Historical survey

The epoch of QSAR (Quantitative Structure-Activity Relationships) studies began in 1963-1964 with two seminal approaches the a-p-7i analysis of Hansch and Fujita and the Free-Wilson method. The former approach involves three types of descriptors related to electronic, steric and hydrophobic characteristics of substituents, whereas the latter considers the substituents themselves as descriptors. Both approaches are confined to strictly congeneric series of compounds. The Free Wilson method additionally requires all types of substituents to be suflficiently present in the training set. A combination of these two approaches has led to QSAR models involving indicator variables, which indicate the presence of some structural fragments in molecules. 

Methodologies based on fragment descriptors in QSAR/QSPR studies are not strictly confined to particular types of properties or compounds. In the 1970s Adamson and coworkers were the first to apply fragment descriptors in multiple linear regression analysis to find correlations with some biological activities,physicochemical properties, and reactivity.  

Starting in the early 1990s, various approaches and related software tools based on fragment descriptors have been developed and are listed in several conceptual and mini-review papers. Because of the wide scope and large variety of different approaches and applications in this field, many important 

The Hofmann and Emde degradations led to many interesting transformations, none of which, however, helped to shed light on the structural problem. 

The discovery of elemental (white) phosphorus was soon followed by the characterisation of its combustion product, phosphorus pentoxide, and in 1694, R. Boyle prepared phosphoric acid by dissolving the latter in water. Phosphorus was found in plants by B. Albino in 1688, and the element was detected in human brain tissue by J.T. Hensing in 1719. 

About 1770 phosphorus was recognised as an essential ingredient of animal bones and teeth by C.W. Scheele, when he prepared the element from bone ash, carbon and sand. By 1779 the first phosphorus-containing mineral, Pyromorphite, had been identified by J.G. Gahn. 

Phosphorus penta sulphide was discovered by Berzelius in 1843 and the red allotrope of phosphorus was prepared by Von Schrotter in 1848. 

The first successful phosphorus-containing striking matches were invented by Sauria in 1831, and the use of the element in match compositions was introduced in England and France abont 1838. Phosphorus sesquisulphide, discovered by Letnoine in 1864, eventually replaced the toxic white form of the element. Safety matches incorporating red phosphorus were introduced by Sevene and Cahen in 1898. Self-igniting sea flares incorporating calcium phosphide were patented by Holmes and Player in 1876. 

During the eighteenth and nineteenth centuries, phosphorus (usually in the white elanental form) was misguidedly introduced into medical treatments moreover, its industrial uses also led to many fatalities as, for example, amongst match workers. 

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These brief examples of developments in semiconductor technology and optoelectronics are offered to give the flavour of recent semiconductor research. An accessible technical account of MBE and its triumphs can be found in an overview by Cho (1995), while a more impressionistic but very vivid account of Capasso and his researches at Bell Labs is in a popular book by Amato (1997). A very extensive historical survey of the enormous advances in optical and optoelectronic physics , with attention to the materials involved, is in a book chapter by Brown and Pike (1995). 

The concept of chemical periodicity is central to the study of inorganic chemistry. No other generalization rivals the periodic table of the elements in its ability to systematize and rationalize known chemical facts or to predict new ones and suggest fruitful areas for further study. Chemical periodicity and the periodic table now find their natural interpretation in the detailed electronic structure of the atom indeed, they played a major role at the turn of the century in elucidating the mysterious phenomena of radioactivity and the quantum effects which led ultimately to Bohr s theory of the hydrogen atom. Because of this central position it is perhaps not surprising that innumerable articles and books have been written on the subject since the seminal papers by Mendeleev in 1869, and some 700 forms of the periodic table (classified into 146 different types or subtypes) have been proposed. A brief historical survey of these developments is summarized in the Panel opposite. 

Gibbs-Smith, C. FI. (197U). Aviation An Historical Survey. London HMSO. 

Chapter 10 covers another important field with a great overlap with CA neural networks. Beginning with a short historical survey of what is really an independent field, chapter 10 discusses the Hopfield model, stochastic nets, Boltzman machines, and multi-layered perceptrons. 

H. Schubert, ChemZtg 97 (9), 486—92 (1973) CA 80,28964 (1974) A brief historical survey of solid rocket proplnts is followed by a description of solid propint motors and of the uses of the proplnts. The compn and the process technology of two fundamentally different types of proplnts, ie, homogeneous or double-base solid proplnts and heterogeneous or composite solid proplnts, are described. Their properties are reviewed... 

Asmussen, E. (1971). Muscle metabolism during exercise in man A historical survey. In Muscle Metabolism During Exercise (Pemow, B. Saltin, B., eds.), pp. 1-12. Plenum Press, New York. 

Qualitative and quantitative relations between enthalpy and entropy were observed several times in the 1920 s, and their importance was rightly recognized by some authors. However, some ideas from this early work seem to have been overlooked later, perhaps because they were connected with obsolete theories or because they were developed independently in the fields of organic chemistry, catalysis, and pure physical chemistry. For this reason, a brief historical survey seems appropriate. 

The study of China s alchemical tradition can provide considerable insight into early Chinese medical theory, pharmaco-therapeutic practice and psychosomatic concepts. Chinese alchemy is a complex blending of philosophical, cosmological, physiological and natural scientific thought. This article presents a historical survey and analysis of some important aspects of Chinese alchemical research and theory"... 

Science and civilisation in China. Volume 5. Chemistry and chemical technology. Part HI Spagyrical discovery and invention Historical survey, from cinnebar elixirs to synthetic insulin, by Joseph Needham, Ho Ping-Yu, Lu Gwei-Djen and Nathan Sivin. Cambridge Cambridge Univ P, 1976. 

The Bibliotheca Philosophica Hermetica and a historical survey of Hermeticism (including an interesting map of the spread of the Corpus Hermeticum). Describes the main subject areas covered by the library (including alchemy)... 

Bowler, Peter J. and Iwan Rhys Morns. Making modern science a historical survey. Chicago (IL) Univ of Chicago P, 2005. 537p. ISBN 0-226-06860-9... 

Sinclair, S.P. Review of The science of matter an historical survey selected readings, by Maurice P. Crosland. In Ambix 19 219.. ... 

The above results mainly apply to the Longuet-Higgins E x e problem, but this historical survey would be incomplete without reference to early work on the much more challenging problems posed by threefold or higher electronic degeneracies in molecules with tetrahedral or octahedral symmetry [3]. For example, tetrahedral species, with electronic symmetry T or T2, have at least five Jahn-Teller active vibrations belonging to the representations E and T with individual coordinates (Qa,Qb) and (Qx. Qx. Q ) say. The linear terms in the nine Hamiltonian matrix elements were shown in 1957 [3] to be... 

Historical Survey of Fire and Explosions in the Hydrocarbon Industries... 

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