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4 天前 · e. The Oxford–AstraZeneca COVID‑19 vaccine, sold under the brand names Covishield [31] and Vaxzevria [1] [32] among others, is a viral vector vaccine for the prevention of COVID-19. It was developed in the United Kingdom by Oxford University and British-Swedish company AstraZeneca, [33] [34] [35] using as a vector the modified chimpanzee ...
3 天前 · Oxytocin is a peptide hormone and neuropeptide normally produced in the hypothalamus and released by the posterior pituitary.[4] Present in animals since early stages of evolution, in humans it plays roles in behavior that include social bonding, love, reproduction, childbirth, and the period after childbirth.[5][6][7][8] Oxytocin is released ...
3 天前 · In a DNA double helix, each type of nucleobase on one strand bonds with just one type of nucleobase on the other strand. This is called complementary base pairing.Purines form hydrogen bonds to pyrimidines, with adenine bonding only to thymine in two hydrogen bonds, and cytosine bonding only to guanine in three hydrogen bonds. . This arrangement of two nucleotides binding together across the ...
2 天前 · The first set of data on the left columns of the table includes estimates for the year 2023 made for each economy of the 196 economies (189 U.N. member states and 7 areas of Aruba, Hong Kong, Kosovo, Macau, Palestine, Puerto Rico, and Taiwan) covered by the International Monetary Fund (IMF)'s International Financial Statistics (IFS) database.
5 天前 · Poliomyelitis (/ ˌ p oʊ l i oʊ ˌ m aɪ ə ˈ l aɪ t ɪ s / POH-lee-oh-MY-ə-LY-tiss), commonly shortened to polio, is an infectious disease caused by the poliovirus. Approximately 75% of cases are asymptomatic; mild symptoms which can occur include sore throat and fever; in a proportion of cases more severe symptoms develop such as headache, neck stiffness, and paresthesia.
5 天前 · The number π (/ p aɪ /; spelled out as "pi") is a mathematical constant that is the ratio of a circle's circumference to its diameter, approximately equal to 3.14159.The number π appears in many formulae across mathematics and physics.It is an irrational number, meaning that it cannot be expressed exactly as a ratio of two integers, although fractions such as are commonly used to ...
3 天前 · Silicon is a chemical element; it has symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic table: carbon is above it; and germanium, tin, lead, and flerovium are below it. It is relatively unreactive ...
