نتایج جستجو برای: ultraviolet rays
تعداد نتایج: 79452 فیلتر نتایج به سال:
BACKGROUND First-degree relatives of melanoma survivors have a substantially higher lifetime risk for melanoma than individuals with no family history. Exposure to ultraviolet radiation (UVR) is the primary modifiable risk factor for the disease. Reducing UV exposure through sun protection may be particularly important for children with a parental history of melanoma. Nonetheless, limited prior...
A convenient protocol has been developed to fabricate one-dimensional nanostructures of a photochromic molecule cis-l,2-dicyano-l,2-bis(2,4,5-trimethyl-3-thieny1)ethene (CMTE). Light-induced self-assembled nanorods and nanowires of the colored form were obtained in situ under UV light irradiation in aqueous dispersion and redissolved under green light. Reversible and fatigue-resistant optical s...
To determine the aetiology of spheroidal degeneration of the cornea (Labrador keratopathy), total population surveys were conducted in 5 communities in coastal Labrador and northern Newfoundland. For 4 years records were also kept on all clinic patients aged 40 or more throughout the region. Both methods gave a peak prevalence at latitudes 55 degrees--56 degrees north. The greatest severity and...
Two experiments demonstrated the pigeon's sensitivity to ultraviolet light. In Experiment I, pigeons' responses were reinforced on a multiple schedule with a variable-interval reinforcement schedule in one component and extinction in the other component. Response rates were quite different in the two components where the 520-nm stimuli signalling each component differed only in that one of them...
In a recent paper' it was shown that the electrons could presumably travel through N2 and H2 gases!in a free state at atmospheric pressure. It was found in some cases impossible to evaluate the mobilities of these electrons with the low frequencies of commutation available. The values of the mobilities indicated by these results appeared to be so much higher than the values obtained by earlier ...
The optical properties of the inflorescence of the high-altitude Leontopodium nivale subsp. alpinum (edelweiss) is investigated, in relation with its submicrometer structure, as determined by scanning electron microscopy. The filaments forming the hair layer have been found to exhibit an internal structure which may be one of the few examples of a photonic structure found in a plant. Measuremen...
The temporary increase in the electrical surface conductivity of low-k organosilicate glass (SiCOH) during exposure to vacuum-ultraviolet radiation (VUV) is investigated. To measure the photoconductivity, patterned " comb structures " are deposited on dielectric films and exposed to synchrotron radiation in the range of 8–25 eV, which is in the energy range of most plasma vacuum-ultraviolet rad...
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