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排序方式: 共有1630条查询结果,搜索用时 416 毫秒
1.
Intracranial circulation: pulse-sequence considerations in three- dimensional (volume) MR angiography 总被引:2,自引:0,他引:2
The technique and feasibility of magnetic resonance (MR) angiography of intracranial vessels were studied in 35 healthy volunteers. Variations in image orientation, repetition time (TR), and flip angle were evaluated to determine their effects on flow-related enhancement. Gradient modifications--including echo time (TE), motion compensation, bandwidth, and field of view--were also studied in an effort to reduce motion-induced phase shifts. Results indicated that a FISP (fast imaging with steady precession) sequence with a TR of 50 msec, TE of 15 msec, velocity compensation in the read and section-select directions, acceleration compensation in the read direction, anisotropic volume, and a 1.25-mm partition thickness produced three-dimensional angiographic MR images that were accurate and reproducible in the depiction of the major intracranial vessels. Difficulties with field of view, persistent signal void secondary to higher-order motion, and spatial resolution remain major problems requiring additional study. 相似文献
2.
Maxillary sinusitis in adults: an evaluation of placebo-controlled double-blind trials 总被引:1,自引:0,他引:1
BACKGROUND: In general practice, acute sinusitis is frequently diagnosed
and treated with antibiotics. OBJECTIVE: This study aimed to determine the
evidence for the effectiveness of antibiotic treatment in acute maxillary
sinusitis in adults by assessing the methodological quality of
placebo-controlled double-blind randomized trials. METHOD: An evaluation by
four raters through a 35-item scoring-scale for internal and external
validity of all placebo-controlled double-blind randomized trials on acute
sinusitis found between January 1966 and July 1996. RESULTS: Eighty-five
trials were excluded because they were not placebo-controlled,
double-blind, randomized, or were carried out in patients with chronic
sinusitis or in children. The three remaining trials were performed in
different populations (one in general practice) between 1973 and 1978. Only
one study claimed superiority of antibiotic treatment. Different inclusion
criteria and major outcome measures were used by the authors. The
reliability of major outcome events was reported poorly or not at all and
in two studies outcome measures were clinically inappropriate. The studies
scored 30-62% of the maximum attainable score for internal validity and
10-20% for external validity. CONCLUSION: The effectiveness of antibiotic
treatment in acute maxillary sinusitis in a general practice population is
not based sufficiently on evidence.
相似文献
3.
L Gannon 《Women & health》1988,14(2):105-127
Research in the last decade has advanced our understanding of menstrual disorders and menopause. Paralleling this research has been both a popular and a scholarly interest in the correlates and consequences of aerobic exercise. The purpose of this paper is to integrate these two domains on a theoretical and, when possible, an empirical level, and to discuss the potential benefits of exercise in the treatment of menstrual disorders and menopausal symptoms - specifically, dysmenorrhea, premenstrual syndrome, hot flashes, and osteoporosis. 相似文献
4.
5.
Psychological distress before and immediately after attendance at a male sub-fertility clinic. 总被引:1,自引:0,他引:1
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Where treatment options are limited, the role of clinical consultation in providing information and support becomes more important. This study examines the immediate impact of medical consultation on male sub-fertility clinic attender's anxiety, depression, self-blame, information appraisal and perceptions of future fertility. Data were collected pre- and immediately post-consultation. Clinical information and consultation details were recorded. Results showed that anxiety levels were high before consultation. Following consultation anxiety and self-blame were both reduced while depression increased. Despite information about poor prognosis being given during consultation, participants remained overly optimistic about their chances of achieving a pregnancy. It appears that the consultation has a distinct psychological impact and possible mechanisms underlying this are discussed. 相似文献
6.
H Angus-Leppan GA Lambert J Michalicek 《Cephalalgia : an international journal of headache》1997,17(6):625-630
Co-existence of facial and occipital pain may occur in occipital neuralgia, migraine and cluster headache; suggesting convergence of trigeminal and cervical afferents. Such convergence has been shown in humans and other animals, but the site and extent of this are uncertain. In anaesthetized adult cats, the superior sagittal sinus and occipital nerve were stimulated electrically, and extracellular recordings made in the dorsolateral area of the upper cervical cord using glass-coated tungsten electrodes. Of 49 units in 10 cats, 33 (67%) had input from the superior sagittal sinus and the occipital nerve. Thirteen (27%) had superior sagittal sinus input and 3 (6%) had occipital nerve input. Convergent receptive fields were identified mechanically in 7 units. These experiments in cats show convergent input from occipital nerve and superior sagittal sinus on dorsolateral area units in two-thirds of cases studied. This experimental site of trigeminocervical convergence may relate to referral of pain in occipital neuralgia and other headaches. 相似文献
7.
In patients with PG-dependent renal function, NSAID administration
constantly reduces GFR and RBF in a dose-dependent fashion. In this
situation, the risk of overt acute renal failure is high and should be
taken into proper account. In contrast, the incidence of NSAID-related
renal structural alterations appears to be very low, yet the absolute
number of patients may be significant considering the wide use of such
drugs. Concerning the antiproteinuric effect of NSAIDs, the unfavourable
ratio risk/benefit does not seem to support their indication in proteinuric
nephropathies. The development of PGHS-2 selective inhibitors is promising,
and may open new therapeutical strategies in the treatment of the
progression of renal disease.
相似文献
8.
Changes in metabolic rates and blood respiratory characteristics during pouch development of a marsupial, Macropus eugenii 总被引:1,自引:0,他引:1
Oxygen levels in the pouch of the tammar wallaby, Macropus eugenii, have been related to the metabolic rate of the young at pouch temperatures and the oxygen transport characteristics of its haemoglobin. Until 100 days of age, pouch young show mass-specific rates of oxygen consumption lower than predicted on the basis of body mass. This contrasts with data presented for laboratory mice. Oxygen levels in the pouch approximate atmospheric levels for the first 20 days and at times approaching pouch evacuation at 200 days. However, levels of around 17-18% occur at about the mid-point of pouch life. The oxygen-haemoglobin equilibrium curve shows a high P50 (up to 50 Torr at 36 degrees C) in the neonate, but after 2-3 weeks of age levels drop to those representative of the adult. Concentrations of 2,3-diphosphoglycerate in early pouch young are higher than in the adult animal and peak at around 30 mumol/g Hb. There is a significant decrease in the concentration of this compound with the age of the young. 相似文献
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