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1.
S. Kohn J. A. Brown R. H. Heffner C. Y. Huang T. A. Kitchens Jr. M. Leon C. E. Olsen M. E. Schillaci W. B. Gauster 《Hyperfine Interactions》1979,6(1-4):283-287
The + depolarization rate in diluteAlGd alloys containing 50 and 450 atomic ppm Gd was measured in a transverse field of 80 Oe over the temperature range 6–300 K. For both alloys, A increased dramatically above 200 K, reaching values of 0.69 and 0.93 s–1, respectively, near room temperature. The results are interpreted as providing evidence for a thermally-activated trapping mechanism.This work was supported by the U.S. Department of Energy. 相似文献
2.
Cumulant functions are introduced to describe the statistical state of a radiation field. These functions are simply related
to the optical coherence functions but have some interesting features. It is shown that if the cumulant functions of all orders
greater than some numberN
0 vanish then they also vanish for all orders greater than 2. Thermal field is the only field having this property. This property
holds whether the field is described by a classical stochastic process or by a quantum density operator. Further the particular
operator ordering used in defining these cumulant functions for the quantized field affects only the second order cumulant
function. To describe the statistical state of a vector field such as partially polarized or unpolarized radiation, one would
need to introduce cumulant tensors. 相似文献
3.
High-performance liquid chromatographic separation of cobalamins 总被引:2,自引:0,他引:2
Physiological cobalamins were separated by means of high-performance liquid chromatography (HPLC). Optimal conditions for elution of methylcobalamin, adenosylcobalamin, hydroxycobalamin and cyanocobalamin were determined. Excellent separation and resolution of these physiological cobalamins by HPLC were achieved. In addition, several cobalamin analogues were also studied and shown to be separable from the physiological forms. HPLC provides a rapid, sensitive, reproducible means of characterizing physiological cobalamins. 相似文献
4.
McLeod MC Kitchens CL Roberts CB 《Langmuir : the ACS journal of surfaces and colloids》2005,21(6):2414-2418
Deposition of nanoparticles into uniform, wide-area thin films using CO(2) as an antisolvent is presented. Ligand-stabilized silver particles are controllably precipitated from organic solvents by pressurizing and expanding the solution with carbon dioxide. Subsequent addition of carbon dioxide as a dense supercritical fluid provides for removal of the organic solvent while avoiding the surface tensions common to evaporating solvents that are detrimental to nanoscale assemblies and structures. This brand new CO(2)-expanded liquid particle deposition technique allows for the targeted deposition of particles and results in more uniform and lower defect metal nanoparticle thin films than are provided by conventional solvent evaporation techniques. 相似文献
5.
MA Freitas CL Hendrickson AG Marshall 《Rapid communications in mass spectrometry : RCM》1999,13(15):1639-1642
We present a novel approach for the determination of activation energy for the unimolecular dissociation of a large (>50 atoms) ion, based on measurement of the unimolecular dissociation rate constant as a function of continuous-wave CO(2) laser intensity. Following a short ( approximately 1 s) induction period, CO(2) laser irradiation produces an essentially blackbody internal energy distribution, whose 'temperature' varies inversely with laser intensity. The only currently available method for measuring such activation energies is blackbody infrared radiative dissociation (BIRD). Compared with BIRD, FRAGMENT: (a) eliminates the need to heat the surrounding ion trap and vacuum chamber to each of several temperatures (each requiring hours for temperature equilibration); (b) offers a three-fold wider range of effective blackbody temperature; and (c) extends the range of applications to include initially cold ions (e.g., gas-phase H/D exchange). Our FRAGMENT-determined activation energy for dissociation of protonated bradykinin, 1.2 +/- 0.1 eV, agrees within experimental error to the value, 1.3 +/- 0.1 eV, previously reported by Williams et al. from BIRD experiments. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
6.
Let φ be a one-dimensional surjective cellular automaton map. We prove that if φ is a closing map, then the configurations which are both spatially and temporally periodic are dense. (If φ is not a closing map, then we do not know whether the temporally periodic configurations must be dense.) The results are special cases of results for shifts of finite type, and the proofs use symbolic dynamical techniques. 相似文献
7.
An irreducible algebraic ℤ
d
-actionα on a compact abelian group X is a ℤ
d
-action by automorphisms of X such that every closed, α-invariant subgroup Y⊊X is finite. We prove the following result: if d≥2, then every measurable conjugacy between irreducible and mixing algebraic ℤ
d
-actions on compact zero-dimensional abelian groups is affine. For irreducible, expansive and mixing algebraic ℤ
d
-actions on compact connected abelian groups the analogous statement follows essentially from a result by Katok and Spatzier
on invariant measures of such actions (cf. [4] and [3]). By combining these two theorems one obtains isomorphism rigidity
of all irreducible, expansive and mixing algebraic ℤ
d
-actions with d≥2.
Oblatum 30-IX-1999 & 4-V-2000?Published online: 16 August 2000 相似文献
8.
Sofic systems are examined using defining semi-groups. The algebraic properties of the semi-groups, the graph-theoretic properties
of the transition matrices, and the dynamic properties of the sofic systems are found to have many strong connections.
Partially supported by NSF Grants MCS-8120790-03 and MCS-8301324. 相似文献
9.
10.
Magnetization measurements have been made on Au-Fe alloys containing from 0·05 to 12·5 at. % Fe at temperatures below the magnetic ordering temperature. In combination with Mössbauer spectroscopy a qualitative explanation is derived for the complex mictomagnetic behavior observed. 相似文献