منابع مشابه
Divergence of sun-rays by atmospheric refraction
Introduction Conclusions References Tables Figures Back Close Abstract Introduction Conclusions References Tables Figures Back Close Abstract For the determination of photolysis rates at large zenith angles it has been demonstrated that refraction by the earth's atmosphere must be taken into account. In fact, due to the modified optical path the optical transmittance is thereby increased in mos...
متن کاملAn Overview of Technological Developments in Medical Applications of X-Rays and Radioactivity
The years 1895 to 1898 were momentous for their impact on health and human well beings. First, Wilhelm Roentgen noted a glowing fluorescent screen, caused by invisible rays. This event subsequently led to the discovery of X-rays in 1895, and thus the birth of the “atomic ageâ€. Next Becquerel’s investigations of these mysterious rays led to his experiments with uranium salt crystals. He th...
متن کاملApplication of characteristic X-rays to measure linear attenuation coefficient of nano-composites used in shielding
Using of X-rays in different industries and especially in medical application is increasing. In this regard, designing of light and efficient protective material based on polymeric nanocomposites and precise study of the effect of adding nanoparticles with different sizes on the X-ray attenuation is necessary. In this study the epoxy nanocomposites with different percentages of copper oxide nan...
متن کاملDiagnostic Utility of Chest X-rays in Neonatal Respiratory Distress: Determining the Sensitivity and Specificity
Background: Chest radiography is one of the most usual diagnostic tools for respiratory distress. Objective: The purpose of this study is to assess the specificity, sensitivity and clinical value of chest radiography of neonates with respiratory distress.Patients and Methods: A descriptive- analytical study was conducted on 102 neonates that were in neonatal intensive care unit of Imam Reza and...
متن کاملSubject headings: galaxies: general—galaxies: spiral—X-rays: general—X-rays: galaxies—X-rays: ISM
We present results from the analysis of deep ROSAT HRI and PSPC observations of the spiral galaxy M81. The inferred total (0.5–2 keV band) luminosity of M81 is ∼ 3×10 ergs s, excluding the contribution from identified interlopers found within the D25 ellipse. The nucleus of the galaxy alone accounts for about 65% of this luminosity. The rest is due to 26 other X-ray sources (contributing ∼ 10%)...
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ژورنال
عنوان ژورنال: Proceedings of the National Academy of Sciences
سال: 1924
ISSN: 0027-8424,1091-6490
DOI: 10.1073/pnas.10.2.60