利用蔗渣制备高取代度羧甲基纤维素钠的研究

以蔗渣为原料,经NaOH／H2O2水溶液体系预处理后,得到蔗渣纤维素。以氯乙酸钠为醚化剂,以85％乙醇水溶液为介质,经一次碱化、二次醚化反应后,制得了取代度（DS）为1．32的羧甲基纤维素钠（CMC）。利用红外光谱（FT-IR）、X射线衍射（xRD）、热重分析（TGA）和扫描电镜（sEM）等分析测试手段,对制得样品的结构进行表征,并研究了羧甲基纤维素钠样品的粘度性能。     

微波辅助法由豆渣制备羧甲基纤维素

以豆渣为原料用超声波清洗除杂后,经微波辅助碱化、醚化制备羧甲基纤维素。通过正交试验和单因素考察优化得到的碱化最佳条件是:m豆渣粉∶mNaOH=1∶1~1.5、m豆渣粉∶m95%乙醇=1∶1.6~2.2、微波辐照下在30~35℃时碱化5~10min;醚化的最佳条件是:m豆渣粉∶m氯乙酸(氯乙酸∶碳酸氢钠=1∶0.5~0.6)=1∶1~1.5、m豆渣粉∶m95%乙醇=1∶1.8~2.6,微波辐照下在50~60℃时醚化10~20min后,羧化中水质量分数为30%~40%,可制得高纯度的豆渣CMC。经测定,在最佳制备条件下制得的豆渣CMC产品的取代度和黏度分别达到了1.096 5、596 MPa.s,较无微波辅助时的取代度0.745 2和黏度467MPa.s分别提高了47.1%、27.6%。所制备的CMC达到了GB 1904—1989食品添加剂的性能要求。     

不敏感含能化合物5,7-二氨基-4,6-二硝基苯并连三唑-1-氧化物的合成、表征与性能（英）

以苦基氯和水合肼为原料,经过环化反应和异常亲核取代氢(VNS)反应合成了不敏感含能化合物5,7--二氨基-4,6-二硝基苯并三连唑-1-氧化物(2),总收率为31％.通过1H NMR,13C NMR,FT-IR和元素分析表征了题称化合物及其中间体的结构.优化了VNS反应条件.推测了4,6-二硝基苯并三连唑-1-氧化物(1)环化反应机理.利用量子化学的方法对题称化合物进行了静电势(ESP)和电子轨道的计算.对中间体4,6-二硝基苯并三连唑-1-氧化物和题称化合物进行了物化爆轰及热性能研究.结果表明,确定的适宜的VNS反应条件为:盐酸羟胺为VNS试剂,室温下反应5h.题称化合物具有不敏感特性及良好的热稳定性.化合物1中引入两个氨基后形成的化合物2的密度和热稳定性均有所提高,两种化合物的热分解温度分别为201.3,248.5℃,密度分别为1.73,1.76 g·cm-3,爆速分别为7371.13,7396.7 m·s-1.     

基于视觉特性及低位替换优化的信息隐藏方法

提出了一种在图像载体中进行信息隐藏的新方法。该方法利用图像的视觉特性,通过硬c均值聚类分析进行秘密信息嵌入。通过对简单低位替换的优化调整,在图像的隐藏量和图像质量上都有很大的改进。另外,采用基于时空混沌映射置乱技术对载体图像进行置换及反向置换,对秘密信息提供了有效的安全防护手段。实验结果表明,该方法在改善图像质量及视觉隐蔽性上都取得了较好的结果。     

利用多媒体技术模拟有机化学反应过程

利用现代化教学手段—计算机多媒体技术和3D MAX三维动画设计软件、Photoshop二维绘图功能软件、Visual Basic程序设计语言软件,对卤代烃亲核取代反应机理,设计制作CAI课件的过程、特点及其应用。该课件形象模拟卤代烃的SN1反应机理、SN2反应机理、离子对机理和邻近基团参与机理等,生动活泼、惟妙惟肖。用于教学中,教学效果极好,极大地调动了学生的学习兴趣和积极性。     

