全文获取类型
收费全文 | 127066篇 |
免费 | 11326篇 |
国内免费 | 17568篇 |
专业分类
化学 | 76596篇 |
晶体学 | 2367篇 |
力学 | 6988篇 |
综合类 | 1692篇 |
数学 | 28059篇 |
物理学 | 40258篇 |
出版年
2024年 | 167篇 |
2023年 | 1450篇 |
2022年 | 1819篇 |
2021年 | 3133篇 |
2020年 | 3263篇 |
2019年 | 3303篇 |
2018年 | 2844篇 |
2017年 | 3507篇 |
2016年 | 3857篇 |
2015年 | 3419篇 |
2014年 | 4727篇 |
2013年 | 9907篇 |
2012年 | 6525篇 |
2011年 | 7000篇 |
2010年 | 5992篇 |
2009年 | 7912篇 |
2008年 | 8109篇 |
2007年 | 8526篇 |
2006年 | 7926篇 |
2005年 | 6832篇 |
2004年 | 6428篇 |
2003年 | 5963篇 |
2002年 | 5259篇 |
2001年 | 4375篇 |
2000年 | 4168篇 |
1999年 | 3708篇 |
1998年 | 3311篇 |
1997年 | 2797篇 |
1996年 | 2502篇 |
1995年 | 2324篇 |
1994年 | 2138篇 |
1993年 | 1789篇 |
1992年 | 1728篇 |
1991年 | 1323篇 |
1990年 | 1014篇 |
1989年 | 879篇 |
1988年 | 788篇 |
1987年 | 581篇 |
1986年 | 498篇 |
1985年 | 559篇 |
1984年 | 537篇 |
1983年 | 259篇 |
1982年 | 421篇 |
1981年 | 483篇 |
1980年 | 369篇 |
1979年 | 356篇 |
1978年 | 262篇 |
1977年 | 245篇 |
1976年 | 187篇 |
1973年 | 136篇 |
排序方式: 共有10000条查询结果,搜索用时 375 毫秒
941.
Xin Tao YE Chong LI 《数学学报(英文版)》2007,23(1):65-76
The BCQ and the Abadie CQ for infinite systems of convex inequalities in Banach spaces are characterized in terms of the upper semi-continuity of the convex cones generated by the subdifferentials of active convex functions. Some relationships with other constraint qualifications such as the CPLV and the Slate condition are also studied. Applications in best approximation theory are provided. 相似文献
942.
943.
944.
Tatsien LI 《数学年刊B辑(英文版)》2007,28(3):265-282
In this paper, the authors consider the inverse piston problem for the system of one-dimensional isentropic flow and obtain that, under suitable conditions, the piston velocity can be uniquely determined by the initial state of the gas on the right side of the piston and the position of the forward shock. 相似文献
945.
以山区高空间分辨率的DEM数据为主要数据源,在提取纬度、坡度、坡向等相应的地形要素栅格数据的基础上,利用GIS技术对山区可照时间的空间分布进行了模拟,实现了山区可照时间空间分布规律的可视化表达,分析了山区可照时间的空间分布特征,对于山区的农业、林业和生态环境等方面的研究具有重要意义. 相似文献
946.
We study theoretically a nonlinear response of the planar metal/dielectric nanostructures constituted from periodical array
of ultra thin silver layers and the layers of Kerr-like nonlinear dielectric. We predict hysteresis-type dependences of the
components of the tensor of effective dielectric permittivity on the field intensity allowing the change in material transmission
properties from transparent to opaque and back at extremely low intensities of the light. It makes possible to control the
light by light in all-optical nanoscale devices and circuits. 相似文献
947.
G. K. Shenoy 《Hyperfine Interactions》2006,170(1-3):5-13
Stanley L. Ruby (1924–2004) made major contributions to Mössbauer spectroscopy and was the first to suggest the feasibility of observing the Mössbauer effect using synchrotron radiation. In this article we recall his scientific legacy that have inspired his scientific colleagues. 相似文献
948.
Summary The modifications induced by a magnetic field of arbitrary direction and intermediate strength (i.e not larger than 2.35·105 tesla, the ?atomic tesla?) on the lowest singlet and triplet energy states of the hydrogen molecule are studied. Using a
linear combination of products of field-modified atomic orbitals, it is found that increasing the field strength the depth
of the singlet energy well increases and the equilibrium internuclear distance decreases, yielding more rigid and localized
nuclear vibrations. For sufficiently strong fields perpendicular to the internuclear axis, the triplet state exhibits a bonding
behaviour. An explanation of the above results is given in terms of the field-modified electronic-charge distributions in
the internuclear region.
Based on the thesis submitted by S. Basile to the University of Palermo for graduation in Physics. 相似文献
949.
W. Kotarski 《Journal of Optimization Theory and Applications》1987,54(3):565-573
Combining the results of Walczak (Ref. 1) and Lasiecka (Refs. 2 and 3), we extend the well-known Dubovicki-Milutin theorem in two directions: (i) We allow for treatment of several equality constraints in optimization problems; and (ii) We assume less regularity of optimization problems by requiring the existence of external cones instead of tangent cones. An example of an optimization problem is also considered. 相似文献
950.
Salvador Hernández 《Topology and its Applications》2007,154(10):2089-2098
Let C(X,G) be the group of continuous functions from a topological space X into a topological group G with pointwise multiplication as the composition law, endowed with the uniform convergence topology. To what extent does the group structure of C(X,G) determine the topology of X? More generally, when does the existence of a group homomorphism H between the groups C(X,G) and C(Y,G) implies that there is a continuous map h of Y into X such that H is canonically represented by h? We prove that, for any topological group G and compact spaces X and Y, every non-vanishing C-isomorphism (defined below) H of C(X,G) into C(Y,G) is automatically continuous and can be canonically represented by a continuous map h of Y into X. Some applications to specific groups and examples are given in the paper. 相似文献