全文获取类型
收费全文 | 49篇 |
免费 | 7篇 |
国内免费 | 4篇 |
专业分类
化学工业 | 8篇 |
无线电 | 9篇 |
一般工业技术 | 43篇 |
出版年
2023年 | 3篇 |
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 3篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2016年 | 2篇 |
2015年 | 1篇 |
2014年 | 3篇 |
2012年 | 1篇 |
2011年 | 1篇 |
2009年 | 1篇 |
2008年 | 2篇 |
2007年 | 2篇 |
2006年 | 1篇 |
2005年 | 3篇 |
2004年 | 4篇 |
2003年 | 3篇 |
2002年 | 3篇 |
2001年 | 1篇 |
2000年 | 5篇 |
1999年 | 6篇 |
1997年 | 4篇 |
1995年 | 2篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1988年 | 1篇 |
排序方式: 共有60条查询结果,搜索用时 0 毫秒
1.
G. Biotteau M. Hennion F. Moussa J. Rodríguez-Carvajal L. Pinsard A. Revcolevschi 《Journal of Superconductivity》1999,12(1):261-262
Mn perovskites La1–x
Ca
x
MnO3 (0x0.1) have been studied by small angle neutron scattering (SANS) and elastic neutron scattering (ESANS). At low temperature, both experiments reveal a broad modulation centered at the same q
m whatever the q direction. This scattering pattern is typical of a liquid-like distribution of similar magnetic droplets, or large magnetic polarons. 相似文献
2.
Lattice polarons play an important role in the mechanism of colossal magnetoresistance in the (La/Sr)
n+1Mn
n
O3n+1 manganites. Local lattice distortions were characterized by the pulsed neutron pair density function (PDF) analysis. The result shows that the doped holes form polarons related to the Jahn–Teller (JT) effect, both in the two-dimensional layered crystals (n=2) and in the perovskites (n=). The temperature effects are also similar in both systems suggesting that lattice polarons are largely independent of the crystal symmetry. 相似文献
3.
T. Egami W. Dmowski R. J. McQueeney M. Arai N. Seiji H. Yamauchi 《Journal of Superconductivity》1995,8(5):587-590
Significant changes in the local atomic structure and lattice dynamics were observed by pulsed neutron inelastic scattering measurements on YBa2Cu4O8 both around the superconducting transition temperature and around the spin-gap temperature. These observations and earlier results of numerical calculations on the enhancement of electron-lattice interaction by electron correlation lead to a novel picture of unconventional lattice-induced superconductivity related to antiferroelectric instability. 相似文献
4.
5.
6.
Using 2-band Peierls-Hubbard cluster and chain models, we illustrate the importance of polarizability and coupled charge-lattice-spin effects in complex electronic materials.We are grateful for discussions with many colleagues, particularly A. Bussmann-Holder, J. Mustre de Leon, H. Röder, Z. Tesanovic, and S. A. Trugman. 相似文献
7.
The magnetic properties of a system of coexisting localized spins and conduction electrons are investigated within an extended version of the one-dimensional Kondo lattice model in which effects stemming from the electron–lattice and on-site Coulomb interactions are explicitly included. After bosonizing the conduction electrons, is it observed that intrinsic inhomogeneities with the statistical scaling properties of a Griffiths phase appear, and determine the spin structure of the localized impurities. The appearance of the inhomogeneities is enhanced by appropriate phonons and acts destructively on the spin ordering. The inhomogeneities appear on well-defined length scales and can be compared to the formation of intrinsic mesoscopic metastable patterns which are found in two-fluid systems. 相似文献
8.
