离子色谱法测定黑炭标志物苯多羧酸的含量

基于苯多羧酸的阴离子特性,建立了离子色谱电导检测器测定黑炭标志物——苯多羧酸含量的方法。采用IonPac AS11-HC阴离子色谱柱(4×250 mm),以KOH为淋洗液进行梯度洗脱,进样量为25μL、流速1.0 mL/min的条件下,测定热解碳经硝酸氧化后的产物中苯多羧酸的含量。结果表明6种苯多羧酸质量浓度在0.1～40.0 mg/L内线性良好,r~2≥0.997 9,检测限在0.016 50～0.069 08 mg/L之间,加标回收率在75.2%～101.0%,方法准确可靠。     

聚苯胺膜修饰电极测定废水中的硝酸根离子

采用恒电位电解法在铂电极上制备了导电聚苯胺膜.研究了在给定氧化还原电位下,聚苯胺膜修饰电极对硝酸根离子的响应电流随硝酸根离子浓度的变化关系.峰电流与硝酸根离子浓度在0.01～0.50mol/L浓度范围内呈线性关系,相关系数为r=0.9928,用于废水中的硝酸根离子测定,结果较为满意.     

南阳烟区土壤养分状况及施肥技术

对南阳烟区植烟土壤519个混合土样进行了分析,结果表明,南阳烟区土壤的pH值平均为7.23,有93.8%的土壤处在5.8～8.0之间;土壤有机质平均含量为1.186%,有79.8%的土壤有机质含量在1.0～1.5%之间;土壤全氮含量平均为0.082%,有效氮含量平均为57.7mg/kg,有76.3%的土壤有效氮在30～65mg/kg之间;土壤全磷含量平均为0.046%,有效磷平均为13.06mg/kg; 土壤全钾含量平均为1.62%,有效钾为1 57.09mg/kg,有85%的土壤有效钾含量在1 00mg/kg以上,根据南阳烟区植烟土壤的养分状况,提出了相应的施肥措施.     

碱性过硫酸钾法总氮测定波长的探究

验证了硝酸根最大吸收峰波长能否作为总氮测定波长及不同波长对总氮测定结果的影响。结果表明,通过波长扫描0.08~2.8 mg/L硝酸根,发现最大吸收峰并非在220 nm,而出现在200~210 nm。采用碱性过硫酸钾法测定水体中的总氮含量,200~210 nm存在盐酸吸收峰干扰,但在211~220 nm波长范围内均有良好的线性关系。不同波长对加标回收率、重现性、精密度及方法检出限检验影响不大。随着测定波长的减小,标准曲线的斜率、相关系数R、摩尔吸光系数依次增加。211 nm处摩尔吸光系数达6.8×103(mol/L)-1/cm,远高于220 nm。同时,211 nm处标准曲线拟合斜率K更大。在实际地表水的测定中,以最大吸收峰(211nm)处测定总氮,与国标220 nm处测定相比较,结果并无明显差异。     

水培与土培离子液体[C_2mim][Val]对小麦的影响

为考察离子液体在水和土壤不同环境介质中对高等植物的潜在毒性,分别采用水培和土培试验方法研究了不同浓度(0、100、200、300、400、500 mg/kg)的离子液体1-甲基-3-乙基-咪唑缬氨酸盐([C2mim][Val])对小麦发芽率(7 d)及生理特性(8～18 d)的影响。实验结果表明:两种培养方式下,离子液体在浓度≥200mg/kg时对小麦种子萌发产生显著的抑制作用,且抑制效应具有典型的剂量依赖型特点。水培胁迫13 d,离子液体浓度≥300 mg/kg处理,及土培胁迫18 d,离子液体浓度≥400 mg/kg时,均造成小麦幼苗叶片SOD、POD酶活性降低,MDA含量显著升高。表明较高浓度的离子液体对高等植物具有一定的毒害作用,水培比土培加重了离子液体对小麦的毒害程度。     

