Abstract: A well cementing method is described for improving cementing quality by controlling the hydration heat of cement slurry. By controlling the degree and/or rate of hydration heat release from cement slurry, the method improves the hydration heat release during formation of cement with curing of cement slurry, improves the binding quality between the cement and the interfaces, and in turn improves the cementing quality at the open hole section and/or the overlap section. The cementing method improves cementing quality of oil and gas wells and reduces the risk of annular pressure.

Abstract: The present invention discloses a method for recycling urea in the process of separating and purifying unsaturated substances through a urea adduction method. The method comprises the following steps: liposoluble substances containing target unsaturated components are used as raw materials, and subjected to urea adduction, crystallization and filtration to produce a filtrate, from which the specific unsaturated components are obtained; the urea adduct is dissolved in a polar solvent, and after the adducted adducts are layered and released, adding a certain solvent to the urea solution to adjust the polarity, then cooling for crystallization, and recycling the urea.

Abstract: The present invention discloses a method for recycling urea in the process of separating and purifying unsaturated substances through a urea adduction method. The method comprises the following steps: liposoluble substances containing target unsaturated components are used as raw materials, and subjected to urea adduction, crystallization and filtration to produce a filtrate, from which the specific unsaturated components are obtained; the urea adduct is dissolved in a polar solvent, and after the adducted adducts are layered and released, adding a certain solvent to the urea solution to adjust the polarity, then cooling for crystallization, and recycling the urea.

Abstract: Disclosed are a printed circuit board and a wireless terminal using the multiple-input multiple-output technology including that printed circuit board, wherein at least two antennas are set on the printed circuit board, among antennas on the printed circuit board, a metal band gap structure is set in a headroom area of at least two adjacent antennas. The printed circuit board and wireless terminal using the multiple-input multiple-output technology including the printed circuit board in the above-mentioned technical scheme effectively improve the isolation between the antennas, solve the interference problem between the multiple antennas, and meet the layout requirements for minimizing multiple antennas of the terminal produces such as cellphones simultaneously.

Abstract: Disclosed is an antenna system, comprising: more than two antennas and a left-handed material isolation layer. The left-handed material isolation layer is disposed between adjacent two antennas in the more than two antennas in a suspended manner. By using the antenna system provided in the present utility model, a coupling effect between antennas can be weakened through the left-handed material isolation layer, thereby improving the isolation between antennas.

Abstract: A wireless device comprises a mainboard (8) and a plurality of antennae. The surface of the mainboard (8) is provided with the plurality of antennae. The interior of the mainboard (8) comprises a mainboard reference ground (9). Each of the plurality of antennae is electrically connected to the mainboard reference ground (9) respectively. This solution improves the isolation degree between common-frequency antennae effectively, thereby avoiding the mutual interference of short-range common-frequency antennae.