全文获取类型
收费全文 | 1458篇 |
免费 | 424篇 |
国内免费 | 150篇 |
专业分类
化学 | 714篇 |
晶体学 | 22篇 |
力学 | 71篇 |
综合类 | 9篇 |
数学 | 208篇 |
物理学 | 1008篇 |
出版年
2024年 | 3篇 |
2023年 | 21篇 |
2022年 | 52篇 |
2021年 | 55篇 |
2020年 | 68篇 |
2019年 | 38篇 |
2018年 | 51篇 |
2017年 | 73篇 |
2016年 | 66篇 |
2015年 | 64篇 |
2014年 | 105篇 |
2013年 | 122篇 |
2012年 | 106篇 |
2011年 | 127篇 |
2010年 | 105篇 |
2009年 | 109篇 |
2008年 | 109篇 |
2007年 | 130篇 |
2006年 | 104篇 |
2005年 | 83篇 |
2004年 | 63篇 |
2003年 | 65篇 |
2002年 | 50篇 |
2001年 | 41篇 |
2000年 | 39篇 |
1999年 | 24篇 |
1998年 | 22篇 |
1997年 | 27篇 |
1996年 | 13篇 |
1995年 | 14篇 |
1994年 | 8篇 |
1993年 | 10篇 |
1992年 | 15篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1989年 | 10篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1986年 | 9篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1973年 | 3篇 |
1959年 | 1篇 |
排序方式: 共有2032条查询结果,搜索用时 31 毫秒
101.
Krzysztof Pomorski José M. Blanco Pavel V. Kostryukov Artur Dobrowolski Bo?ena Nerlo-Pomorska Micha? Warda Zhi-Gang Xiao Yong-Jing Chen Li-Le Liu Jun-Long Tian Xin-Yue Diao Qiang-Hua Wu 《中国物理C(英文版)》2021,45(5):054109-054109-11
Fission properties of the actinide nuclei are deduced from theoretical analysis. We investigate potential energy surfaces and fission barriers and predict the fission fragment mass yields of actinide isotopes. The results are compared with experimental data where available. The calculations were performed in the macroscopic-microscopic approximation with the Lublin-Strasbourg Drop (LSD) for the macroscopic part, and the microscopic energy corrections were evaluated in the Yukawa-folded potential. The Fourier nuclear shape parametrization is used to describe the nuclear shape, including the non-axial degree of freedom. The fission fragment mass yields of the nuclei considered are evaluated within a 3D collective model using the Born-Oppenheimer approximation. 相似文献
102.
Superhydrophobic surfaces have shown inspiring applications in microfluidics, and self-cleaning coatings owing to water-repellent and low-friction properties. However, thermodynamic mechanism responsible for contact angle hysteresis (CAH) and free energy barrier (FEB) have not been understood completely yet. In this work, we propose an intuitional 3-dimension (3D) droplet model along with a reasonable thermodynamic approach to gain a thorough insight into the physical nature of CAH. Based on this model, the relationships between radius of three-phase contact line, change in surface free energy (CFE), average or local FEB and contact angle (CA) are established. Moreover, a thorough theoretical consideration is given to explain the experimental phenomena related to the superhydrophobic behavior. The present study can therefore provide some guidances for the practical fabrications of the superhydrophobic surfaces. 相似文献
103.
为确定三维显示中视差障栅(PB)的最优参数,提出一种基于彩色叠栅条纹的PB参数设计方法。液晶显示器(LCD)和PB简化为相应参数的黑白光栅模型,而具有特定参数的特定辐射光栅作为周期和倾角变化的PB模型,通过序数方程和傅里叶分析方法分析特定辐射光栅和LCD单色等效黑白光栅的叠加图样,由此推断出不同PB周期的低频主导条纹频率组项,然后利用傅里叶理论的部分和提取方法(PSE)分析不同PB周期的低频主导叠栅条纹的强度轮廓,得出PB的最佳节距和相应倾斜角度。实验结果表明,所设计的PB三维显示系统没有出现降低像质的叠栅条纹,具有较好的三维显示效果。 相似文献
104.
