Structuring, definition

The only structures definitely established are those obtained from X-ray measurements. Some of these are shown in Table 30, from which a large number of aromatic pyrazole geometries can be found. 

Both compd types are listed under Nitroimines by Beil and are so presented here. Perhaps this method of presentation is because of the lack of a nitrimine structural definition... 

Humic substances in sediments and soils have commonly been, defined as heteropolycondensates of decomposing plant and animal detritus 46. For lack of a better structural definition, these macromolecular substances have been divided into three categories fulvic acids and humic acid and humin. Fulvic acids and humic acids are soluble in dilute alkaline solutions, whereas humin is insoluble. 

Homogeneous catalysts are very often known as examples of single-site catalysts characterized by complete structural definition and (presumably) complete knowledge of the chemical processes occurring at their catalytic centers. It is a matter of fact that the homogeneous catalysts are molecular complexes constituted by an active core containing a single active atom (of-... 

Thiosemicarbazone (RNH-CS-NH-N=CR/R//, tsc) complexes of cobalt(III) have been extensively studied since the early 1980s and continue to attract attention, gaining particularly from an interest in their biological activity and potential cytotoxicity. A truly extensive range of tsc compounds has now been reported, although structural definition of their complexes widely relied on basic analytical and spectroscopic techniques up to the late 1980s, when X-ray crystal structural studies of tsc compounds became more common. A review of thiosemicarbazone and S-alkyldithiocarbazate complexes has appeared.1053... 

The network is composed by locations and transportation lanes between these locations consistent to supply network structure definitions e.g. in... 

The use of d- and L-prefixes is a nomenclature for orientation of atomic structure of sugar and amino acid molecules. It is a structural definition and is not related to the optical properties. 

While the results of this work are encouraging, it is clear that the structural definition of mutant proteins of this type is critical to development of rational interpretation of the results if for no other reason than that the structural perturbation introduced is presumably greater than for simple point mutations. Moreover, it would be particularly interesting to compare the functional properties of mutants compared in this manner in assays involving protein-protein reactions relevant to the species of cytochrome c on which the mutagenesis is based. For example, comparison of the activities of wild-type yeast cytochrome c with that of a loop-insertion mutant modelled on a photosynthetic cytochrome c in the reaction with the photosynthetic reaction center could help define the structural elements involved in the cytochrome c binding domain for the reaction center. 

The catalytically active species 31 was isolated and its structure definitively determined using X-ray analysis. The complex 31 was seen to be quite stable below 70 °C under an argon atmosphere at pH 2.0-6.0 and in the absence of any reducible carbonyl compounds [50]. When the reducing ability of isolated 31 in acidic media was examined, the catalytic reactions using cyclohexanone and acetophenone (31 ketones HCOOH = 1 200 1000) yielded the corresponding alcohols quantitatively in 2h at pH2.0 at 70°C (Scheme 5.17). 

Ishov, A.M., Stenberg, R.M., and Maui, G.G. (1997) Human cytomegalovirus immediate early interaction with host nuclear structures definition of an immediate transcript environment. J. Cell. Biol. 14 138(1), 5-16. 

We do not yet know the structure of any of the metal clusters in the FeMo or FeV proteins. Nor do we know the arrangement of these clusters in the proteins. However, even with structural definition, which is in progress( -82), we will have to continue to apply the most powerful tools of physical bioinorganic chemistry to determine how hydrogen and substrates are handled by this remarkable enzyme. 

At this point we have mainly considered recognition in terms of rules that apply across any target with defined geometry. Next, we consider how they can be derived within target families and how under these conditions it is possible to use the consistency within families to derive rules for the binding of fragments from experimental data even where structural definition is imprecise. 

Lipids are naturally occurring organic molecules, isolated from animal or plant cells by extraction with nonpolar organic solvents. This definition defines lipids in terms of a physical property (solubility) and differs from structural definitions used for proteins or carbohydrates. Not surprisingly, lipids are highly varied in their structure from the medicinal chemistry perspective, there are five classes of lipids ... 

Let (A, A) be a principally polarized abelian variety of dimension g. In this article a r<)(p)-level structure on (A, A) is a flag of subgroup schemes 0 C Hi C Hg C A p] such that the order of Hi is p and such that Hg is totally isotropic for the Weil-pairing induced by A on A[p. We let S(g,p) be the algebraic stack over Spec(Z) parametrizing principally polarized abelian varieties endowed with a Fo(p)-level structure (Definition 1.1). 

J. B. Casey, W. J. Evans, W. H. PoweU, and T. E. Sloan, "A Structural Definitive Descriptor and Numbering System for Cluster Compound Nomenclature," Chemical Abstract Service, presented at the 198th National Meeting of the American Chemical Society, Miami Beach, FI., Sept. 1989. 

In contrast to outer-sphere reactions, the simple observation that a reaction occurs by an inner-sphere mechanism necessarily introduces an element of structural definition. The relative dispositions of the oxidizing and reducing agents are immediately established and, except for structurally flexible bridging ligands such as NC5H4(CH2) C5H4N, the internuclear separation between redox sites can be inferred from known bond distances. Even so, bimolecular inner-sphere reactions necessarily occur by a sequence of elementary steps (Scheme 2) and the observed rate constant may include contributions from any of the series of steps. 

Although such ratios have proved to be valuable, the whole approach to structure definition through their use is still a relative one. A large volume of standard data is required to set up the appropriate intensity ratio and to prescribe its bounds. To realize our goal of using mass spectrometry as a more absolute structure determining probe, we must deter-... 

The heart of this volume consists of three chapters summarizing work on catalysts that are both industrially applied and structurally well-defined the structural definition has allowed rapid progress in the development of relationships between structure and catalytic properties. 

There is some arbitrariness in the definition of the ion pair, and hence the association constant. Often a structural definition of the ion pairs is preferred—for example, by adopting a cutoff distance such as rc = 2a [141, 207] or similar choices [208, 209]. In contrast, Bjerrum (Bj) theory [140] uses an energetic criterion by defining ions as being associated, when their interaction energy is twice the thermal energy kBT. Bjerrum theory yields... 

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