Occurrence general distribution

Chemistry. For both softwoods and hardwoods, the interpretation of general trends in changing wood chemistry along the tree radius is complicated by the potential occurrence and distribution of reaction wood. Nevertheless, hardwoods show relatively little change in cellulose or lignin contents from pith to bark and from tree base to top (2). However, softwoods have tree cores that are about 3-20% lower in cellulose and up to several percent higher in lignin content (probably due at least in part to the presenc e of cx)mpression wood) (2). 

Sustainable information (e.g. industrial application, occurrence in the environment) about the contaminants which were chosen for quantification are summarised in part I of our study. The quantitative data of the first sample set (taken in August 1999) are shown in Table 2. In order to register temporal changes and/or general distribution pattern, the selected compounds were also quantified in the other water samples sets (Tables 3 to 5). 

Our knowledge of the occurrence and distribution of alkaloids in this family is generally based on (i) traditional isolation and structure elucidation procedures and (ii) different chromatographic methods, predominantly TLC. 

Nature In monitoring a moving threadhne, one criterion of quality would be the frequency of broken filaments. These can be identified as they occur through the threadhne by a broken-filament detector mounted adjacent to the threadhne. In this context, the random occurrences of broken filaments can be modeled by the Poisson distribution. This is called a Poisson process and corresponds to a probabilistic description of the frequency of defects or, in general, what are called arrivals at points on a continuous line or in time. Other examples include ... 

The four isotopes, as those of any element, have the same chemical properties. The four are not, however, uniformly distributed in the earth s crust the occurrence of three of them, in minerals and rocks, is associated with the radioactive decay of isotopes of thorium and uranium. In most minerals and rocks the relative amounts (or the isotopic ratios) of the isotopes of lead (often expressed relative to the amount of stable lead-204) are generally within well-known ranges, which are independent of the composition of the mineral or rock they are, however, directly related to the amounts of radioactive thorium and uranium isotope impurities in them. 

A detailed discussion of the modes of occurrence and biological importance of the polynucleotides is outside the scope of this article. However, in examining the structures of polynucleotides, it is necessary to take into consideration the origins of the materials studied. The pioneer researches of Caspersson114 indicated that deoxyribonucleic acids are present exclusively in the nucleus, whereas ribonucleic acids are found chiefly in the cytoplasm and only to a small extent in the nucleus. This general outline of the distribution of nucleic acids within the cell has been confirmed and extended by more recent work,116 and it has been possible to isolate both types of nucleic acid from different cellular fractions of the same tissue.116... 

In general, each form of ideal flow can be characterized exactly mathematically, as can the consequences of its occurrence in a chemical reactor (some of these are explored in Chapter 2). This is in contrast to nonideal flow, a feature which presents one of the major difficulties in assessing the design and performance of actual reactors, particularly in scale-up from small experimental reactors. This assessment, however, may be helped by statistical approaches, such as provided by residence-time distributions. It... 

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