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排序方式: 共有10000条查询结果,搜索用时 31 毫秒
961.
962.
C Y Chen R A Zimmerman S Faro B Parrish Z Wang L T Bilaniuk T Y Chou 《AJNR. American journal of neuroradiology》1996,17(7):1303
PURPOSETo evaluate abnormalities of the cerebral operculum in infants and children and to propose the embryogenic basis of abnormal opercular formation as determined from MR imaging findings.METHODSEighty-six infants and children who had abnormally wide interopercular distances and/or distorted opercular topography seen on MR images were studied retrospectively. Clinically, patients presented with tonal abnormalities, macrocephaly, microcephaly, seizures, developmental delay, cerebral palsy, or facial dysmorphism. The abnormal opercula were compared with developing opercula at different stages of gestation.RESULTSAmong the 86 infants and children, two categories of opercular abnormalities were identified: an underdeveloped operculum (n = 64) and a malformed operculum (n = 22). The malformed operculum was further classified into three subtypes: nonformation of the operculum with lissencephaly (n = 1, 1%), abnormal opercular formation with pachygyria (n = 11, 13%), and nonformation or abnormal formation of the operculum without pachygyria or lissencephaly (n = 10, 12%). Two subtypes of the underdeveloped operculum were identified: an open operculum without a normal insula (n = 6, 7%) and an open operculum with a normal insula (n = 58, 67%). The five subtypes of abnormal opercular configuration showed a range of maturity that was comparable to the developing operculum at different ages.CONCLUSIONOpercular anomalies appear to follow sequentially predetermined normal steps in development. Arrest in opercular development or malformation may occur after an initial insult. MR imaging is the method of choice by which to identify these abnormalities. 相似文献
963.
To provide better transient performance in controlling robots, a mixed minimum time and quadratic performance index is used. For known and uncertain revolute robot manipulators a conventional optimal control and a robust guaranteed cost control are proposed respectively. Asymptotic stability is also discussed based on the Lyapunov direct method. The proposed robust control is continuous and requires no knowledge of the uncertain system except for bounding functions. 相似文献
964.
Elizabeth Z. Bordayo John R. Fawcett Sarita Lagalwar Aleta L. Svitak William H. Frey 《Journal of molecular neuroscience : MN》1996,27(2):185-194
Arachidonic acid (AA), released in response to muscarinic acetylcholine receptor (mAChR) stimulation, previously has been
reported to function as a reversible feedback inhibitor of the mAChR. To determine if the effects of AA on binding to the
mAChR are subtype specific and whether AA inhibits ligand binding to other G protein-coupled receptors (GPCRs), the effects
of AA on ligand binding to the mAChR subtypes (M1, M2, M3, M4, and M5) and to the μ-opioid receptor, β2-adrenergic receptor (β2-AR), 5-hydroxytryptamine receptor (5-HTR), and nicotinic receptors were examined. AA was found to inhibit ligand binding
to all mAChR subtypes, to the β2-AR, the 5-HTR, and to the μ-opioid receptor. However, AA does not inhibit ligand binding to the nicotinic receptor, even
at high concentrations of AA. Thus, AA inhibits several types of GPCRs, with 50% inhibition occurring at 3–25 μM, whereas the nicotinic receptor, a non-GPCR, remains unaffected. Further research is needed to determine the mechanism by
which AA inhibits GPCR function. 相似文献
965.
