全文获取类型
收费全文 | 1702篇 |
免费 | 106篇 |
国内免费 | 4篇 |
专业分类
化学 | 1093篇 |
晶体学 | 11篇 |
力学 | 70篇 |
数学 | 242篇 |
物理学 | 396篇 |
出版年
2024年 | 2篇 |
2023年 | 11篇 |
2022年 | 31篇 |
2021年 | 43篇 |
2020年 | 57篇 |
2019年 | 33篇 |
2018年 | 36篇 |
2017年 | 40篇 |
2016年 | 76篇 |
2015年 | 84篇 |
2014年 | 83篇 |
2013年 | 101篇 |
2012年 | 158篇 |
2011年 | 191篇 |
2010年 | 109篇 |
2009年 | 63篇 |
2008年 | 146篇 |
2007年 | 120篇 |
2006年 | 106篇 |
2005年 | 78篇 |
2004年 | 55篇 |
2003年 | 36篇 |
2002年 | 24篇 |
2001年 | 10篇 |
2000年 | 12篇 |
1999年 | 11篇 |
1998年 | 13篇 |
1997年 | 5篇 |
1996年 | 12篇 |
1995年 | 4篇 |
1994年 | 7篇 |
1993年 | 7篇 |
1992年 | 7篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1989年 | 5篇 |
1988年 | 3篇 |
1986年 | 2篇 |
1985年 | 5篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有1812条查询结果,搜索用时 15 毫秒
161.
A femtosecond mode-locked laser is used for what is believed to be the first time as a broadband infrared source for high-resolution Fourier transform absorption spectroscopy. A demonstration is made with a Cr(4+):YAG laser. The entire nu(1)+nu(3) vibration-rotation band region of acetylene, observed after passing through a single-pass 80-cm-long cell, is simultaneously recorded between 1480 and 1600 nm, in 7.9 s with a signal-to-noise ratio equal to 1000. Two hot bands of the most abundant acetylene isotopologue and the nu(1)+nu(3) band of the (13)C(12)CH(2) are also present. Replacement of the usual conventional tungsten lamp by the bright laser source reduces by about a factor of 150 the recording time needed to get similar results. The noise equivalent absorption coefficient at 1 s averaging is equal to 7x10(-7) cm(-1)Hz(-1/2) per spectral element. 相似文献
162.
Optical properties of silver and gold semi-continuous films near the percolation threshold are investigated by scanning near field optical microscopy (SNOM) operating in the collection/transmission mode. The electromagnetic enhanced fields, due to plasmon-polariton localizations, are observed and the intensity distribution is shown to present high intensity variations that increase with the wavelength. The local fields are also demonstrated to be polarization dependent. The intensity distribution is investigated as function of the incident wavelength both for gold and silver films. The calculated probability distribution function (PDF) exhibits an exponential decay for large enhancement factors and is proved to be wavelength dependent. 相似文献
163.
Le Gouët J Morvan L Alouini M Bourderionnet J Dolfi D Huignard JP 《Optics letters》2007,32(9):1090-1092
We demonstrate the generation of optically carried, broadly tunable, millimeter-wave signals with a dual-frequency single-axis Nd:YAG laser. A frequency difference as high as 127 GHz is reached thanks to an intracavity electro-optically tunable etalon made of lead zirconate tantalate (PLZT) ceramic. We show that the available frequency range is actually limited by the bandwidth of the amplification medium, namely, far beyond the usually accepted free spectral range value in the case of a single-axis laser. Both coarse discrete and fine continuous tunabilities are obtained with the same voltage-controlled device, opening the way to widely tunable low-phase-noise optically carried submillimeter or even terahertz sources. 相似文献
164.
A new turbulent injection procedure dedicated to fully compressible direct numerical simulation (DNS) or large eddy simulation (LES) solvers is proposed. To avoid the appearance of spurious acoustic waves, this method is based on an accurate tracking of the turbulent structures crossing the boundary at the inlet of the domain. A finite difference DNS solver has been coupled with a spectral simulation in which a statistically stationary homogeneous turbulence evolves to provide fluctuating boundary conditions.A new turbulence forcing method, dedicated to spectral solvers, has been developed as well to control the major properties of the injected flow (turbulent kinetic energy, dissipation rate and integral length scale). One-dimensional Navier–Stokes characteristic boundary conditions extended to non-stationary flows are coupled with the injection procedure to evaluate is potential in four various configurations: spatially decaying turbulence, dispersion of vaporizing sprays, propagation of one- and two-phase V-shape turbulent flames. 相似文献
165.
