全文获取类型
收费全文 | 3325篇 |
免费 | 97篇 |
国内免费 | 24篇 |
专业分类
化学 | 2107篇 |
晶体学 | 11篇 |
力学 | 146篇 |
数学 | 496篇 |
物理学 | 686篇 |
出版年
2024年 | 4篇 |
2023年 | 35篇 |
2022年 | 78篇 |
2021年 | 114篇 |
2020年 | 100篇 |
2019年 | 82篇 |
2018年 | 60篇 |
2017年 | 45篇 |
2016年 | 129篇 |
2015年 | 91篇 |
2014年 | 135篇 |
2013年 | 172篇 |
2012年 | 223篇 |
2011年 | 253篇 |
2010年 | 142篇 |
2009年 | 124篇 |
2008年 | 200篇 |
2007年 | 193篇 |
2006年 | 211篇 |
2005年 | 195篇 |
2004年 | 148篇 |
2003年 | 129篇 |
2002年 | 127篇 |
2001年 | 52篇 |
2000年 | 25篇 |
1999年 | 33篇 |
1998年 | 32篇 |
1997年 | 38篇 |
1996年 | 36篇 |
1995年 | 22篇 |
1994年 | 22篇 |
1993年 | 17篇 |
1992年 | 7篇 |
1991年 | 15篇 |
1990年 | 9篇 |
1989年 | 12篇 |
1988年 | 13篇 |
1987年 | 9篇 |
1986年 | 12篇 |
1985年 | 10篇 |
1984年 | 11篇 |
1983年 | 9篇 |
1982年 | 13篇 |
1981年 | 16篇 |
1980年 | 8篇 |
1979年 | 10篇 |
1978年 | 5篇 |
1977年 | 5篇 |
1976年 | 2篇 |
1975年 | 9篇 |
排序方式: 共有3446条查询结果,搜索用时 15 毫秒
241.
Spectroscopic ellipsometry study of liquid crystal and polymeric thin films in visible and near infrared 总被引:1,自引:0,他引:1
Tkachenko V Marino A Vita F D'Amore F De Stefano L Malinconico M Rippa M Abbate G 《The European physical journal. E, Soft matter》2004,14(2):185-192
In this work, we propose spectroscopic ellipsometry as a suitable method for measuring optical properties in soft materials, polymers and liquid crystals, specially selected for use in photonics applications. We show the results of our measurements on some multilayered samples, in the range from visible to the near-IR region, of interest for telecom applications. We point out potentialities and limits of the technique and compare the obtained results with another experimental method, the m-lines spectroscopy, and/or with existing data in the literature. The results about the optical parameters for the analysed materials (the nematic liquid crystal 5CB, one commercial and one lab made optical polymer, and an Indium Tin Oxide film) are useful and interesting by themselves. In fact, as a paradigmatic example, we briefly discuss how an incomplete knowledge of this kind of data can lead to a wrong design of a Bragg grating device. However, more than in the provided data, we put the interest of the present analysis in the warnings about spectroscopic ellipsometry utilization and eventually the necessity of getting complementary information.Received: 13 May 2004, Published online: 29 June 2004PACS:
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity) - 78.66.Qn Polymers; organic compounds - 07.60.Fs Polarimeters and ellipsometers 相似文献
242.
We show that, in low-dimensional photonic bandgaps, wave diffraction resulting from localization in the translational-invariant directions is strongly influenced by the photonic band structure of the periodic crystal, leading to new kinds of wave localization. In particular, for a periodic layered structure we show that, close to a bandgap edge, diffraction is enhanced, with a transition from a parabolic diffraction curve-typical of isotropic media and supporting Gaussian beams-to hyperbolic or elliptic diffraction curves. In the last two cases localization in the form of stationary X-shaped or sinc-shaped waves is possible. 相似文献
243.
Galzerano G Sani E Toncelli A Della Valle G Taccheo S Tonelli M Laporta P 《Optics letters》2004,29(7):715-717
Continuous-wave laser action at approximately 2 microm is demonstrated in a Tm-Ho:KYF4 single crystal at room temperature. Crystal growth, spectroscopic measurements, and laser results are presented. An output power in excess of 250 mW is obtained with a tuning range of 99 nm, the largest ever published, to our knowledge, for Tm-Ho in any crystalline host. 相似文献
244.
Villoresi P Bonora S Pascolini M Poletto L Tondello G Vozzi C Nisoli M Sansone G Stagira S De Silvestri S 《Optics letters》2004,29(2):207-209
We present a method for the optimization of high-order harmonic generation based on wave-front correction of the driving laser beam. The technique exploits wave-front adaptive control by means of a deformable mirror, governed by an optimization procedure. 相似文献
245.
246.
Fernandez YD Gramatges AP Amendola V Foti F Mangano C Pallavicini P Patroni S 《Chemical communications (Cambridge, England)》2004,(14):1650-1651
A new approach based on self-assembly inside micelles has been individuated to prepare a system behaving as a water-operating selective fluorescent sensor for Cu2+ and Ni2+. 相似文献
247.
Abdallah R Meille V Shaw J Wenn D de Bellefon C 《Chemical communications (Cambridge, England)》2004,(4):372-373
A microstructured mesh contactor that can offer residence time of more than minutes is used for gas-liquid-solid hydrogenations and gas-liquid asymmetric hydrogenations. Applications for catalyst/chiral inductor screening and for kinetic data acquisition are demonstrated. 相似文献
248.
We propose an experimentally feasible scheme to teleport an unkown quantum state onto the vibrational degree of freedom of a macroscopic mirror. The quantum channel between the two parties is established by exploiting radiation pressure effects. 相似文献
249.
Minardi S Yu J Blasi G Varanavicius A Valiulis G Berzanskis A Piskarskas A Di Trapani P 《Physical review letters》2003,91(12):123901
In chi(2) three-wave mixing, the noise-seeded spatiotemporal modulational instability has a dramatic impact on the spatial soliton formation and on their stability, leading to the occurrence of a temporal breakup on the 20 fs scale and to the counterintuitive observation of spatial solitons with no apparent participation of the high-frequency field in the self-trapping. 相似文献
250.
Predicting and characterizing the crystal structure of materials is a key problem in materials research and development. It is typically addressed with highly accurate quantum mechanical computations on a small set of candidate structures, or with empirical rules that have been extracted from a large amount of experimental information, but have limited predictive power. In this Letter, we transfer the concept of heuristic rule extraction to a large library of ab initio calculated information, and we demonstrate that this can be developed into a tool for crystal structure prediction. 相似文献