全文获取类型
收费全文 | 50篇 |
免费 | 1篇 |
国内免费 | 1篇 |
专业分类
化学 | 23篇 |
数学 | 3篇 |
物理学 | 26篇 |
出版年
2019年 | 1篇 |
2016年 | 2篇 |
2015年 | 1篇 |
2013年 | 1篇 |
2012年 | 1篇 |
2011年 | 1篇 |
2010年 | 1篇 |
2009年 | 2篇 |
2008年 | 2篇 |
2007年 | 7篇 |
2006年 | 1篇 |
2005年 | 2篇 |
2004年 | 3篇 |
2003年 | 3篇 |
2002年 | 2篇 |
2001年 | 2篇 |
2000年 | 7篇 |
1999年 | 1篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1975年 | 1篇 |
1962年 | 1篇 |
1913年 | 1篇 |
排序方式: 共有52条查询结果,搜索用时 15 毫秒
31.
Katherine Stott James Keeler Que N. Van A.J. Shaka 《Journal of magnetic resonance (San Diego, Calif. : 1997)》1997,125(2):302-324
Previously, it has been shown that the use of pulsed field gradients in one-dimensional NOE experiments results in spectra of much higher quality than it has previously been possible to record. Such high-quality spectra make it possible to measure, with complete confidence, very small NOE enhancements and also make it straightforward to measure NOE buildup curves. In this paper, the spin dynamics behind these NOE experiments with gradients are analyzed in detail; the effects of strong coupling and molecular diffusion are also examined. It is also shown how the basic experiments can be improved upon, in particular how unwanted anti-phase contributions (SPT effects) can be eliminated entirely. Experimental illustrations of the various methods and improvements are given and practical recommendations made as to how the experiments are best performed. 相似文献
32.
33.
34.
The partial width of the τ → e - v e v τ can be calculated from the tau mass, lifetime and branching ratio. The increasing precision on these measurements is making the partial width sensitive to the mass of the tau neutrino. We present the tau neutrino mass dependence on the partial width and show that this leads to a limit of m r < 71 MeV at the 95% confidence level. We show that the limit is determined by the uncertainty in the tau lifetime and τ → e?v e v τ branching ratio. Additional measurements of these values are expected in the next few years and we show that the limit could become competitive with the direct measurements. 相似文献
35.
36.
The pressure dependence of the metal—nonmetal transition in the hexagonal form of NiS has been measured to 13.7 kbar. An anomalous pressure dependence in the transition temperature was observed near 4.5 kbar. We associate this with the unusual lattice parameter behaviour previously reported for this region. 相似文献
37.
38.
Alternative gauge choices for worldsheet supersymmetry can elucidate dynamical phenomena obscured in the usual superconformal gauge. In the particular example of the tachyonic E8 heterotic string, we use a judicious gauge choice to show that the process of closed-string tachyon condensation can be understood in terms of a worldsheet super-Higgs effect. The worldsheet gravitino assimilates the goldstino and becomes a dynamical propagating field. Conformal, but not superconformal, invariance is maintained throughout. 相似文献
39.
In solution-state NMR spectrometers, there is a systematic deviation between the temperature of the sample and the temperature reported by the spectrometer. In addition, temperature gradients are often present in the sample. The size of both the temperature deviations and the temperature gradients depends on several factors, including the temperature, the flow rate of the heating/cooling gas, and the amount of radiofrequency heating. 相似文献
40.
We experimentally demonstrate operation of a laterally deformable optical nanoelectromechanical system grating transducer. The device is fabricated in amorphous diamond with standard lithographic techniques. For small changes in the spacing of the subwavelength grating elements, lossy propagating resonant modes in the plane of the grating cause a large change in the optical reflection amplitude. An in-plane motion detection sensitivity of 160 fm/square root(Hz) was measured, exceeding that of any other optical microelectromechanical system transducer to our knowledge. Calculations predict that this sensitivity could be improved to better than 40 fm/square root(Hz) in future designs. In addition to having applications in the field of inertial sensors, this device could also be used as an optical modulator. 相似文献