全文获取类型
收费全文 | 105522篇 |
免费 | 1409篇 |
国内免费 | 538篇 |
专业分类
化学 | 43031篇 |
晶体学 | 1051篇 |
力学 | 7598篇 |
综合类 | 1篇 |
数学 | 34153篇 |
物理学 | 21635篇 |
出版年
2023年 | 162篇 |
2022年 | 441篇 |
2021年 | 523篇 |
2020年 | 464篇 |
2019年 | 496篇 |
2018年 | 10680篇 |
2017年 | 10497篇 |
2016年 | 6758篇 |
2015年 | 1517篇 |
2014年 | 1153篇 |
2013年 | 1930篇 |
2012年 | 5804篇 |
2011年 | 12601篇 |
2010年 | 6936篇 |
2009年 | 7171篇 |
2008年 | 8343篇 |
2007年 | 10376篇 |
2006年 | 1824篇 |
2005年 | 2784篇 |
2004年 | 2829篇 |
2003年 | 2974篇 |
2002年 | 2032篇 |
2001年 | 931篇 |
2000年 | 880篇 |
1999年 | 514篇 |
1998年 | 453篇 |
1997年 | 442篇 |
1996年 | 537篇 |
1995年 | 384篇 |
1994年 | 364篇 |
1993年 | 376篇 |
1992年 | 320篇 |
1991年 | 273篇 |
1990年 | 206篇 |
1989年 | 206篇 |
1988年 | 201篇 |
1987年 | 177篇 |
1986年 | 150篇 |
1985年 | 220篇 |
1984年 | 156篇 |
1983年 | 139篇 |
1982年 | 164篇 |
1981年 | 130篇 |
1980年 | 130篇 |
1979年 | 107篇 |
1978年 | 117篇 |
1977年 | 106篇 |
1976年 | 111篇 |
1975年 | 118篇 |
1973年 | 128篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
Sudoku’s french ancestors 总被引:1,自引:0,他引:1
Christian Boyer 《Mathematical Intelligencer》2007,29(1):37-44
This column is a place for those bits of contagious mathematics that travel from person to person in the community, because
they are so elegant, suprising, or appealing that one has an urge to pass them on.
Contributions are most welcome. 相似文献
142.
143.
144.
145.
We prove that any 43-fold covering of the plane with translates of a triangle can be decomposed into two coverings. 相似文献
146.
147.
Wei Wang Li-Ping Pang Zun-Quan Xia 《应用数学学报(英文版)》2007,23(1):29-38
In this paper,the UV-theory and P-differential calculus are employed to study second-order ex-pansion of a class of D.C.functions and minimization problems.Under certain conditions,some properties ofthe U-Lagrangian,the second-order expansion of this class of functions along some trajectories are formulated.Some first and second order optimality conditions for the class of D.C.optimization problems are given. 相似文献
148.
Roderich Tumulka 《Foundations of Physics》2007,37(2):186-197
In a recent paper Conway and Kochen, Found. Phys. 36, 2006, claim to have established that theories of the Ghirardi-Rimini-Weber
(RW) type, i.e., of spontaneous wave function collapse, cannot be made relativistic. On the other hand, relativistic GRW-type
theories have already been presented, in my recent paper, J. Stat. Phys. 125, 2006, and by Dowker and Henson, J. Stat. Phys.
115, 2004. Here, I elucidate why these are not excluded by the arguments of Conway and Kochen.
相似文献
149.
Jae-Yeon Lee Eugene Lubarsky Ben T. Zinn 《Proceedings of the Combustion Institute》2005,30(2):1757-1764
This paper describes an experimental investigation of the feasibility of using “slow” active control approaches, which “instantaneously” change liquid fuel spray properties, to suppress combustion instabilities. The objective of this control approach was to break up the feedback between the combustion process heat release and combustor pressure oscillations that drive the instability by changing the characteristics of the combustion process (e.g., the characteristic combustion time). To demonstrate the feasibility of such control, this study used a proprietary fuel injector (NanomiserTM), which can vary its fuel spray properties, to investigate the dependence of acoustics–combustion process coupling, i.e., the driving of combustion instabilities, upon the fuel spray properties. This study showed that by changing the spray characteristics it is possible to significantly damp combustion instabilities. Furthermore, using combustion zone chemiluminescence distributions, which were obtained by Abel’s deconvolution synchronized with measured acoustic data, it has been shown that the instabilities were mostly driven midway between the combustor centerline and wall, a short distance downstream from the flame holder, where the mean axial flow velocity is approximately zero in the vortex near the flame holder. The results of this study strongly suggest that a “slow” active control system that employs controllable fuel injectors could be effectively used to prevent the onset of detrimental combustion instabilities. 相似文献
150.
The Bekenstein–Hawking entropy of certain black holes can be computed microscopically in string theory by mapping the elusive
problem of counting microstates of a strongly gravitating black hole to the tractable problem of counting microstates of a
weakly coupled D-brane system, which has no event horizon, and indeed comfortably fits on the head of a pin. We show here
that, contrary to widely held beliefs, the entropy of spherically symmetric black holes can easily be dwarfed by that of stationary
multi-black-hole “molecules” of the same total charge and energy. Thus, the corresponding pin-sized D-brane systems do not
even approximately count the microstates of a single black hole, but rather those of a zoo of entropically dominant multicentered
configurations.
Fourth Award in the 2007 Essay Competition of the Gravity Research Foundation. 相似文献