全文获取类型
收费全文 | 400篇 |
免费 | 14篇 |
国内免费 | 2篇 |
专业分类
化学 | 270篇 |
晶体学 | 1篇 |
力学 | 10篇 |
数学 | 108篇 |
物理学 | 27篇 |
出版年
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 5篇 |
2020年 | 10篇 |
2019年 | 11篇 |
2018年 | 15篇 |
2017年 | 8篇 |
2016年 | 30篇 |
2015年 | 16篇 |
2014年 | 20篇 |
2013年 | 34篇 |
2012年 | 20篇 |
2011年 | 37篇 |
2010年 | 26篇 |
2009年 | 21篇 |
2008年 | 30篇 |
2007年 | 31篇 |
2006年 | 22篇 |
2005年 | 20篇 |
2004年 | 14篇 |
2003年 | 15篇 |
2002年 | 11篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1984年 | 1篇 |
1981年 | 1篇 |
1969年 | 1篇 |
1931年 | 1篇 |
排序方式: 共有416条查询结果,搜索用时 37 毫秒
21.
ABSTRACTIn this work, a tunable dual-band near-infrared perfect metamaterial absorber formed by combining a highly birefringent nematic liquid crystal with a nanoscale metamaterial cavity arranged in mirror symmetry is designed and numerically investigated. Electromagnetic simulations indicate that the absorbance greater than 99.4% may be achieved at 328 THz and 364 THz. Perfect absorbance results both form the use of highly lossy metal and the optimization of the metamaterial structure. In addition, absorbance of the metamaterial device can be substantially tuned both in terms of its magnitude and wavelength with the spectral tunability up to 8 THz by switching of liquid crystal alignment. The soft-matter-based metamaterial absorbers may pave a crucial role towards various active multifunctional systems working in the near-infrared range. 相似文献
22.
Rafał Jakieła Marta Galicka Piotr Dziawa Gunther Springholz Adam Barcz 《Surface and interface analysis : SIA》2020,52(3):71-75
Substitutional alloy Pb1 − xSnxSe is a new class of electronic materials called topological crystalline insulators, which at the temperature range from 0 K to 300 K exhibit topological state at compositions in the range 0.18 < x < 0.40 (in the rock-salt structure). In this report, we present a secondary ion mass spectrometry (SIMS) analysis technique to provide accurate Pb and Sn composition based on the measurement of PbCs+ and SnCs+ cluster ions intensities. Studies of Pb1 − xSnxSe bulk samples with various values of x show that x/(1 − x) is linear in relation to the intensity ratio of PbCs+/SnCs+ over the range from x = 0.15 to x = 0.41. This technique allows us to obtain an accurate Sn content for multilayered heterostructures, quantum wells containing Pb1 − xSnxSe with different x values for each layer. 相似文献
23.
Monika Szulc Justyna Samaszko-Fiertek Rafał Ślusarz Kornelia Kowalska Artur Sikorski 《Journal of carbohydrate chemistry》2016,35(3):161-171
Solid phase peptide synthesis (SPPS) of two selected muramyl pentapeptide derivatives is described. The simplicity of removing the protecting groups via one-step deprotection and cleavage from the resin is the biggest advantage of SPPS. Using this method, two muramyl pentapeptide derivatives, D-MurN3-L-Ala-D-iGlu-L-Lys-D-Ala-D-Ser (5) and D-MurN3-L-Ala-D-iGlu-L-Lys-D-Ala-D-Ala (6), were obtained. Their chemical structures were confirmed by high-resolution mass spectrometry (HRMS) and nuclear magnetic resonance (NMR) spectroscopy. To determine the absolute configuration of the carbon atom in the side chain of the muramic acid derivative, single-crystal X-ray diffraction measurements were recorded. 相似文献
24.
Frański R Szymański A Gierczyk B Chlebicki J Frańska M 《Journal of mass spectrometry : JMS》2002,37(4):372-378
Liquid secondary ion (LSI) mass spectra of ion-pair precipitates obtained for Triton X-100 with strontium, lead, cadmium and mercury tetraphenylborates and for selected butoxylene-ethoxylene monoalkyl ethers with barium tetraiodobismuthate(III) are discussed. On the basis of LSI mass spectra, recorded in both positive and negative modes, the formulae of the ion-pair precipitates were determined. On the basis of B/E mass spectra, the fragmentation routes of [M - H + Ba](+) ions for butoxylene-ethoxylene monoalkyl ether complexes of barium and [M - H + Cd](+) ions for the Triton X-100 complex of cadmium are proposed. 相似文献
25.
Alkanes deposited on aqueous substrates exhibit two different types of wetting behavior: alternatively to the usual first-order wetting transition, a sequential-wetting scenario of a long-range critical wetting transition preceded by a first-order thin-thick transition may be observed. Here, we present the first successful experimental attempt to locate the transition point between the standard first-order wetting and the long-range critical wetting: a critical end point, observed in a mixture of pentane and hexane which is deposited on an aqueous solution of glucose. Furthermore, we present the first direct measurement of the contact angle in the intermediate wetting state (frustrated-complete wetting) in the sequential-wetting scenario of hexane on brine and compare to theoretical predictions. 相似文献
26.
27.
28.
29.
Mathematical assessment of homogenisation progress of the granular material mixing process is presented. The mixing process
was realised using a vessel in the form of two partly penetrating horizontal cylinders equipped with two multi-ribbon agitators.
The experimental system consisted of three sets of particles of different colour. Random states of the mixed granular material
were characterised by the sampling procedure at different moments of the mixing process. Informational entropy as well as
the flow of quantum of information were applied to describe the progress of the homogenisation process. Analysis of this process
was based on experimental investigations in the form of informational entropy patterns and described by means of the average
informational entropy or the quantum of information.
Presented at the 34th International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 21–25 May
2007. 相似文献
30.
We give necessary and sufficient conditions for the (bounded) law of the iterated logarithm for U-statistics in Hilbert spaces. As a tool we also develop moment and tail estimates for canonical Hilbert-space valued U-statistics of arbitrary order, which are of independent interest.
R. Adamczak’s research partially supported by MEiN Grant 2 PO3A 019 30.
R. Latała’s research partially supported by MEiN Grant 1 PO3A 012 29. 相似文献