排序方式: 共有29条查询结果,搜索用时 609 毫秒
1.
2.
3.
4.
5.
Jesús S. Pérez Guerrero Todd H. Skaggs M. Th. van Genuchten 《Transport in Porous Media》2009,80(2):373-387
Transport equations governing the movement of multiple solutes undergoing sequential first-order decay reactions have relevance
in analyzing a variety of subsurface contaminant transport problems. In this study, a one-dimensional analytical solution
for multi-species transport is obtained for finite porous media and constant boundary conditions. The solution permits different
retardation factors for the various species. The solution procedure involves a classic algebraic substitution that transforms
the advection-dispersion partial differential equation for each species into an equation that is purely diffusive. The new
system of partial differential equations is solved analytically using the Classic Integral Transform Technique (CITT). Results
for a classic test case involving a three-species nitrification chain are shown to agree with previously reported literature
values. Because the new solution was obtained for a finite domain, it should be especially useful for testing numerical solution
procedures. 相似文献
6.
7.
CM Silva MF Duarte ML Mira MH Florêncio K Versluis AJ Heck 《Rapid communications in mass spectrometry : RCM》1999,13(12):1098-1103
Fast atom bombardment, combined with high-energy collision-induced tandem mass spectrometry, has been used to investigate gas-phase metal-ion interactions with captopril, enalaprilat and lisinopril, all angiotensin-converting enzyme inhibitors.Suggestions for the location of metal-binding sites are presented. For captopril, metal binding occurs most likely at both the sulphur and the nitrogen atom. For enalaprilat and lisinopril, binding preferably occurs at the amine nitrogen. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
8.
[reaction: see text] A dicobalt hexacarbonyl (Co(2)(CO)(6)) cluster is essential for the unusually broad dipolarophile scope and for the sense and degree of diastereoselection in a catalytic, three-component synthesis of tetrahydrofurans and dihydrofurans. Likely involving a new class of carbonyl ylide, these cycloadditions are stereospecific with respect to the dipolarophile and exhibit high diastereoselectivity and regioselectivity in most cases. Differentiation of all four positions of the tetrahydrofuran can thus be accomplished in a triply convergent manner. 相似文献
9.
10.
The purpose of this study was to investigate if there was an effect of task on determination of habitual pitch, or speaking fundamental frequency (SFF). Seven tasks commonly used to elicit habitual pitch in clinical voice evaluations were compared. Three groups of normal subjects (N = 36) were examined (adult males, adult females, and male and female prepubescent children). For the adult male (n = 12) and pediatric (n = 12) subjects, no significant effect of task was found. For the adult female (n = 12) subjects, a statistically significant (P < .001) effect of task was found. All tasks were found to have high (>0.90) test-retest reliability for all subjects. Implications of the use of one task for determination of habitual pitch are discussed, as is the possibility of a task effect on determination of other voice parameters. 相似文献