全文获取类型
收费全文 | 64篇 |
免费 | 1篇 |
国内免费 | 1篇 |
专业分类
化学 | 23篇 |
数学 | 19篇 |
物理学 | 24篇 |
出版年
2018年 | 2篇 |
2017年 | 1篇 |
2016年 | 1篇 |
2014年 | 3篇 |
2013年 | 3篇 |
2012年 | 2篇 |
2011年 | 6篇 |
2010年 | 5篇 |
2009年 | 2篇 |
2008年 | 3篇 |
2007年 | 5篇 |
2006年 | 4篇 |
2005年 | 1篇 |
2004年 | 3篇 |
2003年 | 3篇 |
2002年 | 3篇 |
2001年 | 3篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 5篇 |
1991年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 2篇 |
排序方式: 共有66条查询结果,搜索用时 140 毫秒
41.
42.
The microwave heating of two-dimensional slabs in a long rectangularwaveguide propagating the TE10 mode is examined. The temperaturedependency of the electrical conductivity and the thermal absorptivityis assumed to be governed by the Arrhenius law, while both theelectrical permittivity and the magnetic permeability are assumedconstant. The governing equations are the forced heat equationand the steady-state version of Maxwell's equation while theboundary conditions take into account both convective and radiativeheat loss. Approximate analytical solutions, valid for smallthermal absorptivity, are found for the temperature and theelectric-field amplitude using the Galerkin method. As the Arrheniuslaw is not amenable analytically, it is approximated by a rational-cubicfunction. At the steady state the temperature versus power relationshipis found to be multivalued; at the critical power level thermalrunaway occurs when the temperature jumps from the lower (cool)temperature branch to the upper (hot) temperature branch ofthe solution. In the steady-state limit the approximate analyticalsolutions are compared with the numerical solutions of the governingequations for various special cases. These are the limits ofsmall and large heat loss and an intermediate case involvingradiative heat loss. Results are also presented for a case wheredifferential cooling occurs on the different sides on the slab.An alternative heating scenario, where one end of the waveguideis blocked by a short, is also considered. The approximate solutionsare found for this geometry and compared in the small Biot-numberlimit to Kriegsmann (1997). Also, a control process is presented,which allows thermal runaway to be avoided and the desired finalsteady state to be reached. Various special cases of the feedbackparameters associated with the control process are examined. 相似文献
43.
Pedersen A. S. Pryds N. Linderoth S. Larsen P. H. Kjøller J. 《Journal of Thermal Analysis and Calorimetry》2001,64(3):887-894
Differential Scanning Calorimetric measurements were performed for accurate determination of the solidus and liquidus temperature
of Sn–Pb alloys. The difference between onset and end temperature of the melting peak depended clearly on alloy composition.
The results obtained were found to be in good agreement with the existing equilibrium phase diagram for the Sn–Pb system,
although the data suggested a slight correction of the eutectic composition. Under cooling conditions a large variation in
the onset temperature for solidification was found. A large number of heating and cooling cycles were performed in order to
investigate the statistical variation of the solid nucleation process.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
44.
Jeff Linderoth 《Mathematical Programming》2005,103(2):251-282
We propose a branch-and-bound algorithm for solving nonconvex quadratically-constrained quadratic programs. The algorithm is novel in that branching is done by partitioning the feasible region into the Cartesian product of two-dimensional triangles and rectangles. Explicit formulae for the convex and concave envelopes of bilinear functions over triangles and rectangles are derived and shown to be second-order cone representable. The usefulness of these new relaxations is demonstrated both theoretically and computationally. 相似文献
45.
Ll. Balcells J. L. Tholence S. Linderoth B. Barbara J. Tejada 《Zeitschrift für Physik B Condensed Matter》1992,89(2):209-212
We have achieved the observance of the quantum tunneling of magnetization in a ferrofluid system constituted by small single domain particles of FeC in a nonmagnetic carrier fluid. The constancy of the coercive field below 1 K indicates that this temperature corresponds to the crossover from the thermal to the quantum regime. 相似文献
46.
Søren Linderoth 《Hyperfine Interactions》1992,68(1-4):107-118
Different techniques for the preparation of amorphous alloy particles are reviewed. Special attention is made to the studies
of the preparation and the physical properties of ultrafine amorphous iron-boron and iron-carbon alloy particles. The properties
of the ultrafine alloy particles are in most cases similar to those of bulk amorphous alloys of the same composition, e.g.,
the dependence of the hyperfine parameters on temperature and composition as well as Curie temperatures are similar. 相似文献
47.
S. Linderoth H. E. Hansen B. Nielsen K. Petersen 《Applied Physics A: Materials Science & Processing》1984,33(1):25-28
The penetration of positrons from a22Na source into Ni foils sandwiched between different backscattering materials (Kapton, NaCl, Ni, and Mo) has been studied for the geometry commonly used in PAT experiments. Transmitted intensities and effective mass absorption coefficients have been found and the dependence on the backscattering material is discussed. General formulas for the effective mass absorption coefficients are derived. The large geometrical effects are stressed. Suggestions for source corrections are supplied. 相似文献
48.
The temperature dependence of the magnetic hyperfine field of a metastable iron-mercury alloy has been measured. The Mössbauer spectrum obtained at 12 K can be fitted with two magnetically split components with hyperfine fields of 39.7 and 36.0 T. With increasing temperature the hyperfine fields decrease much more rapidly than that of α-Fe. The temperature dependence is in accordance with the Bloch law up to 220 K. 相似文献
49.
Andreas?Lüthi Martin?A?Wikstr?m Mary?J?Palmer Paul?Matthews Tim?A?Benke John?TR?Isaac Graham?L?CollingridgeEmail author 《BMC neuroscience》2004,5(1):44
Background
Knowledge of how synapses alter their efficiency of communication is central to the understanding of learning and memory. The most extensively studied forms of synaptic plasticity are long-term potentiation (LTP) and its counterpart long-term depression (LTD) of AMPA receptor-mediated synaptic transmission. In the CA1 region of the hippocampus, it has been shown that LTP often involves a rapid increase in the unitary conductance of AMPA receptor channels. However, LTP can also occur in the absence of any alteration in AMPA receptor unitary conductance. In the present study we have used whole-cell dendritic recording, failures analysis and non-stationary fluctuation analysis to investigate the mechanism of depotentiation of LTP. 相似文献50.