益母草中多糖的含量测定

目的 :建立测定益母草中多糖含量的方法。方法 :采用水杨酸法测定还原性单糖的含量和水解后的总糖含量 ,从而间接测出益母草中的多糖含量。结果 :糖浓度 5～ 4 0ug在范围内呈现良好的线性关系 ,益母草中多糖含量为 (31.16± 0 .2 3) % ,平均回收率为 98.92 %。RSD=2 .2 5 %。结论 :该方法简便、快速、准确 ,并且消除了样品中还原性单糖对多糖含量测定的影响 ,该方法特别适合于含有单糖的样品中多糖的含量测定。     

坝上油菜蜂花粉中总黄酮的超声提取及含量测定

目的 :从油菜蜂花粉中提取总黄酮 ,并测定其含量。方法 :采用超声技术提取总黄酮 ,用比色法测定总黄酮含量。结果 :油菜蜂花粉中总黄酮含量为 (30 .5 0± 1.0 0 ) % ,平均回收率为 99.6 0 % ,RSD =2 .95 % (n =6 )。结论 :运用超声技术从油菜蜂花粉中提取总黄酮 ,可提高提取率 ,节省提取时间。     

饮水硼对鸡组织硼含量的影响

选择 1日龄固始鸡 30 0羽 ,随机分成四个组 ,分别在饮水中添加硼 (以硼酸作为硼源 ) ,0、1 0 0、2 0 0和 40 0mg/L ,用姜黄素比色法分别测定 7、1 4、2 1、2 8、35和 42日龄雏鸡的肌肉、骨、脑的硼含量。结果表明 :饮水硼含量≤ 2 0 0mg/L时 ,各组间的差异多不明显。而当水硼添加达 40 0mg/L时 ,组织中的硼含量均显著地升高 ,其中肌肉硼含量升高 47.1 %～ 1 5 4 .4% ,骨硼含量升高 39.8%～ 1 1 5 .9% ,脑硼含量升高 83.3%～ 1 49.2 %。     

催化褪色反应法测定发铜的研究

铜对过氧化氢在硫酸介质中氧化甲基橙的褪色反应有催化作用。本文用吸光光度法进行铜(Ⅱ)的测定,取得满意效果,灵敏度达9.00×10～11g/ml,测定范围0～2.0μgCu2十/50ml。并用本法测定发中Cu(Ⅱ)的含量,报道2-4岁男童发中Cu(Ⅱ)的测定值。     

粉防己和木防己多糖的含量测定

目的 :测定中药粉防己和木防己中单糖和寡糖 (寡糖的量以单糖表示 )的总含量以及多糖的含量。方法 :单糖和寡糖的提取 :用 2 0倍溶媒 (6 0 %乙醇 )浸泡 2 4h后 ,于 5 0℃提取 4h ,共提取 3次 ,每次提取用 2 0倍溶媒。多糖的提取 :用 2 0倍溶媒 (水 )浸泡提尽单糖和寡糖的残渣 2 4h ,于 10 0℃提取 3h ,重复提取一次。检测方法为硫酸 -苯酚法。结果 :粉防己和木防己中单糖和寡糖 (寡糖的量以单糖表示 )的总含量分别为 10 .2 0 %和 7.75 % ;多糖的含量分别为36 .83%和 38.4 4%。结论 :粉防己和木防己中含有大量的多糖 ,为开辟防己类药材新的用途提供理论依据。     

表面活性剂增敏催化光度法测定痕量亚硝酸根

基于在稀硫酸介质中溴代十六烷基吡啶 (CPB)对亚硝酸根 (NO-2 )催化溴酸钾氧化碘曙红褪色反应的增敏作用 ,建立了测定NO-2 的表面活性剂增敏催化动力学光度法 .由于加入增敏剂 ,灵敏度显著提同 .lgA0 /A值与NO-2 含量在 0～ 1.0 μg/mL范围内存在线性关系 ,检出限量为0 .0 6 μg/ml.方法用于水样、蔬菜中痕量亚硝酸根的测定 ,结果较好     