Photophysics of a Ruthenium 4H‐Imidazole Panchromatic Dye in Interaction with Titanium Dioxide
下载免费PDF全文
![点击此处可从《Chemphyschem》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Julian Schindler Dr. Stephan Kupfer Dr. Maria Wächtler Dr. Julien Guthmuller Prof. Dr. Sven Rau Prof. Dr. Benjamin Dietzek 《Chemphyschem》2015,16(5):1061-1070
The photophysics of bis(4,4′‐di‐tert‐butyl‐2,2′‐bipyridine‐κ2N,N′)[2‐(4‐carboxyphenyl)‐4,5‐bis(p‐tolylimino‐κN)imidazolato]ruthenium(II) hexafluorophosphate is investigated, both in solution and attached to a nanocrystalline TiO2 film. The studied substitution pattern of the 4H‐imidazole ligand is observed to block a photoinduced structural reorganization pathway within the 4H‐imidazole ligand that has been previously investigated. Protonation at the 4H‐imidazole ring decreases the excited‐state lifetime in solution. When the unprotonated dye is anchored to TiO2, photoinduced electron injection occurs from thermally nonrelaxed triplet metal‐to‐ligand charge transfer (3MLCT) states with a characteristic time constant of 0.5 ps and an injection efficiency of roughly 25 %. Electron injection from the subsequently populated thermalized 3MLCT state of the dye does not take place. The energy of this state seems to be lower than the conduction band edge of TiO2. 相似文献
166.
The Quest for Polysulfides in Lithium–Sulfur Battery Electrolytes: An Operando Confocal Raman Spectroscopy Study
下载免费PDF全文
![点击此处可从《Chemphyschem》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Julien Hannauer Dr. Johan Scheers Julien Fullenwarth Dr. Bernard Fraisse Prof. Dr. Lorenzo Stievano Prof. Dr. Patrik Johansson 《Chemphyschem》2015,16(13):2755-2759
Confocal Raman spectra of a lithium–sulfur battery electrolyte are recorded operando in a depth‐of‐discharge resolved manner for an electrochemical cell with a realistic electrolyte/sulfur loading ratio. The evolution of various possible polysulfides is unambiguously identified by combining Raman spectroscopy data with DFT simulations. 相似文献
167.
Cover Picture: The Quest for Polysulfides in Lithium–Sulfur Battery Electrolytes: An Operando Confocal Raman Spectroscopy Study (ChemPhysChem 13/2015)
下载免费PDF全文
![点击此处可从《Chemphyschem》网站下载免费的PDF全文](/ch/ext_images/free.gif)
168.
Identification and separation of saxitoxins using hydrophilic interaction liquid chromatography coupled to traveling wave ion mobility‐mass spectrometry
下载免费PDF全文
![点击此处可从《Journal of mass spectrometry : JMS》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Salomé Poyer Corinne Loutelier‐Bourhis Gaël Coadou Florence Mondeguer Julien Enche Anne Bossée Philipp Hess Carlos Afonso 《Journal of mass spectrometry : JMS》2015,50(1):175-181
The aim of this work was to develop a reliable and efficient analytical method to characterise and differentiate saxitoxin analogues (STX), including sulphated (gonyautoxins, GTX) and non‐sulphated analogues. For this purpose, hydrophilic interaction liquid chromatography (HILIC) was used to separate sulphated analogues. We also resorted to ion mobility spectrometry to differentiate the STX analogues because this technique adds a new dimension of separation based on ion gas phase conformation. Positive and negative ionisation modes were used for gonyautoxins while positive ionisation mode was used for non‐sulphated analogues. Subsequently, the coupling of these three complementary techniques, HILIC‐IM‐MS, permitted the separation and identification of STX analogues; isomer differentiation was achieved in HILIC dimension while non‐sulphated analogues were separated in the IM‐MS dimension. Additional structural characteristics concerning the conformation of STXs could be obtained using IM‐MS measurements. Thus, the collision cross sections (CCS) of STXs are reported for the first time in the positive ionisation mode. These experimental CCSs correlated well with the calculated CCS values using the trajectory method. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
169.
170.