3-芳氧基-6-氯哒嗪化合物除草活性与结构关系的研究

应用半经验量子化学AM1法获得18种3-芳氧基-6-氯哒嗪化合物的优势构象,再用AM1法和分子图形学技术获得其电子结构参数和几何结构参数,然后采用多元线性回归分析(MLR)和人工神经网络误差反传算法(BP)将这些参数和化合物对油菜的抑制活性相关联.MLR和BP建模的复相关系数(R2)、去一法(LOO)交互检验复相关系数(R2cv)分别为0.840,0.743和0.889,0.733,表明所建市的QSAR模型的稳定性和预测能力良好.结果表明,苯环上应尽量避免大体积取代基的引入,在2号位引入的取代基可稍大些;在苯环2、4、6位引入供电子基团、3位引入吸电子基团可提高化合物的除草活性,所建模型可为哒嗪类除草剂的设计合成提供理论指导.     

香豆素磺酰脲类化合物降血糖活性的定量构效关系研究

目的：研究新型香豆素磺酰脲化合物降血糖作用与化学结构之间的关系，为进一步设计合成该类化合物提供理论依据。方法：选择10个降血糖活性较强的化合物，利用MM!分子力学和CNDO／2量子化学方法计算有关结构参数并进行定量构效关系研究。结果：香豆素-6-磺酰脲类化合物的降血糖活性与磺酰脲基与母核的二面角呈负相关；与母核1位碳原子LUMO轨道本征矢量负相关；与化合物分子的偶极矩正相关。结论：推测分子中7-位甲基的引入不利于磺酰脲基与香豆素母环共平面，降低化合物的降血糖活性；香豆素母环上引入供电子基团不利于增加降血糖活性，可尝试引入吸电子基团；化合物分子偶极矩的增加对降血糖活性有利。     

后过渡金属催化剂的分子模拟研究

应用量子化学计算程序ADF考察含有不同有机配体的过渡金属镍配合物对催化乙烯聚合反应的作用，对由于取代基不同造成催化活性不同的相关机理进行验证计算；应用分子动力学计算程序考察催化剂失活难易程度，应用量子化学计算程序ADF考察聚合分子双键位置及支化度的变化情况，计算结果表明当吡叮环配体中有甲基取代时，反应活性降低。当苯环上1，3，5位出现甲基取代时；反应不易发生。当配体上有较强的给电子基团取代时，反应活性增强。     

非核苷类逆转录酶抑制剂抗HIV活性与其分子结构的关系

目的：研究非核苷类逆转录酶抑制剂的电子结构与其抑制HIV病毒活性的关系。方法：应用分子力学MM 方法,半经验量子化学MNDO法计算了24个奈韦拉平(nevirapine)类似物的优势构象和电子结构,讨论这类药物的电子结构与其抑制HIV病毒活性的关系。结果：得到其抑制HIV活性与电子结构的定量构效关系方程：pIC50=6．101—53．669Q4 15．980Q7 0．259TA。结果还表明：这类药物抑制HIV病毒活性与药物分子4号位和7号位上的净电荷Q4和Q7有关,分子结构上的4号与7号位是药物作用的活性中心,而分子的扭转角则让分子活性中心处于更适合于与分子结合的位置上,从而产生抑制HIV的活性。结论：所得到的定量构效关系能预测该类化合物的活性,分子中的7号位N和4号位C原子是药物分子的活性中心。     

HEPT类似物的电子结构与抗HIV活性的关系研究

目的：为了研究HEPT类似物的电子结构与其抗HIV活性的关系。方法：应用分子力学MM 方法,半经验量子化学MNDO法计算了23个HEPT类似物的优势构象和电子结构,结合数理方法得到了两个定量构效方程：(1)logl／C=5．138 0．000058231c-c 0．00004894Ee 3．747Q13;(2)ClogP=5．271 0．00013631c-c 0．0001134Ee=10．86Qs13;结果：(1)HEPT类似物的两个苯环作为两个核的核与核之间相互作用Ic-c和分子总电子能Ee是影响其log1／C与ClogP的主要因素,核与核之间的相互作用越强,总电子能越高,则其疏水参数和其抗HIV活性也越强。(2)13号原子上取代基的净电荷Qs13越大时,ClogP越小。当13号原子的净电荷Q13越多,其抗HIV活性则越强。结论：HEPT类似物的抗HIV活性与化合物的核与核之间相互作用、总电子能及13号位的原子的净电荷成正比。     

