نتایج جستجو برای: substances
تعداد نتایج: 56173 فیلتر نتایج به سال:
Humic substances are highly abundant organic compounds formed in soils and sediments by the decay of dead plants, microbes and animals. This book focuses on the important binding properties of these compounds that regulate the chemical reactivity and bioavailability of hydrogen andmetal ions in the natural environment. Topics covered include the physico-chemical properties of humic matter and i...
Amphetamine-group substances are used worldwide and are more prevalent than either cocaine or opioids. We reviewed published reports about amphetamine-group substances and did a meta-analysis of randomised controlled trials of behavioural interventions for their use. Most research was done in developed countries. Many, but not all, studies show an association between amphetamine-group substance...
Timber is a sustainable, economical, completely renewable, CO2-neutral organic material, which requires less energy to process than other construction materials. Wood is also a strong, aesthetically pleasing, and very durable material when properly maintained and used. However, under certain conditions of exposure or use — particularly when it becomes wet — wood may be rapidly decomposed due to...
Dynamic nuclear polarization has enabled hyperpolarization of nuclei such as 13C and 15N in endogenous substances. The resulting high nuclear polarization makes it possible to perform subsecond 13C MRI. By using the dynamic nuclear polarization hyperpolarization technique, 10% polarization was obtained in an aqueous solution of 100 mM 13C-labeled urea, ready for injection. The in vivo T1 relaxa...
Humic substances (HS) which are widespread in the soil, present structural complexity and polyelectrolyte properties. Many techniques and methods have been used to obtain more information about them, as reviewed by Davies and Ghabbour in 1999. The characterization of HS has been the focus of intense research for many years because the organic matter in soil contributes to the quality of the soi...
The law of toxic substances dates back to Medieval England, but the present comprehensive federal regulatory scheme was developed over the past two decades. This article presents a brief overview of the federal law of air and water pollution, solid waste control, and the regulation of chemicals.
Interest is arising in the possible use of higher plants as the source of naturally occurring antibiotic substances. The use of higher plants in the treatment of disease is as old as the art of healing itself. Isaiah of Biblical times suggested that a plaster of figs be placed on boils as a treatment of this form of infection. Hyssop and cedarwood were used in the cleansing of lepers. The Orien...
In the study of bacterial symbiosis and antagonism, considerable interest has centered in the presence or absence of growth when organisms are reinoculated into filtrates of cultures of the same or different species. The nature of the substances which favor or inhibit the simultaneous or subsequent development of bacteria in the same nutritive medium has provoked much discussion and stimulated ...
Performance-enhancing substances (PESs) are used commonly by children and adolescents in attempts to improve athletic performance. More recent data reveal that these same substances often are used for appearance-related reasons as well. PESs include both legal over-the-counter dietary supplements and illicit pharmacologic agents. This report reviews the current epidemiology of PES use in the pe...
The fate and behavior of estrogenic substances in various biological wastewater treatment processes and several advanced sewage treatment processes were examined. The removal of 17beta-estradiol (E2), estrone (E1) and estriol (E3) was investigated by using a pilot-scale activated sludge plant supplied with domestic sewage. Several sewage treatment plants adopting the activated sludge process we...
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