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91.
岩样自然伽玛能谱的数据库管理系统 总被引:3,自引:0,他引:3
本文阐述了岩样自然伽玛能谱数据库管理系统的功能、结构、特点以及它在研究自然伽玛能谱与岩性参数间关系中的应用,为自然伽玛能谱测井的资料解释奠定了理论基础。 相似文献
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PURPOSE: Nitric oxide (NO) is generated in mammalian tissue by the conversion of L-arginine to L-citrulline. The reaction is catalyzed by nitric oxide synthase (NOS). NO has been suggested to have a dual role in tumor biology with both antitumor and tumor promoter activity. Furthermore, it has been proposed that NO contributes to interleukin-2-induced antitumor activity. Since interleukin-2 is used in the treatment of renal cell carcinoma (RCC) it was of interest to study the NOS activity in the human kidney and in RCC and its correlation to tumor grade. Furthermore, the effect of cytokine treatment on NOS activity and the effect of NO donor application was studied in cultured cells. MATERIALS AND METHODS: The effect of cytokine treatment on NOS activity and the effect of NO donor application on cell proliferation was studied in cultured human proximal tubular cells and in RCC cell lines HN4 and HN51. NOS activity was measured by the L-arginine to L-citrulline conversion assay. RESULTS: Calcium-dependent NOS activity was found in all non-malignant kidney tissues (486+/-63 pmol. min(-1) g(-1) tissue). The activity was significantly lower in RCC (24+/-6 pmol. min(-1) g(-1) tissue) and correlated with tumor grade; thus high grade tumors showed lower activity than low grade tumors. Calcium-independent NOS activity was not detected in non-malignant kidney tissue or in RCC tissue. In cultured proximal tubular cells and RCC cell lines HN4 and HN51, cytokine treatment induced a marked increase in NOS activity and NO exerted cytostatic effects on these cell lines. Conclusions: The NOS activity was higher in non-malignant kidney tissue than in RCC tissue and was inversely correlated with tumor grade. Furthermore, cytokine treatment induced a marked increase in NOS activity and NO exerted cytostatic effects on cultured proximal tubular cells and RCC cell lines. 相似文献
95.
Chemical reactions between aluminum and fly ash during synthesis and reheating of Al-fly ash composite 总被引:5,自引:0,他引:5
Thermodynamic analysis indicates that there is the possibility of chemical reactions between aluminum melt and cenosphere
fly ash particles. These particles contain alumina, silica, and iron oxide, which, during solidification processing of aluminum-fly
ash composites or during holding of such composites at temperatures above the melting temperature of aluminum, are likely
to undergo chemical reduction. These chemical reactions between the fly ash and molten aluminum have been studied by metallographic
examination, differential thermal analysis (DTA), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX)
and X-ray analysis after holding the aluminum-fly ash composites for different periods above the liquidus temperature. The
experiments indicate that there is progressive reduction of silica and mullite in the fly ash, and formation of alumina with
holding time of composites at a temperature of 850 °C. The walls of the cenosphere fly ash particles progressively disintegrate
into discrete particles as the reaction progresses. The rate of chemical reaction was high at the start of holding the composite
at a temperature of 850 °C, and then the rate significantly decreased with time. The reaction was almost complete after 10
hours. 相似文献
96.
Li Xi Zuoyan Peng Wei Fan Kui Guo Gu Jianmin Muyu Zhao Wu Guoqiang 《Materials Science and Engineering: B》1996,40(2-3):147-152
SrMgxTi1 - xO3 nanocrystals (x = 0.1–0.6) were synthesized by the stearic acid gel method. Powder samples were characterized by X-ray diffraction and X-ray photoelectron (XP) spectroscopy. The results showed that the lattice parameter a and the O 1s XP spectrum changed not only with the Mg content x but also with the grain size d of the samples. The conductivity of a thick film specimen fabricated on an aluminium oxide wafer was investigated in a nitrogen—oxygen atmosphere. 相似文献
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本文提出了激光功能微调技术在高精度混合集成电路上的应用,讨论了关键技术问题,并以实例具体说明。该技术的应用为研制高精度混合集成电路开辟了新途径。 相似文献
99.
Dr.-Ing. X. Guo H. A. Maier Prof. Dr. Ing. K. Feser 《Electrical Engineering (Archiv fur Elektrotechnik)》1992,76(1):83-91
Contents The long-used restraining principle, based on the detection of 2nd harmonics in the currents, can not always satisfactorily meet the demand of blocking the transformer differential protection for all three phases, because the line currents are not the direct image of the core saturation. The differential protection may become inadequate. A transformer can however be switched on for all cases, without the false or fail-safe tripping, when the harmonic restraint is derived from the magnetic field strength of the core.If a delta-connected winding is present, the magnetic field strengths can not be easily recognized in the line currents, because their zero-sequence component is distorted. A new method is presented, which can estimate the fundamental and the 2nd harmonic of this zero-sequence component. The components of the magnetic field strength can therefore be determined in currents only, whose ratio is known to be characteristic for the core saturation.The proposed method was implemented on an industrial protection system based on a microprocessor and was tested on data obtained from computer-simulation and a model transformer in a laboratory. It turned out that the proposed method performed well on all cases.
Eine neue Methode der Einschalterkennung für den Transformator-Differentialschutz
Übersicht Die üblicherweise benützte Blockierung beim Einschalten eines Transformators beruht auf der Bewertung der zweiten Harmonischen in den Strömen. Dieses Prinzip kann nicht immer den Transformatorvergleichsschutz in allen drei Phasen blockieren. Dagegen kann ein Transformator in allen Fällen ohne Fehlauslösung eingeschaltet werden, wenn die Blockierung aus der Harmonischen der magnetischen Feldstärke des Kerns abgeleitet wird.Eine neue Methode wird vorgestellt, wie die Homopolarkomponente der Grundschwingung und der zweiten Harmonischen näherungsweise berechnet werden kann. Die benötigten Anteile der Feldstärken können damit aus den Differenzströmen ermittelt werden.Das vorgeschlagene Verfahren wurde auf einer industriell gefertigten Schutzkarte implementiert. Die Überprüfung des Verfahrens erfolgte mit Berechnungsverfahren und durch Messungen im Labor.相似文献
100.
椭球反射镜膜厚均匀性 总被引:2,自引:1,他引:1
本文分析了椭球反射镜膜层厚度均匀性对反射率的影响,从理论上得到膜厚计算公式。根据计算的膜厚分布设计了遮蔽板,获得较好的反射特性。 相似文献