首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   27篇
  免费   0篇
化学   15篇
数学   2篇
物理学   10篇
  2013年   4篇
  2012年   5篇
  2009年   1篇
  2008年   1篇
  2005年   2篇
  2001年   1篇
  2000年   1篇
  1995年   1篇
  1994年   1篇
  1987年   2篇
  1981年   1篇
  1980年   1篇
  1976年   1篇
  1973年   2篇
  1971年   1篇
  1969年   1篇
  1931年   1篇
排序方式: 共有27条查询结果,搜索用时 46 毫秒
1.
Isoperimetric inequalities are applied to a moving-boundaryproblem for doubly-connected domains. This problem occurs forexample in electrochemistry, in which case the domains in questionare the electrolyte of an electrolytic cell. The two electrodessurrounding the electrolyte are assumed to grow or dissolve,at different rates in general, by electrochemical reaction.We obtain optimal estimates showing, for example, that the leastchange in volume of each electrode always occurs in sphericalsymmetry.  相似文献   
2.
The flow fields for a sphere sedimenting through a Newtonian and two non-Newtonian liquids near a wall in a square tank are investigated using 3-D stereoscopic particle image velocimetry (PIV) and line integral convolution (LIC) methods. The PIV data were taken using an angular stereoscopic configuration with tilt and shift arrangements for the Scheimpflug condition and a pair of liquid correction prisms. Data were recorded from planes perpendicular and parallel to the wall for each fluid case over a range of distances from the wall. The PIV and LIC results highlight significant differences in the wake structure for all three cases. Out of plane flow was also found to persist up to two sphere diameters downstream in the wake for all cases.  相似文献   
3.
Rotational analyses of the (0,0), (1,1) and (2,2) bands, and a partial analysis of the (3,3) band, of the γ-system (A3Φ - X3Δ) of the molecules 90Zr16O, 94Zr16O, 96Zr16O have been performed. The measured wave numbers and their assignments are presented up to high quantum numbers. The rotational constants are calculated and an estimate is made of the spin-coupling coefficients. Both states belong closely to Hund's coupling case a.  相似文献   
4.
5.
Abstract Global warming is expected to affect the ecosystem in the Northeast Atlantic, and substantial changes will also affect the aquaculture industry. Farming of salmon and trout is the biggest aquaculture industry in Norway, with an export value of about 3 billion US dollars in 2007. The objective of the paper is to analyze the potential economic effect a general increase in sea temperature can have on the Norwegian salmon aquaculture industry. The assessment of the economic impact of global warming is made possible by estimating a growth function, which explicitly includes sea water temperature. The analysis compares the economic effect of a climate change on fish farming plants in the south and the north of Norway. The scenarios are based on a model with monthly seasonal variation in temperature.  相似文献   
6.
The surface activities of lysozyme and dipalmitoyl phosphatidylcholine (DPPC) vesicles at aqueous/compressed fluid interfaces are examined via high-pressure interfacial tension measurements using the pendant drop technique. The density and interfacial tension in compressible fluid systems vary significantly with pressure, providing a versatile medium for elucidating interactions between biomolecules and fluid interfaces and a method to elicit pressure-dependent interfacial morphological responses. The effects of lysozyme concentration (0.0008, 0.01, and 1 mg/mL) and pressure (> or = 7 MPa) on the dynamic surface response in the presence of ethane, propane, N2, and CO2 at 298 K were examined. Interfacial lysozyme adsorption reduced the induction phase and quickly led to interfacial tensions consistent with protein conformational changes and monolayer saturation at the compressed fluid interfaces. Protein adsorption, as indicated by surface pressure, correlated with calculated Hamaker constants for the compressed gases, denoting the importance of dispersion interactions. For DPPC at aqueous/compressed or aqueous/supercritical CO2 interfaces (1.8-20.7 MPa, 308 K), 2-3-fold reductions in interfacial tension were observed relative to the pure binary fluid system. The resulting surface pressures infer pressure-dependent morphological changes within the DPPC monolayer.  相似文献   
7.
Two recommendations are made that can eliminate persistent confusion in the study of diatomic spectroscopy by providing uniform and consistent definitions of the electronic transition moments and the rotational line intensity factors. First, it is recommended that the equation for the line strength of a single rotational line be adopted to specify the relationship between the electronic transition moment and the rotational line intensity factor. Second, it is recommended that the electronic transition moment operator for perpendicular transitions be defined by (1/21/2)(μx ± iμy). The adoption of these conventions results in a value of (2S + 1)(2J + 1) for the sum rule of the rotational line intensity factor for Σ± ↔ Σ± transitions and a value of 2(2S + 1)(2J + 1) for the sum rule for all other spin-allowed transitions.  相似文献   
8.
A red-degraded band head, normally badly overlapped by the gamma system, A3Φ - X′ 3Δ, of zirconium oxide, appears in emission spectra of zirconium arcs and in absorption spectra of S-type stars and of frozen rare gas matrices containing zirconium. The emission band has been examined at high-resolution with the aid of separated zirconium isotopes. Identification of the band as 0-0 of a 1Π - X 1Σ+ system of zirconium oxide is confirmed by rotational analysis where the following constants (cm?1) are obtained for 90Zr16O:
B0′(R,P) = 0.40142 D0′(R,P) = 3.51 × 10?7
B0′(Q) = 0.40166 D0′(Q) =3.52 × 10?7
B0″ = 0.42263 D0″ =3.19 × 10?7
ν0 = 15383.81s
The Λ-type doubling in the 1Π state and the question of whether X 1Σ+ or X′ 3Δ is the true ground state of ZrO are discussed.  相似文献   
9.
We have developed an efficient one-pot, two-step preparation of ethylene blue by eliminating aqueous work-ups and cumbersome purification techniques. Our procedure generates ethylene blue in good overall yields of 45-56% with approximately 95% purity, which is uncommon for the synthesis of a phenothiazinium salt. Due to its unique properties, ethylene blue has great potential for a broad range of biological applications and, as a result, an efficient procedure for the synthesis of ethylene blue is critical.  相似文献   
10.
The spatial angular correlation of electrons in the ground state of the helium atom has been examined using configuration interaction and Hylleraas wave-functions. It was found that, in general, the average angle between the electrons is not a maximum when the two electrons are at the same distance from the nucleus. For configuration interaction wave-functions there is a position of the electrons for which the average value of the angle between the electrons is a maximum. Hylleraas wave-functions do not show this behavior.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号