سبتمبر, 2018

 

العلاقة بين عدد الذرات أو الجزيئات و عدد المولات و عدد أفوجادرو

العلاقة بين عدد الذرات  أو الجزيئات و عدد المولات و عدد أفوجادرو (منهاج الكيمياء المستوى الأول – الكلية الجامعية بالجموم)

عدد أفوجادر هو عدد الذرات الموجوده في 12 جرامات من الكربون 12، و بالتالي اذا قسمنا وزن 12 جرامات من الكربون 12على وزن ذره الكربون نفسها ( تساوي تقريبا 1.99269×10-23 ) فإن عدد أفوجادرو الناتج هو 6.0221×2310، أي أن عدد أفوجادرو و الذي يرمز له بالرمز NA ، هو عدد الجزيئات…

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addition reaction

addition reaction or addition any organic chemical reaction involving the combination of two or more substances to form a single product in which there are more groups attached to carbon atoms than there were in the original reactants. Such reactions thus involve a net reduction of bond multiplicity in one of the reactants, as in the example:

H2C=CH2 + Br2 → H2BrC–CBrH2.

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active-enzyme centrifugation

active-enzyme centrifugation a technique for determining the sedimentation and diffusion coefficients of an enzyme– substrate complex. A thin lamella of an enzyme solution is layered onto a substrate solution in an ultracentrifuge cell and, on rotation, as the enzyme molecules sediment in a band through the substrate solution they catalyse the enzymic reaction, the progress of which is observed optically (e.g. by spectrophotometry). The required coefficients are then…

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activation

activation 1 the action or process of rendering an atom, molecule, or other substance reactive or more reactive, whether physicochemically, chemically, or biochemically. 2 the process of rendering material artificially radioactive: radioactivation. See radioactivation analysis. 3 the initial changes in an ovum during fertilization, covering the periodfrom first contact with a sperm to dissolution of the nuclear membranes. 4 the initial changes in the conversion of a spore…

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acyclovir

acyclovir or acycloguanosine 9-(2-hydroxyethoxymethyl)guanine; an antiviral agent widely used in the treatment of human herpes infections. It is selectively phosphorylated by herpesvirus-induced thymidine kinase and the phosphorylated compound is a potent inhibitor of herpesvirus-induced DNA polymerase. One proprietary name is Zovirax.

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activin

activin one of two gonadal glycoproteins related to transforming growth factor-b (the other is inhibin); present in two forms in human gonads, it exists as a dimer of inhibin bA or bB chains, linked by disulfide bonds. Activin A is a dimer of bA chains; activin AB is a dimer of bA and bB chains. A potent selective stimulator of FSH secretion by the anterior pituitary gland, not…

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active site

active site 1 the general region of an enzyme molecule containing the catalytic residues identified with the binding and reaction of substrate( s). It includes those amino-acid residues that are, in the enzyme– substrate complex, either contact amino acids, i.e. those that at some point are only one bond distance removed from some point of the substrate molecule, or auxiliary amino acids, i.e. those that are not in…

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actinoid

actinoid or actinide any member of the series of 15 metallic elements with proton numbers 89 (actinium) to 103 (lawrencium) inclusive that occur together in group 3 and period 7 of the IUPAC periodic table; sometimes the term is restricted to the 14 elements following actinium. Actinoid is now the preferred name. All actinoids are radioactive, and those of proton number 93 or greater are artificial. They are…

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لوحات (بوسترات) كيميائية (14) – تطور النظرية الذرية عبر التاريخ

لوحات (بوسترات) كيميائية لوحة (بوستر) تطور النظرية الذرية عبر التاريخ

لتحميل اللوحة بالحجم الكبير يرجى الضغط على الصورة بزر الماوس اليمين و اختار حفظ باسم.

chemistry posters

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actinin

actinin a minor protein constituent of muscle, found to be concentrated in both the Z line and the I band. Two components of actinin have been identified: a-actinin, F-actin cross-linking protein, a dimer of ∼200 kDa with an action similar to that of actinogelin.; and b-actinin, a dimer of ∼70 kDa, similar in action to gelsolin.

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