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991.
通过对铝镁合金材料的焊接特性的分析 ,总结出内外两面成型且不加管道内衬的焊接施工工艺 ,以此来提高铝镁合金管道的焊接一次合格率 相似文献
992.
993.
Malyshev S.A. Galwas B.A. Piotrowski J. Chizh A.L. Szczepaniak Z.R. 《Microwave and Wireless Components Letters, IEEE》2002,12(6):201-203
A photovaractor for the remote optical control of microwave circuits was studied. The photovaractor was fabricated as a p-i-n photodiode placed in a pigtailed fiber optical module. The study of the impedance in the frequency range up to 3 GHz in darkness and under illumination has shown that the photovaractor capacitance strongly depends on the incident optical power. The capacitance variation of the photovaractor diode under illumination is discussed 相似文献
994.
An analytical expression for both band-to-band and band-trap-band indirect tunnelings is used to study the gate-induced drain leakage (GIDL) current of MOSFETs measured before and after hot-carrier stress. The voltage and temperature dependence of GIDL are characterized. Both results show that interface traps situated near the midgap participate in the conduction of GIDL, and band-trap-band indirect tunneling could be the major mechanism. This is further supported by the fact that the percentage increase in GIDL induced by hot-carrier stress is about the same as the corresponding increase in interface-trap density. On the other hand, under low-field conditions, trap-assisted Poole–Frenkle emission dominates over tunneling for temperatures even well below room temperature. 相似文献
995.
Bo Jiang Jeffrey L. Brown Jane Sheraton Nathalie Fortin Howard Bussey 《Yeast (Chichester, England)》1994,10(3):341-353
We have identified three yeast genes, KES1, HES1 and OSH1, whose products show homology to the human oxysterol binding protein (OSBP). Mutations in these genes resulted in pleiotropic sterol-related phenotypes. These include tryptophan-transport defects and nystatin resistance, shown by double and triple mutants. In addition, mutant combinations showed small but apparently cumulative reductions in membrane ergosterol levels. The three yeast genes are also functionally related as overexpression of HES1 or KES1 alleviated the tryptophan-transport defect in kes1Δ or osh1Δ mutants, respectively. Our study implicates this new yeast gene family in ergosterol synthesis and provides comparative evidence of a role for human OSBP in cholesterol synthesis. 相似文献
996.
V. Carelli G. Di Colo E. Nannipieri M. F. Serafini 《Drug development and industrial pharmacy》1994,20(9):1673-1681
The enhancement effects of some chemicals on the percutaneous absorption of alprazolam through human skin was investigated in vitro. Linoleic acid, oleic acid, Comperlan F® (linoleic acid diethanolamide), Comperlan KD® (coconut fatty acid diethanolamide) and Ethomeen C12® (bis-(2-hydroxyethyl)cocamine) were evaluated for their enhancing effect either as neat solvents or combined with propylene glycol. The effects of skin pretreatment with the enhancers on the percutaneous absorption of alprazolam from a drug suspension in an aqueous gel were also investigated: skin pretreatment with some enhancers has shown potentially interesting aspects. The determination of alprazolam partitioning into untreated and pretreated horny layer supported the idea that, with oleic and linoleic acid, a contribution to the modification of the diffusional resistance of the skin was given by an increase of the drug solubility in the stratum coraeum. 相似文献
997.
The influence of the specimen thickness B and the ligament length b on the J
R
-curves is numerically investigated for CT specimens. The thickness effect is taken into account with 2-D analyses by dividing a plain sided specimen into a plane stress part and a plane strain part. The fracture process is controlled by experimentally determined critical values of the crack tip opening displacement for crack growth initiation (CTODi) and the crack tip opening angle for stable crack growth (CTOAC). It is shown that for the global behaviour of a plain sided specimen, the B/b ratio is essential. The difference between the geometry dependence of the initiation value of the J-integral and the geometry dependence of the slope of the J
R
-curves is also shown. 相似文献
998.
This article examines the special features of the III-V semiconductors, such as gallium arsenide and chemically related compounds, which make them an attractive alternative to silicon-based technology in the field of microelectromechanical systems. As in conventional electronic systems, it is not expected that the III-V compounds will become exclusively used in all instances, but rather a substantial niche market-exploiting the special advantages of the compound semiconductors-is likely to be established 相似文献
999.
1000.
Damage to multilayer coatings under thermal cyclic loading is investigated. The mechanisms of crack formation are established and studied as a function of the composition of the coatings, the base metal, and the form of cycle. On the basis of these results, we suggest a composition of multilayer coating with high heat resistance.Science and Production Department, Polzunov Central Design and Technological Institute, St. Petersburg. Translated from Fiziko-Khimicheskaya Mekhanika Materialov, Vol. 29, No. 6, pp. 48–55, November–December, 1993. 相似文献