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UVB from the sun and intake from food are the only human sources of vitamin D. Tibet is a unique region for comparisons of these sources: (1) it lies at a low latitude and at a high altitude and has very large annual fluences of UVB; (2) the traditional Tibetan food is poor in vitamin D. Blood samples were taken from 63 persons of different age, with different occupations and staying at different places. UVB doses at these places were measured. The samples were analyzed by a standard radioimmune assay for determination of the serum concentration of 25 hydroxyvitamin D (25(OH)D). The main finding was that among nomads, there seems to be severe vitamin D deficiency (serum levels of 25(OH)D < 30 n m ). We tentatively propose that the low level of 25(OH)D of nomads is related to their clothing and sun exposure habits. For persons of other occupations (students, teachers and farmers) the levels are higher, although a significant fraction of these persons also have lower levels than 75 n m , by many regarded as a limit for insufficiency related to a number of negative health conditions. The annual dose of vitamin D-generating UVB is about five times larger in Lhasa than in Oslo. Despite this, the average vitamin D status seems to be similar, except in the case of nomads. This phenomenon is certainly related to food habits. In conclusion, the 25(OH)D status among nomads in Tibet appears to be alarmingly low. However, for people of other occupations the status is more normal.  相似文献   
2.
报道了以2-甲(乙)基苯胺1a,1b为原料经Sandmeyer反应得到7-甲(乙)基靛红2a,2b;再以环境友好的聚乙二醇-400为溶剂,N-溴代丁二酰亚胺(NBS)为绿色溴代试剂对2a,2b进行5位溴代,得到5-溴-7-甲(乙)基靛红3a,3b;2a,2b,3a,3b进一步氮烃基化得到1-烃基-7-甲(乙)基靛红4a~4j和1-烃基-5-溴-7-甲(乙)基靛红5a~5j.2a,2b,3a,3b,4a~4j,5a~5j分别与硫代氨基脲,在以二氧六环为溶剂,碳酸钾存在的条件下回流反应,简便地合成了24种5H-[1,2,4]三嗪并[5,6-b]吲哚-3-硫醇类杂环化合物6a~6x.大部分化合物未见文献报道,其结构经红外光谱、质谱、核磁氢谱(碳谱)和元素分析确认.  相似文献   
3.
如果图G的一个正常边染色满足相邻点的色集不同,且任意两种颜色所染边数相差不超过1,则称为均匀邻强边染色,其所用最少染色数称为均匀邻强边色数.本文得到在m=1,2,3,n≥1和m=n≥4时的均匀邻强边色数.  相似文献   
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From the aerial parts of Senecio dianthus, four new eremophilenolides ( 1 – 4 , resp.) and one new eremophilenolide alkaloid ( 5 ), of the relatively uncommon eremophilenoid‐type sesquiterpenoid lactones, were isolated together with three known sesquiterpenoid lactones, 10β‐hydroxyeremophil‐7(11)‐en‐12,8α‐olide ( 6 ), 8β,10β‐dihydroxyeremophil‐7(11)‐en‐12,8α‐olide ( 7 ), and 10α‐hydroxy‐1‐oxoeremophila‐7(11),8(9)‐dien‐12,8‐olide ( 8 ). On the basis of IR, MS, and NMR data, particularly 2D‐NMR analyses, the structures of the new compounds were established as: 2β‐(angeloyloxy)‐10β‐hydroxyeremophil‐7(11)‐en‐12,8α‐olide ( 1 ), 6β‐(angeloyloxy)‐10β‐hydroxyeremophil‐7(11)‐en‐12,8α‐olide ( 2 ), 2β‐(angeloyloxy)‐8β,10β‐dihydroxyeremophil‐7(11)‐en‐12,8α‐olide ( 3 ), 2β‐(angeloyloxy)‐8α‐hydroxyeremophila‐7(11),9(10)‐dien‐12,8β‐olide ( 4 ), and 8β‐amino‐10β‐hydroxyeremophil‐7(11)‐en‐12,8α‐olide ( 5 ). In addition, the relative configuration of 1 was corroborated by X‐ray diffraction analysis.  相似文献   
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In recent years, direct and indirect evidence has been found of the efficacy of the traditional Chinese medicine Bergenia purpurascens in treating arthritis and osteoarthritis. Several major components, such as bergenin and 11‐O‐galloylbergenin, have good anti‐inflammatory activity. Since research on the chemical components of Bergenia purpurascens and related mechanisms for the treatment of osteoarthritis has never been performed, this study aimed to analyze the chemical components of Bergenia purpurascens through ultra high performance liquid chromatography coupled with quadrupole time‐of‐flight mass spectrometry technology and the UNIFI screening platform to predict the underlying mechanisms in treating osteoarthritis by analyzing the network pharmacology. In total, 43 chemical constituents were identified, mainly flavonoids (18), phenolic glycosides (13), and organic acids (7). Among them, 16 components were found in Bergenia purpurascens for the first time. Through the analysis of network pharmacology, several potential candidate targets and pathways were initially predicted, including AKT1, MAPK1, and MAPK3, as well as the apoptosis, estrogen, and MAPK signaling pathways. Bergenin, 11‐O‐galloylbergenin, arbutin, catechin‐3‐O‐gallate, and other components play a synergistic role in treating osteoarthritis. This study analyzed the chemical components of Bergenia purpurascens and preliminarily revealed potential mechanisms of treating osteoarthritis, providing a basis for further evaluating the drug's efficacy.  相似文献   
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