首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 78 毫秒
1.
将银杏叶提取物经酸水解得到其中黄酮甙元槲皮素、山萘酚和异鼠李素,采用高效液相色谱、YWG-C18柱,甲醇:水(含04%磷酸)为流动相,UV360nm检测,以槲皮素为对照品计算出银杏叶提取物中总黄酮甙含量。槲皮素浓度在001~02mg/ml之间,浓度与峰面积呈直线关系,相关系数为09992,回收率为974%,相对标准偏差161%。该方法简便、准确,易于银杏叶提取物的质量控制。  相似文献   

2.
本文建立了可用于婴幼儿配方乳粉中13种邻苯二甲酸酯类环境激素测定的超高效液相色谱-二极管阵列紫外检测器分析方法.样品经甲醇饱和正己烷超声提取、柱分离富集与净化后,以乙腈和水为流动相进行梯度洗脱.所检测的13种邻苯二甲酸酯的线性范围为0.5-50 mg/L,检测下限在0.05-0.4 mg/L之间,加标回收率为92-102%,相对标准偏差均小于10%,该方法操作简便、分析时间短、灵敏度高,适用于婴幼儿配方乳粉中邻苯二甲酸酯的筛查分析.  相似文献   

3.
微波辅助萃取-高效液相色谱法测定土壤中多环芳烃   总被引:5,自引:1,他引:4  
建立了用微波辅助萃取-高效液相色谱测定土壤中16种多环芳烃的方法.对萃取剂的种类,萃取方式以及微波条件进行了优化.该方法线性范围宽,检测限为0.16~11.2μg/L,相对标准偏差在1.63%~6.51%之间,加标回收率在61.3%~129.2%之间.结果表明,该方法用于测定土壤中的多环芳烃具有简便、灵敏度高和重复性好等优点,是一个有实用价值的检测方法。  相似文献   

4.
为了解献血员人群HIV感染情况,我们对1995~1997年献血员HIV抗体检测情况进行了分析。方法:献血员HIV抗体的初筛试验采用抗-HIV抗体ELISA法,HIV抗体初筛试验阳性者用蛋白印迹法(WB)进行确认。结果:3年内共检测140028人次,初筛HIV抗体阳性18例献血员,并全部经WB法确认为HIV抗体阳性。其中15例为男性,3例女性,均为来自外省的流动人口。18例HIV抗体阳性献血员中,HCV抗体阳性检出率为833%(15/18),HBsAg阳性检出率为611%(11/18),HBsAg和HCV抗体阳性检出率为333%(6/8)。结论:在献血员人群中HIV抗体阳性检出率呈上升趋势,为此献血员HIV抗体筛查对预防和控制输血传播HIV具有重要意义。HIV与HBV和HCV具有较高的重叠感染率  相似文献   

5.
高效液相色谱法测定烟草中的淀粉含量   总被引:4,自引:0,他引:4  
研究了用高效液相色谱法测定烟草中的淀粉含量,方法检测限为3.0mg/L,相对标准偏差为1.6-2.1%,标准回收率在95~105%之间。新方法用于几种烟草样品中淀粉含量测定,结果令人满意。  相似文献   

6.
高效液相色谱——高灵敏催化光度法测定钛   总被引:2,自引:0,他引:2  
在100℃稀硝酸介质中及活化关吡啶存在的条件下,痕量钛(IV)对过氧化物氢氧化甲基橙褪色这一缓慢反应具有很强的催化作用用自来水冷却中止反应,采用高效液相色谱检测甲基橙浓度的变化,建立了一个新测量0.8ng/mL~60ng/mL钛的高效液相色谱新方法,并用于试样分析。  相似文献   

7.
刘峥  刘百秋 《广西科学》1999,6(3):197-200
用氢溴酸东莨菪碱- 四苯硼离子缔合物为电活性物质,以邻苯二甲酸二丁酯为增塑剂,研制成 P V C为基质膜的东莨菪碱离子选择性电极。东莨菪碱浓度在10×10- 4m ol/ L~10×10- 2m ol/ L时,电极电位服从能斯特方程式, 响应斜率为5907 m V/△pc, 检测下限为794×10- 5 m ol/ L, 对东莨菪碱的回收率为979% ~1092% , 变异系数为045% 。本文考察了电极的各种性能, 测定了20种常见离子选择性系数。方法用于实际样品中东莨菪碱的测定, 与药典标准方法比较, 相对误差282% , 结果满意  相似文献   

8.
本文研究了应用高效液相色谱法测定玉米样品中痕量柄曲霉毒素的新方法。样品先用甲醇:水(1:1)浸取,环已烷除油脂.再用二氯甲烷萃取毒素,然后将二氯甲烷在真空中蒸发至干,用乙腈溶解器内壁残留物并定容供分析用。柄曲霉毒素的乙腈溶液用反相色谱系统分离,乙腈/水(55/45,V/V)作流动相,紫外检测器检测(λ=325nm),检出限lpmo1,回收率76.5%。  相似文献   

9.
用高效液相色谱(HPLC)配紫外检测器,分离测定大鼠脑组织中腺苷含量。经实验确定以甲醇(10%~62%)、磷酸缓冲液(90%~38%)为流动相梯度洗脱,样品液中腺苷含量在2mg/L~10mg/L范围内线性关系良好。加入标准样品的平均回收率为(966±20)%。对6mg/L样品10次重复测定结果的标准偏差为014,变异系数为31%。对大鼠脑组织样品测定结果发现:与3~6月龄成龄鼠比较,18~20月龄老龄大鼠大脑皮层、海马、纹状体中腺苷含量分别增加了667%、372%和273%,不同脑区腺苷含量也有明显差异。结果提示不同脑区腺苷含量的随龄增加可作为研究衰老的一项指标;而中枢神经系统中随龄增长腺苷的堆积使Ach释放受到抑制可能是出现记忆衰退等常见老年性功能障碍的一个重要原因  相似文献   

10.
研究了用双波长高效液相色谱法检测饲料中V_E和V_D含量,采用两个波长下峰高比和保留时间相结合进行测定,提高了检测结果的可靠性,平均回收率V_E为89.3%,V_D为85%,测定变异性V_E为2.9%,V_D为1.4%。  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

13.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

14.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

15.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

16.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

17.
本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。  相似文献   

18.
There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.  相似文献   

19.
20.
The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to  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