排序方式: 共有24条查询结果,搜索用时 15 毫秒
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利用ABEEMσπ浮动电荷力场与连续介质模型相结合的方法,计算了受体和配体的结合自由能.将结合自由能分解为真空中的力场作用项、溶剂化能量以及熵效应.由于ABEEMσπ/MM方法充分考虑了外界环境发生变化引起的体系中各个位点之间的电荷极化,因而极大地提高了结合自由能的计算精度.利用该方法计算的2个复合物的结合自由能与实验值的偏差均小于0.5kJ/mol. 相似文献
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传统的霍夫变换、Cannylines直线检测算法、霍夫概率变换方法在图像上的直线检测效果不佳,存在检测线段不连续不正确的问题,因而,利用Sobel滤波对红外图像横轴和纵轴两个方向分别进行锐化,通过线段检测(LSD)算法实现线段特征检测,进而经线段聚类拟合获得图像中完整的直线,通过对直线交点计算获得消失点,最后依据透视关系计算得到校正图像。实验结果表明,该方法可以实现对中性束红外图像的自动有效校正。 相似文献
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In this paper, the adsorption characteristics of sodium tetraphenylborate(NaBPh4) on activated carbon at 298.2,303.2,308.2,313..2 and 323.2 K was studied.The results show that the adsorption isotherm of NaBPh4 on activated carbon at different temperatures could be described using Langrnuir equation. Furthermore, the standard Gibbs energy, enthalpy, entropy and hydrophobic interaction Gibbs energy for the adsorption of NaBPh4 on activated carbon were studied, and the result shows that the hydrophobic interaction of BPh4^- ion plays the most important role for the transfer of NaBPh4 from water to activated carbon surface. 相似文献
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滤膜吸附结合超声辅助分散液液微萃取/高效液相色谱法测定空气中溴氰菊酯残留 总被引:1,自引:0,他引:1
建立了滤膜吸附结合超声辅助分散液液微萃取与高效液相色谱(HPLC)联用测定空气中溴氰菊酯残留的方法。空气样品用甲醇-水(1∶4)混合溶液提取,加入三氯甲烷进行微萃取,超声,离心,得到沉积相,进行HPLC分析。溴氰菊酯在5~1 000μg/L范围内线性关系良好,相关系数(r)为0.999 8,富集倍数达520倍。当空气样品的加标浓度为10,50,100μg/L时,加标回收率为78.6%~106.7%,相对标准偏差(RSD)为2.2%~4.3%。空气样品中溴氰菊酯的检出限为1μg/L,最低检出浓度为0.04μg/m~3。该方法具有简便快捷、准确灵敏、萃取效率高、有机溶剂消耗少等优点,可用于空气中溴氰菊酯残留的测定。 相似文献
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磷蛋白对牙本质晶脱矿动力学的影响 总被引:2,自引:1,他引:1
应用等组分晶体生长方法,研究了牙本质晶、羟基磷灰石、釉质晶脱矿动力学.并探索了磷蛋白对牙本质晶脱矿动力学过程的影响.实验条件为:溶液温度:T=37±0.5℃;溶液酸度:pH=4.5±0.03;初始离子强度:IS=0.15mol/L;溶液的饱和度:δ=-0.60;-0.74;-0.86.研究结果表明:当δ=-0.60时,牙本质晶、釉质晶和羟磷灰石脱矿反应过程的特征明显不同.前两者的饱和溶解量比后者大一个数量级.羟磷灰石的特征反应周期比釉质晶和牙本质晶短15倍左右,初始反应速率慢30倍.牙本质晶脱矿初始反应速率Ri随δ的减低而快速增加.磷蛋白对牙本质晶的脱矿过程起抑制作用,但存在临界值.当磷蛋白在溶液中的浓度超过临界值后,其反应速率的变化很小.磷蛋白抑制作用在较大程度上依赖于溶液的饱和度. 相似文献
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STUDIES ON THE ORIGIN OF B CHROMOSOMES IN RYE 总被引:1,自引:0,他引:1
The morphological structure, classification and meiotic behaviour as well as the possible origin of the extra centric fragment produced after intercellular chromatin migration (cytomixis) in pollen mother cells during synizesis in rye have been studied by the squash and Giemsa·C-banding techniques. The results showed that the structures of extra centric fragments are metacentric, submetacentric, telocentric or subtelocentric, being quite different from each other. Their originations are stochastic, because any chromosome can be formed by the fragment. The meiotic behaviour of extra centric fragments is identical with that of B chromosomes. We consider that extra centric fragments are B chromosomes. The fragments originated from the fragmentation of A chromosomes at synizesis during cytomixis. Thus we consider that cytomixis could be one of the origins of B chromosomes. 相似文献