铁铵矾为催化剂对合成乙酸仲丁酯的影响研究

以铁铵矾为催化剂,对冰乙酸与仲丁醇之间的酯化反应进行了研究,考察了催化剂用量、酸醇摩尔比、反应时间对合成乙酸仲丁酯的影响,结果表明:铁铵矾有一定催化活性。当冰乙酸物质的量为0.12mol,冰乙酸、仲丁醇及铁铵矾的摩尔比为1∶2∶0.12,催化剂质量为7.0g,反应2.5h后,收率可达75.12%,所得产品无色透明。     

智能站二次设备的运行分析

比较了智能变电站与常规站的管理和结构特点,深入研究了二者的差异以及智能变电站二次设备运行的调试、维护等相关问题,并且提出了几点建议,以期对实际工作起到一定的指导作用。     

中专计算机教学中如何提高学生能力水平

目前,在任何一个行业的发展中都离不开计算机。因此,中专教学中需要将计算机教学作为重点,以其为基础创新教学方法,提升学生的能力水平。就当前计算机教学中存在的问题,对如何改变教学方式、提升学生的综合能力进行了分析。     

变电站电气二次系统自动化设计分析

通过分析自动化变电站的特点,探讨了变电站电气二次系统的自动化设计,以期为变电站二次系统的设计人员提供参考。     

长链α-烯烃在有机硅产品中的应用

长链烷基的引入赋予了有机硅产品更好的脱模、润滑、消泡等特殊性能,获得了广泛应用。该文系统地介绍了长链烷基硅烷偶联剂、长链烷基硅油及二次加工品的合成及用途,并对其应用前景进行了展望。引文11 篇。     

《动态网站开发》课程教学改革探索

《动态网站开发》课程是中职学校计算机专业的核心课程,传统的授课方式以讲授理论为主,实际操作较少,这种方式很难适应现在中职学校的教学,必须打破传统的教学理念,对《动态网站开发》课程进行改革。     

LTE小区搜索中一种新的SSS检测算法

主要研究了SSS检测, 提出一种新的SSS检测算法。该算法首先利用滑动平均窗修正接收的PSS处估计出的信道频率响应, 并用修正后的信道频率响应对接收的SSS序列进行信道补偿; 其次, 算法对信道补偿后的序列进行实数提取操作, 消除虚部数据干扰; 最后算法联合两个连续的SSS接收序列进行检测进一步提高检测性能。TDD和FFD两种模式下的仿真结果表明：该算法可以较好地实现SSS检测且比现有几种SSS检测算法在低信噪比（SNR<0 dB）条件下具有更好的检测性能。     

Use of polymeric nitrosation reagents for the N‐nitrosation of secondary amines under mild and heterogeneous conditions

A combination of crosslinked poly(4‐vinylpyridinium)chloride [P₄‐H]Cl ( I ) and sodium nitrite or quaternized crosslinked poly(N‐methyl‐4‐vinylpyridinium)nitrite [P₄‐Me]NO₂ ( II ) was used as effective nitrosating agents for the N‐nitrosation of secondary amines under mild and heterogeneous conditions in moderate to excellent yields. The spent polymeric reagents can usually be removed quantitatively and regenerated. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1064–1067, 2007     

石油系二元族烃型橡胶增塑剂

以重油催化裂化装置生产的重组分油为原料，采用二次脱沥青精制工艺，可制备二元族烃型橡胶增塑剂。该增塑剂与国外同类产品的质量相当，仅凝点有一定差距，前者为２９．０℃，后者为－１０．６℃。应用试验表明，该产品替代传统增塑剂，且添充后硫化胶综合胶综合性能良好，耐磨性能优于添加传统增塑剂者。     

Family of G protein {alpha} chains: amphipathic analysis and predicted structure of functional domains

The G proteins transduce hormonal and other signals into regulationof enzymes such as adenylyl cyclase and retinal cGMP phosphodiesterase.Each G protein contains an subunit that binds and hydrolyzesguanine nucleotides and interacts with ß subunitsand specific receptor and effector proteins. Amphipathic andsecondary structure analysis of the primary sequences of fivedifferent chains (bovine _s, _t1 and _t2, mouse _i, and rat _o)predicted the secondary structure of a composite chain (_avg).The chains contain four short regions of sequence homologousto regions in the GDP binding domain of bacterial elongationfactor Tu (EF-Tu). Similarities between the predicted secondarystructures of these regions in _avg and the known secondary structureof EF-Tu allowed us to construct a three-dimensional model ofthe GDP binding domain of _avg. Identification of the GDP bindingdomain of _avg defined three additional domains in the compositepolypeptide. The first includes the amino terminal 41 residuesof _avg, with a predicted am phipathic helical structure; thisdomain may control binding of the chains to the ßcomplex. The second domain, containing predicted ßstrands and helices, several of which are strongly amphipathic,probably contains sequences responsible for interaction of chains with effector enzymes. The predicted structure of thethird domain, containing the carhoxy terminal 100 amino acids,is predominantly ß sheet with an amphipathic helixat the carboxy terminus. We propose that this domain is reponsiblefor receptor binding. Our model should help direct further experimentsinto the structure and function of the G protein chain.