全文获取类型
收费全文 | 3080篇 |
免费 | 833篇 |
国内免费 | 212篇 |
专业分类
化学 | 1420篇 |
晶体学 | 22篇 |
力学 | 275篇 |
综合类 | 40篇 |
数学 | 153篇 |
物理学 | 2215篇 |
出版年
2024年 | 13篇 |
2023年 | 78篇 |
2022年 | 287篇 |
2021年 | 234篇 |
2020年 | 176篇 |
2019年 | 125篇 |
2018年 | 103篇 |
2017年 | 103篇 |
2016年 | 118篇 |
2015年 | 121篇 |
2014年 | 126篇 |
2013年 | 192篇 |
2012年 | 162篇 |
2011年 | 202篇 |
2010年 | 152篇 |
2009年 | 205篇 |
2008年 | 206篇 |
2007年 | 200篇 |
2006年 | 222篇 |
2005年 | 172篇 |
2004年 | 155篇 |
2003年 | 135篇 |
2002年 | 110篇 |
2001年 | 102篇 |
2000年 | 76篇 |
1999年 | 47篇 |
1998年 | 47篇 |
1997年 | 36篇 |
1996年 | 39篇 |
1995年 | 31篇 |
1994年 | 27篇 |
1993年 | 16篇 |
1992年 | 18篇 |
1991年 | 7篇 |
1990年 | 11篇 |
1989年 | 12篇 |
1988年 | 5篇 |
1987年 | 7篇 |
1986年 | 4篇 |
1985年 | 12篇 |
1984年 | 6篇 |
1983年 | 2篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1977年 | 2篇 |
1974年 | 2篇 |
1971年 | 2篇 |
1959年 | 2篇 |
排序方式: 共有4125条查询结果,搜索用时 15 毫秒
21.
The properties of pulsed laser vapor doping on p-Si(1 0 0) with a KrF (248 nm) excimer pulsed laser (248 nm) and BCl3 gas are reported in this paper. The doped samples are characterized by the resistance measured using a four-probe method, since the sheet resistance changes with the carrier concentration of the sample. The doping effects with the variation of laser energy density, pulse number, and the pressure of BCl3 were investigated in terms of the sheet resistance. In this way, the optimized parameters were obtained and used for the positive heavy doping on p-Si(1 0 0) and p-Si(1 1 1). Then, using a square mesh under the above conditions, an image doping was completed. Finally, the metal–semiconductor Ohmic contacts were realized by plating Ag and Cu films on the doped surface. 相似文献
22.
Gu-Qiang Li 《Theoretical and Mathematical Physics》2007,151(1):586-589
We use the Parikh-Wilczek method to treat Hawking radiation as a tunneling process across the event horizon and calculate
the emission rate of a Gibbons-Maeda dilaton black hole. We show that if self-gravitation is taken into account, then the
radiation deviates from the purely thermal spectrum, and the corrected spectrum is consistent with an underlying unitary theory.
__________
Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 151, No. 1, pp. 172–175, April, 2007. 相似文献
23.
The Hawking radiation of Dirac particles in an arbitrarily rectilinearly accelerating Kinnersley black hole with electromagnetic charge and cosmological constant is investigated by using the generalized tortoise coordinate transformation. Both the location and the temperature of the event horizon depend on the time and the polar angle. The Hawking thermal radiation spectrum of Dirac particles is also derived. 相似文献
24.
将DLTS用于对InAs/GaAsQD结构样品的测量,测定了QD能级发射载流子的热激活能;获得了QD能级俘获电子过程伴随有多声子发射(MPE)、QD能级存在一定程度的展宽、以及在某些特定的生长条件下,存在亚稳生长构形的实验证据.结果表明:DLTS在QD体系的研究中有其特有的功能 相似文献
25.
26.
After taking into account energy conservation and the particle’s self-gravitation interaction, Hawking radiation of the massive
particle as tunneling from Schwarzshild-anti-de Sitter black hole is studied by using Parikh-Wilczek’s semi-classical quantum
tunneling approach. Meanwhile, Hawking radiation as tunneling from the black hole is reexamined by developing Angheben–Nadalini–Vanzo–Zerbini
(ANVZ) covariant method to cover energy conservation and the particle’s self-gravitation interaction. Both the results perfectly
generalize those obtained by Parikh and Wilczek, and show that the tunneling rate is related to the change of Bekenstein-Hawking
entropy, and the factual emission spectrum is not exactly thermal, but satisfies the underlying unitary theory.
PACS: 04.70-s, 9760. Lf. 相似文献
27.
28.
F. Herfurth K. Blaum S. Eliseev O. Kester H.-J. Kluge S. Koszudowski C. Kozhuharov G. Maero D. Neidherr W. Quint S. Schwarz S. Stahl G. Vorobjev 《Hyperfine Interactions》2006,173(1-3):93-101
A decelerator will be installed at GSI in order to provide and study heavy nuclei without or with only few electrons at very
low energies or even at rest. Highly-charged ions will be produced by stripping at relativistic energies. After electron cooling
and deceleration in the Experimental Storage Ring (ESR) the ions are ejected out of the storage ring at 4 MeV/u and further
decelerated in a combination of linear accelerator structures operated in reverse. Finally, they are injected into a Penning
trap where the ions are cooled to 4 K by electron cooling in combination with resistive cooling. From here, the ions can be
transferred in a quasi DC or in a pulsed mode to different experimental setups. This article describes the technical concepts
of this project focused on the Penning trap.
相似文献
29.
挖坑机钻头主轴纵向振动系统模型的建立与控制 总被引:1,自引:0,他引:1
首先利用弹性杆理论和H am ilton变分原理建立了挖坑机钻头主轴及钻尖在工作过程中由于外激励的作用使钻尖与土壤互相作用而产生纵向振动的动力学模型,同时给出边界条件和初始条件.其次通过把系统外激励函数当作控制变量,利用Banach空间几何性质证明了此系统存在唯一最优控制元. 相似文献
30.
对短程飞行时间法(tim e-of-flight,TOF)中推算冷原子温度的理论拟合公式与近似拟合公式进行了误差分析与比较。研究表明:对于使用短程飞行吸收光谱信号推测冷原子团温度,当探测光光斑半径与冷原子团高斯半径之比k小于0.2时,理论拟合公式和近似拟合公式能很好的相符,随着探测光光斑半径与冷原子团高斯半径比值的逐渐增大,用近似拟合公式所得TOF吸收信号与用理论拟合公式所得TOF吸收信号的误差也将逐渐增大,当比值为0.5时,用近似拟合公式所得TOF吸收信号的误差将增大到20%。 相似文献