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排序方式: 共有282条查询结果,搜索用时 17 毫秒
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Penny F Whiting Marie E Weswood Anne WS Rutjes Johannes B Reitsma Patrick NM Bossuyt Jos Kleijnen 《BMC medical research methodology》2006,6(1):1-8
Background
In clinical trials, both unequal randomization design and sequential analyses have ethical and economic advantages. In the single-stage-design (SSD), however, if the sample size is not adjusted based on unequal randomization, the power of the trial will decrease, whereas with sequential analysis the power will always remain constant. Our aim was to compare sequential boundaries approach with the SSD when the allocation ratio (R) was not equal. 相似文献33.
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A 1-mm-thick, stationary, ultrahigh-strip-density, focused grid was evaluated with respect to patient radiation dose and mammographic image quality as it affected the resolution of microcalcifications and masses. Radiographic technique was varied to determine the most useful alteration to improve image quality with the grid. Results from 89 patients demonstrated that no improvement in diagnostic ability was found in women with fatty breasts. As breast density increased, the advantage of the grid technique became more apparent. Grid mammography also often solved the problem of questionable microcalcifications with improved visualization of their number and geometry. 相似文献
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Feinberg DA; Mills CM; Posin JP; Ortendahl DA; Hylton NM; Crooks LE; Watts JC; Kaufman L; Arakawa M; Hoenninger JC 《Radiology》1985,155(2):437-442
Spin-echo magnetic resonance (MR) imaging detects a variety of pathologic states with great sensitivity. A technique for producing multiple spin-echo images in multisection operation is presented. This method of intensity-image acquisition is compared with retrospective intensity-image synthesis from routine data sets. Both yield long echo time (TE) images with similar image contrast and comparable and often increased diagnostic utility. Technical and clinical considerations are addressed, including signal-to-noise levels, flow effects, and patient throughput. 相似文献
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Karen Broekhuizen Mireille NM van Poppel Lando LJ Koppes Johannes Brug Willem van Mechelen 《BMC public health》2010,10(1):69
Background
Because of a high cardiovascular disease (CVD) risk in people with Familial Hypercholesterolemia (FH), early prevention of cardiovascular disease is important for health gain and cost reduction. This project focuses on the development and evaluation of an innovative intervention aiming to reduce CVD risk by promoting a healthy lifestyle among people with FH. 相似文献40.
KR Rathi Vikram Uppal NM Bewal Debraj Sen Anurag Khanna 《Medical Journal Armed Forces India》2012,68(2):142-144