首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   35篇
  免费   11篇
化学   16篇
晶体学   1篇
力学   1篇
数学   12篇
物理学   16篇
  2021年   1篇
  2017年   2篇
  2015年   1篇
  2014年   1篇
  2013年   3篇
  2012年   4篇
  2011年   3篇
  2010年   3篇
  2008年   14篇
  2007年   5篇
  2006年   4篇
  2005年   1篇
  2003年   1篇
  2002年   1篇
  2001年   2篇
排序方式: 共有46条查询结果,搜索用时 15 毫秒
1.
杜芹芹  张旭  宋凤瑞  刘志强  刘淑莹 《应用化学》2010,27(10):1209-1214
采用高效液相色谱与电喷雾质谱联用技术(HPLC-ESI-MS),对不同质量比的人参与干姜或赤芍配伍过程中人参皂苷的变化进行了研究,发现随加入的干姜量增加,共煎液中的人参皂苷含量依次降低;少量的赤芍可以使各皂苷的溶出量增加;同时测定了人参单煎液、人参与干姜、赤芍共煎液中正丁醇提取物和水提物的抗氧化活性。 以抗坏血酸(500 μmol/L)作对照,人参与干姜、赤芍配伍溶液的抗氧化活性比人参单煎液要好,同时人参与干姜、赤芍共煎液中正丁醇提取物的FRAP(铁离子还原/抗氧化能力测定)值分别为1562.29和2969.78 μmol/L,高于人参与2种药单煎液(1260.27和2502.07 μmol/L)之和。  相似文献   
2.
Iodine release in potassium iodide solution has been investigated under the irradiations of ultrasound and visible light respectively and simultaneously. We have observed that the amount of iodine liberated under the combined irradiation of ultrasound and visible light is larger than the sum of that under the respective irradiations of ultrasound and visible light, indicating a synergistic effect of ultrasound and visible light irradiations. Based on the investigation of the reaction kinetics of iodine liberated, we have ascribed the synergistic effect to the perfect stirring of the photochemical reactor induced by the applying simultaneous ultrasound. The ideal stirring can result in the homogenization of the primary light effect in the whole reaction medium, which induces the acceleration of the photochemical reaction. On behavior of our knowledge, there are few reports on the investigations of utilizing the combination of ultrasonic energy and light energy to accelerate the reaction yield and rate as well as the kinetics of the reaction.  相似文献   
3.
利用高效液相色谱-飞行时间质谱联用的方法,分别对人参配伍山楂前后人参皂苷的变化进行分析,同时对人参皂苷Re、Rg1、Rb1、Rd与山楂配伍的水解规律进行系统研究,并与单独煎煮液、仿山楂配伍pH值煎煮液的水解产物进行比较,结果发现人参与山楂配伍后人参皂苷Rg1、Rb1含量明显减少,而人参皂苷Re、Rd、Rg2、Rg3、F2、Rh1含量明显增加,其中人参皂苷Re与山楂配伍后水解产物为人参皂苷20(R)-Rg2、20(S)-Rg2,仿山楂配伍pH值水解产物为人参皂苷20(R)-Rg2、20(S)-Rg2、Rg4、Rg6;人参皂苷Rg1与山楂配伍后水解产物为20(S)-Rh1、20(R)-Rh1,仿山楂pH值水解产物为20(S)-Rh1、20(R)-Rh1、Rh4、Rk3;人参皂苷Rb1与山楂配伍后水解产物为Rd、20(S)-Rg3,仿山楂pH值水解产物为F2、20(S)-Rg3;人参皂苷Rd与山楂配伍后水解产物为F2、20(S)-Rg3、20(R)-Rg3,仿山楂pH值水解产物为20(S)-Rg3、20(R)-Rg3。研究表明,不同人参皂苷和山楂配伍后与仿山楂pH值的水解产物并不相同,人参与山楂配伍改变了人参皂苷成分的种类及含量。本研究为临床方剂中人参与山楂配伍后成分的变化提供物质基础数据。  相似文献   
4.
The purpose of this paper is to characterize the pointwise rate of convergence for the combinations of Szász-Mirakjan operators using Ditzian-Totik modulus of smoothness.  相似文献   
5.
In order to prove up the interaction between konjac glucomannan (KGM) and other amyloses, by using KGM, guaran gum and carrageenan as materials, their blending in different external conditions was modeled by means of molecular dynamics (MD) method. The result showed that 323 K was a significant turning point for the formation of hydrogen bond, and KGM and guaran gum were just juxtaposed together via intermolecular hydrogen bond; but with the addition of carrageenan, KGM, guaran gum and carrageenan were spirally twisted together, and when their blending proportion is 3:2:9 the combination was the most compact. Moreover, the research result has provided the sequent studies afterwards on amyloses with some references.  相似文献   
6.
The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.  相似文献   
7.
轴对称折叠组合腔输出的多束高斯光束的并和   总被引:2,自引:0,他引:2  
提出一种新腔型激光器—轴对称折叠 组合腔He Ne激光器。对该腔型输出的多束高斯光束,建立了一种简化的光束并和计算模型。并对相干并合和和非相干并和后的光强分布和光斑做了分析和模拟。结果表明,轴对称折叠 组合腔He Ne激光器输出有相干情形的光束在医疗上是有实用价值的。  相似文献   
8.
Hydroquinone combined with FeCl3 can reduce the methanolysis time of N‐vinylcarbazole in CH3OH from 9 h to 1 h, but the addition of hydroquinone to Fe(NO3)3 will slow the methanolysis and quench the cyclobutanation process. The addition of H2O2 successfully made the FeCl3 catalytic cyclobutanization of N‐vinylcarbazole in the yield from zero up to 33%. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   
9.
借助于密度泛函理论的B3LYP方法,以冠丙四肽为模型基础,对铷、锶、铯、钡等金属离子与该冠丙四肽的结合形式进行了几何构型优化、能量计算、Mulliken布局数分析等理论研究.结果表明,冠丙四肽的构型在与ⅠA金属离子结合前后略有改变,结合过程中电子由冠肽移向金属离子,碱金属离子铷、铯与冠型环丙四肽的结合作用相差不大,其最佳结合位距冠丙四肽中心的距离依次为0.375和0.400 nm;碱土离子锶、钡与冠型环丙四肽的结合作用明显优于碱金属离子,其最佳结合位距冠丙四肽中心的距离依次为0.250和0.300 nm,其中以锶离子的结合更突出.  相似文献   
10.
The purpose of this paper is to characterize the pointwise rate of convergence for the combinations of Szász-Mirakjan operators using Ditzian-Totik modulus of smoothness.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号