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921.
Alois W. Schmalwieser Veronika T. Schmalwieser Susanne S. Schmalwieser 《Photochemistry and photobiology》2019,95(4):1068-1075
Clothing is one of the main influencing factors for personal ultraviolet radiation (UVR) exposure. Despite that, little attention was put on this topic till now. In this study, the clothing habits of young females have been investigated in dependence of meteorological conditions. Observations were made from spring to autumn during daylight in the urban region of Vienna, Austria. For this, a scheme dividing the body into six different sections was developed as well as a coding scale that corresponds to the different garments and indicates the body sites that are exposed. It was found that air temperature is the dominating factor for exposure. With increasing temperature, the first area of the body to be exposed to solar UVR is, aside from face and hands, the décolleté, followed by nape, ankles, instep and forearms. Observations further indicate that the frequency of people's being outdoors decreases significantly at temperatures higher than 30°C. This paper provides detailed frequency distributions of uncovered body sites in dependence of temperature. These can be used together with measurements of temperature and UVR to calculate the relative exposure at any time and at many locations, and could help to explain the body distribution of UVR caused skin alterations. 相似文献
922.
The synthesis of new 2-(pyrrolidine-3-yl)acetic acid derivatives as cyclic γ-aminobutyric acid analogues, which are additionally substituted at the 4-position, is reported. A de Mayo reaction, i.e. a combination of an intermolecular [2+2]-photocycloaddition of 1,3-dioxinones with N-protected 3-pyrroline and a fragmentation reaction of the resulting cyclobutane moiety, represent the key steps. 相似文献
923.
Dr. Bin Li Dr. Susanne Bauer Dr. Michael Seidl Prof. Dr. Alexey Y. Timoshkin Prof. Dr. Manfred Scheer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(60):13714-13718
The pnictogenyl Group 13 compounds (Dipp2Nacnac)M[E(SiMe3)2]Cl and (Dipp2Nacnac)M(EH2)2 (Dipp2Nacnac=HC[C(Me)N(Ar)]2, Ar: Dipp=2,6-iPr2C6H3; M=Al, Ga, In; E=P, As) were successfully synthesized. The salt metathesis between (Dipp2Nacnac)MCl2 and LiE(SiMe3)2 only led to monosubstituted compounds (Dipp2Nacnac)M[E(SiMe3)2]Cl [E=P, M=Ga( 1 ), In ( 2 ); E=As, M=Ga ( 3 ), In ( 4 )], regardless of the stoichiometric ratios used. In contrast to the steric effect of the SiMe3 groups in 1 – 4 , the reactions of the corresponding halides with LiPH2⋅DME (or KAsH2) facilely yielded the dipnictogenide compounds (Dipp2Nacnac)M(EH2)2 (E=P, M=Al ( 5 ), Ga ( 6 ), In ( 7 ); E=As, M=Al ( 8 ), Ga ( 9 )), avoiding the use of flammable and toxic PH3 and AsH3 for their synthesis. The compounds 5 – 9 are the first examples of monomeric Group 13 diphosphanides and diarsanides in which the metal center is bound to two terminal PH2 and AsH2 groups, respectively. In contrast to the successful synthesis of the indium diphosphanide (Dipp2Nacnac)In(PH2)2, the reaction of (Dipp2Nacnac)InCl2 with KAsH2 led to an indium mirror due to the instability of the target product. 相似文献
924.
The positive axial zero-field splitting parameter D relevant for the S = 2 ground state of [Mn(cyclam)I2]I (cyclam = 1,4,8,11-tetraazacyclotetradecane) is interpreted using the valence bond configuration interaction model which explicitly considers the covalency of the manganese-iodide bond. 相似文献
925.
926.
Voss S Zimmermann DJ Hesse A von Unruh GE 《Isotopes in environmental and health studies》2004,40(3):199-205
Calcium oxalate (CaOx) urolithiasis is the most common urinary stone disease (70-75 % of all stones consist of CaOx in countries with western diet). Oxalate is the most lithogenic substance in CaOx crystallisation in urine. Oxalate is either synthesized within the body or absorbed from food. As oxalate is not metabolized in the human body, it appears unchanged in urine. Conventional analysis methods cannot distinguish between endogenous and exogenous oxalate. Our [13C2]oxalate absorption test enabled measurement of intestinal oxalate absorption and quantification of the influence of Ca- and Mg-supplementation on it. The effects of the oral administration of these supplements were compared in order to obtain valid data for recommendations for CaOx urolithiasis patients. A 10 mmol supplement of both ions decreased the oxalate absorption significantly, calcium being more than twice as effective. 相似文献
927.
Susanne C. Brenner. 《Mathematics of Computation》2004,73(247):1041-1066
The convergence of -cycle and -cycle multigrid algorithms with a sufficiently large number of smoothing steps is established for nonconforming finite element methods for second order elliptic boundary value problems.
928.
929.
Busch S 《Angewandte Chemie (International ed. in English)》2004,43(11):1428-1431
930.
Intense radiation in the terahertz (THz) frequency range can be generated by focusing of an ultrashort laser pulse composed of both a fundamental wave and its second-harmonic field into air, as reported previously by Cook et al. [Opt. Lett. 25, 1210 (2000)]. We identify a threshold for THz generation that proves that generation of a plasma is required and that the nonlinearity of air is insufficient to explain our measurements. An additional THz field component generated in the type I beta-barium borate crystal used for second-harmonic generation has to be considered if one is to avoid misinterpretation of this kind of experiment. We conclude with a comparison that shows that the plasma emitter is competitive with other state-of-the-art THz emitters. 相似文献