用注射器测定空气中氧气含量

用标有刻度的 5 0ｍｌ注射器测定空气中氧气的含量 ,与化学课本以钟置、水槽等仪器测定空气中氧气的含量相比较 ,有仪器简单易得、操作方便 ,能够从量的方面直接显示氧气含量等特点。装置如图。　　步骤 :1　将套有胶皮管的注射器筒拉至 5 0ｍｌ处。装置图2　将胶皮管伸入水中吸水 ,调节针筒 ,使水充满前端细管恰好与注射器底部平齐。3　平放注射器 ,使前端细管中水进入注射器内 ,将针筒拉出 ,放入 1小粒 (约 0 0 6～ 0 0 7ｇ)擦干水份的白磷 ,再将针筒固定在 5 0ｍｌ处。 (操作中注意不要将注射器中的水放出 )。如装置图直立注射器 ,用弹…     

薄层扫描法测定雷公藤口服液中总内脂的含量

目的 :建立雷公藤口服液含量测定方位 方法 :采用醇提 ,氧化铝柱层分离 ,以醋酸∶石油醚 (2∶1 )为展开剂 ,薄层扫描法测定雷公藤总内酯的含量 (λS=52 5nm ,λR=70 0nm) 结果 :线性范围 :1 0～ 5 0 μg,平均回收率 :99 83 % ,RSD为 0 2 6 % 结论 :该方法准确可靠 ,操作简单 ,可适用于该制剂质量控制     

重庆涪陵部分蚕区大气氟污染的监测

本实验运用石灰滤纸法(LTP法)对重庆涪陵部分蚕区的大气氟化物进行较长时间(10天左右)的吸收，再用氟离子选择电极法测定其含量，进而根据能斯特方程推算出大气中氟的含量以测定大气氟污染情况。同时还比较了各种测定方法的优缺点及实用性等。通过对涪陵地区的三个不同采样点的滤纸样品氟含量和空白滤纸氟含量的测定，测得1#、2#、3#大气含氟量的平均值分别为0．598μg/dm2．d、2．357μg/dm2．d、1．567μg/dm2．d，与国家环境空气质量标准(GB 3095—1996)比较对照可知涪陵蚕区1#表现正常；2#点含氟量极高，严重超标；3#点轻微超标。     

直接进样法测定植物油中的脂肪酸

对植物油不经衍生化直接进样对脂肪酸进行测定 ,采用毛细管气相色谱法分析植物油中的脂肪酸成分和含量 ,其灵敏度比 GC(普通填充柱气相色谱法 )提高了 1 0 2～ 1 0 3倍     

卡思卡特城堡

It is worthy of noting that, whilst Crookston Castle witnessed the earlier and happier portion of Mary's variegated life,     

不同的吃喝玩乐

一、吃和喝吃苹果 eat an apple, 吃药 take medicine,吃糖 have some sweets,吃饭 have one's meals,吃馆子 dine out,吃惊 be surprised/     

漏洞百出的教育

Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help?     

只要努力,不要后悔

There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love.     

浅谈移民问题

Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject.     

Sister Carrie, an Adherent of Desires

Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities.     

Improvement of one-cycle controller by use of proportional integral differential controller

1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec…     

库克斯顿城堡

城堡, 是欧洲典型的建筑之一, 每个城堡都有一个美丽的传说或是一段历史。从本期开始, 我们将推出“城堡之旅”, 带各位读者去浏览、观赏欧洲各地的城堡, 开始一段文化与历史的旅途!     

The Reader Response Approach to Teaching of English Literature

During interview with English majors, it was found that a majority of students expressed disappointment with their experience of English literature classes. Students' dislike of learning English literature appears to be the major problem of teaching English literature in China. Reader response approach is a good way to solve this problem. In this paper, I explain the rationale behind the reader response approach, such as its origin, definition, features, assumptions, and strategies. Then I illustrate how reader response approach works as a teaching strategy by presenting several teaching models. At last I evaluate its usefuiness for teachers and present the advantages of reader response approach in Chinese context.