共查询到20条相似文献，搜索用时 62 毫秒
1.
杨蓉 《中国科教创新导刊》1996,(11)
可免氯气有害副作用的饮用水消毒法发达国家广泛采用氯气消毒饮用水，这种作法利弊参半。氯气虽能有效而廉价地杀死水中的载病微生物，但它的副产品却被人们怀疑为是致癌且对环境有害的物质。现在发明家已为美航天局（ＮＡＳＡ）的长期太空飞行设计出一套水的净化系统，他... 相似文献
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本文讨论了溴与碘离子分别进行倍增反应的条件，并以碘量祛对还原产生的碘单质进行滴定。据此，实现了在大量氯离子存在下微量溴与碘的连续测定。结果可靠，方法简便。RSD：Br－2．0％I-1．5％回收率；Br－99％～101％I-99％～101％ 相似文献
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本研究建立了快速溶剂萃取-固相萃取-高效液相色谱（ASE—SPE—HPLC）分析湖泊环境中沉积物、水体及鱼样品中四溴双酚A的方法。沉积物和鱼样品用正己烷-二氯甲烷提取后,与水样一起用固相萃取C18小柱富集纯化,外标法定量,高效液相色谱检测。结果表明,加标浓度0．11000ng·mL^-1四溴双酚A的平均回收率为：96．8799．3％;不同浓度平行测量的相对标准偏差为0．161．00％。应用建立的方法对巢湖湖泊环境样品进行了测定,沉积物四溴双酚A浓度为21．96—481．80μg·kg^-1,水体为0-4．77μg·L^-1,鱼为7．9—83．5μg·kg^-1。 相似文献
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研究了在NH_3．H_2O-NH_4Cl 介质中锰催化 H_2O_2氧化二溴羧基偶氮胂褪色的最佳条件。λ_(max)=565nm，表观摩尔吸光系数为2．6×10~4 L·moL~(-1)·cm~(-1)，线性范围为0～2．1 μg/25 mL。用于水样中痕量锰的测定，结果满意。 相似文献
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在5．3mol·L－1的H2SO4介质中．锗与4．5-二溴苯基荧光酮，十二烷基硫酸钠生成三元配合物。其λmax为509nm，表观摩尔吸光率为1．77×105L·mol-1·cm-1．锗量在0～7μg／25mL遵守比耳定律。显色反应具高选择性，各种低价和高价金属离子均不干扰测定。测定了有机锗口服液中微量锗。 相似文献
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赵家喜 《安徽技术师范学院学报》2001,15(3):52-53
本试验应用0．3％的过氧乙酸和1：3000百毒杀对肉种鸡进行带鸡消毒，以观察带鸡消毒对肉种鸡存活率及生长发育的影响，同时测定鸡体细菌灭活率，试验结果表明带鸡消毒可明显提高肉种鸡存活率（40日龄可提高3．6％，80日龄提高4．1％），而对肉种鸡生长发育无显著影响，鸡体杀菌率可达88．9％。 相似文献
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本文详细研究了新显色剂3，5-二溴苯基荧光酮的离解性质，利用光度法测定其离解常数pk1,pk2,pk3,pk4分别为1.85,5.42,10.51,12.44。与苯基荧光酮试剂比较，该试剂分子引入溴吸电子基团，使试剂的酸性增强，金属离子显色反应灵敏度、选择性有很大的提高。 相似文献
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蒋天智 《黔东南民族师专学报》2003,21(6):27-27
研究了显色剂溴邻苯三酚红在溴化十六烷基三甲基铵存在下，测定六价铬的方法．在pH5．3—5．8范围内，六价铬与溴邻苯三酚和溴化十六烷基三甲基铵生成蓝色络合物，最大吸收波长为635nm．表观摩尔吸光系数为3．64&;#215;10，本法灵敏度高，选择性好，应用于水相中微量铬(VI)的测定，结果满意。 相似文献
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本方法是采用一种较为简单的方法测定含溴阻燃剂中溴含量。它是用氧气瓶法燃烧样品，用H2O2-NaOH溶液作为气体吸收液，将有机物中的Br全部转化为无机的Br。然后用1：1的浓硝酸调节溶液的pH值使吸收液呈强酸性，然后用二苯卡巴腙作为指示剂，用无水乙醇作为胶体保护剂保护HgBr^2胶体。最后用标准硝酸汞作为吸收液的滴定剂，滴定完全后溶液呈现血红色。准确的记录消耗的硝酸汞溶液的量，用公式计算出Br的含量。从该实验可以看出：此种方法的检测范围很宽阔，相对误差小于1%。 相似文献
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《海外英语》2007,(5):10-11
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? 相似文献
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罗艳萍 《读与写:教育教学刊》2008,5(6)
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. 相似文献
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《海外英语》2007,(4):36
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. 相似文献
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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. 相似文献
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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. 相似文献
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RUZBEHANI Mohsen 《重庆大学学报(英文版)》2004,3(1):20-25
1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec… 相似文献
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Richard Denner 《海外英语》2007,(4):14-15
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. 相似文献