WordNet

stated explicitly or in detail; "needed a specific amount"
a medicine that has a mitigating effect on a specific disease; "quinine is a specific for malaria"
(sometimes followed by `to'
being or affecting a disease produced by a particular microorganism or condition; used also of stains or dyes used in making microscope slides; "quinine is highly specific for malaria"; "a specific remedy"; "a specific stain is one having a specific affinity for particular structural elements"
relating to or distinguishing or constituting a taxonomic species; "specific characters"

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《名詞の前にのみ用いて》『特定の』,一定の・『明確な』,明白な・(そのものに)『特有の』,独特の《+『to』+『名』》・〈C〉(…の)特効薬《+『for』+『名』》・《複数形で》明細,細部(details)
放射能;放射性

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/01/01 11:33:25」(JST)

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This article is about specific activity radioactivity. For the use in biochemistry, see Enzyme assay#Specific activity.

In nuclear sciences and technologies, "activity" is the SI quantity related to the phenomenon of natural and artificial radioactivity. The SI unit of "activity" is becquerel, Bq, while that of "specific activity" is Bq/kg. The old unit of "activity" was curie, Ci, while that of "specific activity" was Ci/g. For its use in radiochemistry, see radioactivity.

One can use the experimentally measured specific activity to calculate the half-life of an element.

Starting from the definition of the half-life (T_1/2) - with, N₀, atoms of an element, the number of atoms, N, remaining after time, t, is giving by:

Take the natural log of both sides:

Take the derivative with respect to time, t:

Multiply both sides by N:

Which is:

dN/dt represents the decay rate of atoms. The negative sign shows that the rate is negative, so the number of atoms is decreasing with time as you would expect. Rearranging terms:

Example: determine the half-life of Rb-87

Suppose you have a gram of rubidium-87 and with your Geiger counter, you get a count rate which, after taking solid angle effects into account, is consistent with a decay rate of 3200 decays per second; this would correspond to a specific activity of 3.2×10⁶ Bq/kg. The atomic weight is of the rubidium is 87, so one gram is one 87th of a mole, or N=6.9×10²¹ atoms. Plugging in the numbers:

Formulation[edit]

First, radioactivity is expressed as the decay rate of a particular radionuclide with decay constant λ and the number of atoms N:

Next, mass of the radionuclide is given by

where m is mass number of the radionuclide and N_A is Avogadro constant.

Specific radioactivity S is defined as radioactivity per unit mass of the radionuclide:

In addition, decay constant λ is related to the half-life T_1/2 by the following equation:

Thus, specific radioactivity can also be described by

This equation is simplified by

When the unit of half-life converts a year

For example, specific radioactivity of radium 226 with a half-life of 1600 years is obtained by

This value derived from radium 226 was defined as unit of radioactivity known as Curie (Ci)

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Clinical pharmacokinetics of tyrosine kinase inhibitors: focus on pyrimidines, pyridines and pyrroles.

Di Gion P, Kanefendt F, Lindauer A, Scheffler M, Doroshyenko O, Fuhr U, Wolf J, Jaehde U.SourceClinical Pharmacology Unit, Department of Pharmacology, University Hospital, University of Cologne, Cologne, Germany.
Clinical pharmacokinetics.Clin Pharmacokinet.2011 Sep 1;50(9):551-603. doi: 10.2165/11593320-000000000-00000.
Pyrimidine (imatinib, dasatinib, nilotinib and pazopanib), pyridine (sorafenib) and pyrrole (sunitinib) tyrosine kinase inhibitors (TKIs) are multi-targeted TKIs with high activity towards several families of receptor and non-receptor tyrosine kinases involved in angiogenesis, tumour growth and meta
PMID 21827214

Investigating incorporation and distribution of radionuclides in trinitite.

Belloni F, Himbert J, Marzocchi O, Romanello V.SourceEuropean Commission, Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, 76125 Karlsruhe, Germany. fabio.belloni@ec.europa.eu
Journal of environmental radioactivity.J Environ Radioact.2011 Sep;102(9):852-62. Epub 2011 Jun 1.
Most of the surface explosions in nuclear tests have released radioactivity to the environment in the form of bulk glassy materials originating from the melting of sandy soil in the neighbourhood of ground zero. In view of clarifying issues concerning the mechanism of formation and the radiological
PMID 21636184

Japanese Journal

1-(3′-[125I]Iodophenyl)-3-methy-2-pyrazolin-5-one: Preparation, Solution Stability, and Biodistribution in Normal Mice

Sano Yuuhei,Motomura Tomokazu,Yamamoto Fumihiko,Fukuda Miki,Mukai Takahiro,Maeda Minoru
CHEMICAL & PHARMACEUTICAL BULLETIN 58(8), 1020-1025, 2010
… The former gave specific activities of 0.2—0.6 kBq/μmol, whereas the latter approach achieved specific activities of more than 0.14 GBq/μmol. … On attempting to prepare an injectable formulation for 125I-2 with high specific activity, its radiochemical purities dropped to about 60—70%. …
NAID 130000299808

Implementation of the NCRP Wound Model for Interpretation of Bioassay Data for Intake of Radionuclides Through Contaminated Wounds

ISHIGURE Nobuhito
Journal of radiation research 50(3), 267-276, 2009-05-16
… The NCRP wound model was linked to the current ICRP systemic model at each blood compartment and simultaneous differential equations for the content of radioactivity in each compartment and excreta were solved with the Runge-Kutta method. … The results of the calculation of wound, whole-body or specific organ retention and daily urinary or faecal excretion rate of some selected elements will be useful for the interpretation of bioassay data and dose assessment for cases of wound contamination. …
NAID 10025911903