Improved Charge Generation via Ultrafast Effective Hole‐Transfer in All‐Polymer Photovoltaic Blends with Large Highest Occupied Molecular Orbital (HOMO) Energy Offset and Proper Crystal Orientation
下载免费PDF全文
![点击此处可从《Advanced functional materials》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Feng Jin Jianyu Yuan Wenping Guo Yalong Xu Yannan Zhang Chuanxiang Sheng Wanli Ma Haibin Zhao 《Advanced functional materials》2018,28(31)
Improved charge generation via fast and effective hole transfer in all‐polymer solar cells (all‐PSCs) with large highest occupied molecular orbital (HOMO) energy offset (ΔEH) is revealed utilizing ultrafast transient absorption (TA) spectroscopy. Blending the same nonfullerene acceptor poly{[N,N′‐bis(2‐octyldodecyl)‐naphthalene‐1,4,5,8‐bis(dicarboximide)‐2,6‐diyl]‐alt‐5,5′‐(2,2′‐bithiophene) (N2200) with three different donor polymers produces all‐polymer blends with different ΔEH. The selective excitation of N2200 component in blends enables to uncover the hole transfer process from hole polaron‐induced bleaching and absorption signals probed at different wavelength. As the ΔEH is enhanced from 0.14 to 0.37 eV, the hole transfer rate rises more than one order and the hole transfer efficiency increases from 12.9% to 86.8%, in agreement with the trend of internal quantum efficiency in the infrared region where only N2200 has absorption. Additionally, Grazing‐incidence wide‐angle X‐ray scattering measurements indicate that face‐on crystal orientation in both polymer donor and acceptor also plays an important role in facilitating the charge generation via hole transfer in all‐PSCs. Hence, large ΔEH and proper crystal orientation should be considered in material design for efficient hole transfer in N2200‐based heterostructures. These results can provide valuable guidance for fabrication of all‐PSCs to further improve power conversion efficiency. 相似文献
9.
Felix Deschler Antonietta De Sio Elizabeth von Hauff Peter Kutka Tobias Sauermann Hans‐J. Egelhaaf Jens Hauch Enrico Da Como 《Advanced functional materials》2012,22(7):1461-1469
A study of how light‐induced degradation influences the fundamental photophysical processes in the active layer of poly(3‐hexylthiophene)/[6,6]‐phenyl C61‐butyric acid methyl ester (P3HT/PCBM) solar cells is presented. Non‐encapsulated samples are systematically aged by exposure to AM 1.5 illumination in the presence of dry air for different periods of time. The extent of degradation is quantified by the relative loss in the absorption maximum of the P3HT, which is varied in the range 0% to 20%. For degraded samples an increasing loss in the number of excitons within the P3HT domains is observed with longer ageing periods. This loss occurs rapidly, within the first 15 ps after photoexcitation. A more pronounced decrease in the population of polarons than excitons is observed, which also occurs on a timescale of a few picoseconds. These observations, complemented by a quantitative analysis of the polaron and exciton population dynamics, unravel two primary loss mechanisms for the performances of aged P3HT/PCBM solar cells. One is an initial ultrafast decrease in the polaron generation, apparently not related to the exciton diffusion to the polymer/fullerene interface; the second, less significant, is a loss in the exciton population within the photoexcited P3HT domains. The steady‐state photoinduced absorption spectra of degraded samples exhibits the appearance of a signal ascribed to triplet excitons, which is absent for non‐degraded samples. This latter observation is interpreted considering the formation of degraded sites where intersystem crossing and triplet exciton formation is more effective. The photovoltaic characteristics of same blends are also studied and discussed by comparing the decrease in the overall power conversion efficiency of solar cells. 相似文献
10.
A. S. Alexandrov 《Journal of Superconductivity》2000,13(6):985-988
The Fröhlich electron–phonon interaction in cuprates, manganites, and other charge-transfer ionic Mott insulators is much stronger than any magnetic interaction. The polaron shift due to the Fröhlich interaction, which is about 1 eV, suggests that carriers in those systems are small (bi)polarons at all temperatures and doping levels. We show both analytically and numerically that (bi)polarons exist in the itinerant Bloch states at temperatures below the characteristic phonon frequency no matter which values the parameters of the system take. The small Fröhlich polaron has spectral features compatible with the single-particle tunneling and photoemission in cuprates. Whereas the band energy dispersion of intersite bipolarons is responsible for the d-wave symmetry of the condensate wave-function, the single-particle excitation spectrum is s-like in agreement with the tunneling data. Two different energy scales in Giaver tunneling and Andreev reflection experiments in cuprates can be understood in the framework of the bipolaron theory as well. 相似文献