排序方式: 共有51条查询结果,搜索用时 703 毫秒
1.
Lone-Wen Tai Harlan U. Anderson Paul A. Lessing 《Journal of the American Ceramic Society》1992,75(12):3490-3494
Submicrometer powders of complex oxides were prepared via resin intermediates based on a starch type of organic precursor. A commercially available water-soluble starch derivative was (for the first time) used as the organic base for solution synthesis of ceramic powders. Calcination of the charred, fluffy, amorphous resins at a temperature below 600°C for 4 h yielded perovskite powders of Sr-doped LaMnO3 and Sr-doped La(Fe,Co)O3 . Sr-doped LaCrO3 needed to be calcined above 750°C to ensure phase purity and to remove organic residue. Due to the low cost of starch derivatives, the process has the potential of being more economical than the commonly used Pechini's type process, which utilizes citric acid and ethylene glycol. 相似文献
2.
3.
It is suggested that the use of multiple informants in diagnostic evaluations exacerbates a major difficulty in the use of symptom checklists—establishing replicable syndromes across data sources. The present study attempted to develop symptom scales for 3 parallel checklists for 3 types of informants to maximize the comparability of data across informants without sacrificing all of the distinctiveness of different evaluators' frames of reference. Separate cluster analyses of 450 parent checklists, 300 teacher checklists, and 299 clinician checklists yielded 9 syndromes that were comparable across all 3 informants, 4 that were identifiable in the data from only 2 informants, and 5 that were unique to the data from a single type of informant. (53 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
4.
MJ Kupferminc I Gull A Bar-Am Y Daniel A Jaffa M Shenhav JB Lessing 《Canadian Metallurgical Quarterly》1998,77(5):548-550
We report a 27-year-old woman who developed Coombs' negative hemolytic anemia and fulminant hepatic failure as the initial manifestation of Wilson's disease. Unmeasurably low level of serum alkaline phosphatase provided a clue to the diagnosis of Wilson's disease. The diagnosis was established with the presence of Kayser-Fleischer ring, decreased serum ceruloplasmin level, and elevated urine and serum copper levels. In spite of repeated plasmapheresis, she died of multiorgan failure on the fifth hospital day. 相似文献
5.
Paul A. Lessing 《Journal of Materials Science》2007,42(10):3477-3487
A review is presented of materials that could be utilized as electrolytes (and their associated electrodes and interconnect
materials) in solid-state electrolysis cells to convert water (or steam) into hydrogen and oxygen. Electrolytes that function
as oxygen ion conductors or proton conductors are considered for various operating temperatures from approximately 80 °C to
1000 °C. The fundamental electrochemical reactions are reviewed with some discussion of special sources of steam and DC electricity
(advanced nuclear) to drive the reactions at the higher temperatures. 相似文献
6.
Y Yaron A Amit A Kogosowski MR Peyser MP David JB Lessing 《Canadian Metallurgical Quarterly》1997,12(4):699-702
There has been growing concern about the number of multiple gestations resulting from assisted reproductive technologies. For in-vitro fertilization (IVF), there are guidelines concerning the number of embryos to be transferred. In oocyte donation, however, there is a paucity of studies addressing this issue and common practice is extrapolated from standard IVF procedures. This may not be correct since endometrial receptivity has been shown to be altered in oocyte donation. Thus the purpose of this study was to assess the optimal number of embryos to be transferred in oocyte donation. The study population included 254 patients with ovarian failure who underwent a total of 601 embryo transfers in a single shared oocyte donation programme. Pregnancy rates (PRs), multiple pregnancies, triplet pregnancy rates, and implantation rates were evaluated according to the number of embryos transferred. A significant linear increase in PRs was noted with the increasing number of embryos transferred up to five (11.1% for one embryo, 36.7% for five embryos). Multiple pregnancies increased significantly from 15.8% for two embryos transferred, to 44.4% for five embryos. The rate of triplet pregnancies also increased from 2.7% for three embryos transferred, to 8.3% for five embryos. Optimization of the number of embryos to be transferred is discussed. 相似文献
7.
