全文获取类型
收费全文 | 13486篇 |
免费 | 5568篇 |
国内免费 | 3409篇 |
专业分类
化学 | 4332篇 |
晶体学 | 285篇 |
力学 | 698篇 |
综合类 | 207篇 |
数学 | 483篇 |
物理学 | 16458篇 |
出版年
2024年 | 129篇 |
2023年 | 416篇 |
2022年 | 412篇 |
2021年 | 527篇 |
2020年 | 280篇 |
2019年 | 450篇 |
2018年 | 266篇 |
2017年 | 435篇 |
2016年 | 472篇 |
2015年 | 597篇 |
2014年 | 1304篇 |
2013年 | 889篇 |
2012年 | 924篇 |
2011年 | 1012篇 |
2010年 | 934篇 |
2009年 | 1085篇 |
2008年 | 1293篇 |
2007年 | 1023篇 |
2006年 | 1055篇 |
2005年 | 1013篇 |
2004年 | 914篇 |
2003年 | 844篇 |
2002年 | 758篇 |
2001年 | 671篇 |
2000年 | 517篇 |
1999年 | 435篇 |
1998年 | 398篇 |
1997年 | 500篇 |
1996年 | 464篇 |
1995年 | 442篇 |
1994年 | 380篇 |
1993年 | 316篇 |
1992年 | 337篇 |
1991年 | 297篇 |
1990年 | 254篇 |
1989年 | 234篇 |
1988年 | 79篇 |
1987年 | 63篇 |
1986年 | 20篇 |
1985年 | 9篇 |
1984年 | 3篇 |
1983年 | 7篇 |
1982年 | 4篇 |
1979年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
WeiMinSHI JianWU YiFengWU KaiXianQIAN 《中国化学快报》2004,15(12):1427-1429
A mono-funtionalised tetraphenylporphyrin (TPP) bearing valine moiety at the phenyl ring was synthesized for photocytotoxicity examination in four steps, starting from regiospecific mono-nitration of TPP at the phenyl ring. The in vitro photocytotoxicitic effect against SPC-Al adenocarcinona cell line was tested. 相似文献
82.
83.
84.
两段级联掺铒光纤放大器的优化研究 总被引:7,自引:4,他引:3
基于Giles模型,研究了980 nm和1480 nm泵浦的两段级联掺铒光纤放大器(EDFA)的设计,得出了掺铒光纤(EDF)的最佳长度和光隔离器的最佳位置随泵浦功率和信号功率的变化关系.比较980 nm和1480 nm泵浦的两段级联EDFA,可以发现,前者的最佳EDF长度短,而光隔离器最佳位置距EDFA输入端远. 相似文献
85.
A layer of 40nm-thick Ag-SiN film with Ag nano-particles embedded and distributed randomly in the SiN thin film were deposited by the method of radiant-frequency magnetron sputtering. Specimens orderly comprising a random Ag-SiN film and an optical phase change recording layer were exposed to a focused laser beam with wavelength of 69Ohm. It is shown that, with a random Ag-SiN layer deposited above the recording layer. Calculation by the finite difference time domain method of a 4Ohm-thick SiN film under a Gaussian beam irradiation has been carried out to simulate the near-field distribution in the film, which showed a huge local near-field intensity enhancement of about 200 times if small Ag particles with diameter of 6 nm were modelled inthe SiN film in the central region of the in cident laser spot. 相似文献
86.
Spin-Polarized Tunnelling Magnetoresistance Effects in La0.833K0.167MnO3/SrTiO3 Polycrystalline Perovskite Manganites
下载免费PDF全文
![点击此处可从《中国物理快报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A sample of La0.833K0.167MnO3-SrTiO3 (LKMO/STO) is fabricated by the sol-gel method. The microstructure,magnetic and transportation properties have been studied. X-ray diffraction patterns indicate that the structure of LKMO/STO is a homogeneous solid solution phase. The resistivity of LKMO/STO shows the insulator behaviour, which is different from La0.833K0.167MnO3 (LKMO) whose resistivity shows metal-insulator transition with decreasing temperature. The low-field (moH = 0.02 T) magnetoresistance decreases from 11% to 0.2% with the increasing temperature from 4 K‘to 220K for the LKMO/STO sample. The magnitude of magnetoresistance in a strong field (μoH = 5.5 T) almost increases linearly with decreasing temperature and reaches the maximum of 65% at the low temperature of 4.2K, which is much higher than that oE LKMO (40%). The enhanced low-field magnetoresistance effects are quantitatively explained by the spin-polarized tunnelling at grain boundaries. 相似文献
87.
Structure and Photoluminescence of Nano-ZnO Films Grown on a Si (100) Substrate by Oxygen- and Argon-Plasma-Assisted Thermal Evaporation of Metallic Zn
下载免费PDF全文
![点击此处可从《中国物理快报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Nano-ZnO thin films were prepared by oxygen- and argon-plasma-assisted thermal evaporation of metallic Zn at low temperature, followed by low-temperature annealing at 300℃ to 500℃ in oxygen ambient. X-ray diffraction patterns indicate that the nano-ZnO films have a polycrystalline hexagonal wurtzite structure. Raman scattering spectra demonstrate the existence of interface layers between Zn and ZnO. Upon annealing at 400℃ for i h, the interface mode disappears, and photoluminescence spectra show a very strong ultraviolet emission peak around 381 nm. The temperature-dependent PL spectra indicate that the UV band is due to free-exciton emission. 相似文献
88.
89.
90.
本文报道了在Zn0.76Cd0.24Se/ZnSe多量子阱(MQWs)中,用不同的Ar+激光线激发,观察到了共振增强的喇曼散射。首次在室温和77K的条件下,用Ar+的457.9nm谱线激发,观察到分别来自ZnSe垒层和Zn0.76Cd0.24Se阱层的限制纵光学声子模(LO)的喇曼散射,并对上述不同的光学模的起因进行了分析。 相似文献