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排序方式: 共有176条查询结果,搜索用时 15 毫秒
61.
Yu. O. Chetverikov N. N. Aruev S. A. Bulat K. A. Gruzdov V. F. Ezhov P. Jean-Baptiste I. L. Kamenskii V. Ya. Lipenkov E. M. Prasolov V. A. Solovei R. V. Tyukal’tsev I. L. Fedichkin 《Technical Physics》2018,63(5):738-746
Isotope ratios of noble gases (He, Ne, Ar) were studied in samples collected by degassing of cores of water frozen over a glacier of Lake Vostok. The gases were collected into glass retorts during three days of degassing of cores, which have just been extracted from the borehole. Within the error, the isotope 3He/4He ratios of 0.28 ± 0.08 RA (RA = 1.38 × 10–6 is the ratio for air) correspond to those from [1]. The 4He/20Ne and 40Ar/36Ar ratios (12.4 ± 4.6 RA and 1.0074 ± 0.0023 RA, respectively) exceed their contents in air (4He/20NeA = 0.29; 40Ar/36ArA = 298.6) and may indicate some contribution of terrigenous gas to the gaseous balance of the lake, as well as the high content of ancient ground waters in the lake. The 3He/4He ratio of 0.28 RA means low mantle 3He flux typical of continental platforms far from active rift zones. 相似文献
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Bulat L. P. Ivanov A. A. Osvenskii V. B. Pshenay-Severin D. A. Sorokin A. I. 《Physics of the Solid State》2017,59(10):2097-2102
Physics of the Solid State - The temperature dependence of the thermal conductivity of nanostructured samples of copper selenide prepared by mechanochemical synthesis from initial pure components... 相似文献
64.
本文引入并论证了描述动态位错场的张量势(A与B)的规范交换问题,而且证明这种变换可采取这样的形式:B′=B+▽F, A′=A-ρ?/(?t)▽G,x′=x-ρ?/(?t)F,其中xi=eiklAkl。至于F与G,则为带有很大任意性的时空坐标的矢量函数,但它们要满足以下关系式:F=▽×G,▽2F-1/Gt2-(?2/?t2)F=0.进
关键词: 相似文献
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Nicolaou KC Safina BS Zak M Lee SH Nevalainen M Bella M Estrada AA Funke C Zécri FJ Bulat S 《Journal of the American Chemical Society》2005,127(31):11159-11175
The first phase of the total synthesis of thiostrepton (1), a highly complex thiopeptide antibiotic, is described. After a brief introduction to the target molecule and its structural motifs, it is shown that retrosynthetic analysis of thiostrepton reveals compounds 23, 24, 26, 28, and 29 as potential key building blocks for the projected total synthesis. Concise and stereoselective constructions of all these intermediates are then described. The synthesis of the dehydropiperidine core 28 was based on a biosynthetically inspired aza-Diels-Alder dimerization of an appropriate azadiene system, an approach that was initially plagued with several problems which were, however, resolved satisfactorily by systematic investigations. The quinaldic acid fragment 24 and the thiazoline-thiazole segment 26 were synthesized by a series of reactions that included asymmetric and other stereoselective processes. The dehydroalanine tail precursor 23 and the alanine equivalent 29 were also prepared from the appropriate amino acids. Finally, a method was developed for the direct coupling of the labile dehydropiperidine key building block 28 to the more advanced and stable peptide intermediate 27 through capture with the highly reactive alanine equivalent 67 under conditions that avoided the initially encountered destructive ring contraction process. 相似文献
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Dr. André A. Neves Dr. Yéléna A. Wainman Dr. Alan Wright Dr. Mikko I. Kettunen Dr. Tiago B. Rodrigues Sarah McGuire Dr. De‐En Hu Flaviu Bulat Dr. Simonetta Geninatti Crich Dr. Henning Stöckmann Dr. Finian J. Leeper Prof. Kevin M. Brindle 《Angewandte Chemie (International ed. in English)》2016,55(4):1286-1290
Glycosylation is a ubiquitous post‐translational modification, present in over 50 % of the proteins in the human genome, 1 with important roles in cell–cell communication and migration. Interest in glycome profiling has increased with the realization that glycans can be used as biomarkers of many diseases, 2 including cancer. 3 We report here the first tomographic imaging of glycosylated tissues in live mice by using metabolic labeling and a gadolinium‐based bioorthogonal MRI probe. Significant N‐azidoacetylgalactosamine dependent T1 contrast was observed in vivo two hours after probe administration. Tumor, kidney, and liver showed significant contrast, and several other tissues, including the pancreas, spleen, heart, and intestines, showed a very high contrast (>10‐fold). This approach has the potential to enable the rapid and non‐invasive magnetic resonance imaging of glycosylated tissues in vivo in preclinical models of disease. 相似文献
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