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991.
992.
V. A. Pozdnyakov 《Technical Physics Letters》2003,29(2):151-153
The problem of brittle crack development in a nanocrystalline material has been theoretically studied. Expressions describing
the conditions of crack stability are obtained. 相似文献
993.
I. I. Vintizenko V. I. Gusel’nikov A. I. Zarevich S. S. Novikov 《Technical Physics Letters》2003,29(4):294-296
Autooscillation regimes in a relativistic magnetron with external mutual coupling of cavities have been studied. It is demonstrated that the interaction of oscillations under mode competition conditions significantly increases the stability of the working oscillation mode and improves the spectral characteristics of radiation. 相似文献
994.
A. K. Shuaibov A. I. Dashchenko I. V. Shevera A. A. General 《Technical Physics Letters》2003,29(12):1009-1010
We report on the optimized characteristics of a small-size bactericidal lamp pumped by transverse RF (f=1.76 MHz) discharge, operating on a system of the molecular emission bands of chlorine in a wavelength range of 195–310 nm.
The spectral characteristics of the plasma emission were measured and the intensity of chlorine emission bands were studied
as functions of the total pressure and partial composition of a helium-chlorine mixture. Oscillograms of the pumping current
and output radiation intensity were measured and the total output radiation power was determined. It is established that the
lamp radiates predominantly in a bactericidal wavelength interval on an electron-vibrational transition at 200 nm in Cl2** molecules. The optimum partial pressures of helium and chlorine are 100–300 and 90–120 Pa, respectively. The maximum output
power of UV emission from the side cylindrical surface of the lamp reached 10 W. The lamp can be used in photochemistry, ecology,
genetics, and medicine. 相似文献
995.
The following modes of isotope exchange of azidothymidine (3'-azido-3'-deoxythymidine) with tritium were studied: solid- and liquid-phase isotope exchange with gaseous tritium and isotope exchange in solution with tritium water. Catalytic reactions of azidothymidine with gaseous tritium in solution result in virtually complete reduction of the azido group to amino group. This reduction also occurs in the course of solid-phase catalytic hydrogenation; the yield of 3'-amino-3'-deoxythymidine ranges from 20 to 70%. The molar radioactivity of tritium-labeled azidothymidine prepared by solid-phase catalytic isotope exchange with gaseous tritium and by isotope exchange in solution with tritium water does not exceed 0.5 Ci mmol-
1. 相似文献
996.
Prediction of Undrained Sinkhole Collapse 总被引:2,自引:0,他引:2
Charles E. Augarde Andrei V. Lyamin Scott W. Sloan 《Canadian Metallurgical Quarterly》2003,129(3):197-205
Sinkholes are surface depressions or shafts resulting from the collapse of a submerged cavity in soil. The cavities that lead to sinkholes form as a result of underlying geology in limestone areas, or as a result of human activity such as mining or leakage from a sewer. The formation of sinkholes is often sudden and can lead to extensive damage and loss of life, especially in urban areas. Much of the literature on the subject of sinkhole formation is empirical in nature, often being associated with specific locations. This paper presents the results of a study, using numerical modeling, of the undrained stability of the submerged cavities that lead to sinkhole formation. Finite-element limit analysis techniques (using programs developed at the University of Newcastle) are used to obtain upper and lower bound values of a suitable load parameter, which bracket the exact solution. The results are compared to analytical solutions, both from literature and derived independently. 相似文献
997.
D. V. V. Satyanarayana G. Malakondaiah D. S. Sarma 《Metallurgical and Materials Transactions A》2003,34(11):2579-2590
The effect of prior oxidation at 1473 K on the creep behavior of an Fe-Ni-Cr-Al alloy, hardened by ordered NiAl precipitates,
has been investigated at 873 K over a stress range of 275 to 450 MPa. The alloy in the as-electroslag remelted (ESR) as well
as the ESR-plus-hot-worked conditions was considered. Prior oxidation causes creep strengthening in the Fe-Ni-Cr-Al alloy,
resulting in a decrease in minimum creep rate and increase in time to rupture, in contrast to the observations reported on
nickel-based superalloys. Creep strengthening is, however, accompanied by a significant reduction in creep ductility. Oxidation-induced
creep strengthening in the current alloy can be attributed to the improved adherence of surface oxide caused by the presence
of yttrium. An effective stress that incorporates the contributions of load transfer as well as substructural strengthening
is used to account for the observed oxidation-induced creep strengthening. While creep strengthening is more pronounced in
the ESR cast alloy, the loss in creep ductility is more intense in the ESR wrought alloy. Increasing the oxidation time beyond
1 hour has a minimal effect on creep strengthening of both the alloys, though it lowers significantly the creep ductility
of the wrought alloy. The observed differences in creep behavior of the alloy in the two different conditions could be attributed
to the differences in grain size as well as morphology and related oxidation-induced damage. 相似文献
998.
N. E. Shchepina V. V. Avrorin G. A. Badun V. M. Fedoseev S. E. Ukhanov S. B. Lewis 《Radiochemistry》2007,49(6):630-632
Ion-molecule reactions of free phenyl cations with six-membered nitrogen-containing heterocyclic compounds: α-, β-, and γ-picolines, were studied. Phenyl cations were generated by tritium β-decay in double-labeled benzene. The mechanism of competing reactions of electrophilic addition to the nitrogen heteroatom in the ring and electrophilic substitution of the C-H bond in the pyridine ring was examined. The effect of methyl substituent in the pyridine molecule on the reaction pathway was evaluated. A one-step procedure for nuclear-chemical synthesis of tritium-labeled N-phenylpicolinium salts and phenyl-substituted picolines was developed. 相似文献
999.
基于PSOS的TM1300应用系统中的BSP研究 总被引:1,自引:0,他引:1
通过在应用软件与板级支持包BSP之间加一层库函数的方法较好地解决了应用程序与板级支持包函数间的通信问题,减少了板级支持包函数的维护复杂度,从而为嵌入式系统板级支持包的实现提供了一个有价值的思路。 相似文献
1000.
Behavior of hydrated 238-242Pu(IV) oxide in 0.09-0.9 M NaOH containing 1 ×10-
3 M Na2SiO3 and in 0.1-0.2 M NaClO4 containing 1×10-
3-0.09 M Na2SiO3 (pH 11 and 9) was studied radiometrically with the aid of a scintillation counter. In alkaline solutions with pH 13.8-11 and high Na2SiO3 content, the Pu(IV) solubility increases owing to the reaction Pu(IV) + nSiO3
2
- = PuI
V(SiO3
2
-)
n
. At pH 9, Na2SiO3 has virtually no effect on the Pu(IV) solubility. 相似文献