基于牛顿多边形的曲线亏格公式

曲线的亏格数是重要的双有理不变量,曲线的分类问题便由亏格数给出解答．文中给出了一种计算不可约曲线的亏格的新公式,通过给出一条不可约曲线所对应的牛顿多边形,可以建立单项式变换,因此利用单项式变换达到对曲线奇点的分解,并得到曲线亏格公式中所需的其他变量,这种算法能够更直观更快速的计算曲线的亏格．     

断裂力学的工程应用

脆性破坏是零件失效的主要形式之一,传统的防脆断方法要么很保守要么照样产生脆性破坏.从断裂力学的角度讨论带裂纹体在实际工程中的应用.     

再谈“李广难封”

李广难封的主要原因是军功不够。李广将军所遭遇的匈奴兵力的强大,以及李广自身的一些弱点,是导致军功不够的直接原因,而其中也包含了一些偶然因素,因此,要分析李广难封的原因需要从主客观两方面来分析,同时不能忽视偶然因素的作用。     

聚合物混合膜修饰玻碳电极的制备

应用循环伏安法制备聚茜素红（Alizarin Red）和溴甲酚绿（Bromocresol Blue）混合膜修饰玻碳电极,并研究其应用．探讨影响聚合物混合膜修饰电极制备的因素,研究pH值以及不同支持电解质等制备条件对该修饰电极性能的影响,并研究其对氯霉素（Chloramphenicol,CAP）的电催化作用．     

影响科技学术期刊学术质量的能力因素——兼与蓝华和于渤商榷

影响科技学术期刊学术质量的主要能力因素为作者的信息捕捉能力、创新思维能力、归纳梳理能力、语言表达能力及编辑和审稿专家的赏鉴能力,而不仅是作者的单位、职称、学历及课题的级别等.     

数字出版网络影响因子研究

网络影响因子是某一时刻链接到网络上某一特定网站或区域的网页数与这一网站或区域本身所包含的网页数的比值,可以用于对期刊网站进行评价.搜索引擎有AltaVista、Fast、Coogle.通过开发专业搜索引擎来完善网络影响因子的计算.     

大学图书馆服务地方60年述略及思考

新中国成立后,大学图书馆服务地方的工作经历了不同的发展阶段,虽然进行了一些有益的尝试,但由于思想观念、主客观条件、社会大环境等因素的制约,发展十分缓慢。21世纪后,大学图书馆应肩负社会公益服务使命、转变服务理念、重新进行服务定位、拓展服务内容、积极开展理论与实践研究,从而更好地为地方政治、经济与文化发展服务。     

Science Letters：IGFBP7 plays a potential tumor suppressor role against colorectal carcinogenesis with its expression associated with DNA hypomethylation of exon 1

Insulin-like growth factor binding-protein-7 （IGFBP7） was obtained from our previous colonic adenocarcinoma （CRC） and normal mucosa suppression subtraction hybridization （SSH） cDNA libraries. By RT-PCR and immunohistochemistry, we found that IGFBP7 was overexpressed in CRC tissue compared to normal tissue. However, our in vitro experiments performed in 10 CRC cell lines showed that IGFBP7 expressed only in SW480 and Caco2 cell lines, which implied an underlying reversible regulatory mechanism. Using methylation-specific PCR （MSP） and bisulfite sodium PCR （BSP）, we found that its expression was associated with DNA hypomethylation of exonl. This was further supported by the in vitro study which showed restored IGFBP7 expression after demethylation agent 5-aza-2＇-deoxycytidine treatment. Correlation analysis between IGFBP7 expression and prognosis indicated that overexpression of IGFBP7 in CRC tissue correlated with favourable survival. Investigation of the functional role of IGFBP7 through transfection studies showed that IGFBP7 protein could inhibit growth rate, decrease colony formation activity, and induce apoptosis in RKO and SW620 cells, suggesting it a potential tumor suppressor protein in colorectal carcinogenesis. In conclusion, our study clearly demonstrated that IGFBP7 plays a potential tumor suppressor role against colorectal carcinogenesis and its expression is associated with DNA hypomethylation of exon 1.     

Proliferation of endothelial cell on polytetrafluoroethylene vascular graft materials carried VEGF gene plasmid

Objective： To investigate whether vascular endothelial growth factor （VEGF） gene plasmid carried by polytetrafluoroethylene （PTFE） vascular graft materials could transfect endothelial cells （ECs） and promote their growth. Methods： PTFE vascular graft materials carried with pCDI-hVEGF121, pCDI or pEGFP were incubated in Tris-buffer solution and the values of optical density of 260 nm at different time were plotted, then the DNA controlled release curve was made. ECs derived from human umbilical vein were seeded on the pCDI-hVEGF121/pCDI/pEGFP-PTFE materials or tissue culture plates, ECs numbers were counted and VEGF protein concentrations at different time were measured by enzyme-linked immunoadsorbent assay method. Green fluorescent protein （GFP） expression in ECs on pEGFP-PTFE materials was examined with fluorescence mi- croscopy. Results： The controlled release curve showed that the gene released from PTFE materials was rapid within 8 h, then slowed down and that the gene released continuously even after 72 h. At 24, 72 and 120 h, ECs number and proliferation rate of pCDI-hVEGFI21-PTFE materials were higher than those ofpCDI or pEGFP-PTFE materials （P〈0.05）. VEGF protein concentration of pCDI-hVEGF121-PTFE materials was higher than that of pC DI or pEGFP-PTFE materials at 6, 24, 72 and 120 h （P〈0.01）. GFP expression in ECs on the pEGFP-PTFE materials could be detected by fluorescence microscopy. Conclusion： PTFE graft can be used as a carrier of VEGF gene plasmid, VEGF gene carried by PTFE can transfect ECs and promote ECs growth.     

如何提高《毛泽东思想概论》课教学的针对性

文章针对提高《毛泽东思想概论》课教学的针对性提出了四项有关措施。