This paper presents a unified linear Markovian analysis of complex processing systems with imperfect review. The model is not only applicable to traditional quality control operations but also to systems processing reports or schedules whose quality can be measured discretely. The analysis goes beyond the more traditional approaches by modeling imperfect inspection, addressing the output quality-workload tradeoff and defining transient response to feedback systems. The model itself uses three basic stages, an operational one which allows changes in the discrete error-level of a product, a branching one which allows dispersion of the incoming product based on the number of defects observed and a merging one which allows for the converging of products from different sources. By introducing two special matrices, the resulting analysis is quite simple even for the transient response to complicated feedback systems. This ease of analysis is particularly useful in sensitivity evaluations and consideration of alternative system configurations. 相似文献
8.
Results are presented from low temperature hydrogen permeation experiments using a palladium/copper membrane. Inlet pressure was varied from 5 psig to 180 psig, while temperature was varied from 25°C to 275°C. The palladium/copper membranes exhibited flow stability problems at low temperatures and pressures when using ultra high purity hydrogen. A preconditioning step of high temperatures and inlet pressures of pure hydrogen was necessary to stimulate any substantial permeate flows. After pre-conditioning, results showed zero hydrogen flow when using 3–4% hydrogen mixed with helium or argon. It is thought that the inert gas atoms were adsorbed into the membrane surface and thus blocked the hydrogen atom dissolution. When using pure hydrogen at low to moderate temperatures and low pressures, no measurable permeate flow was observed. Also, zero permeate flow was observed at relatively high temperatures (e.g., 150°C) and a low inlet pressure (5 psig). The cause of the zero permeate flow, when using pure hydrogen, was attributed to interface control of the permeation process. Interface control could be due to: (a) insufficient energy to split the hydrogen molecule into hydrogen atoms, or (b) a reversible phase change from beta to alpha of crystals at the near surface. 相似文献
9.
Y Daniel MJ Kupferminc A Baram AJ Jaffa I Wolman M Shenhav JB Lessing 《Canadian Metallurgical Quarterly》1998,13(12):3537-3541
The study was conducted to determine whether altered plasma concentrations of soluble selectins are involved in the pathogenesis of pre-eclampsia. Maternal plasma samples were collected from 20 patients with pre-eclampsia, and from 20 matched normotensive patients with uncomplicated pregnancies. Samples were assayed for soluble endothelial selectin (sES), platelet selectin (sPS) and leukocyte selectin (sLS) by specific enzyme-linked immunosorbent assay. The three soluble selectins were detectable in the plasma of all pre-eclamptic and control patients. The mean plasma concentrations of sPS and sLS were comparable between the groups. However, the mean plasma concentration of sES was significantly higher in the pre-eclamptic group compared with the control group (61 ng/ml +/- 30 ng/ml compared with 40 ng/ml +/- 17 ng/ml; P < 0.01). The selective increased plasma concentrations of sES in patients with pre-eclampsia provide specific evidence for endothelial activation and may reflect distinct pathways for neutrophil activation in pre-eclampsia. 相似文献
10.
A Amit Y Yaron F Azem MR Peyser MP David JB Lessing 《Canadian Metallurgical Quarterly》1995,40(9):633-637
OBJECTIVE: To examine the efficacy of extending ovulation induction for the in vivo maturation of oocytes. STUDY DESIGN: Fifty-nine high responders underwent 72 in vitro fertilization (IVF) cycles with a conventional protocol of human menopausal gonadotropin and a gonadotropin-releasing hormone analog. These patients donated oocytes to 81 recipients. The same 59 patients underwent 90 subsequent cycles in which the duration of induction was extended by two to three days. The oocytes were also donated to 138 patients. RESULTS: With the extended protocol, significantly more oocytes were retrieved (29.1 vs. 20.6), and a greater proportion of them were mature. Fertilization rates were significantly higher for both donors (67.7% vs. 36.2%) and recipients (67.5% vs. 47.1%). Conception rates were also significantly higher for both donors (24.4% vs. 11.1%) and recipients (38.4% vs. 24.7%). CONCLUSION: Extending the duration of ovulation induction in high responders is associated with in vivo maturation of oocytes and improved success rates in IVF and ovum-donation programs. 相似文献