全文获取类型
收费全文 | 811篇 |
免费 | 52篇 |
国内免费 | 3篇 |
专业分类
化学 | 538篇 |
晶体学 | 8篇 |
力学 | 17篇 |
数学 | 108篇 |
物理学 | 126篇 |
无线电 | 69篇 |
出版年
2023年 | 5篇 |
2022年 | 13篇 |
2021年 | 15篇 |
2020年 | 25篇 |
2019年 | 14篇 |
2018年 | 9篇 |
2017年 | 13篇 |
2016年 | 23篇 |
2015年 | 25篇 |
2014年 | 21篇 |
2013年 | 36篇 |
2012年 | 63篇 |
2011年 | 61篇 |
2010年 | 48篇 |
2009年 | 22篇 |
2008年 | 61篇 |
2007年 | 48篇 |
2006年 | 41篇 |
2005年 | 37篇 |
2004年 | 27篇 |
2003年 | 19篇 |
2002年 | 17篇 |
2001年 | 11篇 |
2000年 | 7篇 |
1999年 | 6篇 |
1998年 | 9篇 |
1997年 | 7篇 |
1996年 | 8篇 |
1995年 | 12篇 |
1994年 | 6篇 |
1993年 | 8篇 |
1992年 | 10篇 |
1991年 | 9篇 |
1990年 | 4篇 |
1989年 | 11篇 |
1988年 | 6篇 |
1985年 | 7篇 |
1984年 | 8篇 |
1983年 | 9篇 |
1982年 | 6篇 |
1980年 | 5篇 |
1978年 | 6篇 |
1977年 | 4篇 |
1976年 | 5篇 |
1975年 | 7篇 |
1974年 | 7篇 |
1939年 | 4篇 |
1938年 | 4篇 |
1919年 | 3篇 |
1909年 | 3篇 |
排序方式: 共有866条查询结果,搜索用时 15 毫秒
861.
Renaud Lambiotte Vincent D. Blondel Etienne Huens Zbigniew Smoreda 《Physica A》2008,387(21):5317-5325
In this paper, we analyze statistical properties of a communication network constructed from the records of a mobile phone company. The network consists of 2.5 million customers that have placed 810 million communications (phone calls and text messages) over a period of 6 months and for whom we have geographical home localization information. It is shown that the degree distribution in this network has a power-law degree distribution k−5 and that the probability that two customers are connected by a link follows a gravity model, i.e. decreases as d−2, where d is the distance between the customers. We also consider the geographical extension of communication triangles and we show that communication triangles are not only composed of geographically adjacent nodes but that they may extend over large distances. This last property is not captured by the existing models of geographical networks and in a last section we propose a new model that reproduces the observed property. Our model, which is based on the migration and on the local adaptation of agents, is then studied analytically and the resulting predictions are confirmed by computer simulations. 相似文献
862.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option. 相似文献
863.
Guillaume Vidon Pia Dally Mirella Al-Katrib Daniel Ory Minjin Kim Etienne Soret Eva Rangayen Marie Legrand Alexandre Blaizot Philip Schulz Jean-Baptiste Puel Daniel Suchet Jean-François Guillemoles Arnaud Etcheberry Muriel Bouttemy Stefania Cacovich 《Advanced functional materials》2023,33(45):2304730
Understanding the effects of X-rays on halide perovskite thin films is critical for accurate and reliable characterization of this class of materials, as well as their use in detection systems. In this study, advanced optical imaging techniques are employed, both spectrally and temporally resolved, coupled with chemical characterizations to obtain a comprehensive picture of the degradation mechanism occurring in the material during photoemission spectroscopy measurements. Two main degradation pathways are identified through the use of local correlative physico-chemical analysis. The first one, at low X-Ray fluence, shows minor changes of the surface chemistry and composition associated with the formation of electronic defects. Moreover, a second degradation route occurring at higher fluence leads to the evaporation of the organic cations and the formation of an iodine-poor perovskite. Based on the local variation of the optoelectronic properties, a kinetic model describing the different mechanisms is proposed. These findings provide valuable insight on the impact of X-rays on the perovskite layers during investigations using X-ray based techniques. More generally, a deep understanding of the interaction mechanism of X-rays with perovskite thin films is essential for the development of perovskite-based X-ray detectors and solar for space applications. 相似文献
864.
865.
Etienne Garand Torsten Wende Daniel J. Goebbert Risshu Bergmann Gerard Meijer Daniel M. Neumark Knut R. Asmis 《ChemInform》2010,41(18):no-no
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option. 相似文献
866.
Dr. Youssef Doubi Prof. Bouchaib Hartiti Prof. Maryam Siadat Prof. Hicham Labrim Prof. Salah Fadili Prof. Mounia Tahri Prof. Mohamed Stitou Prof. Philippe Thevenin Etienne Losson 《欧洲无机化学杂志》2023,26(22):e202300047
The semiconductor realization is a very significant stage in gas sensor application. Herein, the Mn3O4 semiconductor was deposited using chemical spray pyrolysis. The effect of deposition temperature on structural, vibrational optical and electrical Mn3O4 thin layers properties were investigated through: X-ray diffraction, Raman spectroscopy, UV-visible spectrophotometer, and two points electrometers respectively. The X-ray diffraction showed the appearance of spinel phase of tetragonal Mn3O4 with strong formation direction along (101) plan and without any secondary phase indicating the formation of pure Mn3O4. The Raman spectroscopy confirmed the results obtained in XRD and certified the high-quality formation of Mn3O4. In addition, the crystallinity improvement (the increase of crystallite size and the decrease of dislocation density) was caused by the increasing of deposition temperature from 350 °C to 450 °C. Optical properties such as transmittance, absorbance and band gap energy were extracted by UV-Visible spectrophotometer. Thus, low transmittance, high absorbance and small band gap energy were observed at the highest substrate temperature (450 °C). The electrical conductivity showed good values between 4.83 and 13.89 mS.cm−1. These properties make Mn3O4 an appropriate material to be used as a sensitive layer in gas sensors applications. 相似文献