共查询到20条相似文献，搜索用时 78 毫秒
1.
采用1，4—丁二醇水溶液的高沸醇溶剂法，从松木、杉木、稻草等原料制备纤维素与木质素。使用上述材料，在70％—90％1，4—丁二醇水溶液中添加少量催化荆、并在190℃-220℃条件下蒸煮1—3小时的方法制得纤维素和木质素。高沸醇法制得的纤维素可用于造纸，纤维素的聚合度在一定范围内可以调节。不溶于水的高沸醇(HBS)木质素则可以通过加水沉淀的方法，从反应后的液体混合物中分离。HBs木质素具有较高的反应活性，通过进一步改性，还有更多潜在的应用价值。回收的高沸醇溶剂，可作为制浆溶剂循环使用。高沸醇溶剂法是一种适用于从木材、草木秸秆类原料剞备纤维素与木质素，且具有节能、环保等众多优点的好方法。 相似文献
2.
3.
4.
5.
6.
HBS木质素的制备方法及其性质 总被引：1，自引：0，他引：1
1 .前言 :木质素是一种无定形带芳香的网状聚合物 ,在自然界中的含量仅次于纤维素。在自然界中含有木质素大约 3× 1 0 1 1 吨 ,而每年生成的木质素约 2× 1 0 1 0 吨。[1 ] 木质素结构相当复杂 ,在木材中木质素、纤维素和半纤维素相互渗透 ,形成交互贯通的网状结构 ,用普通的方法难以把木质素从这个网络中分离出来。近年来 ,许多研究者正致力于造纸厂黑液中木质素的分离和应用。高沸醇溶剂 (ＨＢＳ)法是纸浆制备的新工艺 ,具有无污染、节能等特点。[2 ] 本文介绍了用高沸醇溶剂法从松木和杉木中获得木质素的制备方法及其产品性质。2 .结果… 相似文献
7.
利用高沸醇木质素和甘油合成松香改性树脂,测定改性树脂的软化点、酸值、DSC-TGA曲线,并与原料松香进行比较.实验结果表明高沸醇木质素可以替代部分甘油改性松香树脂,松香的软化点、酸值、粘度以及耐热稳定性通过高沸醇木质素的改性得到改善.结果还表明用高沸醇木质素制备松香改性树脂比木质素磺酸钙改性效果更好. 相似文献
8.
9.
10.
11.
12.
《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
13.
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
14.
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
15.
16.
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
17.
Rajesh Kanoi 《海外英语》2007,(1):52
Today, Sunday morning, I sit thinking and typing at my computer. My thoughts are in my homeland, India and my body is in China. The body is here and mind there for a good reason. Mr. Hu is president and I am resident and both are in each other's countries (what a difference the absence of one small letter makes!). Mr. Hu will return in a few days and I will stay on longer. 相似文献
18.
正A One day a pig went to the stable(马棚)to see his good friend,an oldhorse,and was going to stay there forthenight.Night came and it was time forsleep.The pig went into the straw heap(稻草堆)and lay comfortably.A longtime passed,but the horse was stillstanding there and did not move.Thepig asked the horse why he did not go tosleep."Standing like this is the begin-ning ofsleeping,"answered the horse. 相似文献
19.
《今日中学生》2014,(9)
正1.Any fool can count the seeds in an apple.Only God can count all the apples in one seed.2.Happy families are all alike;every unhappy family is unhappy in its own way.3.Memories are the key not to the past,but to the future.4.Sometimes in the dark you see what you want to see.5.There is a great difference between 相似文献
20.
《重庆大学学报(英文版)》2014,(2)
正Scope and Policy The Journal of Chongqing University-English Edition(JCQU-E)is a peerreviewed journal publishing research articles in multiple disciplines of science and technology,covering civil and environmental engineering,chemical engineering,biotechnology,mechanical and electrical engineering,computer and data processing,mining,metallurgy,materials science,and interdisciplines thereof. 相似文献