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101.
为了使曲线易于实现光滑拼接,同时具有对应于相同控制顶点的不同形状,定义了具有凸包性、对称性、形状可调性等基本性质的新曲线.文中分析了基函数及曲线的性质和2个形状参数的几何意义,给出了2条Said-Ball型曲线的G0,G1,G2连续拼接条件.类似构造了局部形状可调的组合曲面.数值实例说明了所给方法的正确性和有效性. 相似文献
102.
BS Iyengar RT Dorr DS Alberts EM Hersh SE Salmon WA Remers 《Canadian Metallurgical Quarterly》1999,42(3):510-514
A set of 20 2-cyanoaziridine-1-carboxamides was synthesized from 2-cyanoaziridine and appropriate isocyanates. These compounds were active against a variety of solid and hematological tumor cells in culture, including strains resistant to doxorubicin and mitoxantrone. Their potencies in these assays correlated with the lipophilicity of substituents. The N-phenyl derivative was more potent and equally effective to imexon, a cyclized 2-cyanoaziridine-1-carboxamide of clinical interest, against cloned fresh human tumors. 相似文献
103.
NP Camacho L Hou TR Toledano WA Ilg CF Brayton CL Raggio L Root AL Boskey 《Canadian Metallurgical Quarterly》1999,14(2):264-272
Osteogenesis imperfecta (OI), a heritable disease caused by molecular defects in type I collagen, is characterized by skeletal deformities and brittle bones. The heterozygous and homozygous oim mice (oim/+ and oim/oim) exhibit mild and severe OI phenotypes, respectively, serving as controlled animal models of this disease. In the current study, bone geometry, mechanics, and material properties of 1-year-old mice were evaluated to determine factors that influence the severity of phenotype in OI. The oim/oim mice exhibited significantly smaller body size, femur length, and moment of area compared with oim/+ and wild-type (+/+) controls. The oim/oim femur mechanical properties of failure torque and stiffness were 40% and 30%, respectively, of the +/+ values, and 53% and 36% of the oim/+ values. Collagen content was reduced by 20% in the oim/oim compared with +/+ bone and tended to be intermediate to these values for the oim/+. Mineral content was not significantly different between the oim/oim and +/+ bones. However, the oim/oim ash content was significantly reduced compared with that of the oim/+. Mineral carbonate content was reduced by 23% in the oim/oim bone compared with controls. Mineral crystallinity was reduced in the oim/oim and oim/+ bone compared with controls. Overall, for the majority of parameters examined (geometrical, mechanical, and material), the oim/+ values were intermediate to those of the oim/oim and +/+, a finding that parallels the phenotypes of the mice. This provides evidence that specific material properties, such as mineral crystallinity and collagen content, are indicative and possibly predictive of bone fragility in this mouse model, and by analogy in human OI. 相似文献
104.
105.
Heparin co-factor II is in addition to antithrombin III another heparin dependent thrombin inhibitor. This glycoprotein blocks thrombin action not only in haemostasis but also in its other effects. Congenital deficiency of heparin co-factor II was found equally frequently among asymptomatic subjects and patients with thrombotic complications. Although its deficiency probably is not a serious risk factor of thromboembolic disease, it can promote its development in a significant way. The authors describe the case of a child with thrombotic complications and a congenital deficiency of heparin co-factor II. 相似文献
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108.
Vincristine was inadvertently injected into a thigh of three children. In each case the accident occurred as a result of the mixing of a syringe containing vincristine with a syringe of L-asparaginase which the patient was scheduled to receive on the same day. Within minutes, each patient was treated topically with cold compresses and the area was infiltrated with a solution of 8.4% sodium bicarbonate. Only one patient had discomfort of the thigh after the injection, none of the patients have had any sequelae, either acute or delayed. Measures to avoid mistaken injection of vincristine for asparaginase are readily achievable and have prevented recurrences of intramuscular vincristine administration at the institutions where they have been implemented. Nonetheless, other instances of intramuscular vincristine injection are anticipated and should be rapidly recognized and quickly managed with local applications of cold and sodium bicarbonate. 相似文献
109.
Low-frequency modes in vitreous silica 总被引:1,自引:0,他引:1
U Buchenau M Prager N Nücker AJ Dianoux N Ahmad WA Phillips 《Canadian Metallurgical Quarterly》1986,34(8):5665-5673
110.
WA Walker 《Canadian Metallurgical Quarterly》1997,38(5):321-331
In this review of the protective properties of human breast milk, a new perspective is taken to underscore the passive and active protection properties of breast milk in providing specific protection against selective gastrointestinal disease affecting the neonate and preterm infant. The normal protective properties of the gastrointestinal epithelial barrier (immunologic and nonimmunologic) are considered as is the development of barriers to antigen absorption in the immature infant human intestine as a background for considering three accelerated gastrointestinal diseases-necrotizing enterocolitis, intestinal allergy, and bacterial gastroenteritis. In each of these conditions, the developmental protective defect is considered and the role of breast milk plays in filling the protective void discussed. Besides considering passive protection of breast milk including the new roles assigned to nutrients such as lactoferrin and nucleotides, and importance of active substances in breast milk such as growth factors, cytokines and hormones are discussed in the context of actively stimulating the infant's own intestinal defenses to function as a protective barrier. Future studies at the cellular and molecular level should be helpful in designing both preventative and treatment strategies to deal with these diseases. 相似文献