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991.
毛细管柱气相色谱法测定樟脑丸中萘 总被引:5,自引:0,他引:5
毛细管柱气相色谱法测定樟脑丸中萘 ,含量在 0 .0 0 5— 0 .2 0 mg/ m L范围内有良好的线性关系 ,线性回归方程为 :y=0 .35 6 5 5 6 .2 x,相关系数 r=0 .9999。测定下限为 0 .0 0 5 mg/ m L。方法简便、快速、准确 相似文献
992.
Adsorption of argon and nitrogen at their respective boiling points in cylindrical pores of MCM-41 type silica-like adsorbents is studied by means of a non-local density functional theory (NLDFT), which is modified to deal with amorphous solids. By matching the theoretical results of the pore filling pressure versus pore diameter against the experimental data, we arrive at a conclusion that the adsorption branch (rather than desorption) corresponds to the true thermodynamic equilibrium. If this is accepted, we derive the optimal values for the solid-fluid molecular parameters for the system amorphous silica-Ar and amorphous silica-N2, and at the same time we could derive reliably the specific surface area of non-porous and mesoporous silica-like adsorbents, without a recourse to the BET method. This method is then logically extended to describe the local adsorption isotherms of argon and nitrogen in silica-like pores, which are then used as the bases (kernel) to determine the pore size distribution. We test this with a number of adsorption isotherms on the MCM-41 samples, and the results are quite realistic and in excellent agreement with the XRD results, justifying the approach adopted in this paper. 相似文献
993.
热管技术已在电子设备散热领域得到广泛应用。热管的传热能力虽然很大,但不能无限加大热负荷。文中讨论了热管的主要极限如沸腾极限、毛细极限、粘性极限、声速极限、携带极限等的理论表达式,就一种实验用微槽平板热管进行了理论计算,得出了毛细极限是实验热管主要传热极限的结论。 相似文献
994.
A numerical model for an electrohydrodynamic (EHD) grooved Flat Miniature Heat Pipe (FMHP) is developed. Two microchannel shapes are considered as axial capillary structures: square and triangle grooves. For both groove shapes, the electric field affects the liquid-vapor radius of curvature which decreases in the condenser and increases in the evaporator under the action of the electric field. The liquid and vapor velocities are also affected by the EHD effects. The electric field effects on the velocities depend on the FMHP zone. It is also demonstrated that the electric field increases the vapor pressure drop; however, it decreases the liquid pressure drop. The liquid-wall and vapor-wall viscous forces as well as the shear liquid-vapor forces are affected by the electric field. The analysis of the electric forces shows that the dielectrophoretic forces which act on the liquid-vapor interface are predominant and their order of magnitude is much higher than the Coulomb forces. Finally, it is also demonstrated that the capillary limit increases with the electric field for both groove shapes. 相似文献
995.
996.
《Physics letters. A》2020,384(20):126412
Capillary condensation, which takes place in confined geometries, is the first-order vapor-to-liquid phase transition and is explained by the Kelvin equation, but the equation's applicability for arbitrarily curved surface has been long debated and is severe problem. Recently, we have proposed generic dynamic equations for moving surfaces. Application of the equations to the vapor/fluid interfaces in chemical equilibrium conditions nearly trivially solves the generalization problem for the Kelvin equation. The equations are universally true for any surfaces: atomic, molecular, micro or macro scale, real or virtual, Riemannian or pseudo-Riemannian, active or passive. 相似文献
997.
998.
以哈尔滨工业大学可调谐激光技术国家重点实验室中的Marx发生器的放电脉冲波形为基础,理论上模拟计算了在不同放电参数下充氩气的毛细管放电产生的等离子体状态和类氖氩离子3p_3s跃迁线的增益系数的时空演变过程。中心模型中,选取内径为3.1 mm 的陶瓷毛细管并充入初始密度为1.07×10-6g·cm-3的氩气,电流脉冲峰值为27.81 kA,脉冲宽度为61.4 ns。改变放电参数进行模拟,结果表明:上升前沿越陡,则增益系数越大,电流脉冲上升时间在20~40 ns,电流峰值在25~40 kA,电流脉冲宽度在50~70 ns范围内,毛细管放电产生的等离子体状态比较理想,可获得较高的增益系数。 相似文献
999.
1000.