全文获取类型
收费全文 | 758篇 |
免费 | 179篇 |
国内免费 | 85篇 |
专业分类
化学 | 340篇 |
晶体学 | 14篇 |
力学 | 34篇 |
综合类 | 10篇 |
数学 | 143篇 |
物理学 | 481篇 |
出版年
2024年 | 2篇 |
2023年 | 5篇 |
2022年 | 16篇 |
2021年 | 12篇 |
2020年 | 34篇 |
2019年 | 24篇 |
2018年 | 24篇 |
2017年 | 28篇 |
2016年 | 32篇 |
2015年 | 41篇 |
2014年 | 64篇 |
2013年 | 70篇 |
2012年 | 58篇 |
2011年 | 98篇 |
2010年 | 58篇 |
2009年 | 68篇 |
2008年 | 53篇 |
2007年 | 56篇 |
2006年 | 39篇 |
2005年 | 42篇 |
2004年 | 34篇 |
2003年 | 26篇 |
2002年 | 20篇 |
2001年 | 17篇 |
2000年 | 15篇 |
1999年 | 13篇 |
1998年 | 14篇 |
1997年 | 8篇 |
1996年 | 7篇 |
1995年 | 8篇 |
1994年 | 7篇 |
1993年 | 5篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 4篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 4篇 |
1979年 | 1篇 |
排序方式: 共有1022条查询结果,搜索用时 15 毫秒
71.
72.
Generalizing a classical idea of Biermann, we study a way of constructing a unisolvent array for Lagrange interpolation in Cn+m out of two suitably ordered unisolvent arrays respectively in Cn and Cm. For this new array, important objects of Lagrange interpolation theory (fundamental Lagrange polynomials, Newton polynomials, divided difference operator, vandermondian, etc.) are computed.
AMS subject classification 41A05, 41A63 相似文献
73.
Tunable Surface‐Enhanced Raman Scattering from High‐Density Gold Semishell Arrays with Controllable Dimensions 下载免费PDF全文
Xianzhong Lang Dr. Jiaqi Li Xiaoguang Luo Yan Zhang Yin Yin Prof. Teng Qiu 《Chemphyschem》2014,15(2):337-343
A convenient reproducible technique is reported for the fabrication of large‐area gold semishell arrays by mechanically pressing porous anodic alumina (PAA) stamps into gold/polymer bilayer structures that serve as robust and cost‐efficient surface‐enhanced Raman‐scattering (SERS) substrates. The surface structure can be tuned further to optimize the enhancement factor according to optional PAA fabrication parameters and imprinting pressures. Finite‐difference time‐domain calculations indicate that the structure may possess excellent SERS characteristics due to the high density and abundance of hot spots. 相似文献
74.
D.F. Underwood T. Kippeny S.J. Rosenthal 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):241-244
The dynamics of photo-generated electrons and holes in CdSe quantum dots have been studied using the femtosecond fluorescence
upconversion technique, permitting an unambiguous examination of the excited state. The band edge emission shows an expected
size dependence on the decay rate. We find that the deep trap emission is coupled to the band edge fluorescence, implicating
surface states as important factors in the excited state lifetime of the hole. As a factor of the overall efficiency of solar
cells, the rate of charge separation and the fate of the exciton are important considerations in the design of nanocrystal-based
photovoltaic devices.
Received 30 November 2000 相似文献
75.
We propose a square-core metallic nanotube array and investigate its optical transmission property theoretically. We find that the transmission spectra can be tuned by the width of square-core edge, the intertube spacing and the dielectric constants of the core and the embedding medium between the nanotubes. We show that there is a band gap over a wide optical wavelength, and its width, number and position are sensitive to the tunable parameters. We also discuss the situation of the rectangular-core nanotube arrays and present that modification of the size of internal holes leads to redshift of the transmission spectra. Based on the localized nature of the field distributions, we show that there are local plasmonic resonant modes that originate from multipolar plasmon polaritons and a large number of opposing surface charges build up in the gap between adjacent nanotubes. 相似文献
76.
报道了一种用共轴全对光学系统补偿激光二极管本征像散的新方法,该方法结构简单,易制造,且费用低,文中还给同了几种准直和聚焦的光学系统。 相似文献
77.
正交平衡区组设计(或者广义正交表)是一种类似于正交拉丁方(或者正交表)的新设计,但试验次数大幅减少.定义了一种基于正交相遇平衡区组设计(或者广义正交表)的统计分析模型,根据这个模型,给出了参数的最小二乘估计的矩阵形式. 相似文献
78.
Novel electrocatalysts Au/TiO2 nanotube arrays (Au/TiO2NTs) were prepared by loading low-content(1.9 at.%) of Au nanoparticles (AuNPs) onto highly ordered TiO2 nanotube arrays (TiO2NTs). Ethanol electrooxidation indicates that visible-light (λ > 400 nm) irradiation can significantly enhance the activity as well as resistpoisoning of Au/TiO2NTs electrocatalysts that are activated by plasmon resonance. Au/TiO2NTs catalysts calcinated at 300 °C display the highest performance due to the strong synergistic interactions between TiO2 and Au NPs. The combination of visible-light irradiation with a controllable potential offers a new strategyfor enhancing the performance of anodes in direct ethanol fuel cell (DEFC). 相似文献
79.
José Agapito Ângela Mestre Pasquale Petrullo Maria M. Torres 《Linear algebra and its applications》2013
We approach Riordan arrays and their generalizations via umbral symbolic methods. This new approach allows us to derive fundamental aspects of the theory of Riordan arrays as immediate consequences of the umbral version of the classical Abel?s identity for polynomials. In particular, we obtain a novel non-recursive formula for Riordan arrays and derive, from this new formula, some known recurrences and a new recurrence relation for Riordan arrays. 相似文献
80.
Jianhui Zhu 《Journal of solid state chemistry》2011,184(3):578-7251
Porous NiO nanowall arrays (NWAs) grown on flexible Fe-Co-Ni alloy have been successfully synthesized by using nullaginite (Ni2(OH)2CO3) as precursor and investigated as supercapacitor electrodes. In details, we adopted a simple hydrothermal method to realize Ni2(OH)2CO3 NWAs and examined their robust mechanical adhesion to substrate via a long-time ultrasonication test. Porous NiO NWAs were then obtained by a post-calcination towards precursors at 500 °C in nitrogen atmosphere. Electrochemical properties of as-synthesized NiO NWAs were evaluated by cyclic voltammetry and galvanostatic charge/discharge; porous NiO NWAs electrode delivered a specific capacitance of 270 F/g (0.67 A/g); even at high current densities, the electrode could still deliver a high capacitance up to 236 F/g (13.35 A/g). Meanwhile, it exhibited excellent cycle lifetime with ∼93% specific capacitance kept after 4000 cycles. These results suggest that as-made porous NiO NWAs electrode is a promising candidate for future thin-film supercapacitors and other microelectronic systems. 相似文献