1-环丙基-5-取代-7-(4-甲基哌嗪基)-6,8-二氟-1,4-二氢-4-氧-3-喹啉羧酸的定量构效关系

通过量子化学AM 1和MonteCarlo模拟计算 ,对 1 环丙基 5 取代 7 ( 4 甲基哌嗪基 ) 6,8 二氟 1 ,4 二氢 4 氧 3 喹啉羧酸的定量构效关系进行了研究 ,结果显示 5 位取代基的体积V、表面积S、与母核紧连原子的净电荷、指示变量等对抗菌活性有很大影响 ,回归得到了相关性好的方程 :( ( 4)R =0 9,( 5)R =0 94 ) ,( 6)R =0 95)。 5 位小的取代基、 4 位和 5 位形成氢键对抗菌活性有利。计算表明5 为被甲基取代后具有更好的抑制金葡萄菌和绿脓杆菌的抗菌活性。     

1-环丙基-5-取代-7-(4-甲基哌嗪基）-6,8-二氟-1,4-二氢 -4-氧-3-喹啉羧酸的定量构效关系

通过量子化学AM1和Monte Carlo模拟计算,对1-环丙基-5-取代-7-(4-甲基哌嗪基）-6,8-二氟-1,4-二氢-4-氧-3-喹啉羧酸的定量构效关系进行了研究,结果显示5-位取代基的体积V、表面积S、与母核紧连原子的净电荷、指示变量等对抗菌活性有很大影响,回归得到了相关性好的方程：((4)R=0.9,(5)R=0.94),(6)R=0.95)。5-位小的取代基、4-位和5-位形成氢键对抗菌活性有利。计算表明5-为被甲基取代后具有更好的抑制金葡萄菌和绿脓杆菌的抗菌活性。     

海南中橡将上线富基可视化流程管理

近日，海南中橡电子交易市场有限公司与富基公司签订合作协议，全面上线富基可视化流程管理。富基将把原有的电子交易系统进行可视化流程监控改造，帮助其根据变化需求及时修改采购计划，减少库存差错，提升供应链效率。     

硫化钼基加氢脱硫催化剂活性位的研究进展

硫化钼基催化剂是加氢脱硫过程的常用催化剂,其活性相结构与加氢脱硫性能的关系一直是催化加氢领域研究的热点问题,该问题对开发更高活性和选择性的催化剂具有十分重要的意义。本文综述了近年来加氢脱硫催化剂的表征和理论计算方面的研究进展,对MoS_2、CoMoS和NiMoS的具体微观结构进行了分析,并对可能的加氢脱硫活性位以及噻吩在活性位上加氢脱硫的反应路径进行了探讨。     

电子工业中的免清洗技术

电子工业中的免清洗技术清华大学化学系副教授刘密新一、引言多年来，电子工业中所用的助焊剂均是松香基助焊剂，松香基助焊剂的主要成分是松香、卤素和溶剂。这种助焊剂焊后残留多，有腐蚀牲。为了保证印制板的质量，焊后需要用氟利昂进行清洗，日本、美国等发达国家，每...     

嘧啶硫苯甲酸类的三维构效关系研究

利用比较分子场分析（ＣｏＭＦＡ）对１６嘧啶硫苯甲酸类化合物进行了三维定量构效关系研究，得到了具有较强预测能力的ＱＳＡＲ模型。研究结果表明袖章效应是影响构效关系的主要因素，为更好地解释结构与活性的关系，设计新型嘧啶苯甲酸类除草剂提供了有益的指导。     

Estimating energy expenditure in wildland fire fighters using a physical activity monitor

This study piloted the use of an electronic activity monitor (MTI AM 7164-1.2) as a tool for estimating activity (EE(ACT), kcal day(-1)) and total (EE(TOT) kcal day(-1)) energy expenditure in wildland fire fighters during extended periods of wildland fire suppression. Ten Hot Shot fire fighters (9 men, 1 woman) volunteered to wear a MTI monitor during every work shift for 21 consecutive days. Summarizing whole-body motion data each 1 min, the raw activity data (counts min(-1)) were transformed into units of kcal min(-1) using a custom computer program with standard conversion equations. EE(TOT) averaged (Mean+/-SD) 4768+/-478 kcal day(-1), while EE(ACT) averaged 2585+/-406 kcal day(-1), neither of which differed significantly (P = 0.198 and 0.268, respectively) from literature values reported for Hot Shots using the doubly labeled water technique. These data suggest that the electronic activity monitor provided reasonable estimates of EE in wildland fire fighters. This study should be verified, however, with a more complete validation methodology to ensure these findings.     

