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21.
Raman, UV and XRD studies have been performed to characterize the structures of differently prepared samples of poly(methyl-n-propylsilane). The results demonstrate polymorphism of this polymer between Tc and Tg. At room temperature the polymer can exist in up to four modifications which comprise one amorphous disordered phase and three more ordered modifications, differing in the interchain organization and in the silicon backbone conformations. The latter are considered to be deviant, transoid and all-anti, respectively. The number of the modifications present and relative amount of each strongly depends on the preparation method and thermal history of the sample as well as on the molecular weight. 相似文献
22.
Jeung Hee Lee Casimir C. Akoh Ki-Teak Lee 《Journal of the American Oil Chemists' Society》2008,85(1):1-11
Lipase-catalyzed interesterified solid fat was produced with fully hydrogenated soybean oil (FHSBO), and rapeseed oil (RSO)
and palm stearin (PS) in a weight ratio of 15:20:65, 15:40:45 and 15:50:35. The interesterified fats contained palmitic (27.8–44.6%),
stearic (15.6–16.2%), oleic (27.5–36.5%) and linoleic acids (8.0–13.5%). After interesterification of the blends, the physical
properties of the products changed and showed lower melting points and solid fat contents, different melting and crystallization
behaviors as well as the formation of more stable crystals. The produced interesterified fats (FHSBO:RSO:PS 15:20:65, 15:40:45
and 15:50:35 blends) contained desirable crystal polymorphism (β′ form) as determined by X-ray diffraction spectroscopy, a
long plastic range with solid fat content of 51–63% at 10 °C to 4–12% at 40 °C, and melting points of 39 (15:50:35), 42 (15:50:45)
and 45 °C (15:20:65). However, a reduction in tocopherols (α and γ) content and a reduced oxidative stability were observed
in the interesterified fats. The physical properties of the interesterifed fats were influenced by the amount of PS, resulting
in more hardness and higher solid fat contents for 15:20:65 than 15:40:45 and 15:50:35 blends. The present study suggested
that the produced interesterified fats containing trans-free fatty acids could be used as alternatives to hydrogenated types of bakery shortenings. 相似文献
23.
It was revealed that poly(octamethylene 2,6-naphthalate) (PON) existed in two different crystal structures, α- and β-form, depending on crystallization process: The α-form crystal was dominantly developed from the cold-crystallization, whereas the β-form was from the melt-crystallization. The apparent melting temperatures of α- and β-form crystals were characterized to be 175 and 183 °C, respectively. On the basis of X-ray diffraction and molecular modeling studies, the crystal structure of β-form, developed dominantly from the melt-crystallization, was identified to be triclinic with dimensions of a = 0.601 nm, b = 1.069 nm, c = 2.068 nm, α = 155.68°, β = 123.25°, γ = 52.85°, and with the space group of . The calculated crystal density was 1.243 g/cm3, supporting that one repeating unit of PON exists in a unit cell. The octamethylene units in the PON backbone take largely all-trans conformation in the β-form unit cell. 相似文献
24.
目的探讨表皮生长因子(EGF)G61A位点(EGF +61)多态性与慢性乙型肝炎肝细胞癌的相关性。方法运用多聚酶链式反应-限制性片段长度多态性(PCR-RFLP)技术,检测中国人群中215例慢性乙型肝炎肝细胞癌患者和104例正常对照者EGF+61位点的基因型,分析基因型及等位基因的分布频率。结果EGF +61位点基因型及等位基因在乙型肝炎肝细胞癌患者及对照者的分布频率差异均无统计学意义。TNMⅠ、Ⅱ及TNMⅢ、Ⅳ两组的基因型及等位基因的分布频率差异也无统计学意义。结论在中国人群中,EGF +61位点的基因多态性与乙型肝炎肝细胞癌的发生和进展程度无密切关系。 相似文献
25.
蓝雯飞 《数字社区&智能家居》2005,(33)
动态多态性提高了代码的可重用性和程序执行时的灵活性。本文详细讨论了C++语言对动态多态的支持机制,并结合例子说明了动态多态在程序设计中的应用。 相似文献
26.
