全文获取类型
收费全文 | 9932篇 |
免费 | 487篇 |
国内免费 | 68篇 |
专业分类
化学 | 7165篇 |
晶体学 | 80篇 |
力学 | 215篇 |
数学 | 960篇 |
物理学 | 2067篇 |
出版年
2023年 | 46篇 |
2022年 | 150篇 |
2021年 | 192篇 |
2020年 | 169篇 |
2019年 | 175篇 |
2018年 | 153篇 |
2017年 | 136篇 |
2016年 | 308篇 |
2015年 | 291篇 |
2014年 | 348篇 |
2013年 | 584篇 |
2012年 | 717篇 |
2011年 | 830篇 |
2010年 | 474篇 |
2009年 | 399篇 |
2008年 | 648篇 |
2007年 | 581篇 |
2006年 | 572篇 |
2005年 | 509篇 |
2004年 | 437篇 |
2003年 | 378篇 |
2002年 | 340篇 |
2001年 | 199篇 |
2000年 | 183篇 |
1999年 | 141篇 |
1998年 | 106篇 |
1997年 | 83篇 |
1996年 | 108篇 |
1995年 | 93篇 |
1994年 | 98篇 |
1993年 | 76篇 |
1992年 | 64篇 |
1991年 | 47篇 |
1990年 | 69篇 |
1989年 | 56篇 |
1988年 | 35篇 |
1987年 | 32篇 |
1986年 | 34篇 |
1985年 | 55篇 |
1984年 | 36篇 |
1983年 | 29篇 |
1982年 | 39篇 |
1981年 | 33篇 |
1980年 | 34篇 |
1979年 | 40篇 |
1978年 | 29篇 |
1977年 | 43篇 |
1976年 | 34篇 |
1975年 | 24篇 |
1973年 | 34篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
31.
This paper presents a new scheduling method for manufacturing system based on the Timed Petri Net model and a reactive fast graph search algorithm. The following two typical problems are addressed in this paper. (1) Minimization of the maximum completion time. (2) Minimization of the total tardiness. As for the problem (1), a new search algorithm which combines the RTA∗ and a rule-based supervisor is proposed. As for problem (2), the original Petri Net model is converted to its reverse model and the algorithm developed for the problem (1) is applied, regarding the due date as the starting time in the reverse model. Some numerical experiments are carried out to demonstrate usefulness of our algorithm. 相似文献
32.
The bifurcation point where a satellite component buds from another component is characterized by the existence of the common tangent line between the two osculating components appearing in the degree-n bifurcation set. We investigate the existence, location and number of bifurcation points for satellite components budding from the main component in the degree-n bifurcation set as well as a parametric boundary equation of the main component of the degree-n bifurcation set. Cusp points are also located on the boundary of the main component. Typical degree-n bifurcation sets and their components are illustrated with some computational results. 相似文献
33.
34.
Chan Sik Cho Jun Ho KimHeung-Jin Choi Tae-Jeong KimSang Chul Shim 《Tetrahedron letters》2003,44(14):2975-2977
Anilines react with epoxides in dioxane at 180°C in the presence of a catalytic amount of a ruthenium catalyst along with tin(II) chloride to afford 2-substituted indoles in moderate to good yields. 相似文献
35.
Monodisperse polyaniline nanoparticles (PAPSSA) were synthesized from an oxidative dispersion polymerization using poly(sodium 4-styrenesulfonate) (PSSA) as both a polymeric stabilizer and a dopant agent due to its acidity. The nanoparticles were being stabilized with two different molecular weight of PSSA. Size effect of PAPSSA particles were examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and dynamic light scattering (DLS). The d.c. electrical conductivity of composite films on the glass substrate was measured by a four-probe method. It was found that the electrical properties of the composite films are affected by the content of nano-sized polyaniline and different molecular weights of stabilizer in the poly(vinyl alcohol) (PVA) matrix. 相似文献
36.
Young Ja Park 《Proceedings of the American Mathematical Society》2004,132(7):2075-2083
A logarithmic Sobolev trace inequality is derived. Bounds on the best constant for this inequality from above and below are investigated using the sharp Sobolev inequality and the sharp logarithmic Sobolev inequality.
37.
38.
Al2O3 incorporated HfO2 films grown by atomic layer deposition (ALD) were investigated by high-resolution X-ray photoelectron spectroscopy (HRXPS). The core level energy state of a 15 Å thick film showed a shift to higher binding energy, as the result of a silicate formation and Al2O3 incorporation. The incorporation of Al2O3 into the HfO2 film had no effect on silicate formation at the interface between the film and Si, while the ionic bonding characteristics and hybridization effects were enhanced compared to a pure HfO2 film. The dissociation of the film in an ultrahigh vacuum (UHV) is effectively suppressed compared to a pure HfO2 film, indicating an enhanced thermal stability of Hf-Al-O. Any dissociated Al2O3 on the film surface was completely removed into the vacuum by vacuum annealing treatment over 850 °C, while HfO2 contributed to Hf silicide formation on the film surface. 相似文献
39.
On the harmonic Bergman space of the half-space, we give characterizations for an arbitrary positive Toeplitz operator to
be a Schatten (or Schatten-Herz) class operator in terms of averaging functions and Berezin transforms. Examples are provided
to show that various results are sharp.
This research was supported by KOSEF(R01-2003-000-10243-0). 相似文献
40.
S. S. Dragomir Y. J. Cho S. S. Kim J. Roumeliotis 《Journal of Applied Mathematics and Computing》2006,20(1-2):279-292
A reverse of Bessel’s inequality in 2-inner product spaces and companions of Grüss inequality with applications for determinantal integral inequalities are given. 相似文献