不同病情魔芋植株根际土壤营养成分研究

为探明不同病情魔芋(Amorphophallus konjac)植株根际土壤的营养成分差异及其与病情的相关性。以丹凤凯农魔芋种植基地为调查对象,对不同发病情况样地的根际土壤进行采样及营养成分比较分析。结果显示,六个样地的土壤样本在有机质、速效氮、速效磷、速效钾、全氮含量以及pH等方面均存在显著性差异。在调查的土壤样本中,正常生长植株根际土壤的有机质、速效钾、全氮含量均显著高于发病植株,而速效氮、速效磷呈现不一致的结果。有机质和全氮含量以阳河村最高,分别达2.15%和0.1%;速效钾含量以南丈沟村最高,达131.5 mg·kg~(-1)。魔芋根际土壤中有机质、速效钾、全氮的含量可能是影响魔芋软腐病发生的关键营养因子。建议在魔芋栽培管理中,适当控制磷肥,而增加有机质和钾肥增强魔芋植株的抗病能力。     

离子色谱法测定大气中的氮氧化物

为简便、快速地测定空气中氮氧化物的含量,建立以内含质量分数为0.9%过氧化氢的混合溶液(混合溶液由2.2 mmol/L的Na2CO3和2.7 mmol/L的NaHCO3组成),混合溶液为吸收液,吸收大气中的氮氧化物,使大气中的氮氧化物全部转变为硝酸根.用离子色谱法测定表明,吸收剂中硝酸根在0.1～60μg/mL的浓度范围,峰面积与浓度之间呈良好的线性关系,回归方程为Y=779563X 7021,相关系数为0.9996,检出限为0.002μ/g/mL.此方法简便、快速、准确、选择性好,对环境无二次污染,完全满足环境监测对大气中氮氧化物的测定.     

芹菜不同部位黄酮含量与抗氧化性量效关系的分析

对芹菜不同部位黄酮化合物进行提取,采用光谱法对其含量进行分析.测定波长为510 nm,线性范围为0.2557～0.7670 mg/mL,方法的回收率为101.5％～104.6％,变异系数小于0.27％.用流动注射化学发光法分析了芹菜不同部位的抗氧化性,实验结果表明芹菜中含有丰富的黄酮类化合物.芹菜不同部位中黄酮化合物含量不同,芹菜叶中黄酮含量最高,芹菜根中黄酮含量次之,而芹菜茎中黄酮含量最低.芹菜具有较强的抗氧化性,芹菜不同部位抗氧化性不同,芹菜叶的抗氧化性最强,芹菜根次之,而芹菜茎中抗氧化性最低.芹菜不同部位即根、茎、叶中黄酮类化合物含量与抗氧化性增加趋势相同.芹菜根、茎、叶的黄酮含量与抗氧化性呈现明显的量效关系.     

土壤介质中镉污染对辣椒的影响

以盆栽辣椒为试验材料,用不同浓度的外源Cd处理土壤,观察记录辣椒的生长变化同时监测辣椒根、茎、叶、果实对Cd的累积吸收量;通过线性方程确定安全种植辣椒的Cd污染土壤的阈值.结果表明,随着土壤中添加的外源Cd量的增加,辣椒的长势明显变差,产量均小于对照,辣椒的根、叶、果实对Cd的吸收随着外源Cd量的增大而呈上升趋势,Cd在根内的积累大于在茎、叶、果实中的积累.当外源Cd质量浓度达到1.0 mg· kg^-1时,辣椒中的Cd含量可达到0.069 mg·kg^-1,超出GB2762-2005食品中污染物限量.该论文的工作为建立更加完善的绿色辣椒生产提供参考.     

萘乙酸处理葡萄苗木根系的效应

1994～2000年对萘乙酸(NAA)处理葡萄(玫瑰香)苗木根系的促根作用、生理反应、高质量浓度下促进皮层组织异常生长的机制进行了探讨。结果表明，100mg／L NAA可有效增加葡萄根量和促进新根生长；促进根皮内蛋白质水解，新根内蛋白质含量增加；高质量浓度的NAA(800mg／L)诱使葡萄根系皮层异常生长，表现为皮层组织松软肿胀，含水量显著增加，离子外渗显著增多，组织液质量浓度明显降低；通过切片观察，高质量浓度的NAA处理的葡萄根皮组织异常分裂而膨胀，最终解体。     

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.