the spin-Zeeman effect and strong spin–orbit interaction caused by the asymmetric potential at the interface (Rashba term). The zero-field spin splitting energy of Δ013 meV, the electron effective mass of m*0.10m0 seven times of the band edge mass in bulk InSb and the effective g-factor of |g*|15 in the accumulation layer have been inferred from fits of MR for the 0.1 μm thick film to the 2D WL theory. 相似文献
43.
We investigate the effects of adding uniformity requirements to concepts in computable structure theory such as computable categoricity (of a structure) and intrinsic computability (of a relation on a computable structure). We consider and compare two different notions of uniformity, previously studied by Kudinov and by Ventsov. We discuss some of their results and establish new ones, while also exploring the connections with the relative computable structure theory of Ash, Knight, Manasse, and Slaman and Chisholm and with previous work of Ash, Knight, and Slaman on uniformity in a general computable structure-theoretical setting. 相似文献
44.
用热传导方程控制激光辐照温度,建立了一种新回归方程以控制激光辐照硬化深度,选用卡尔丹公式列热传导方程及同归方程联立求解,可得到同时满足一定的硬化深度及表面最高温度双重要求的工艺参数,此种方法可作为激光硬化处理工艺参数的控制或预报,对本合金铸铁的激光硬化处理,其表面温度的下限应大于其熔点温度,即以表面产生微熔的快速冷凝处理为宜,并以选取低功率慢扫描为最佳。 相似文献
45.
In this paper, space adaptivity is introduced to control the error in the numerical solution of hyperbolic systems of conservation laws. The reference numerical scheme is a new version of the discontinuous Galerkin method, which uses an implicit diffusive term in the direction of the streamlines, for stability purposes. The decision whether to refine or to unrefine the grid in a certain location is taken according to the magnitude of wavelet coefficients, which are indicators of local smoothness of the numerical solution. Numerical solutions of the nonlinear Euler equations illustrate the efficiency of the method. 相似文献
46.
Krzysztof Pawaowski 《K-Theory》1998,13(1):41-55
The paper presents a procedure for constructing smooth actions of finite perfect groups on spheres with fixed point sets having certain prescribed properties (Theorem A); in particular, having any prescribed configuration of Chern and Pontryagin numbers (Corollary C). The main ingredients used are equivariant thickening and equivariant surgery. 相似文献
47.
本文得到了广义区间空间中几个参数型非空交定理,并用此结果证明了一些新型极大极小定理,截口定理,重合定理,以及变分不等式解的存在性定理。本文中的结果包含(1,3,5-12,14-16)中相应结果。 相似文献
48.
Yoshikazu Takada 《Annals of the Institute of Statistical Mathematics》1998,50(2):325-335
This paper gives a condition which implies the nonexistence of parametric statistical procedures with bounded risk or error performance characteristics. Many examples for which such a condition is satisfied are considered. 相似文献
49.
Hidetoshi Shimodaira 《Annals of the Institute of Statistical Mathematics》1997,49(3):395-410
The asymptotic error probability of Linhart's model selection test isevaluated, and compared with the nominal significance level. We examine thecase where the expected discrepancies of the candidate models from the truemodel are asymptotically equal. The local alternatives method is employed inthe limiting operation of the asymptotic evaluation. Although the errorprobability under the null hypothesis is actually shown to be equal to orless than the level for most situations, intolerable violations of the errorcontrol are observed for nested models: It is often erroneously concludedthat the smaller model is significantly better than the larger model. Toprevent this violation, a modification of Linhart's test statistic isproposed. The effectiveness of the proposed test is confirmed throughtheoretical analysis and numerical simulations. 相似文献
50.
Fusion-evaporation cross-sections for the α-induced reactions upon197Au,193Ir,191Ir,185Re,181Ta,121Sb and69Ga nuclei at bombarding energies near the Coulomb barrier have been measured by off-line observation of the γ-rays emitted
in the radioactive decay of the residual nuclei using stacked foil technique. The total fusion cross-section for the systems
have been compared with simple statistical model calculations using the code ALICE/91 as well as with the coupled channel
calculations that include the β2 and ν4 slatic deformations and dynamic couplings of the vibrational/rotational states of the target and the projet tile using the
code CCDEF. 相似文献