AIM: To study the effect of catecholamic acid (CBMIDA) on detoxication of NiCl2. METHODS: Mice and rats were injected s.c. or i.m. CBMIDA immediately after i.p. NiCl2. Each mouse was injected i.p. CBMIDA after i.v. 63NiCl2 185 kBq, and radioactivities of various tissues were measured with liquid scintillation counter at 24 h. The localization of 63Ni was shown by the whole-body autoradiography. RESULTS: CBMIDA s.c. 0.5-1.5 g.kg-1 markedly reduced the mortality from acute poisoning of i.p. NiCl2 500 mg.kg-1. After i.p. NiCl2 in mice, the LD50 was 82.7 mg.kg-1. Mice were injected s.c. CBMIDA 1.5 or 2.5 g.kg-1 after Ni poisoning, the LD50 of NiCl2 were raised to 789 or 820 mg.kg-1, respectively. The LD50 of NiCl2 was 39 mg.kg-1 in rat. If CBMIDA was injected i.m. 0.5 g.kg-1 after i.p. NiCl2, the LD50 was 332 mg.kg-1. CBMIDA 1.5 g.kg-1 i.m. after i.v. 63NiCl2, decreased the contents of 63Ni in blood and lung of mice vs control mice at 24 h. The contents of 63Ni in brain, heart, spleen, and kidney were similar to those of the control mice. The content of 63Ni in bone was more than the control. The excretions of 63Ni through urine and feces were not increased by CBMIDA at 24 h. The whole-body autoradiography showed that the radioactivity was highly localized in the kidney, lung, and Harder's gland. There was a moderate level of 63Ni in the liver, bone, skin, and blood. A pronounced accumulation occurred in the bone. There was a marked reduction of 63Ni in the lung, skin, liver, and blood after i.p. CBMIDA. CONCLUSION: The CBMIDA markedly raised the survival rate of nickel-poisoned mice and rats, and decreased 63Ni levels in lung and blood. 相似文献
966.
N. Çeviker M. K. Baykaner M.D. I. S. Keskil H. Sencer Ö. Ataoğlu M. Özsoy Z. S. Ercan 《Acta neurochirurgica》1995,132(1-3):104-109
Summary In this study intra-arterial Endothelin-1 was applied to rabbit basilar arteries and morphological findings were compared between two groups who were either perfusion fixed or immersion fixed. We planned to establish the quantitative dimension of the drug-induced morphological alterations, independent of the fixation technique's effect.There was an abundance of collagenous fibres deposited among the smooth muscle cells which was not observed in control arteries and after immersion fixation. These degenerative changes are similar to the finding following subarachnoid haemorrhage. The only fixation-related difference was the fact that lamina elastica interna was not corrugated in the perfusion fixation group.It is concluded that, the observed changes in the connective tissue of the arterial wall alter the passive elastic properties and so affect the degree of the response to the vasoactive messengers. 相似文献
967.
舌下腺囊肿口外型临床治疗(附17例分析) 总被引:7,自引:0,他引:7
舌下腺囊肿口外型临床治疗(附17例分析)张伟杰,张志勇,哈 ,胡永杰舌下腺囊肿是口腔颌面外科学中常见疾病之一,而其口外型临床较少见,易引起误诊,造成手术进路的错误,增加病员的痛苦。本文报告我科1990~1995年17例舌下腺囊肿口外型的临床表现,诊断... 相似文献
968.
下体负压作用下心率变异性的线性和非线性动力学分析 总被引:1,自引:1,他引:0
胡志红 《航天医学与医学工程》1998,11(4):235-239
为了评估下体负压作用下心率变异性的变化,本文应用了时域,频域分析和复杂度分析了HRV。受试者为15名健康男性。下体负压作用的强度和时间分别为-2.7kPa,2min;-4.0kPa,3min;-5.3kPa,5min;-6.7kPa,10min。 相似文献
969.
970.
Digital subtraction arthrography in preoperative evaluation of painful total hip arthroplasty 总被引:1,自引:0,他引:1
A. Z. Ginai F. C. van Biezen P. A. M. Kint H. Y. Oei W. C. J. Hop 《Skeletal radiology》1996,25(4):357-363
Objective. The objective of this clinical study was to define the diagnostic value of plain radiography, digital subtraction arthrography
and two-phase bone scintigraphy in patients with clinically loose or infected hip prostheses. Design. Digital subtraction arthrograms, scintigrams and plain radiographs of 70 consecutive patients who underwent revision hip arthroplasty
were scored individually and in masked fashion for the presence or absence of features indicating loosening of femoral and/or
acetabular components. The operative findings acted as the gold standard. Results. Digital subtraction arthrography was best (P<0.001) for predicting a loose acetabular component, while no significant additional predictive value was found for plain
radiographs (P=0.24) and scintigraphy (P=0.27). Digital subtraction arthrography was also the most important modality for predicting a loose femoral component (P=0.001), while the plain radiograph was of significant (P=0.04) additional value and scintigraphy was of no additional value (P=0.13) on multivariate analysis. Conclusion. Digital subtraction arthrography gives the best results in the prediction of loosening of acetabular and femoral components.
Plain radiographs give additional information on loosening of the femoral component, but scintigraphy offers no additional
advantage. 相似文献