全文获取类型
收费全文 | 16429篇 |
免费 | 3273篇 |
国内免费 | 2758篇 |
专业分类
化学 | 9701篇 |
晶体学 | 187篇 |
力学 | 1571篇 |
综合类 | 147篇 |
数学 | 1417篇 |
物理学 | 9437篇 |
出版年
2024年 | 58篇 |
2023年 | 209篇 |
2022年 | 451篇 |
2021年 | 556篇 |
2020年 | 730篇 |
2019年 | 569篇 |
2018年 | 554篇 |
2017年 | 624篇 |
2016年 | 734篇 |
2015年 | 665篇 |
2014年 | 948篇 |
2013年 | 1460篇 |
2012年 | 1005篇 |
2011年 | 1094篇 |
2010年 | 945篇 |
2009年 | 1153篇 |
2008年 | 1153篇 |
2007年 | 1177篇 |
2006年 | 1144篇 |
2005年 | 896篇 |
2004年 | 814篇 |
2003年 | 759篇 |
2002年 | 627篇 |
2001年 | 553篇 |
2000年 | 526篇 |
1999年 | 474篇 |
1998年 | 415篇 |
1997年 | 326篇 |
1996年 | 267篇 |
1995年 | 239篇 |
1994年 | 201篇 |
1993年 | 155篇 |
1992年 | 130篇 |
1991年 | 129篇 |
1990年 | 88篇 |
1989年 | 85篇 |
1988年 | 77篇 |
1987年 | 67篇 |
1986年 | 61篇 |
1985年 | 57篇 |
1984年 | 44篇 |
1983年 | 25篇 |
1982年 | 37篇 |
1981年 | 36篇 |
1980年 | 29篇 |
1979年 | 28篇 |
1978年 | 12篇 |
1977年 | 21篇 |
1976年 | 12篇 |
1974年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
191.
S. Longo G. Comunale C. Gorse M. Capitelli 《Plasma Chemistry and Plasma Processing》1993,13(4):685-700
Two simple kinetic models of a Ne-buffered XeCl laser discharge are presented based on different simplifications of the chemical kinetics of a complex model that recently appeared in the literature. When applied to the study of a small-volume XeCl laser, the results of both simple and complex models are in satisfactory agreement with the experiments. Shifting to a larger-volume laser, both models show problems due to loss of stability of the discharge. A one-dimensional modelling is performed, and it is found that different assumptions on the kinetics of the NeXe+ ion in the discharge lead to completely different results as regards the effect of a preionization-triggered instability. 相似文献
192.
193.
194.
Li Chen Ling Hsiao Gerald Warnecke 《应用数学学报(英文版)》2007,23(1):9-28
This paper considers a kind of strongly coupled cross diffusion parabolic system,which can be usedas the multi-dimensional Lyumkis energy transport model in semiconductor science.The global existence andlarge time behavior are obtained for smooth solution to the initial boundary value problem.When the initialdata are a small perturbation of an isothermal stationary solution,the smooth solution of the problem under theinsulating boundary condition,converges to that stationary solution exponentially fast as time goes to infinity. 相似文献
195.
黎勇 《数学物理学报(B辑英文版)》2007,27(2):437-448
In this article, two relaxation time limits, namely, the momentum relaxation time limit and the energy relaxation time limit are considered. By the compactness argument, it is obtained that the smooth solutions of the multidimensional nonisentropic Euler-Poisson problem converge to the solutions of an energy transport model or a drift diffusion model, respectively, with respect to different time scales. 相似文献
196.
讨论了带有背景矢量场的动力学标量场作为暗能量在闭宇宙的情形下的演化. 选取适当的标量场势函数后, 在得到的暗能量有效状态方程中, 参数w在红移z≈0.2处可以越过-1, 而且在z≈1.7处宇宙从减速膨胀的状态转变为加速膨胀状态, 这与最近的宇宙学观测相符. 相似文献
197.
Spherically symmetric static cosmological models filled with black-body radiation are considered. The models are isotropic
about a central observer but inhomogeneous. It is suggested that the energy density of the free gravitational field, which
is coupled to the isotropic radiation energy density, might play an important role in generating sufficient field (vacuum)
energy (when converted into thermal energy) and initiate processes like inflation. On the central world line the energy density
of the free gravitational field vanishes whereas the proper pressure and density of the isotropic black-body radiation are
constants. Further, it is shown that the cosmological constant is no more arbitrary but given in terms of the central pressure
and density. Also, at its maximum value the energy density of the free gravitational field is proved to be equal to one third
of the combined value of radiation pressure and density. 相似文献
198.
199.
在HL-1托卡马克上进行了辅助加热、加料、电流驱动的物理实验研究。在改善等离子体约束方面,某些实验取得了较好的结果。在适当的稳定放电条件下,低杂波电流驱动和弹丸注入辅助加料,均能使等离子体能量约束得到一定程度的改善,与相同密度条件下的欧姆加热放电相比,能量约束时间提高了约30%。在电子回旋共振加热等离子体实验中,等离子体总能量明显增加,但与相同密度条件下的欧姆加热放电相比,能量约束时间减少了约20%。 相似文献
200.
Recent X-ray diffraction studies on α-quartz (SiO2) by Kingmaet al [1], have shown the occurrence of a reversible, crystalline-to-crystalline, phase transition just prior to amorphization
at ≈ 21 GPa. This precursor transition has also been confirmed by our recent molecular dynamics simulation study [2]. In order
to investigate the possibility of a similar behaviour in other isostructural compounds, which also undergo pressure induced
amorphization, α-GeO2 and α-AlPO4 (berlinite form) were studied using energy dispersive X-ray diffraction. In either of these materials, no such phase transition
is detected prior to amorphization. The onset of amorphization and its reversal is found to be time dependent in GeO2. 相似文献