全文获取类型
收费全文 | 3762篇 |
免费 | 834篇 |
国内免费 | 1347篇 |
专业分类
化学 | 2646篇 |
晶体学 | 170篇 |
力学 | 289篇 |
综合类 | 176篇 |
数学 | 681篇 |
物理学 | 1981篇 |
出版年
2024年 | 12篇 |
2023年 | 33篇 |
2022年 | 126篇 |
2021年 | 118篇 |
2020年 | 140篇 |
2019年 | 131篇 |
2018年 | 99篇 |
2017年 | 181篇 |
2016年 | 121篇 |
2015年 | 187篇 |
2014年 | 200篇 |
2013年 | 283篇 |
2012年 | 289篇 |
2011年 | 297篇 |
2010年 | 345篇 |
2009年 | 371篇 |
2008年 | 422篇 |
2007年 | 405篇 |
2006年 | 362篇 |
2005年 | 300篇 |
2004年 | 200篇 |
2003年 | 143篇 |
2002年 | 187篇 |
2001年 | 200篇 |
2000年 | 160篇 |
1999年 | 105篇 |
1998年 | 57篇 |
1997年 | 42篇 |
1996年 | 51篇 |
1995年 | 46篇 |
1994年 | 51篇 |
1993年 | 45篇 |
1992年 | 45篇 |
1991年 | 25篇 |
1990年 | 33篇 |
1989年 | 27篇 |
1988年 | 25篇 |
1987年 | 13篇 |
1986年 | 9篇 |
1985年 | 15篇 |
1984年 | 7篇 |
1983年 | 7篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1980年 | 3篇 |
1979年 | 5篇 |
1978年 | 5篇 |
1971年 | 1篇 |
1965年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有5943条查询结果,搜索用时 15 毫秒
991.
In the weakly coupled electron-phonon systems, the existing theory pointed out that the energy spectra of polaron include four electronic bound states. Our work shows that, due to the non-nearest neighbor hopping interactions, the electron-hole symmetry of the energy band structure implied by SSH model is broken, and the numbers of the bound electronic states are changed. For a negative charged polaron, one new bound state is found near the bottom of conduction band, and the original two bound states below the bottom of the valence band and above the top of the conduction band disappear. For a positive charged polaron, five bound states have been found: one of them is an additional bound state at the top of the conduction band, the others are just the states found in the SSH model. Besides, the energy gap 2Δ is slightly shifted by turning on the long-range hopping interactions. 相似文献
992.
HAO Qiang LI Wen-lian ZHANG Yan YU Gui YANG Hong ZHAO Xu YAO Qi-Zhi LI Qing-shan 《高等学校化学研究》1995,11(4):279-283
The interaction of lanthanide (Ln3+)ions with trchosanthin(TCS)was investi-gated using Tb3+ as fluorescent probe.The metal-binding sites of the protein were probed by means of adding the Tb3+ into the protein solutions.If other Ln3+ ions exist in the Tb3+ protein complex system, they would compete against Tb3+ in the binding sites of the protein, and so the fluorescence intensity of Tb3+ decreased,which is called quenching effect.The quencliing effect is related to the ionic radii of the Ln3+ ions and energy transfer from Tb3+ protein to Ln3+ ions.Based on the ex-perimental results,a schematic of the energy transfer from protein-Tb3+ complex to protein-Ln3+ complex is suggested. 相似文献
993.
THE SYSTEMATIC CALCULATIONS OF (n,2n) AND (n,3n) REACTION CROSS SECTIONS FOR MEDIUM-HEAVY NUCLEI AT 14.5MeV 下载免费PDF全文
The (n,2n) and (n,3n) reaction processes have been studied by mechanism analysis of the neutron-induced nuclear reactions,formulae for evaluating the reduced cross section have been given.The cross sections of 14.5MeV (n,2n),(n,3n) reactions have been calculated according to the systematic method for Z=58—83 about 53 nuclei.A good agreement between the results of the systematic calculations and the experimental data has been reached. 相似文献
994.
YAO Kai-lun 《理论物理通讯》1984,3(2):149-153
The numerical simulation of the irreversiblity of magnetization and the anisotropy field is studied in a spin glass with RXKY and DM interactions, It is found that the anisotropy field increases linearly with the concentration of nonmagnetic impurities, but the remanent magnetization and the saturation remain unchanged with different concentrations. A comparison is made with experiment. 相似文献
995.
996.
997.
200 nm Supercontinuum Generated by Subpicosecond Optical Pulses and its Evolution Process Observation 总被引:1,自引:0,他引:1
XU Lei YAO Minyu LI Yuhua WU Jian CHEN Minghua ZHANG Jianfeng ZHANG Hongming LOU Caiyun GAO Yizhi 《Chinese Journal of Lasers》1999,8(4):289-293
Introduction Whenultrashortopticalpulseswithhighintensity(pumpinglight)areinjectedintodispersionshiftedfiber(DSF),duetothenonlineareffectsinfibersuchasselfphasemodulation(SPM),fourwavemixing(FWM),crossphasemodulation(XPM)andstimulatedRamanscatteri… 相似文献
998.
1INTRODUCTIONAmongthewidevarietyofphotosystemI(PSI)photosyntheticelectrontrans portinhibitors,thehighlypotentcyanoacrylatePSI... 相似文献
999.
We suggest a local pinning feedback control for stabilizing periodic pattern in spatially extended systems. Analytical and numerical investigations of this method for a system described by the one-dimensional complex Ginzburg-Landau equation are carried out. We found that it is possible to suppress spatiotemporal chaos by using a few pinning signals in the presence of a large gradient force. Our analytical predictions well coincide with numerical observations. 相似文献
1000.
运用248nm激光光解瞬态吸收光谱研究了SO4·-与DNA及其核苷酸和多聚核苷酸poly[G]、poly[A]和poly[C]的相互作用,观察了各体系的作用过程,结果表明,poly[G]、poly[A]与SO4·-发生单电子氧化反应生成嘌呤端基自由基;dCMP与SO4·-单电子氧化生成阳离子自由基,随后与水反应生成5-羟基-6C自由基;而poly[C],SO4·-先在碱基上加成,生成的加成自由基再从核糖上抽氢生成C2’-糖自由基;DNA与SO4·-作用生成的主要瞬态产物是鸟嘌呤端基自由基。 相似文献