全文获取类型
收费全文 | 38243篇 |
免费 | 634篇 |
国内免费 | 312篇 |
专业分类
化学 | 17379篇 |
晶体学 | 291篇 |
力学 | 1532篇 |
综合类 | 12篇 |
数学 | 10447篇 |
物理学 | 9528篇 |
出版年
2023年 | 82篇 |
2022年 | 69篇 |
2021年 | 168篇 |
2020年 | 248篇 |
2019年 | 210篇 |
2018年 | 1326篇 |
2017年 | 1562篇 |
2016年 | 1111篇 |
2015年 | 920篇 |
2014年 | 856篇 |
2013年 | 1107篇 |
2012年 | 3734篇 |
2011年 | 2979篇 |
2010年 | 2267篇 |
2009年 | 1930篇 |
2008年 | 1191篇 |
2007年 | 1163篇 |
2006年 | 1138篇 |
2005年 | 4941篇 |
2004年 | 4354篇 |
2003年 | 2614篇 |
2002年 | 786篇 |
2001年 | 446篇 |
2000年 | 222篇 |
1999年 | 320篇 |
1998年 | 226篇 |
1997年 | 211篇 |
1996年 | 131篇 |
1995年 | 163篇 |
1994年 | 143篇 |
1993年 | 116篇 |
1992年 | 256篇 |
1991年 | 214篇 |
1990年 | 177篇 |
1989年 | 178篇 |
1988年 | 151篇 |
1987年 | 93篇 |
1986年 | 75篇 |
1985年 | 91篇 |
1984年 | 73篇 |
1983年 | 57篇 |
1982年 | 68篇 |
1981年 | 52篇 |
1979年 | 58篇 |
1976年 | 97篇 |
1975年 | 61篇 |
1974年 | 53篇 |
1973年 | 70篇 |
1969年 | 49篇 |
1968年 | 52篇 |
排序方式: 共有10000条查询结果,搜索用时 156 毫秒
11.
The versatile behavior of a trihydrazidophosphoradamantane allowing the synthesis of a variety of neutral, mono- or di-cationic water-soluble molecules of potential interest for biphasic catalysis is reported. 相似文献
12.
In this paper we construct an example of a word metric on an infinite cyclic subgroup. This example shows that subexponential
distortion does not obstruct non-trivial growth of connected radii. This answers a question of Gromov [6]. The constructed
metric has other pathological properies. Specifically, its asymptotic cone depends on the choice of ultrafilter and scaling
sequence.
The work has been partially supported by the Swiss National Science Foundation. 相似文献
13.
The finite-size corrections, central chargesc, and scaling dimensionsx of tricritical hard squares and critical hard hexagons are calculated analytically. This is achieved by solving the special functional equation or inversion identity satisfied by the commuting row transfer matrices of these lattice models at criticality. The results are expressed in terms of Rogers dilogarithms. For tricritical hard squares we obtainc=7/10,x=3/40, 1/5, 7/8, 6/5 and for hard hexagons we obtainc=4/5,x=2/15, 4/5, 17/15, 4/3, 9/5, in accord with the predictions of conformal and modular invariance. 相似文献
14.
We build a metric space which is homeomorphic to a Cantor set but cannot be realized as the attractor of an iterated function system. We give also an example of a Cantor set K in R3 such that every homeomorphism f of R3 which preserves K coincides with the identity on K. 相似文献
15.
Milan Medved? 《Journal of Mathematical Analysis and Applications》2002,267(2):643-650
A criterion for the nonexplosion of solutions to semilinear evolution equations on Banach spaces is proved. The result is obtained by applying a modification of the Bihari type inequality to the case of a weakly singular nonlinear integral inequality. 相似文献
16.
Aspects of Generic Entanglement 总被引:4,自引:4,他引:0
Patrick Hayden Debbie W. Leung Andreas Winter 《Communications in Mathematical Physics》2006,265(1):95-117
We study entanglement and other correlation properties of random states in high-dimensional bipartite systems. These correlations
are quantified by parameters that are subject to the ``concentration of measure' phenomenon, meaning that on a large-probability
set these parameters are close to their expectation. For the entropy of entanglement, this has the counterintuitive consequence
that there exist large subspaces in which all pure states are close to maximally entangled. This, in turn, implies the existence
of mixed states with entanglement of formation near that of a maximally entangled state, but with negligible quantum mutual
information and, therefore, negligible distillable entanglement, secret key, and common randomness. It also implies a very
strong locking effect for the entanglement of formation: its value can jump from maximal to near zero by tracing over a number
of qubits negligible compared to the size of the total system. Furthermore, such properties are generic. Similar phenomena
are observed for random multiparty states, leading us to speculate on the possibility that the theory of entanglement is much
simplified when restricted to asymptotically generic states. Further consequences of our results include a complete derandomization
of the protocol for universal superdense coding of quantum states. 相似文献
17.
We investigate an operator renormalization group method to extract and describe the relevant degrees of freedom in the evolution of partial differential equations. The proposed renormalization group approach is formulated as an analytical method providing the fundamental concepts of a numerical algorithm applicable to various dynamical systems. We examine dynamical scaling characteristics in the short-time and the long-time evolution regime providing only a reduced number of degrees of freedom to the evolution process. 相似文献
18.
We consider the one-dimensional steady-state semiconductor deviceequations modelling a pnpn device. There are two relevant scalingsof the equations corresponding to small and large applied voltages.In both scalings, the semiconductor equations can be consideredas singularly perturbed. It turns out that the small-voltagescaling breaks down for current values between two saturationcurrents. In that interval, the large-voltage scaling has tobe employed. For both scalings, we derive the first-order termsof an asymptotic expansion and show that the reduced problemhas a solution. An example verifies that the current-voltagecurves obtained have the expected qualitative structure. 相似文献
19.
Could simple intraannular-arm macrocyclic systems exist in enantiopure stable forms? The effective synthesis of two representative compounds of such a class, their resolution into enantiomers, and experiments justifying their stability toward racemization are presented. 相似文献
20.
Andreas Speiser 《Monatshefte für Mathematik》1939,48(1):240-244
Ohne Zusammenfassung 相似文献