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991.
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994.
Review of Studies on Rare Earth against Plant Disease 总被引：12，自引：7，他引：5
Agricultural application of rare earth (RE) has been generalized for several decades, and it is involved in crops, vegetables and stock raising in China. However, all the researches on RE mainly focus on the fields such as plant physiological activity, physiological and biochemical mechanism, sanitation toxicology and environmental security. Plant protection by using RE and the induced resistance of plant against diseases were summarized. The mechanism of rare earth against plant disease is highlighted, which includes following two aspects. First, RE elements can control some phytopathogen directly and reduce its virulence to host plant. Another possibility is that RE elements can affect host plant and induce the plant to produce some resistance to disease. 相似文献
995.
R. Xu Y. Y. Cui D. M. Xu D. Li Q. C. Li Z. Q. Hu 《Metallurgical and Materials Transactions A》1996,27(8):2221-2228
A variety of heat treatments have been employed to explore the microstructure in Ti-25Al-10Nb-3V-lMo alloy prepared by gas atomization and hot pressing. These treatments include quenching by oil cooling and water cooling and aging at temperatures between 530 °C and 950 °C. Quenching transformations from the β-phase field include the formation ofO phase in oil quenching and β (disordered) +O phase in water quenching. The metastable β phase decomposes intoO + “Ω”,O, or α2 + βo/B2 phase when the as-quenched alloy is aged at various temperatures. By comparing the selection area diffraction patterns, it has been found that the ordered w phase in the alloy studied in this article is distinct in structure to the “Ω type” (P3m1) and B82 phase which are formed in the parent matrix of the ordered β(B2,D03) phases. It has also been shown by X-ray diffraction (XRD) analyses that the lattice parameters of the as-agedO phase do not remain constant in the alloy at various temperatures. 相似文献
996.
The adjacent pixel nonlinearity refers to the dependence of the luminance of a given pixel on the preceding pixel or pixels. We measured this nonlinearity for two CRT displays by measuring the average luminances of a variety of test patterns with different luminance jumps. A two-stage model proposed by Mulligan and Stone was used to fit the data [Mulligan, J.B. & Stone, L. S., (1989). Journal of the Optical Society of America A, 6, 1217-1227 (1989)]. The results show that the model predicts our data well. Based on our measurements and the modeling results, a double-entry look-up table was created to compensate for this nonlinearity. This compensation method works even if the current pixel depends on more than one preceding pixel. Observers commented that at small pixel sizes the compensation results in a sharp, accurate image. Advantages and problems of this compensation will be discussed. 相似文献
997.
W. R. Sun S. R. Guo D. Z. Lu Z. Q. Hu 《Metallurgical and Materials Transactions A》1997,28(3):649-654
This article describes the effect of phosphorus on the microstructure and stress rupture property at 650 °C in an Fe-Ni-Cr base superalloy. The results showed that phosphorus markedly improved the intergranular precipitation in the range of 0.0005 to 0.016 wt pct, which facilitated M23C6 and M3B2 precipitation but inhibited the formation of MC carbide. A too high phosphorus addition (0.051 wt pct P) resulted in an excessive precipitation at grain boundaries, while a too low phosphorus content (0.0005 wt pct P) led to many precipitate-free grain boundaries. Phosphorus also enlarged the size of the γ′ particles and lowered its stability, that η-Ni3Ti preferred to form in the alloy with 0.051 wt pct P. Due to the improvement of the microstructure, appropriate amount of P content significantly prolonged the rupture life of the alloys in the range of 0.0005 to 0.016 wt pct. The peak value was 660 hours at 0.016 wt pct, more than 4 times that of the alloy with 0.0005 wt pct phosphorus, but phosphorus reduced the fracture elongation. The mechanism by which phosphorus influenced the alloy is discussed. 相似文献
998.
A total of 71 Staphylococcus aureus strains isolated from bovine mammary glands were identified and subtyped. The methods used to differentiate between the S. aureus isolates were the DNA polymorphism pattern after amplification with a Polymerase Chain Reaction using several primer combinations and phage typing. The DNA fingerprinting technique using RAPD, ERIC1R and ERIC primers proved to be useful in differentiating isolates of S. aureus. Differentiation of isolates using phage typing gave no additional information compared to the DNA technique. The outbreak of S. aureus in the herd studied was mainly caused by one S. aureus strain. Other strains were only found on three occasions, twice in subclinical infections and once from a case of clinical mastitis. In the latter case the dominant strain was isolated from a different quarter of the same cow. Four of the ten cows studied suffered from clinical mastitis. From those four cows, three remained infected with the same S. aureus strain despite antibiotic treatment. 相似文献
999.
煤体的渗透性与裂隙分维的关系 总被引：15，自引：8，他引：7
通过研究煤体的渗透性与裂隙的分型规律,揭示了煤体的裂隙发育程度与分形维数的关系,得出煤体渗透性与裂隙分维关系式及煤体渗透性随体积应力、水压、分形锥数、强度的定量变化规律,对工程实际具有重要的指导意义。 相似文献
1000.
三聚氰胺系列减水剂的研制与应用 总被引：6，自引：0，他引：6
深入研究了三聚氰胺系列减水剂的基本合成工艺参数,为其工业化生产提供必要的技术依据;通过掺入某些廉价组分制成复合型外加剂,使得三聚氰胺减水剂的生产成本大幅降低,从而提高其推广应用价值。进一步探讨了不同类型和掺量的三聚氰胺复合型外加剂对水泥胶砂和混凝土强度的影响。 相似文献