盐浓度梯度对DNA通过固态纳米孔的影响（英文）

针对DNA过孔速度过快以及信噪比低等制约固态纳米孔应用于DNA分子检测的问题,通过改变纳米孔两侧盐溶液的浓度,研究了其对DNA的过孔时间以及信噪比的影响.实验结果表明,当纳米孔两侧氯化钾溶液浓度相同时,λ-DNA的过孔时间以及电流堵塞信号都随着氯化钾浓度的提高而增加.但当纳米孔cis端的KCL浓度保持在1 mol/L,trans端的氯化钾浓度由1 mol/L变为0.1 mol/L时,归一化后的电流信号幅值增加了1个数量级.因此,调整纳米孔两端盐溶液的浓度梯度可以有效降低DNA的过孔速度和提高信噪比,从而大大提高了纳米孔在DNA分子检测方面的灵敏度.     

辣椒SRAP-PCR反应体系优化与引物筛选

本研究以辣椒基因组DNA为模板,优化辣椒SRAP反应体系中的参数,建立了一套适用于辣椒的SRAP-PCR最佳反应体系。在25μL反应体系中,模板DNA 50 ng、上下游引物各0.1μmol/L、dNTPs 0.1mmol/L、Taq DNA聚合酶1.5 U、Mg2+浓度为2.0 mmol/L。扩增程序为:94℃3 min;94℃30 s、35℃30 s、72℃1.5 min,5 cycles;94℃30 s、54℃30 s、72℃30 s,35 cycles;72℃10 min,用2%琼脂糖凝胶电泳和8%非变性聚丙烯酰胺凝胶电泳检测扩增结果。利用该优化体系筛选引物,筛选出条带清晰、重复性好的15对SRAP引物组合,验证了体系的实用性。     

改良CTAB法对白梨品种DNA提取效果的研究

采用改良CTAB法对15个白梨品种叶片DNA提取情况进行了研究,考察了Vc和β-巯基乙醇抗氧化效果,所获得DNA样品经电泳、单酶切以及PCR检测,结果表明用氯仿/异戊醇混合萃取液多萃取几次可有效减少高蛋白质含量样品中的蛋白质的含量;用5mol/L的NaCl溶液能有效降低梨DNA样品中多糖的含量;Vc抗氧化效果优于β-巯基乙醇,Vc用量在0.1~0.30g/g样品时,可有效减少提取过程中酚类氧化。     

哈密瓜SSR体系的建立及反应条件的优化

以新疆哈密瓜为试验材料,利用正交试验设计研究了4个主要因子(Mg2+、DNA聚合酶、SSR引物和dNTP)对SSR扩增结果的影响,并对该哈密瓜SSR反应体系进行了优化,同时尝试用降落(Touchdown,TD)PCR方法扩增目的片段.最终筛选出如下最佳反应体系:总反应体积为25 μL,其中dNTP 200 μmol/L,SSR引物0.75μmol/L,Taq DNA聚合酶1.0 U,Mg2+ 1.5 mmol/L;降落PCR省却了常规PCR中摸索最适退火温度的过程,对一些Tm值相近的PCR反应可应用一套温度程序扩增,是一种行之有效的方法.     

中国特有濒危裸子植物白豆杉RAPD反应体系的优化

采用改进的CTAB法提取中国特有濒危裸子植物白豆杉(Pseudotaxus chienii)嫩叶总DNA,进行RAPD分析.分别研究了模板DNA、引物、dNTPs、Mg2 和TaqDNA聚合酶用量对RAPD PCR扩增反应结果的影响.筛选并建立了适合于白豆杉RAPD扩增的反应体系:总体积25μL,其中10×PCR缓冲液(500 mmol/L KCl,100 mmol/L Tris-HCl,1.0%Triton X-100,20 mmol/L MgCl2)2.0μL,引物(1.5μmol/L)0.5μL,dNTPs(10 mmol/L)0.4μL,模板1μL(35 ng),Taq酶0.8μL(0.5 U),水20.3 μL.     

几种混合溶液中离子浓度大小的比较

1.0.1mol/L的CH_3COOH溶液与0.1mol/L的NaOH溶液等体积混合.分析:NaOH与HAc恰好完全反应,反应后即为NaAc溶液,由于CH_3COO~- H_2(?)CH_3COOH OH~-,所以c(Na~ )>c(CH_3COO~-)>c(OH~-)>c(H~ ).2.pH=1的HAc与pH=13的NaOH溶液等体积混合.分析:混合前CH_3COOH溶液中,c(H~ )=0.1mol/L,NaOH溶液中c(OH~-)=0.1mol/L,而CH_3COOH为弱酸,部分电离,即     

影响聚式酶链式反应实验效果的基本因素

研究聚式酶链式反应(PCR)实验中影响其扩增效果的多种因素,寻求反应体系中理想的各因素浓度配比。选取含5+10优质亚基的小麦品种为材料,以特异扩增1DX5基因PCR实验为例,从模板DNA、引物终浓度、Taq酶、二价镁离子、4dNTPs混合液、缓冲液浓度几方面入手,通过设计梯度实验,研究不同因素对PCR扩增效果的影响。结果表明,反应体系6个基本因素,缺少任何1个都扩增不出产物。在反应总体积25μL的PCR反应体系中,模板DNA选用32 ng/μL,Mg2+终浓度2 mmol/L,Taq酶1.2 U/25μL,引物0.8μmol/μL,4dNTPs0.3 mmol/L,缓冲液1×buffer最为合适,能扩增出理想的结果。     

利用“手持技术”比较碳酸钠和碳酸氢钠与稀盐酸反应的速率

碳酸钠和碳酸氢钠是钠的重要化合物,其性质研究是中学化学教学中的一个重点。碳酸钠与碳酸氢钠作为钠的碳酸盐,都能与盐酸等强酸反应,但是如何比较他们与盐酸反应的化学反应速率一直都是实验研究的难点。苏教版化学2中设置的实验方案"取两支试管,分别加入5ml0.1mol/LNa2CO3溶液、NaHCO3溶液,再各加入3ml0.1mol/L稀盐酸,观察     

小麦酯酶的纯化研究

采用DEAE-52,Sephadex G-200柱层析法从辽春9号小麦面粉里提取分离纯化小麦酯酶,分别用二次蒸馏水、0.1～0.5 moL/J 的NaCl溶液进行梯度洗脱,最终确定,粗酶液经DEAE-52用二次蒸馏水、0.2 moL/L的Nacl溶液洗脱后的两组份为纯化组份.上述两组份经sephadex G-200用0.2mol/L的NaCl溶液洗脱后的3组份中第1组份分别为纯化组份,本法第1组份纯化倍数为4.9771倍,回收率为20.09%;第2组份纯化倍数为1.5276倍.回收率为8.55%.     

“模拟生物体维持pH的稳定”实验改进

2017年人教版高中生物学选择性必修1教材中“模拟生物体维持pH的稳定”实验使用0.1 mol/L盐酸溶液与0.1 mol/L氢氧化钠溶液检测生物体维持pH稳定的机制,并利用pH试纸进行酸碱度检测。盐酸溶液和氢氧化钠溶液均具有强烈的刺激性与腐蚀性,对pH试纸精确读数要求也较高。为此,利用天然试剂代替教材中的实验试剂,并对实验设计进行创新。实验结果表明,利用柠檬汁代替0.1 mol/L盐酸溶液、苏打溶液代替0.1 mol/L氢氧化钠溶液、天然紫草溶液代替pH试纸具有可行性,实验操作简单且显色更为明显。     

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?     

Western and Eastern culture differences in commercial field

The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity.     

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…     

风的曲线

Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose.