Results 251 to 260 of about 544,173 (300)

Modification of Macromolecular Substances

2012
The term “modification of macromolecular substances” is used for chemical and physical processes that are carried out after the actual synthesis, i.e., on the finished macromolecule. Chemical modifications are, for example, the conversion of ester side groups to hydroxy groups, chemical degradation and crosslinking reactions. Physical modifications are
Dietrich Braun, Harald Cherdron, Matthias Rehahn, Helmut Ritter, Brigitte Voit   +4 more
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Imaging of Humic Substance Macromolecular Structures in Water and Soils

Science, 1999
Humic substances (HSs) are the natural organic polyelectrolytes formed from the biochemical weathering of plant and animal remains. Their macromolecular structure and chemistry determine their role in biogeochemical processes. In situ spectromicroscopic evidence showed that the HS macromolecular structures (size and shape) vary as a function of HS ...
, Myneni, , Brown, , Martinez, , Meyer-Ilse   +3 more
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The Crystalline State of Macromolecular Substances

Angewandte Chemie International Edition in English, 1974
AbstractUnlike low molecular weight substances, high polymers do not crystallize completely. However long the crystallization process is continued, they still consist of a mixture of crystalline and non crystalline regions. In the undrawn material, these regions form larger units which are known as spherulites.
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SORPTION AND CHROMATOGRAPHY OF MACROMOLECULAR SUBSTANCES

Russian Chemical Reviews, 1961
CONTENTS I. Introduction 612 II. Elution chromatography 613 III. Frontal chromatography 614 IV. New chromatographic methods 615 V. Polyelectrolytes 616 VI.
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Synthesis of Macromolecular Substances by Addition Polymerization

2001
As already explained, polymerization reactions can proceed by various mechanisms and can be catalyzed by initiators of different kinds. For addition polymerization of single compounds, initiation of chains may occur via radical, cationic, anionic, or so-called coordinative-acting initiators, but some monomers will not polymerize by more than one ...
Dietrich Braun, Harald Cherdron, Helmut Ritter   +2 more
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Chapter 49 Macromolecular substances and plastics

1975
Publisher Summary This chapter discusses macromolecular substances and plastics. In industry, gel permeation chromatography (GPC) serves as a method for characterizing and analyzing new polymeric products and for controlling the quality of standard products (Harmon).
M. Kubín, J. Čoupek
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A new phenomenon in flow birefringence of solutions of macromolecular substances

Journal of Polymer Science, 1953
AbstractMeasurements on flow birefringence of solutions of polyvinyl chloride in cyclohexanone revealed that the angle of orientation increases with decreasing concentration of the solution. That this surprising effect was not due to constructional or experimental errors was demonstrated by results obtained with polystyrene, which were in agreement ...
E. J. Arlman, W. Boog, D. J. Coumou
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Clearance of macromolecular and particulate substances from the cerebrospinal fluid system of the rat

Journal of Neurosurgery, 1979
✓ Arachnoid villi in the intracranial dural sinuses constitute the principal sites for absorption of proteins and particulates from the cerebrospinal fluid (CSF) system. Although arachnoid villi in the rat are morphologically less complex than those found in other mammals, their resistance to CSF outflow, as assessed by a graded series of constant flow
J D, Mann, A B, Butler, R N, Johnson, N H, Bass   +3 more
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Modes of Absorption of Macromolecular Substances

1995
When we speak about absorption of macromolecular substances we must take into consideration the barriers of the gastrointestinal tract which hinder their uptake and transportation into the lymphatics and the blood. These barriers can be differentiated into morphological and functional barriers.
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Macromolecular material (humic substance) in the water column and sediments

Marine Chemistry, 1992
Abstract The progress during the past 10–15 years in the studies of organic macromolecules (humic substances, HS) in seawater and sediments is reviewed. The review describes the advances in the characterization of seawater and sedimentary HS, HS formation models, studies on the geochemical role of marine HS, and future research needs.
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