数学的学术形态向教育形态的转化——例谈转化思想在高中数学教学中的应用

数学问题的解决过程本质上是人们在面对新的数学问题时,运用已有的数学知识,包括数学语言、概念、定理、法则和范例等,通过冷静思考,仔细分析,将原问题转化为与之相关的自己熟悉的问题去加以解答.结合教学的具体实例,将高中数学教学中的常见转化归纳为四类,力求将数学的学术形态转化为教育形态.具体为:将隐性条件转化为显性条件;将复杂条件转化为简单条件;将抽象条件转化为数学图象;将应用问题转化为数学建模.     

猕猴桃酵素生产工艺条件优化

为得到更高品质的猕猴桃酵素饮品,以猕猴桃为主原料,红糖为辅料,采用自然发酵的方法,进行猕猴桃酵素生产工艺条件优化研究.设计单因素试验和正交试验,以酵母菌和乳酸菌接种量、发酵温度和发酵时间为影响因素对猕猴桃酵素生产工艺条件进行优化.结果表明,菌种接种量为影响猕猴桃酵素品质的主要因素.最佳工艺条件为:发酵时间为5 d,发酵温度为30℃,菌种接种量为4%.最佳工艺条件下生产的猕猴桃酵素糖度为4°Brix,酒精度为0. 25%vol(20℃),感官得分93分,感官指标、理化指标和微生物指标完全符合国家标准.     

响应面法优化脐橙渣中类黄酮的提取工艺

为优化在超声波辅助条件下脐橙渣中类黄酮的提取条件,在单因素试验的基础上,采用Box-Behnken试验设计和响应面法,研究乙醇浓度、液料比、提取温度对类黄酮得率的影响,建立了各因子与类黄酮得率关系的回归方程.试验结果表明最佳提取条件为:乙醇浓度64%、液料比26 mL/g、提取温度70℃.此条件下类黄酮的得率为3.59%,与预测值3.67%接近.     

定值条件的构造技巧

用均值不等式求函数的最值.应注意三个必要条件:即一正、二定、三相等.其中正数、相等条件容易获得,而要获得定值条件却常常被设计为一个难点,它需要一定的灵活性和变形技巧.下面举例谈谈常用构造定值条件的技巧.     

初中数学中容易忽视的隐含条件

数学中的隐含条件是指题目中没有直接给出来,但从定义、实际意义等出发又必须满足的条件.初中数学中容易忽视的隐含条件有三角形三边关系的隐含条件、分式和分式方程中分母不能为0的隐含条件和二次问题中的隐含条件等.     

电子表格中高级筛选条件填写问题探讨

以Excel为例,探讨了电子表格高级筛选条件的填写方法、技巧及易出现的问题,并通过实例讨论了如何避免和改正错误.填写高级筛选条件时,需要把问题中的条件分解成最小的逻辑条件,并弄清楚条件之间的逻辑关系.     

响应曲面法优化山茱萸多糖提取

以山茱萸为主要原料,确定了微波辅助萃取山茱萸多糖的最佳工艺条件.采用响应曲面优化试验方法,以山茱萸多糖的提取率为响应值,物料比、微波时间、微波功率为因素.最终得到最佳工艺条件为:物料比0.05(1:19),微波功率541.17 W,微波处理时间8.87 min.在该条件下,多糖提取率为12.34%±0.50.     

气相色谱法测定硬脂酸甲酯催化加氢产物中十八醇的含量

建立了气相色谱法测定硬脂酸甲酯催化加氢产物中十八醇含量的方法,从而能够简便地对实验室合成十八醇方法的可行性及有效性进行评估.考察了氢气压强、载气压强、空气压强和色谱柱温度等因素对硬脂酸甲酯催化加氢产物分离分析的影响.选定的最佳分离条件为：氢气压强为0.08 MPa,载气（N2）压强为0.18 MPa,空气压强为0.1 MPa,色谱柱温度为205℃.在这种条件下,十八醇能够在5 min得到分离检测.最终测得实验室采用的两种不同合成条件下产物1和2中十八醇的含量分别为8.7%和30.1%.结果表明,合成条件2优于合成条件1,但仍需改进以提高十八醇的产率.     

磁处理对金针菇菌丝体生长的生物学效应研究

为了筛选最佳磁处理条件,为磁处理在金针菇菌种生产中的有效应用提供理论依据和参数,以金针菇菌丝体为对象,用6、12、17、27mT四种磁感应强度进行不同时间的磁处理,研究磁场对金针菇菌丝体生长所产生的正负生物学效应,从而筛选出具有正生物学效应的最佳磁处理条件.结果表明不同磁处理条件对金针菇菌丝体生长所产生的生物学效应不同.适当条件的磁处理能够产生良好的正生物学效应,从而能够促进金针菇菌丝体的生长.本实验中,对金针菇菌丝体生长具有正生物学效应的最佳磁处理条件为:27mT/50min.     

滑动摩擦力的“五性”

一、条件性滑动摩擦力产生的条件有三点:(1)接触面不光滑;(2)相互接触的物体间有弹力存在;(3)物体间存在相对运动或相对运动趋势.这三个条件,缺一个则滑动摩擦力为零.但当滑动摩擦力为零时,不具备的条件则多种多样.     

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?     

汉字倒说

汉字的六书,《说文》对“转注”一类,语焉不详。后世学者提及转注,也仅限于许慎所举出的例字。《汉字例说》一文,作者从转注的角度综合考虑,对部分现代常用字作了分析,跟传统的解释有所不同。希望能抛砖引玉,互相切磋,以推进学术研究。     

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…     

钱生钱!

我们绝大部分人都同意一件事情——我们喜欢金钱。但是你对金钱的喜欢之情足够到让你创立一份事业么?.财富通常被人忽视,主要在于人们不能真正了