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Many electrophiles are chiral and optically stable. Typically chiral electrophiles are also optically pure. One such reagent is the fructose-derived organocatalyst used in the Shi epoxidation. [11] The catalyst can accomplish highly enantioselective epoxidations of trans-disubstituted and trisubstituted alkenes.
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Penile-vaginal intercourse or vaginal intercourse is a form of penetrative sexual intercourse in human sexuality, in which an erect penis is inserted into a vagina. [1] Synonyms are: vaginal sex, cohabitation, coitus (Latin: coitus per vaginam), (in elegant colloquial language) intimacy, or (poetic) lovemaking.
A nitrogen bound to both a good electrofuge and a good nucleofuge is known as a nitrenoid (for its resemblance to a nitrene). [2] Nitrenes lack a full octet of electrons are thus highly electrophilic; nitrenoids exhibit analogous behavior and are often good substrates for electrophilic amination reactions.
The Human Cell Atlas project, which started in 2016, had as one of its goals to "catalog all cell types (for example, immune cells or brain cells) and sub-types in the human body". [13] By 2018, the Human Cell Atlas description based the project on the assumption that "our characterization of the hundreds of types and subtypes of cells in the ...
The present scientific definition took form in the 1970s, when an increasing number of researchers began to measure the magnetic fields produced by the human body. The first valid measurement was actually made in 1963, [ 1 ] but the field of research began to expand only after a low-noise technique was developed in 1970. [ 2 ]
The thrill of raw power, the brutal ecstasy of life on the edge. “It was,” said Nick, “the worst, best experience of my life.” But the boy’s death haunts him, mired in the swamp of moral confusion and contradiction so familiar to returning veterans of the wars in Iraq and Afghanistan.
Among the many-celled groups are animals and plants. The number of cells in these groups vary with species; it has been estimated that the human body contains around 37 trillion (3.72×10 13) cells, [7] and more recent studies put this number at around 30 trillion (~36 trillion cells in the male, ~28 trillion in the female). [8]