全文获取类型
收费全文 | 1505篇 |
免费 | 149篇 |
国内免费 | 85篇 |
专业分类
化学 | 528篇 |
晶体学 | 4篇 |
力学 | 243篇 |
综合类 | 47篇 |
数学 | 427篇 |
物理学 | 490篇 |
出版年
2024年 | 4篇 |
2023年 | 21篇 |
2022年 | 64篇 |
2021年 | 48篇 |
2020年 | 47篇 |
2019年 | 45篇 |
2018年 | 36篇 |
2017年 | 43篇 |
2016年 | 75篇 |
2015年 | 44篇 |
2014年 | 68篇 |
2013年 | 126篇 |
2012年 | 63篇 |
2011年 | 93篇 |
2010年 | 76篇 |
2009年 | 89篇 |
2008年 | 84篇 |
2007年 | 88篇 |
2006年 | 55篇 |
2005年 | 83篇 |
2004年 | 54篇 |
2003年 | 51篇 |
2002年 | 56篇 |
2001年 | 50篇 |
2000年 | 41篇 |
1999年 | 31篇 |
1998年 | 20篇 |
1997年 | 19篇 |
1996年 | 26篇 |
1995年 | 17篇 |
1994年 | 13篇 |
1993年 | 10篇 |
1992年 | 13篇 |
1991年 | 10篇 |
1990年 | 5篇 |
1989年 | 6篇 |
1988年 | 10篇 |
1987年 | 6篇 |
1986年 | 6篇 |
1985年 | 9篇 |
1984年 | 4篇 |
1983年 | 1篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1979年 | 6篇 |
1978年 | 5篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 1篇 |
排序方式: 共有1739条查询结果,搜索用时 15 毫秒
91.
On "Problems on von Neumann Algebras by R. Kadison, 1967" 总被引:1,自引:0,他引:1
LiMingGE 《数学学报(英文版)》2003,19(3):619-624
A brief summary of the development on Kadison‘s famous problems (1967) is given. A new set of problems in von Neumann algebras is listed. 相似文献
92.
G. Pancheri O. Shekhovtsova G. Venanzoni 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):458-460
Effects due to the non-pointlike behaviour of pions in the process e
+
e
-→π
+
π
-
γ can arise for hard photons in the final state. By means of a Monte Carlo event generator, which also includes the contribution
of the direct decay φ→π
+
π
-
γ, we estimate these effects in the framework of the resonance perturbation theory. We consider angular cuts used in the KLOE
analysis of the pion form factor at threshold. A method to reveal the effects of the non-pointlike behaviour of pions in a
model-independent way is proposed. 相似文献
93.
D. Khalil A. Makhoute A. Maquet G. Rahali M. Zitane 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(2):287-295
The dynamics of laser-assisted elastic collisions in
helium is studied using the second-order Born approximation.
Detailed calculations of the scattering amplitudes are performed
by using the Sturmian basis expansion. Differential cross sections
for elastic scattering with the net absorption/emission of up to
two photons are calculated for collision energies of 5 eV, 10 eV,
and 20 eV. We discuss the influence of the low-energy electrons on
the differential cross section (DCS) as a function of the
scattering angle for selected choices of the laser frequency and
the number of photons exchanged between the external field and
electron-helium system. 相似文献
94.
David Salzmann 《Journal of Quantitative Spectroscopy & Radiative Transfer》2007,107(1):141-153
In this paper we present explicit formulas for the escape factors of strong spectral lines in spherical-symmetric plasmas. The plasma does not necessarily have a homogeneous density. The calculations include two new elements: the first incorporates an accurate calculation of the angle-averaged areal density of ions from any internal point to the edge of the sphere. The second is the use of a saddle point method to carry out the integration over the line profile. Approximate expressions for the asymptotic behavior of the escape factor are given for Gaussian, Lorentzian and Holtsmarkian line shapes. 相似文献
95.
晶体学研究曾认为分子式是NaNiQ2HQCLO4的结构并不含有钠而应为H3ONiQCLO4.相似地,稀土-Ni络合物YQHQ2NiQ3CLO4也不含有钇而应为H3ONi2Q3CLO4.晶体结构描述的修正系根据文献报导的原子坐标计算结构因子所导出的结果. 相似文献
96.
97.
Let G be a finite k‐edge‐connected simple graph. We consider when a set of independent edges can be extended to a 2‐factor such that this 2‐factor avoids a fixed set of independent edges. A complete characterization is provided in those cases, where this is feasible. © 2005 Wiley Periodicals, Inc. J Graph Theory 49: 48–58, 2005 相似文献
98.
Four-point bend specimen is one of the most important specimens of the fracture mechanics because it can produce mixed modes I and II. Therefore, computation of stress intensity factors in this specimen is of practical interest. Several relations have been suggested that no one of them has completely considered the effects of the loading point and crack geometry. In this paper, mixed mode stress intensity factors of the bend specimen are computed by finite element method (FEM) and after validating by comparing with the available results in the literature, the results will be assessed to determine the effects of different crack location and loading distances from the middle of the specimen. Finally, two new coefficients comprising these effects are introduced. 相似文献
99.
100.
袁中许 《数学的实践与认识》2008,38(1):27-32
针对知识产权屡禁不止的侵权行为现状,运用模糊数学、数理统计方法和博弈论原理,从知识产权保护和侵犯双方效用及模型出发,以系统和动态的视角对双方行为进了博弈分析.研究结果表明保护与侵犯构成为一对均衡策略状态,其主要原因在于一定条件下,保护方期望的效用均衡处于低水平态势,从而提出在效用模糊因子的调整中不断提高保护方的动态效用水平是推进有效保护知识产权的动力途径. 相似文献