全文获取类型
收费全文 | 14553篇 |
免费 | 3560篇 |
国内免费 | 1651篇 |
专业分类
化学 | 5097篇 |
晶体学 | 88篇 |
力学 | 340篇 |
综合类 | 88篇 |
数学 | 1387篇 |
物理学 | 12764篇 |
出版年
2024年 | 67篇 |
2023年 | 267篇 |
2022年 | 649篇 |
2021年 | 615篇 |
2020年 | 575篇 |
2019年 | 506篇 |
2018年 | 485篇 |
2017年 | 499篇 |
2016年 | 672篇 |
2015年 | 630篇 |
2014年 | 881篇 |
2013年 | 1157篇 |
2012年 | 866篇 |
2011年 | 1014篇 |
2010年 | 837篇 |
2009年 | 897篇 |
2008年 | 1026篇 |
2007年 | 1082篇 |
2006年 | 1065篇 |
2005年 | 856篇 |
2004年 | 763篇 |
2003年 | 692篇 |
2002年 | 612篇 |
2001年 | 482篇 |
2000年 | 511篇 |
1999年 | 349篇 |
1998年 | 376篇 |
1997年 | 266篇 |
1996年 | 201篇 |
1995年 | 160篇 |
1994年 | 91篇 |
1993年 | 89篇 |
1992年 | 95篇 |
1991年 | 72篇 |
1990年 | 60篇 |
1989年 | 61篇 |
1988年 | 35篇 |
1987年 | 24篇 |
1986年 | 31篇 |
1985年 | 29篇 |
1984年 | 26篇 |
1983年 | 11篇 |
1982年 | 15篇 |
1981年 | 16篇 |
1980年 | 6篇 |
1979年 | 8篇 |
1978年 | 8篇 |
1977年 | 4篇 |
1976年 | 7篇 |
1957年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
901.
902.
Luminescent Carbon Nanodots: Emergent Nanolights 总被引:2,自引:0,他引:2
Dr. Sheila N. Baker Dr. Gary A. Baker 《Angewandte Chemie (International ed. in English)》2010,49(38):6726-6744
Similar to its popular older cousins the fullerene, the carbon nanotube, and graphene, the latest form of nanocarbon, the carbon nanodot, is inspiring intensive research efforts in its own right. These surface‐passivated carbonaceous quantum dots, so‐called C‐dots, combine several favorable attributes of traditional semiconductor‐based quantum dots (namely, size‐ and wavelength‐dependent luminescence emission, resistance to photobleaching, ease of bioconjugation) without incurring the burden of intrinsic toxicity or elemental scarcity and without the need for stringent, intricate, tedious, costly, or inefficient preparation steps. C‐dots can be produced inexpensively and on a large scale (frequently using a one‐step pathway and potentially from biomass waste‐derived sources) by many approaches, ranging from simple candle burning to in situ dehydration reactions to laser ablation methods. In this Review, we summarize recent advances in the synthesis and characterization of C‐dots. We also speculate on their future and discuss potential developments for their use in energy conversion/storage, bioimaging, drug delivery, sensors, diagnostics, and composites. 相似文献
903.
904.
We investigate the quantum-classical transition of a kicked rotor (KR) under perturbation by a second one. The influence of such a chaotic KR makes decoherence of the first one, resulting in the emergence of classical diffusion from its quantum dynamics. Such quantum-classical transition persists by decreasing the effective Planck's constant h, and at the same time, decreasing the mass of the second KR and the interaction strength proportionally. In the limit of h → 0, due to vanishing small mass and interaction, the second KR has almost no effect on the classieal dynamics of the first one. We demonstrate this via two different coupling potentials. 相似文献
905.
We calculate the energy eigenvalues and the sate functions of one-electron Quantum Dot (QD) by using a combination of Quantum Genetic Algorithm (QGA) and Hartre-Fock-Roothaan (HFR) method. The linear and the third-order nonlinear optical absorption coefficients for the 1s-1p, 1p-1d, and 1d-1f transitions are examined as a function of the incident photon energy for three different values of the stoichiometric ratio. The results show that the stoichiometric ratio, impurity, relaxation time, and dot size have great influence on the optical absorption coefficients of QDs. 相似文献
906.
We have theoretically analyzed the quasibound states in a Mraphene quantum dot (GO, D) with a magnetic flux -φ in the centre. It is shown that the two-fold time reversal degeneracy is broken and the quasibound states of GQD with positive~negative angular momentum shifted upwards/downwards with increasing the magnetic flux. The variation of the quasibound energy depends linearly on the magnetic flux, which is quite different from the parabolic relationship for SchrSdinger electrons. The GQD's quasibound states spectrum shows an obvious Aharonov-Bohm (AB) oscillations with the magnetic flux. It is also shown that the quasibound state with energy equal to the barrier height becomes a bound state completely confined in GQD. 相似文献
907.
I. Babushkin 《Physics letters. A》2010,374(6):896-900
We study deviation from the Poissonian statistics of the frequency spacing distribution, appearing due to coupling of polarizational and transverse degrees of freedom in a perfectly square vertical cavity surface emitting laser. The deviation can be controlled by strength of the intracavity anisotropy and its alignment to the device boundaries. 相似文献
908.
In the non-commutative space, wave functions and geometric phases are derived for the time-dependent harmonic oscillator in external time-dependent magnetic and electric field. Explicit forms of the coherent states are also given, which are not the minimum uncertainty states for the coordinates and momenta. 相似文献
909.
理想量子气体的尺度效应 总被引:1,自引:0,他引:1
根据欧拉-麦克劳林(Euler-MacLaurin)公式,导出有限理想量子气体的热力学量表达式,揭示系统尺度和边界形状对其性质的影响.结果表明,有限尺度效应导致了一系列与热力学极限条件下不同的性质特征,如系统的非广延性和压强的各向异性等. 相似文献
910.