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A surgical approach to the clivus and anterior spine from C-1 to the upper part of C-5 is described. It is a direct approach that provides a wider and longer exposure than does the transoral approach. Despite the seemingly radical incision, the cosmetic deformity and functional loss are minimal. This approach is useful for the surgical treatment of a variety of processes that are situated ventral to the upper cervical spinal cord and the cervicomedullary junction. 相似文献
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This paper discusses the biokinetic and dosimetric models adopted in ICRP Publication 88 for the evaluation of fetal doses resulting from maternal intakes of radioiodine. The biokinetic model is used to simulate the behaviour of iodine in both the mother and the fetus. Such simulations provide the basis for the estimation of the dose to the embryo and determine the distribution of maternal iodine at the beginning of the fetal period. The model considers iodine to accumulate in the fetal thyroid from the 11th week. The dose to the fetus delivered following birth is evaluated with the biokinetic and dosimetric models described in ICRP Publication 67. Although a substantial fraction of the emitted energy of electrons and photons is less than 10 keV, conventionally assumed to be non-penetrating radiation, these emissions can escape the small fetal thyroid. Absorbed fractions for both self-dose and crossfire were evaluated for the requirements of radioiodine dosimetry in ICRP Publication 88. 相似文献
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An overview is given of the models recommended by the International Commission on Radiological Protection (ICRP) for assessing intakes and doses, and summarises biokinetic data obtained after the deposition of different chemical compounds of thorium in the rat lung. The results emphasise the importance of using material-specific data rather than default reference values for absorption into blood. The limitations of external monitoring of the chest or urine analysis are discussed, and comments made on alternative strategies for radiological protection of the worker. 相似文献
96.
D. S. Boyd P. C. Phipps G. M. Foody R. P. D. Walsh 《International journal of remote sensing》2013,34(23):5141-5147
The ever-wet tropics are under threat from ENSO events and there is a need for a monitoring system to analyse and describe their responses to such events. This letter explores the relative value of using NOAA AVHRR middle infrared (MIR) reflectance data and NDVI data for the monitoring of ENSO-related drought stress of a tropical forest ecosystem in Sabah, Malaysia. Relationships between rainfall and MIR reflectance were examined. Correlation coefficients are generally large and significant (at 0.1 level) while those between rainfall and NDVI were small and insignificant. This letter concludes that there is potential in using MIR reflectance for monitoring the effects of ENSO-induced drought stress on these forests and this has a bearing on how NOAA AVHRR data may be used to further our knowledge on the impacts of ENSO events on tropical forest environments. 相似文献
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RH Enns 《Canadian Metallurgical Quarterly》1987,36(11):5441-5443
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