全文获取类型
收费全文 | 86493篇 |
免费 | 983篇 |
国内免费 | 567篇 |
专业分类
化学 | 30357篇 |
晶体学 | 882篇 |
力学 | 6958篇 |
综合类 | 20篇 |
数学 | 32525篇 |
物理学 | 17301篇 |
出版年
2023年 | 92篇 |
2022年 | 211篇 |
2021年 | 252篇 |
2020年 | 243篇 |
2019年 | 238篇 |
2018年 | 10577篇 |
2017年 | 10400篇 |
2016年 | 6332篇 |
2015年 | 1162篇 |
2014年 | 671篇 |
2013年 | 879篇 |
2012年 | 4399篇 |
2011年 | 11159篇 |
2010年 | 6068篇 |
2009年 | 6409篇 |
2008年 | 7158篇 |
2007年 | 9214篇 |
2006年 | 721篇 |
2005年 | 1723篇 |
2004年 | 1915篇 |
2003年 | 2306篇 |
2002年 | 1339篇 |
2001年 | 468篇 |
2000年 | 461篇 |
1999年 | 307篇 |
1998年 | 282篇 |
1997年 | 206篇 |
1996年 | 283篇 |
1995年 | 205篇 |
1994年 | 142篇 |
1993年 | 147篇 |
1992年 | 102篇 |
1991年 | 98篇 |
1990年 | 95篇 |
1989年 | 98篇 |
1988年 | 86篇 |
1987年 | 85篇 |
1986年 | 68篇 |
1985年 | 80篇 |
1984年 | 64篇 |
1983年 | 55篇 |
1982年 | 62篇 |
1981年 | 65篇 |
1980年 | 64篇 |
1979年 | 54篇 |
1978年 | 41篇 |
1914年 | 45篇 |
1912年 | 40篇 |
1909年 | 41篇 |
1908年 | 40篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
92.
93.
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
94.
95.
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
96.
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
97.
Sang Kyu Lee Min Ju Cho Jung‐Il Jin Dong Hoon Choi 《Journal of polymer science. Part A, Polymer chemistry》2007,45(3):531-542
New photocrosslinkable maleimide copolymers have been synthesized by the attachment of a tricyanopyrrolidene‐based chromophore. The 2‐(3‐cyano‐4‐(2‐{4‐[hexyl‐(6‐hydroxy‐hexyl)‐amino]‐phenyl}‐vinyl)‐5‐oxo‐1‐{4‐[4‐(3‐oxo‐3‐phenyl‐propenyl)‐ phenoxy]‐butyl}‐1,5‐dihydro‐pyrrol‐2‐ylidene)‐malononitrile chromophore exhibits nonlinear optical activity and contains a chalcone moiety that is sensitive to UV light (λ = 330–360 nm) for crosslink formation. The maleimide monomers have also been functionalized with chalcone moieties. The resultant copolymers exhibit great processability, and one of them shows a maximum electrooptic coefficient of 90 pm/V at 1300 nm. We could control the thermal stability of the electrooptic coefficient with the newly synthesized photoreactive copolymers successfully. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 531–542, 2007 相似文献
98.
M. Vedani G. Angella Paola Bassani D. Ripamonti A. Tuissi 《Journal of Thermal Analysis and Calorimetry》2007,87(1):277-284
Equal channel angular
pressing (ECAP) was carried out on solution annealed samples of Al–Mg–Si–Zr
and Al–Mg–Si–Zr–Sc alloys to achieve a substantial
grain refinement of the materials. Post ECAP aging was then investigated on
the ultrafine grained alloys by DSC and TEM analyses.
DSC scans
were carried out with heating rates ranging from 5 to 30°C min–1.
Peak identification was performed by the support of literature information
and TEM analyses. Precipitation kinetics revealed to be similar for both alloys
but the Sc-free alloy showed a recrystallization peak at temperatures ranging
from 310 to 340°C, depending on the strain accumulated during ECAP. On
the contrary, the Sc-containing alloy showed a greater grain stability. Analyses
of peak positions and of activation energies as a function of ECAP passes
experienced by the samples revealed large modifications of precipitation kinetics
in the ultrafine-grained alloys with respect to the coarse-grained materials. 相似文献
99.
Maxim V. Pavlov 《Communications in Mathematical Physics》2007,272(2):469-505
The algebro-geometric approach for integrability of semi-Hamiltonian hydrodynamic type systems is presented. The class of
symmetric hydrodynamic type systems is defined and the calculation of the associated Riemann surfaces is greatly simplified for this
class. Many interesting and physically motivated examples are investigated. 相似文献
100.
Kwang-Hua W. Chu 《International Journal of Theoretical Physics》2007,46(12):3230-3233
The modified Gross–Pitaevskii equation was derived and solved to obtain the 1D solution in the zero-energy limit. This stationary
solution could account for the dominated contributions due to the kinetic effect as well as the chemical potential in inhomogeneous
Bose gases. 相似文献