Habitual Physical Activity of Rural Burmese Women

Abstract

Habitual physical activity of 16 Burmese women aged 19-24 yrs residing in a rural Burmese village was assessed by the questionnaire method together with the diary method and heart rate measurements. The pattern of their habitual physical activity had a seasonal variation. Their heart rate during transplanting paddy, pounding glutinous paddy and carrying water ranged from 108-132, 119-144 and 120-168 beats min_?1 respectively. Their work intensity expressed as a percentage of their maximal aerobic power varied from 1304 to 79-47. It was found that the habitual physical activity of these rural women could contribute a positive effect towards their physical performance capacity.     

Activity analysis of English Premiership rugby football union refereeing.

Little is known about the physiological demands placed on officials during sporting activities. The purpose of this study was to ascertain the movement activities of referees during English Premiership rugby football union matches, and to determine the frequency and duration of these activities. Nine referees who were ranked in the top 20 referees in England were videotaped during a total of 19 matches. During playback of the videotapes, a single observer coded the referees' activities into one of six distinct categories (standing, walking forwards, walking backwards, jogging, running and sprinting) using a computerized video editing system (Observer Video-Pro). The referees were timed over a 20 m distance for the modes of locomotory activity, and the average velocity of the referee for each activity was used to calculate the total distance covered in each mode of activity during matches. The total distance covered during a match was (chi +/- SD) 8581 +/- 668 m. The mean percentage of total playing time spent in each activity was: standing still, 37.0 +/- 11.0%; walking forward, 29.5 +/- 7.2%; walking backward, 9.9 +/- 3.2%; jogging, 12.8 +/- 3.2%; running, 9.8 +/- 2.3%; and sprinting, 1.0 +/- 0.4%. There were a total of 672 transitions between modes of activity during a match. The results of this study suggest that refereeing top English rugby football union matches is physically demanding. Although the major physiological load is placed on the oxygen transport system, frequent sprint bouts and the associated requirements for acceleration and deceleration impose additional metabolic demands on referees. This information may be used in the design of physical training programmes to optimize performance in referees.     

Continuous physical activity recognition for intelligent labour monitoring

Multimedia Tools and Applications - The paper addresses the problem of human activity recognition based on the data from wearable sensors. Human activity recognition depends on a wide context of...     

Physical activity levels among adult computer users

As computer use becomes prevalent at work and in leisure pursuits it presents a potential barrier to regular physical activity. However an individual’s confidence in overcoming such barriers may moderate the relationship between computer use and physical activity levels. This study examined the associations among computer use, self-efficacy in overcoming barriers to exercise, and physical activity levels among adult computer users. Participants (N = 615) were recruited through national email and newsletters announcements, and completed standardized self-report questionnaires online. Computer use was not associated with meeting physical activity guidelines (adjusted odds ratio, AOR = 0.63-1.00, n.s.). Among leisure computer users, the moderate efficacy group (AOR = 3.72, 95% CI = 1.59-8.69) and the high efficacy group (AOR = 5.31, 95% CI = 2.37-11.91) had higher odds of meeting physical activity guidelines compared to the low efficacy group. Among the work related computer users, the high efficacy group (AOR = 2.83, 95% CI = 1.18-6.77) had higher odds of meeting physical activity guidelines than the low efficacy group. These results suggest that barriers posed by high levels of computer use are surmountable. Efforts to increase efficacy in overcoming barriers to exercise may be more practical and have a greater impact on physical activity levels than trying to decrease computer use among adults.     

Osmotic and activity coefficients in the solutions of 1- and 2-naphthol in methanol and ethanol at 298.15 K

The osmotic coefficient of the solution, activity of the solvent and activity coefficient of the solute in solutions of 1- and 2-naphthol in methanol and ethanol have been measured by the isopiestic method. The experimental osmotic coefficient data were correlated using the Non-Random Two Liquid model (NRTL), the Non-Random Factor model (NRF), the two suffix Margules equation and a polynomial in terms of the molality of the solute. The models give reliable results for the correlation of the osmotic coefficient data. The activity coefficients of 1- and 2-naphthol were evaluated according to the considered methods using the parameters obtained by the correlation of osmotic coefficients.     

A novel chaotic map based compressive classification scheme for human activity recognition using a tri-axial accelerometer

Multimedia Tools and Applications - Human activity recognition using wearable body sensors plays a vital role in the field of pervasive computing. In this paper, we present human activity...     

Denial-of-service attack-detection techniques

Denial-of-service (DoS) detection techniques - such as activity profiling, change-point detection, and wavelet-based signal analysis - face the considerable challenge of discriminating network-based flooding attacks from sudden increases in legitimate activity or flash events. This survey of techniques and testing results provides insight into our ability to successfully identify DoS flooding attacks. Although each detector shows promise in limited testing, none completely solve the detection problem. Combining various approaches with experienced network operators most likely produce the best results.