全文获取类型
收费全文 | 1822篇 |
免费 | 484篇 |
国内免费 | 391篇 |
专业分类
化学 | 164篇 |
晶体学 | 6篇 |
力学 | 80篇 |
综合类 | 25篇 |
数学 | 13篇 |
物理学 | 631篇 |
无线电 | 1778篇 |
出版年
2024年 | 7篇 |
2023年 | 33篇 |
2022年 | 64篇 |
2021年 | 57篇 |
2020年 | 71篇 |
2019年 | 59篇 |
2018年 | 49篇 |
2017年 | 101篇 |
2016年 | 99篇 |
2015年 | 115篇 |
2014年 | 154篇 |
2013年 | 153篇 |
2012年 | 165篇 |
2011年 | 225篇 |
2010年 | 142篇 |
2009年 | 150篇 |
2008年 | 170篇 |
2007年 | 136篇 |
2006年 | 131篇 |
2005年 | 89篇 |
2004年 | 83篇 |
2003年 | 73篇 |
2002年 | 71篇 |
2001年 | 68篇 |
2000年 | 45篇 |
1999年 | 23篇 |
1998年 | 28篇 |
1997年 | 18篇 |
1996年 | 23篇 |
1995年 | 18篇 |
1994年 | 11篇 |
1993年 | 10篇 |
1992年 | 16篇 |
1991年 | 6篇 |
1990年 | 5篇 |
1989年 | 9篇 |
1988年 | 9篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有2697条查询结果,搜索用时 15 毫秒
91.
Standard IC processes, as well as those involving the use of ionizing radiation, such as x-ray lithography etc., result in
the generation of bulk defects, and interface states in the gate insulator, or underlying substrate, respectively, of insulated
gate field effect transistors. Bulk defects are believed to be present as positively and negatively charged electron and hole
traps, respectively, as well as neutral hole and “large” and “small” neutral electron traps. This paper provides a perspective
of the current state of knowledge about the spatial distributions of large bulk defects, their areal densities, sizes, possible
interrelationships among them, and the special cases of defects created by ion implanted silicon and oxygen, where knock-on
effects have been simulated. It appears that bulk defects may all have their origin in neutral hole traps, (so-called E′ centers)
and that when the insulator thickness is decreased to about 6-7 nm, defects are either no longer present, or, more likely,
are incapable of trapping charge at room temperature because trapped carriers can either tunnel to one of the interfaces,
or be annihilated by a reverse process. It appears possible also that the precursor of the several types of defects only forms
at a “grown” silicon-silicon oxide interface. In theory, this would make it possible to grow defect free insulators by a combination
of deposition and oxidation processes. 相似文献
92.
93.
PENG Zhaohui ZHOU Jixun & ZHANG Renhe .Institute of Acoustics Chinese Academy of Sciences Beijing China .School of Mechanical Engineering Georgia Institute of Technology Atlanta GA USA 《中国科学G辑(英文版)》2004,47(6):702-716
1 Introduction Backward scattering of sound due to sediment is the main source of shallow waterreverberation. In order to predict the reverberation or detect sediment properties frommeasured reverberation data, a reasonable in-plane bistatic backward scattering (BBS)model is essential. The scattering can be caused by the roughness of water-sediment in-terface or by inhomogeneities within the volume of sediment. A great deal of researchhas been done on sediment backscattering, most of which h… 相似文献
94.
95.
96.
Brian R. Bennett J. Brad Boos Mario G. Ancona N. A. Papanicolaou Graham A. Cooke H. Kheyrandish 《Journal of Electronic Materials》2007,36(2):99-104
Heterostructures for InAs-channel high-electron-mobility transistors (HEMTs) were investigated. Reactive AlSb buffer and barrier
layers were replaced by more stable Al0.7Ga0.3Sb and In0.2Al0.8Sb alloys. The distance between the gate and the channel was reduced to 7–13 nm to allow good aspect ratios for very short
gate lengths. In addition, n+-InAs caps were successfully deposited on the In0.2Al0.8Sb upper barrier allowing for low sheet resistance with relatively low sheet carrier density in the channel. These advances
are expected to result in InAs-channel HEMTs with enhanced microwave performance and better reliability. 相似文献
97.
以NH3和SiH4为反应源气体,采用射频等离子体增强化学气相沉积(RF-PECVD)法在多晶硅(p-Si)衬底上沉积了一系列SiN薄膜,并利用椭圆偏振测厚仪、超高电阻-微电流计、C-V测试仪对所沉积的薄膜作了相关性能测试.系统分析了沉积温度和射频功率对SiN薄膜的相对介电常数、电学性能及界面特性的影响.分析表明,沉积温度和射频功率主要是通过影响SiN薄膜中的Si/N比影响薄膜的性能,在制备高质量的p-Si TFT栅绝缘层用SiN薄膜方面具有重要的参考价值. 相似文献
98.
异质栅非对称Halo SOI MOSFET 总被引:2,自引:1,他引:2
为了抑制异质栅SOI MOSFET的漏致势垒降低效应,在沟道源端一侧引入了高掺杂Halo结构.通过求解二维电势Poisson方程,为新结构器件建立了全耗尽条件下表面势和阈值电压解析模型,并对其性能改进情况进行了研究.结果表明,新结构器件比传统的异质栅SOI MOSFETs能更有效地抑制漏致势垒降低效应,并进一步提高载流子输运效率.新结构器件的漏致势垒降低效应随着Halo区掺杂浓度的增加而减弱,但随Halo区长度非单调变化.解析模型与数值模拟软件MEDICI所得结果高度吻合. 相似文献
99.
Yu-Ming Lin Joerg Appenzeller Zhihong Chen Phaedon Avouris 《Physica E: Low-dimensional Systems and Nanostructures》2007,37(1-2):72
We investigate electrical transport and noise in semiconducting carbon nanotubes. By studying carbon nanotube devices with various diameters and contact metals, we show that the ON-currents of CNFETs are governed by the heights of the Schottky barriers at the metal/nanotube interfaces. The current fluctuations are dominated by 1/f noise at low-frequencies and correlate with the number of transport carriers in the device regardless of contact metal. 相似文献
100.
Remote interactions between two d-dimensional distributed quantum systems: nonlocal generalized quantum control-NOT gate and entanglement swapping
下载免费PDF全文
![点击此处可从《中国物理》网站下载免费的PDF全文](/ch/ext_images/free.gif)
We present a systematic simple method to implement a generalized quantum control-NOT (CNOT) gate on two d-dimensional distributed systems. First, we show how the nonlocal generalized quantum CNOT gate can be implemented with unity fidelity and unity probability by using a maximally entangled pair of qudits as a quantum channel. We also put forward a scheme for probabilistically implementing the nonlocal operation with unity fidelity by employing a partially entangled qudit pair as a quantum channel. Analysis of the scheme indicates that the use of partially entangled quantum channel for implementing the nonlocal generalized quantum CNOT gate leads to the problem of 'the general optimal information extraction'. We also point out that the nonlocal generalized quantum CNOT gate can be used in the entanglement swapping between particles belonging to distant users in a communication network and distributed quantum computer.[第一段] 相似文献