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排序方式: 共有681条查询结果,搜索用时 15 毫秒
81.
本文的写作目的既不是为了展示研究成果,也不是为了批评(或表扬)规制(regulation).我的目的是提出两个问题:有没有替代规制的可行方法?如果有,我们能在哪里找到模型?我建议通过关注一个领域来完成这个任务. 相似文献
82.
Falk John L.; Schuster Charles R.; Bigelow George E.; Woods James H. 《Canadian Metallurgical Quarterly》1982,37(10):1124
Examines the literature on drug dependence from a behavioral viewpoint. Dependence on drugs and alcohol results from an interaction between the individual and the substance within precipitating environmental conditions. Animals and humans self-administer the same drugs, suggesting the biological normality of chemical dependency and the value of laboratory research on the generation and alleviation of such dependencies. Functional or behavioral toxicity can be a serious social problem, and research is needed on why many individuals do not become addicted to drugs and alcohol to which they are exposed, and how social processes can be used to increase an individual's resistance to substance abuse. The cost effectiveness of drug research and treatment is also discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
83.
J. C. Schuster 《Journal of Nuclear Materials》1984,120(2-3):133-136
Phase equilibria in the ternary system Hf-Al-N are investigated. At 1273 K, the ternary phase Hf3AlN (isotypic with Zr3AlN, monoclinic, a = 0.59011 nm, 6 = 0.88646 nm, c = 0.33185 nm, β = 106.33°) coexists with HfN1−x, A1N, Hf2Al3, HfAl, Hf4Al3, Hf3Al3 and -Hf(s.s.). At 1673 K, a second ternary phase Hf5Al3N (isotypic with Zr5Al3N1−x, hexagonal, a = 0.8062 nm, c = 0.5603 nm) occurs. A1N in contact with hafnium or hafnium-rich Hf-Al alloys decomposes at this temperature into HfN1−x and HfAl2. No ternary solubilities are observed further to the extended solid solutions of -Hf. 相似文献
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The influence of thermal history on the thermomechanical properties of a graft polymer (ABS) is investigated. The thermal pretreatments are: sharp quenching from above the glas-transition of the matrix resin, annealing below the glas transition. A first characterization of the influence of these two pretreatments is done by measuring density, probe length as function of temperature and by DTA. The less modulus in the region below the glas transition of the matrix resin is very sensitive to thermal pretreatment. Small but reproducible influences are observed in the glas transition region of the polybutadien particles. At room temperature stress-strain measurements are achieved until fracture happens. Crazing is observed (which is often called stress-whitening) in all cases, but the extent of craze growing is dependent on thermal history. The measurements are completed by scanning micrographs of the fracture surfaces. Annealing of the fracture surfaces gives additional informations. The results are discussed using the concept of free volume which is variated by thermal pretreatment. At room temperature the phase-boundary between polybutadion particle and matrix resin is considered as transition zone from high to small hole concentration. The sharpness of this zone is supposed to be a decisive parameter for the macroscopic deformation behaviour. 相似文献
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87.
A Busjahn A Voss H Knoblauch M Knoblauch E Jeschke N Wessel J Bohlender J McCarron HD Faulhaber H Schuster R Dietz FC Luft 《Canadian Metallurgical Quarterly》1998,81(6):755-760
Decreased heart rate variability (HRV) is associated with congestive heart failure, post-myocardial infarction, ventricular arrhythmias, sudden cardiac death, and advancing age. A deletion/insertion polymorphism in the angiotensin-converting enzyme (ACE) gene and a substitution (M235T) in the angiotensinogen gene have been associated with risk for heart disease. The aim of this study was to determine the heritability of HRV and related parameters in monozygotic and dizygotic twins and to assess the influence of ACE and angiotensinogen polymorphisms. We studied 95 MZ pairs and 46 DZ pairs. We measured HRV and related parameters, ACE and angiotensinogen levels, plasma norepinephrine, ACE, and angiotensinogen genotypes. We found that HRV and related parameters were significantly influenced by genetic variability, although nonshared genetic effects were also important. Angiotensinogen and plasma norepinephrine were generally correlated with decreased HRV, whereas ACE was correlated with perturbances of normal rhythmic HRV. Nevertheless, the DD ACE genotype was associated with increased HRV (p <0.05), whereas angiotensinogen polymorphisms had no effect. We conclude that HRV and related parameters are in part heritable. Interestingly, the DD ACE genotype is associated with increased HRV. 相似文献
88.
Effect of Emulsifiers on the Behaviour of Fat in Ice Cream Mix During Ageing Ageing of ice cream mix takes up most of the time in the production of ice cream. This is due to the fat crystallisation which is important for the processing of the mix in the freezer. The influence of emulsifiers is investigated with regard to their degree of saturation and their hydrophilic-lipophilic balance using simple laboratory methods such as the determination of the free extractable fat and the emulsion stability. Saturated emulsifiers do not show any remarkable changes of the extractable fat and the emulsion stability during the ageing time. Saturated emulsifiers cause an increase of the extractable fat and a deterioration of the emulsion stability. These changes are especially obvious during the first three to six hours of ageing. The definite orientation of the protein-emulsifier membrane around the fat globules is only finished after twelve to twenty-four hours of ageing. This might explain the fact that in practice three hours of ageing are considered as absolutely necessary and that a longer ageing time causes a further improve of ice cream quality. 相似文献
89.
90.
Chemical engineering aspects and the chemical practicability of a vanadium/chlorine hydrogen-producing cycle were investigated on a laboratory scale. The most significant results are presented and discussed. The total process was balanced and optimized using the experimental results as the basis. The overall thermal efficiency was calculated to be 42.5% (see Part 1). 相似文献