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排序方式: 共有1812条查询结果,搜索用时 15 毫秒
1.
J Harbott M Mancini C Verellen-Dumoulin AV Moorman LM Secker-Walker 《Canadian Metallurgical Quarterly》1998,12(5):823-827
OBJECTIVE: Using receiver-operating characteristic (ROC) curves, we tried to determine the diagnostic threshold of amniotic fluid index (AFI) that will identify abnormal fetal size (birth weights under 2500 g or at least 4000 g) at 37 weeks or beyond. METHODS: We analyzed prospectively over 2 years all parturients with intact membranes and known AFI in early labor. Patients with the following conditions were excluded: pregestational or gestational diabetes, known anomalies, and preterm labor. Two ROC curves were constructed, and the areas (+/- standard error of the mean [SE]) under the curves were calculated. P < .05 was considered significant. RESULTS: Of the 1038 subjects meeting study criteria, 3.6% and 11.5% gave birth to infants who were small for gestational age (SGA) or macrosomic, respectively. Overall, 28.7% had oligohydramnios (AFI at most 5.0 cm) and 3.6% had hydramnios (AFI at least 24.0 cm). Small for gestational age was more common in patients with AFI at most 5.0 cm (6.4%) than in those with adequate fluid (AFI 5.1-23.9; 2.5%), or hydramnios (2.7%; P = .012). Macrosomic newborns were less likely to be born to women with oligohydramnios (7.7%) than to those with adequate amniotic fluid (13.1%) or hydramnios (13.5%). Areas under ROC curves are not significantly different from the area under the nondiagnostic line, indicating that AFI (0-34 cm) cannot differentiate between newborns under 2500 g and at or over 2500 g or under 4000 and at or more 4000 g. CONCLUSION: Intraparterium AFI appears to be a poor screening test to identify risk for delivery of SGA or macrosomic fetus. 相似文献
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We evaluated the effect of the image acquisition parameters on the accuracy of the principal axes and surface-fitting techniques for three-dimensional image registration. Using two types of phantom objects, MR brain image and a mathematically defined ellipsoid, we simulated pairs of scans with known acquisition parameters, including longitudinal coverage, magnitude of mis-registration, number of sections and section thickness. Both methods are sensitive to the systematic deformation of contours. The principal axes method is also sensitive to incomplete scan coverage and to the x-axis and y-axis misangulation. Both methods are insensitive to the number of sections, section thickness and the number of points per section. Surface fitting performed well without user supervision. There is no need for routine inclusion of the scaling factors as search parameters. The results confirm the feasibility of three-dimensional multimodality registration of brain scans with accuracy 1-2 mm, with surface fitting being the method of choice. 相似文献
6.
AV Kishtovich 《Canadian Metallurgical Quarterly》1998,84(9):869-873
Depressing neurogenic and humoral (acetylcholine, papaverine and histamine) effects against the background of dilatation of arterial vessels were shown to exert different results: the former stimuli led to blood output from the veins, whereas humoral stimuli enhanced the depot role of the veins in animals. The smallest possible doses of acetylcholine did sometimes reduce the vessels' capacity. 相似文献
7.
1. | Raising the cobalt concentration from 0 to 40% improves the oxidation resistance of Ni–20Cr alloys, since the amount of Cr2O3 in the scale increases. The oxidation resistance is highest for the alloy with 40% Co. Larger amounts of Co up to 70% lead to the formation of CoO in the scale and smaller amounts of chromium oxide, which has a negative effect on the oxidation resistance of Ni–Cr alloys. |
2. | The addition of up to 25% Fe to Ni–20Cr–Co alloys reduces the amount of Cr2O3 in the scale and lowers the oxidation resistance. With larger amounts of Fe the amount of Cr2O3 in the scale again increases, the oxidation resistance increasing correspondingly. Alloys with 45% Fe have the same oxidation resistance as alloys without Fe. |
8.
R. I. Kozlov O. R. Kozlova 《Journal of Computer and Systems Sciences International》2009,48(2):262-271
Modification and extension of procedures of strict analysis of stability and estimates of domains of attraction based on the reduction method with sublinear vector Lyapunov function is given for sufficiently wide class of nonlinear stabilization systems of continuous objects using piecewise constant control formed using discrete state measurements. The new type of realization of heterogeneous comparison systems in the form of interconnected differential and discrete impulse subsystems with varying right-hand side allowing to avoid preliminary discretization of the original system and thus increasing accuracy of investigations is proposed. In the case of nonlinearities (including those with respect to control and measurements), limited by semi-homogeneous functions. Constructive conditions of exponential stability with necessary quantitative estimates are formulated. Application to investigation of stability of economic growth in the Phillips-Bergstrom model with discrete monetary regulation is presented. The paper consists of two parts. In this part, the studied models are described, the studied stability property is defined, procedures for construction of vector Lyapunov function and comparison system are given, and some of their specific features are established. 相似文献
9.
Yilin Han Marianne King Evgenii Tikhomirov Povilas Barasa Cleide Dos Santos Souza Jonas Lindh Daiva Baltriukiene Laura Ferraiuolo Mimoun Azzouz Maurizio R. Gullo Elena N. Kozlova 《International journal of molecular sciences》2022,23(10)
Three-dimensional (3D) cultures, so-called organoids, have emerged as an attractive tool for disease modeling and therapeutic innovations. Here, we aim to determine if boundary cap neural crest stem cells (BC) can survive and differentiate in gelatin-based 3D bioprinted bioink scaffolds in order to establish an enabling technology for the fabrication of spinal cord organoids on a chip. BC previously demonstrated the ability to support survival and differentiation of co-implanted or co-cultured cells and supported motor neuron survival in excitotoxically challenged spinal cord slice cultures. We tested different combinations of bioink and cross-linked material, analyzed the survival of BC on the surface and inside the scaffolds, and then tested if human iPSC-derived neural cells (motor neuron precursors and astrocytes) can be printed with the same protocol, which was developed for BC. We showed that this protocol is applicable for human cells. Neural differentiation was more prominent in the peripheral compared to central parts of the printed construct, presumably because of easier access to differentiation-promoting factors in the medium. These findings show that the gelatin-based and enzymatically cross-linked hydrogel is a suitable bioink for building a multicellular, bioprinted spinal cord organoid, but that further measures are still required to achieve uniform neural differentiation. 相似文献
10.
I V Lerina A M Belous T L Kolesnik G N Shatrov V F Kozlova A N Za?tsev 《Voprosy pitaniia》1990,(1):61-64
Toxicologic and hygienic study of a pigment from abattoir blood--carboxyn (based on carboxyhemoglobin) was conducted on noninbred white rats in subacute (3 months) and chronic (12 months) experiments. The condition of the animals, their bw growth, blood morphology, erythrocyte sedimentation rate, the content of hemoglobin, protein and iron in the blood serum were evaluated. Activity of the following enzymes was studied: catalase and sorbitol dehydrogenase--in the blood serum; glucose 6-phosphate dehydrogenase, lactate dehydrogenase and cytochrome P-450 content--in the liver. Internal organs of the rats were subjected to histological investigation. The data obtained have evidenced the absence of some signs of biotransformation of the red complex of carboxyhemoglobin, or its toxic effect on the experimental animals. It has been concluded that carboxyn can be used as a coloring component in the production of sausage (in the amount of up to 2% of the sausage meat mass). 相似文献