全文获取类型
收费全文 | 4683篇 |
免费 | 3361篇 |
国内免费 | 871篇 |
专业分类
化学 | 1017篇 |
晶体学 | 110篇 |
力学 | 321篇 |
综合类 | 105篇 |
数学 | 709篇 |
物理学 | 6653篇 |
出版年
2024年 | 65篇 |
2023年 | 126篇 |
2022年 | 156篇 |
2021年 | 168篇 |
2020年 | 128篇 |
2019年 | 171篇 |
2018年 | 142篇 |
2017年 | 155篇 |
2016年 | 218篇 |
2015年 | 228篇 |
2014年 | 551篇 |
2013年 | 378篇 |
2012年 | 415篇 |
2011年 | 443篇 |
2010年 | 456篇 |
2009年 | 526篇 |
2008年 | 578篇 |
2007年 | 464篇 |
2006年 | 436篇 |
2005年 | 425篇 |
2004年 | 402篇 |
2003年 | 314篇 |
2002年 | 241篇 |
2001年 | 240篇 |
2000年 | 163篇 |
1999年 | 170篇 |
1998年 | 161篇 |
1997年 | 155篇 |
1996年 | 136篇 |
1995年 | 112篇 |
1994年 | 92篇 |
1993年 | 77篇 |
1992年 | 99篇 |
1991年 | 90篇 |
1990年 | 63篇 |
1989年 | 58篇 |
1988年 | 34篇 |
1987年 | 32篇 |
1986年 | 8篇 |
1985年 | 14篇 |
1984年 | 9篇 |
1983年 | 8篇 |
1982年 | 8篇 |
排序方式: 共有8915条查询结果,搜索用时 31 毫秒
81.
Generation of Ultrashort Light Bullets in Dispersive Kerr Media Using the Fourth—Order Dispersion—Dependent Spatiotemporal Instability 下载免费PDF全文
A new method for generation of a train of ultrashort pulses or a sequence of ultrashort light bullets is proposed. This method is based on the fourth-order dispersion-dependent spatiotemporal instability in dispersive Kerr media. The repetition-rate of the generated bullets can be made quite large by increasing the corresponding spatial modulation frequency locating in the new instability region resulted from fourth-order dispersion. 相似文献
82.
83.
几种常见光源特性的研究 总被引:2,自引:1,他引:1
本通过大学物理实验中常用光源特性的分析,说明了实验中光源使用的合理性。 相似文献
84.
Elimination of Spiral Waves and Competition between Travelling Wave Impulses and Spiral Waves 下载免费PDF全文
The interaction between travelling wave impulses and spiral waves is studied and the results of their competition are related to the exciting period. From the results, it is known that the formation and development of spiral waves in cardiac tissue depend on the period by which the travelling wave impulses are excited. A method is proposed to eliminate spiral waves, which is easily operated. 相似文献
85.
86.
87.
Deposition of Diamond-Like carbon Films by High-Intensity Pulsed Ion Beam Ablation at Various Substrate Temperatures 下载免费PDF全文
Diamond-like carbon (DLC) films have been deposited on to Si substrates at substrate temperatures from 255℃ to 400O℃ by a high-intensity pulsed-ion-beam (HIPIB) ablation deposition technique. The formation of DLC is confirmed by Raman spectroscopy. According to an x-ray photoelectron spectroscopy analysis, the concentration of sp^3 carbon in the films is about 40% when the substrate temperature is below 300℃ C. With increasing substratetemperature from 25℃ to 400℃, the concentration of sp^3 carbon decreases from 43% to 8%. In other words,sp3 carbon is graphitized into sp^2 carbon when the substrate temperature is above 300℃. The results of xray diffraction and atomic force microscopy show that, with increasing the substrate temperature, the surface roughness and the friction coefficient increase, and the microhardness and the residual stress of the films decrease. 相似文献
88.
89.
用高功率脉冲激光轰击Zn1-xCoxO,得到锌、钴和氧的原子、分子和团簇等混合体,并在p型单晶Si表面反应生成n型Zn1-xCoxO.X射线衍射(XRD)、原子力显微镜(AFM)研究表明,这层材料是结构致密均匀、呈c轴高度择优取向的薄膜,与p型Si材料形成n-Zn1-xCoxO/p-Si异质结.在Zn1-xCoxO中加入H,生成了Co-H-Co聚合体,异质结的势垒高度随着Co含量的增加而增加,同时深能级的Co-d轨道捕获作为浅施主的间隙H提供的电子,造成的体系n型半导体层的载流子浓度降低,电阻率提高,使得n-Zn1-xCoxO/p-Si异质结在6.5V时漏电流降致6×10-3 mA,反向击穿电压超过20V,电学性能得到显著改进. 相似文献
90.
We have experimentally studied the characteristics of fifth-order harmonic radiation produced by two coherent femtosecond laser pulses with a changeable relative phase.The intensities of harmonic generation are found to increase with the coherent degree.In one optical Period,the temporal variation of harmonics exhibits an asymmetric characteristic,which is interpreted in terms of ionization theory and the deformation of the wave packets of fundamental field contribution to harmonic generation. 相似文献