程贤智 《数字社区&智能家居》2005,(36)
面向对象技术(OOT)是一种软件开发和程序设计技术,直接描述客观世界的对象及其相互关系。这篇文章对于面向对象技术的基本原理,分析,设计方法及其应用作了较全面较深入的论述,并附有图解,对于初学者了解这方面的知识有较好的帮助作用。 相似文献
27.
David MacQueen 《Formal Aspects of Computing》2002,13(3-5):214-232
At a fundamental level, functional and object-oriented programming languages are all ‘higher-order’, in the sense that they
support computing with values that are themselves pieces of program code encapsulated with a local environment. In functional
languages these ‘active’ values are functions, while in object-oriented languages they are objects. Both styles of higher-order
language claim to provide good support for writing adaptable programs, but functional and object-oriented languages achieve
this adaptability in different ways: functional programs rely on parameterisation at the value, type and module level, while
object-oriented languages rely primarily on subtyping and implementation inheritance. Here we compare these two approaches,
mainly in terms of the features and properties of their type systems, and consider the benefits and disadvantages of unifying
(or merging) the two paradigms by adding object-oriented features to ML as a base language. We argue that while some of the
simpler aspects of object-oriented languages are compatible with ML, adding a full- edged class-based object system to ML
leads to an excessively complex type system and relatively little expressive gain, especially if we aim to preserve that mostly
functional style of programming that is a major advantage of ML.
Received March 2002 / Accepted in revised form April 2002 相似文献
28.
Roberto Passerone Jerry R. Burch Alberto L. Sangiovanni-Vincentelli 《Formal Methods in System Design》2007,31(1):1-33
Embedded systems are electronic devices that function in the context of a real environment, by sensing and reacting to a set
of stimuli. Because of their close interaction with the environment, and to simplify their design, different parts of an embedded
system are best described using different notations and different techniques. In this case, we say that the system is heterogeneous. We informally refer to the notation and the rules that are used to specify and verify the elements of heterogeneous systems
and their collective behavior as a model of computation. In this paper, we consider different classes of relationships between models of computation and discuss their preservation
properties with respect to the model's refinement relation and composition operator. In particular, we focus on abstraction
and refinement relationships in the form of abstract interpretations and introduce the notion of conservative approximation. We show that, unlike abstract interpretations, conservative approximations preserve refinement verification results from
an abstract to a concrete model while avoiding false positives. We also characterize the relationship between abstract interpretations
and conservative approximations, and derive necessary and sufficient conditions to obtain a conservative approximation from
a pair of abstract interpretations. In addition, we use the inverse of a conservative approximation to identify components
that can be used indifferently in several models, thus enabling reuse across models of computation. The concepts described
in this paper are illustrated with examples from continuous time and discrete time models of computation. 相似文献
29.
The association between acyl-CoA synthetase (ACSL4) polymorphism and intramuscular fat content in (Landrace × Yorkshire) × Duroc pigs 总被引:1,自引:0,他引:1
Ruść A Sieczkowska H Krzęcio E Antosik K Zybert A Koćwin-Podsiadła M Kamiński S 《Meat science》2011,89(4):440-443
The aim of the study was to check whether different genotypes at acyl-CoA synthetase (ACSL4 locus, SNP G2645A) are associated with pork quality. 132 (Landrace × Yorkshire) × Duroc fatteners were genotyped by originally developed PCR-RFLP method. Upon the slaughter, the samples of longissimus lumborum muscle were taken from each carcass to determine the following parameters: content of water, protein and fat, pH (45 min, 24, 48, 96, and 144 h post mortem), electrical conductivity, drip loss, meat lightness, glycolytic potential, glycogen and lactate contents in meat. Among several associations observed, the highly significant (p<0.01) was found for intramuscular fat (IMF) content. Pigs with genotype GG revealed the highest content of IMF - 2.47%. 相似文献
30.
王军 《上海第二工业大学学报》2003,20(1):50-54
介绍了软件工程领域的技术同实际应用相结合的具体方法,面向对象技术是当今的主流软件开发方法,它具有封装性、继承性和多态性。文中讨论了面向对象技术的封装性和多态性在冷冲模CAD系统中的应用,分析他们在提高系统可扩充性、降低系统复杂度方面的作用,并举例分别加以说明。 相似文献