D.M. Murape N. Eassa C. Nyamhere J.H. Neethling R. Betz E. Coetsee H.C. Swart J.R. Botha A. Venter 《Physica B: Condensed Matter》2012,407(10):1675-1678
Bulk (1 0 0) n-GaSb surfaces have been treated with a sulphur based solution ((NH4)2S/(NH4)2SO4) to which sulphur has been added, not previously reported for the passivation of GaSb surfaces. Au/n-GaSb Schottky barrier diodes (SBDs) fabricated on the treated material show significant improvement compared to that of the similar SBDs on the as-received material as evidenced by the lower ideality factor (n), higher barrier height (?b) and lower contact resistance obtained. Additionally, the reverse leakage current, although not saturating, has been reduced by almost an order of magnitude at −0.2 V. The sample surfaces were studied by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The native oxide, Sb–O, present on the as-received material is effectively removed on treating with ([(NH4)2S/(NH4)2SO4]+S) and (NH4)2S. Analysis of the as-received surface by XPS, prior to and after argon sputtering, suggests that the native oxide layer is ≤8.5 nm. 相似文献
105.
106.
107.
利用分子动力学模拟统计了几种不同温度下三种不同二聚物(Cu2, Ag2和Pd2)在铜衬底(100), (111)表面上的扩散和解离行为, 探讨同质和异质二聚物在Cu表面上扩散和解离的特点; 采用分子动力学中的静态计算方法计算了这三种二聚物在扩散和解离过程中的能量势垒, 并与动力学模拟、二聚物与衬底的结合能等结果进行了比较, 探讨二聚物扩散和解离过程与扩散势垒、结合能、表面性质和温度等的关系. 原子间相互作用采用半经验EAM势. 结果表明: 同质和异质二聚物在各个不同表面上的扩散势垒、解离势垒有一定的规律, 并和二聚物与衬底的结合性质有关; 二聚物是否易解离与衬底表面的结构以及二聚物与衬底的结合性质关系密切; 二聚物解离前协同扩散的快慢与二聚物和衬底的结合性质以及二聚物在表面的扩散和解离势垒密切相关. 相似文献
108.
在介质阻挡放电体系中产生辉光放电可以有效的提高放电体系产生高能电子的性能, 为等离子体化学反应提供更加丰富的活性粒子.本文对针-板介质阻挡放电体系下的放电模式进行了研究,实验发现放电正负半周期表现出不同的放电模式, 激励电压为3 kV时放电正负半周期分别为微流注放电和电晕放电(或者Trichel脉冲放电),激励电压为6 kV时放电正负半周期分别为微流注放电和微辉光放电.微辉光放电形貌具有与典型辉光放电相同的分层次放电结构, 分析了激励电压6 kV时的放电过程,认为足够强的阴极电场强度和裸露针状电极形成的有效的二次电子发射过程是形成微辉光放电的主要因素,绝缘介质层的存在避免了微辉光放电向弧光放电过渡. 相似文献
109.
Svetlana V. Kirpichenko Bagrat A. Shainyan Erich Kleinpeter 《Journal of Physical Organic Chemistry》2012,25(12):1321-1327
The conformational analysis of the first representative of the Si‐alkoxy substituted six‐membered Si,N‐heterocycles, 1,3‐dimethyl‐3‐isopropoxy‐3‐silapiperidine, was performed by low‐temperature 1H and 13C NMR spectroscopy and DFT theoretical calculations. In contrast to the expectations from the conformational energies of methyl and alkoxy substituents, the Meaxi‐PrOeq conformer was found to predominate in the conformational equilibrium in the ratio Meaxi‐PrOeq : Meeqi‐PrOax of ca. 2 : 1 as from the 1H and 13C NMR study. The thermodynamic parameters obtained by the complete line shape analysis showed that the main contribution to the barrier to ring inversion originates from the entropy term of the free energy of activation. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
110.
The influence of interfacial barrier engineering on the resistance switching of In<sub>2</sub>O<sub>3</sub>:SnO<sub>2</sub>/TiO<sub>2</sub>/In<sub>2</sub>O<sub>3</sub>:SnO<sub>2</sub> device 下载免费PDF全文
The I–V characteristics of In2O3:SnO2/TiO2/In2O3:SnO2 junctions with different interfacial barriers are inves- tigated by comparing experiments. A two-step resistance switching process is found for samples with two interfacial barriers produced by specific thermal treatment on the interfaces. The nonsynchronous occurrence of conducting filament formation through the oxide bulk and the reduction in the interfacial barrier due to the migration of oxygen vacancies under the electric field is supposed to explain the two-step resistive switching process. The unique switching properties of the device, based on interfacial barrier engineering, could be exploited for novel applications in nonvolatile memory devices. 相似文献