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排序方式: 共有633条查询结果,搜索用时 31 毫秒
61.
T. K. Lee Chang-Ming Ho Naoto Nagaosa Wei-Cheng Lee 《Journal of Low Temperature Physics》2003,131(3-4):169-179
Trial wavefunctions, constructed explicitly from the unique 2-dimensional Mott insulating state with antiferromagnetic order, are proposed to describe the low-energy states of a Mott insulator slightly doped with holes or electrons. With the state behaving like charged quasi-particles with well-defined momenta, a rigid band is observed. These states have much less pairing correlations than previously studied ones. Small Fermi patches obtained are consistent with recent experiments on high T
c cuprates doped lightly with holes or electrons. States showing the incoherent and spin-bag behaviors are also discussed. Using these wavefunctions, a number of results obtained by exact calculations are reproduced. 相似文献
62.
63.
This paper considers the optimal spare ordering policies for a cold standby redundant system with two dissimilar units. Especially, the planned maintenance schedule with salvage cost is discussed. The failure time distributions for respective units are assumed to be arbitrary. By applying the expected cost per unit time in the steady-state and the stationary availability as criteria of optimality, the optimal ordering policy minimizing or maximizing each criterion is obtained under some economical and/or physical assumptions. Finally, numerical examples are presented, and the effect of the failure time distributions for the optimal ordering policy is examined in detail. 相似文献
64.
PURPOSE: Acanthamoeba is an uncommon cause of corneal infection in which the best visual outcome follows prompt diagnosis and a long course of appropriate antimicrobial therapy. Because conventional detection techniques for Acanthamoeba have certain limitations, we investigated the ability of the polymerase chain reaction (PCR) to confirm the clinical diagnosis of Acanthamoeba keratitis, with the ultimate aim of achieving early diagnosis. METHODS: Using two different pairs of primers, PCR was performed on representative cultured Acanthamoeba isolates to confirm the assay's ability to amplify Acanthamoeba DNA from a wide range of acanthamoebae. Subsequently, corneal epithelial samples from 19 patients and tear samples from 12 patients with Acanthamoeba keratitis were analyzed by PCR for the presence of Acanthamoeba DNA. RESULTS: Acanthamoeba DNA was amplified by PCR from 16 (84%) of 19 corneal epithelial samples, whereas Acanthamoeba was cultured from 10 samples (53%), all of which were PCR positive. Tear samples from 8 (66%) of 12 patients were positive on PCR testing, and one tear sample was PCR positive, whereas the corresponding epithelial biopsy had yielded a negative PCR result. Samples from culture-positive patients were positive on PCR testing more frequently than those from culture-negative patients (10/10 culture-positive corneal epithelial and 5/7 [71%] culture-positive initial tear samples versus 6/9 [66%] culture-negative corneal epithelial and 2/5 [40%] culture-negative tear samples). All control epithelial (n = 15) and tear (n = 15) samples yielded negative results. CONcLUSIONS: PCR was a more sensitive diagnostic test than a culture for Acanthamoeba keratitis, and the use of two different primers achieved better sensitivity than a single set. A PCR of a tear sample also may be a useful complementary test and, in combination with PCR of epithelial samples, would prove particularly helpful in confirming the clinical diagnosis in culture-negative cases. 相似文献
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67.
We discuss optimum inspection policies by introducing the inspection density. We derive the optimum inspection policy by using this inspection density. The models discussed are: 1) the basic model, 2) the basic model with checking time, and 3) the basic model with imperfect inspection. For each model, we obtain the approximate optimum inspection policy minimizing the total s-expected cost by applying the calculus of variations. 相似文献
68.
K Nakanishi C Iwahashi Y Handa N Hara K Hamada Y Nagai S Kawamura K Nakamura 《Canadian Metallurgical Quarterly》1998,40(8):607-611
A 30-year-old man had been treated for malignant rheumatoid arthritis from 1989 with a non-steroidal anti-inflammatory drug, then bucillamine for six months and prednisolone. Mild proteinuria appeared in May 1994, 4 years after bucillamine therapy was conducted. The patient was admitted to our hospital for a renal biopsy in July 1994. The specimen revealed secondary amyloidosis and membranous nephropathy (MGN). These findings suggest that MGN unrelated to bucillamine therapy might have occurred with secondary amyloidosis in rheumatoid arthritis. 相似文献
69.
Yoshinori Iwahashi Zenji Horita Minoru Nemoto Terence G. Langdon 《Metallurgical and Materials Transactions A》1998,29(10):2503-2510
Experiments were undertaken to compare the equal-channel angular (ECA) pressing of Al-1 pct Mg and Al-3 pct Mg solid-solution
alloys with pure Al. The results reveal both similarities and differences between these three materials. Bands of subgrains
are formed in all three materials in a single passage through the die, and these subgrains subsequently evolve, on further
pressings through the die, into an array of grains with high-angle boundaries. However, the addition of magnesium to an aluminum
matrix decreases the rate of recovery and this leads, with an increasing Mg content, both to an increase in the number of
pressings required to establish a homogeneous microstructure and to a decrease in the ultimate equiaxed equilibrium grain
size. It is concluded that alloys exhibiting low rates of recovery should be especially attractive candidate materials for
establishing ultrafine structures through grain refinement using the ECA pressing technique. 相似文献
70.
H Obo S Kozawa T Asada N Mukohara T Higami K Gan K Iwahashi H Nohara K Ogawa 《Canadian Metallurgical Quarterly》1998,28(8):797-801
We assessed the efficacy of emergency percutaneous cardiopulmonary bypass support (PCPS) in the treatment of patients with acute myocardial infarction complicated by cardiogenic shock. Emergency PCPS was instituted in 21 consecutive patients beginning in 1991. After the stabilization of the hemodynamics, coronary reperfusion was performed by means of coronary artery bypass grafting or percutaneous transluminal coronary angioplasty. Of the seven patients with acute myocardial infarction involving either the left main or two-vessel territories, five survived more than 1 month, but only one patient remained alive and well after 20 months. The main cause of death for this group was low output syndrome. Four of 12 patients with acute left main trunkal occlusion in the catheter laboratory survived and showed a preserved cardiac function (mean followup 28.5 months). The main cause of death for this group was brain damage. Two patients with single-vessel territory acute myocardial infarction underwent PCPS to treat refractory ventricular fibrillation. Both patients were still alive and well at a 12-month followup. Percutaneous cardiopulmonary bypass support successfully stabilized the hemodynamics, allowing time to perform revascularization for all three groups of patients with life-threatening acute myocardial infarction. Recanalization was nevertheless unable to salvage the damaged myocardium in cases of prolonged ischemic time. 相似文献