全文获取类型
收费全文 | 213篇 |
免费 | 4篇 |
专业分类
化学 | 139篇 |
力学 | 2篇 |
数学 | 16篇 |
物理学 | 60篇 |
出版年
2021年 | 2篇 |
2020年 | 2篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2015年 | 3篇 |
2014年 | 3篇 |
2013年 | 7篇 |
2012年 | 6篇 |
2011年 | 16篇 |
2010年 | 8篇 |
2009年 | 2篇 |
2008年 | 18篇 |
2007年 | 12篇 |
2006年 | 19篇 |
2005年 | 8篇 |
2004年 | 12篇 |
2003年 | 6篇 |
2002年 | 3篇 |
2001年 | 4篇 |
2000年 | 6篇 |
1999年 | 4篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 5篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1988年 | 1篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1976年 | 3篇 |
1975年 | 5篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1969年 | 1篇 |
1961年 | 1篇 |
1958年 | 2篇 |
1939年 | 1篇 |
1932年 | 2篇 |
排序方式: 共有217条查询结果,搜索用时 15 毫秒
211.
In a previous paper, we reported preliminary results on the multiphoton dissociation of a linear triatomic molecule. This model consists of a dissociative mode (ν3) coupled non-linearly to an IR inactive harmonic mode (ν1). We present here extensive calculations of the dissociation probability as a function of the laser frequency for different pulses of constant fluence. It is shown that dissociation occurs at frequencies either very red-shifted from the ν3 IR active absorption band or located at the ν2 and ν3 bands (due to a 2:1 Fermi resonance). A Hose—Taylor analysis reveals that in the former case excitation proceeds through an anharmonic ladder, while a harmonic one is used in the latter case. In both cases essentially Q states are populated during the excitation process. The dissociation process has been dealt with explicitly by using metastable states to represent the continuum. It is shown that the actual structure of the continuum, due to the presence of Feshbach resonant states, has no real influence on the dissociation probability. Fragment analysis for the ABC → nhw A + BC dissociation process has been performed and shows only a slight departure from statistical distributions, except at very high intensities. 相似文献
212.
213.
Although the liquid- 4He-cesium system is a nearly ideal one for studying wetting phenomena, it can show extreme hysteresis which is profoundly nonideal in behavior. It is suggested that this is due to the roughness of these Cs surfaces. We show that stable micropuddles of liquid 4He can form in shallow cavities on a Cs surface. It is the potential to form micropuddles, as the liquid tries to recede, which pins the contact line due to the large energy needed to create the surface of a micropuddle. This model also accounts for the memory that these surfaces have of being in contact with liquid 4He. 相似文献
214.
The scattered wave formalism is developed for a quantum subsystem interacting with the external environment through open boundaries. The total wave function is divided into incident and scattered components and Markovian outgoing wave boundary conditions are applied to the scattered wave function. This formalism significantly reduces the computational effort relative to other methods which rely on Green functions and memory kernels. The method is applied to one-dimensional barrier scattering and to a three-dimensional model for the field effect transistor. 相似文献
215.
Wyatt MF 《Journal of mass spectrometry : JMS》2011,46(7):712-719
A mini-review of the characterisation of metal-containing compounds by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOFMS) is presented. Organometallic and coordination compounds have many varied applications, most notably in industrial catalytic processes and also in the electronics and healthcare sectors. In general, the compounds discussed, be they small or large molecules, have a high percentage metal content, rather than simply containing 'a metal atom'. A brief history of the field is given, but the main scope over the last 5 years is covered in some detail. How MALDI-TOFMS compliments electrospray for metal-containing compounds is highlighted. Perspectives on recent advances, such as solvent-free and air/moisture-sensitive sample preparation, and potential future challenges and developments, such as nanomaterials and metallodrug/metallometabolite imaging, are given. 相似文献
216.
Markovian outgoing wave boundary conditions are introduced as an approximate method to reduce the size of the computational grid for time integration of the time‐dependent Schrödinger equation. The ratio and polynomial methods developed as open boundary conditions are applied to the wave function at the boundaries of the computational grid. This computational method is used to study the wave packet dynamics for a metastable well, a double well, and strong‐field ionization of a model atom. Accurate results demonstrate that this method can significantly reduce the number of grid points required in a dynamical calculation for quantum dynamical problems. © 2012 Wiley Periodicals, Inc. 相似文献
217.
By designing and implementing a new experimental method, we have measured the dynamic advancing and receding contact angles and the resulting hysteresis of droplets under electrowetting-on-dielectric (EWOD). Measurements were obtained over wide ranges of applied EWOD voltages, or electrowetting numbers (0 ≤ Ew ≤ 0.9), and droplet sliding speeds, or capillary numbers (1.4 × 10(-5) ≤ Ca ≤ 6.9 × 10(-3)). If Ew or Ca is low, dynamic contact angle hysteresis is not affected much by the EWOD voltage or the sliding speed; that is, the hysteresis increases by less than 50% with a 2 order-of-magnitude increase in sliding speed when Ca < 10(-3). If both Ew and Ca are high, however, the hysteresis increases with either the EWOD voltage or the sliding speed. Stick-slip oscillations were observed at Ew > 0.4. Data are interpreted with simplified hydrodynamic (Cox-Voinov) and molecular-kinetic theory (MKT) models; the Cox-Voinov model captures the trend of the data, but it yields unreasonable fitting parameters. MKT fitting parameters associated with the advancing contact line are reasonable, but a lack of symmetry indicates that a more intricate model is required. 相似文献