The ultrastructural changes during the development of sieve element companion cell complex (SE/CC complex) in Populus deltoides were investigated using electronic microscopy. The result showed that SE and CC tome from the same secondary phloem mother cell. The development of sieve element went through three stages, i. e. immature, mature, and degenerate stage. In immature stages the sieve element presented radial expansion, cell wall thickening, and production of sieve plastid and P-protein. The cytoplasma selectivly autolysed in mature stage. At the same time, karyoplasm was dispersed, and nuclear envelope was not clear, or karyoplasm was disorgnized, and nuclear envelope was clear. The karyopalsm finally turned into P-protein. In degenerate stage, the cytoplasm completely disappeared, and the function was lost.

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Meshing properties and application of major conical surface double envelope Hourglass worm gearing;2. In this paper, the regularities of undercutting and topping of major conical surface envelope hourglass worm is researched.

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The project proposed and established the strict unique mathematical model of instantaneous frequency aiming at the currently existed problems in Hilbert Huang Transform form the viewpoint of physical connotative meaning; proposed and established the strict mathematical model of general intrinsic mode signal based on the concept of general continuous intrinsic mode signal and the compositive principle of practical general intrinsic mode signal; researched and proposed the fitting method of envelope lines in HHT from the viewpoint of theory, conquered the blindness and random in quondam EMD envelope line fitting and boundary treatment; developed a virtual time-frequency analyzer based on general intrinsic mode signal decomposition to open out the local time-frequency characteristics of nonlinear and nonstationary signal more deeply and accurately.

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The suggested method was applied to varying excitation pulse shapes: square envelope and chirped hyperbolic secant envelope.

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Results With the new procedure, the tip of the prostate was peeled off completely without extra treatment, and this piece of the urethra,which was composed of surgical envelope, formed a vase-shaped natural surface to avoid urine irretention. The resected plane was covered by fibre and epithelium of surgical envelope,which could reduce irritation of urethra and bladder, and shorten hematuria and repair time. After enucleation of the enlarged prostate, the borderline became clear and blood supply was reduced, which facilitated the rapid resection without injury.

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