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In situ measurements of the physical characteristics of Titan's environment   总被引:1,自引:0,他引:1  
On the basis of previous ground-based and fly-by information, we knew that Titan's atmosphere was mainly nitrogen, with some methane, but its temperature and pressure profiles were poorly constrained because of uncertainties in the detailed composition. The extent of atmospheric electricity ('lightning') was also hitherto unknown. Here we report the temperature and density profiles, as determined by the Huygens Atmospheric Structure Instrument (HASI), from an altitude of 1,400 km down to the surface. In the upper part of the atmosphere, the temperature and density were both higher than expected. There is a lower ionospheric layer between 140 km and 40 km, with electrical conductivity peaking near 60 km. We may also have seen the signature of lightning. At the surface, the temperature was 93.65 +/- 0.25 K, and the pressure was 1,467 +/- 1 hPa.  相似文献   
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本文较深入地研究了脱硫石膏粉煤灰化学成分、杂质、颗粒特征和激发剂等对脱硫石膏、粉煤灰胶结材性能的影响 研究表明 ,激发剂是影响脱硫石膏、粉煤灰胶结材性能的主要因素 这为脱硫石膏、粉煤灰资源化利用打下良好理论基础 经实际应用表明 ,研究结果与实际情况能很好相符  相似文献   
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Tests of Einstein's general theory of relativity have mostly been carried out in weak gravitational fields where the space-time curvature effects are first-order deviations from Newton's theory. Binary pulsars provide a means of probing the strong gravitational field around a neutron star, but strong-field effects may be best tested in systems containing black holes. Here we report such a test in a close binary system of two candidate black holes in the quasar OJ 287. This quasar shows quasi-periodic optical outbursts at 12-year intervals, with two outburst peaks per interval. The latest outburst occurred in September 2007, within a day of the time predicted by the binary black-hole model and general relativity. The observations confirm the binary nature of the system and also provide evidence for the loss of orbital energy in agreement (within 10 per cent) with the emission of gravitational waves from the system. In the absence of gravitational wave emission the outburst would have happened 20 days later.  相似文献   
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Carcinoid tumor of the colon was studied in electron microscope. In cytoplasm, prominent intermediate-sized filaments were seen frequently attaching to nucleus and mitochondria. Direct contacts of intermediate filaments with secretory granules were not observed.  相似文献   
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介绍用计算机软件产生正弦稳态扫频信号的编程方法。通过对D/A变换与A/D采集的同步输出可以获得不同频率量程和设定电压的扫频输出  相似文献   
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一类高阶非线性系统的零解稳定性   总被引:1,自引:0,他引:1  
由Барбащин公式得到的四阶常系数线性系统的Ляпунов函数出发,通过类比法构造了一类四阶非线性系统的Ляпунов函数,并由此得到了这些系统零解的全局渐近稳定性的充分条件  相似文献   
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Summary Carcinoid tumor of the colon was studied in electron microscope. In cytoplasm, prominent intermediate-sized filaments were seen frequently attaching to nucleus and mitochondria. Direct contacts of intermediate filaments with secretory granules were not observed.Acknowledgments. The skilful technical assistance of Ms Tuire Koro is gratefully acknowledged. — This study was supported by grants from the Finnish Medical Research Council, Finnish Culture Foundation and J.K. Paasikivi Foundation for Cancer Research.  相似文献   
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