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nanohero

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11楼2011-10-18 14:48:13
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nanohero

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12楼2011-10-18 14:51:01
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585368yaya

铜虫 (小有名气)

引用回帖:
7楼: Originally posted by baigang at 2011-10-18 14:13:28:
i learn a new word : postgraduate

Your image r so cute~
13楼2011-10-18 15:00:07
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holypapa

木虫 (职业作家)

引用回帖:
4楼: Originally posted by mooncakexzj at 2011-10-18 14:03:14:
Everything can change in the blink of an eye

just as it was said by xiaoshenyang , with your eyes being openned and closed once ,in the blink of an eye,one day has passed. and with your eyes being closed and never openned again,that is  in the no  blink of an eye, a whole life has passed. So the blink of  an eye is very significant. please try to blink your eyes as often as possible and never stop.

Aappleadaykeepsdoctoraway.
14楼2011-10-18 16:25:46
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nanohero

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15楼2011-10-18 17:24:19
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nanohero

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16楼2011-10-18 17:26:23
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张冬凯-

铜虫 (小有名气)

The addition of nitrogen oxides and other sources of NO2 across the double bonds of alkenes is an important route to nitro compounds. Alkenes react with dinitrogen tetroxide in the presence of oxygen to form a mixture of vic-dinitro(a), β-nitro-nitrate ester (b) and β-nitro-nitrite ester(c) compounds; the nitrite ester being oxidized to the nitrate ester in the presence of excess dinitrogen tetroxide. A steam of oxygen gas is normally bubbled through the reaction mixture to expel nitrous oxide formed during the reaction and so prevent more complex being formed. These reactions can be synthetically useful for the synthesis of vic-dinitroalkanes because nitrate and nitrous ester by -products are chemically unstable and are readily hydrolyzed to the corresponding β-nitro alcohol on treatment with methanol.
        1,2-Dinitroethane and 1,2-dinitrocyclohexane can be formed in this way from corresponding alkenes in 42% and 37% yield respectively.
        the addition of dinitrogen tetroxide across the double bonds of electrons deficient fluorinated alkenes is a particularly useful route to  vic-dinitro compounds where yields are frequently high, tetrafluoroethylene gives a 53% yield of 1,2-dinitro-1,1,2,2-tetrafluoroethane.
没有最牛逼,只有更牛逼
17楼2011-10-18 18:01:38
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zzyhyuan

木虫 (著名写手)

As we all know,it is so hard to find out what to eat in the university canteen.Everyday every-meals,and yes,not a bit change at all.
原来爱本身可爱在于束缚
18楼2011-10-18 19:43:26
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19楼2011-10-18 20:54:20
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witch_girl

金虫 (文坛精英)

yes, it is.
Make it or Break it
20楼2011-10-18 22:37:42
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