Na和Ti掺杂对Bi_2(Zn_(1/3)Nb_(2/3))_2O_7陶瓷性能的影响

采用传统固相反应法制备了Na-Ti掺杂Bi2(Zn1/3Nb2/3)2O7陶瓷。研究了Na+替代Bi3+,Ti4+替代Nb5+对Bi2(Zn1/3Nb2/3)2O7陶瓷烧结特性、显微结构和介电性能的影响。结果表明,掺入Na+和Ti4+后,Bi2(Zn1/3Nb2/3)2O7陶瓷的烧结温度从1000℃降到了860℃左右;在–30℃～+130℃的温度范围内,Na-Ti掺杂Bi2(Zn1/3Nb2/3)2O7陶瓷表现出明显的、激活能约为0.3eV的介电弛豫现象。这主要是由缺陷偶极子和晶格畸变在陶瓷中的出现引起的。     

Recent trends in the chemistry of 2-aminobenzothiazoles

The chemistry of 2-aminobenzothiazoles has gained increased interest in both synthetic organic chemistry and biological fields, since a large number of developments in the use of such compounds, covering the literature up to 2007, seem to be of considerable value. The present review presents their synthetic methods and chemical reactions. The reactions are subdivided in groups that cover reactions at the amino substituent without touching the benzene ring and reactions which involve both nitrogen in the formal amidine system to give fused heterocyclic systems. Most imaginable reaction types have been successfully applied and used, as many of the synthesized compounds exhibit interesting biological activity in various fields.     

Asymmetry in object substitution masking occurs relative to the direction of spatial attention shift.

A sparse mask that persists beyond the duration of a target can reduce its visibility, a phenomenon called object substitution masking. Y. Jiang and M. M. Chun (2001a) found an asymmetric pattern of substitution masking such that a mask on the peripheral side of the target caused stronger substitution masking than on the central side. Assuming spatial attention was focused toward the target, the peripheral and central masks were located in the same and opposite direction of an attentional path with reference to the target in their study. We hypothesized that this asymmetric mask configuration relative to the attentional shift contributes to asymmetric substitution masking. To test this hypothesis, we conducted four experiments among which the presence or absence of the center–periphery relationship and the presence or absence of the asymmetric mask configuration were manipulated independently and orthogonally. The results suggest that asymmetric substitution masking occurs relative to the direction of spatial attention irrespective of the central–peripheral relation. We propose that the asymmetry in substitution masking might be explained by attentional momentum associated with orienting toward the target. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

中国工业生产的劳动、资本和能源的替代分析

用实证的方法对中国工业生产部门劳动、资本和能源之间的替代与互补关系进行了分析。研究工作以超越对数形式的成本函数为出发点,以局部替代弹性、交叉价格弹性和相对替代弹性为工具,结合1986年—2006年间的年度劳动、资本和能源价格的有关数据,对劳动或资本价格的下降所导致的能源使用比例下降效果进行了计算。计算结果表明:放开能源市场、容许能源价格按照市场供求关系上浮,是降低经济结构中能源消耗的一条可行路径;虽然下降幅度相当有限,但是资本或劳动价格的下降都可以减少能源使用比例,其中能源对劳动的替代程度要高于能源对资本的替代程度。     

Effects of climate change on biomass production and substitution in north-central Sweden

In this study we estimate the effects of climate change on forest production in north-central Sweden, as well as the potential climate change mitigation feedback effects of the resulting increased carbon stock and forest product use. Our results show that an average regional temperature rise of 4 °C over the next 100 years may increase annual forest production by 33% and potential annual harvest by 32%, compared to a reference case without climate change. This increased biomass production, if used to substitute fossil fuels and energy-intensive materials, can result in a significant net carbon emission reduction. We find that carbon stock in forest biomass, forest soils, and wood products also increase, but this effect is less significant than biomass substitution. A total net reduction in carbon emissions of up to 104 Tg of carbon can occur over 100 years, depending on harvest level and reference fossil fuel.