谈现代小说中人力车夫形象

通过《一件小事》、《薄奠》和《骆驼祥子》三部作品中的比较分析,从“人力车夫”这一都市劳动人民的主人公形象,我们可以看到其工人阶级的友爱精神和高尚品质,同时,要清醒认识到在旧制度下劳动者的悲剧命运是无法避免的。     

Non-Ligand-Induced Dimerization is Sufficient to Initiate the Signalling and Endocytosis of EGF Receptor

The binding of epidermal growth factor (EGF) to EGF receptor (EGFR) stimulates cell mitogenesis and survival through various signalling cascades. EGF also stimulates rapid EGFR endocytosis and its eventual degradation in lysosomes. The immediate events induced by ligand binding include receptor dimerization, activation of intrinsic tyrosine kinase and autophosphorylation. However, in spite of intensified efforts, the results regarding the roles of these events in EGFR signalling and internalization is still very controversial. In this study, we constructed a chimeric EGFR by replacing its extracellular domain with leucine zipper (LZ) and tagged a green fluorescent protein (GFP) at its C-terminus. We showed that the chimeric LZ-EGFR-GFP was constitutively dimerized. The LZ-EGFR-GFP dimer autophosphorylated each of its five well-defined C-terminal tyrosine residues as the ligand-induced EGFR dimer does. Phosphorylated LZ-EGFR-GFP was localized to both the plasma membrane and endosomes, suggesting it is capable of endocytosis. We also showed that LZ-EGFR-GFP activated major signalling proteins including Src homology collagen-like (Shc), extracellular signal-regulated kinase (ERK) and Akt. Moreover, LZ-EGFR-GFP was able to stimulate cell proliferation. These results indicate that non-ligand induced dimerization is sufficient to activate EGFR and initiate cell signalling and EGFR endocytosis. We conclude that receptor dimerization is a critical event in EGF-induced cell signalling and EGFR endocytosis.     

The sequence of 55 kb on the left arm of yeast chromosome XVI identifies a small nuclear RNA,a new putative protein kinase and two new putative regulators

We have sequenced and analysed a 55 786 bp fragment located on the left arm of chromosome XVI of Saccharomyces cerevisiae. The sequence contains 29 non-overlapping open reading frames (ORFs) longer than 300 bp, among which 12 genes have previously been sequenced: OYE3, REV3, SVS1, BEM4, CDC60, KIP2, PEP4, SPK1, PAL1, KES1, SNR17B and RPL37A. Three new ORFs, P2591, P2594 and P2597 are highly homologous to the human phosphotyrosyl phosphatase activator PTPA, to the pleiotropic regulator PRL1 of PP1 and PP2a protein phosphatases in plants and to the protein kinase PAR-1 in Caenorhabditis elegans, respectively. Three other ORFs, P2545, P2567 and P2578 have significant homology with ORFs of unknown function located on yeast chromosomes VIII, XVI and IV respectively. The sequences in nucleotides and in amino acids have been deposited in the EMBL data library under the Accession Number X96770.     

循环设计理念下可循环拉链邮袋的研究

目的-为进一步加强塑料污染治理,限制塑料制品使用,研究设计可循环拉链邮袋。方法-了解可循环拉链邮袋的总体要求,目前可循环拉链邮袋的使用情况和现状,以及存在的问题。对比社会主流快递企业循环邮袋各项性能指标并分析,设计可循环拉链邮袋并进行实验验证。结果-经过对比,设计完成DL01和DL02两种型号可循环拉链邮袋,采用双头防爆拉链,可循环拉链邮袋循环使用次数可达50次以上。结论-可循环拉链邮袋可实现拉链自锁效果,具有防盗、绿色环保、可循环再利用的特点,对减少塑料制品使用,推动绿色包装发展具有重要意义,为塑料污染治理提供基础。     

细胞注射玻璃微针拉针器的研制

为了解决拉针器国产化的问题,设计出温度、拉力、拉伸速度等参数可变的试验机。以国产玻璃毛细管为拉制原材料,进行了基于方差分析基础上的4组加热温度、拉力、拉伸速度的不同配置的系列实验,分析了在毛细玻璃管拉伸预拉力在1280～1310g强度允许范围内变化及加热温度对针的长度影响,在试验机上进行了用于微流量分析的圆形玻璃微管道拉制试验,研究了拉伸行程及加热温度对微管道内径的影响,实现了仪器的性能多样化。最后提出了拉针器商品化的设计方案。     

稀土金属真空提纯炉的研制

介绍了一种用于稀土金属提纯的单晶炉,根据区熔法提纯单晶的特殊工艺要求,分析了其主要结构及特点。该设备也适用于多种激光晶体的生长和激光晶体的真空退火。     

多色混色POM注塑拉链注射成型机设计

简要介绍了多色混色聚甲醛注塑拉链注射成型机的注射装置、锁模装置、拉链带输送装置、液压系统、气动系统等主要部件结构及成型特征,并对该机的应用与改进进行了概述.     

一起直流调速系统故障处理及原因分析

简要介绍了丰城电厂翻车机系统拨车机直流调速系统工作原理及一次拨车机行走异常故障,对各种可能故障因素进行查找分析,归纳出由于PLC模拟量输出模块故障导致拨车机异常行走的结论,并对同类直流调速系统的维护上作提出了建议。     

The Sequence of 32 kb on the Left Arm of Yeast Chromosome XII Reveals Six Known Genes,a New Member of the Seripauperins Family and a New ABC Transporter Homologous to the Human Multidrug Resistance Protein

The analysis of a 32 kb DNA fragment from cosmid 2G12 on the left arm of chromosome XII identifies 14 open reading frames (ORFs) numbered L0948 to L1325, a new tRNA for proline, a delta remnant and two putative ARS. Six ORFs have been previously identified: HSP104, SSA2, SPA2, KNS1, DPS1/APS and SDC25. Three putative ORFs have significant homology with known proteins: L0968 is a new member of the very large ‘seripauperins’ family, comprising at least 20 yeast members; L1313 is a new ABC transporter highly homologous to the yeast cadmium resistance protein Ycf1p and to the human multidrug resistance protein hMRP1; the C-terminal part of L1325 present in our sequence is very homologous to the fruit fly abdominal segment formation protein Pumilio. Finally, two ORFs, L1201 and L1205, have weak homology with two yeast hypothetical proteins of unknown function identified by the yeast systematic sequencing genome. Since our nucleotide sequence overlaps by 11·6 kb the cosmid 2B18 sequenced by Miosga and Zimmerman (1996) on the right end, we have not reported here the analysis of the ORFs L1313, L1321 and L1325. The complete nucleotide sequence of 32,088 bp and the deduced ORFs were submitted to the EMBL database under Accession Number X97560.© 1997 John Wiley & Sons, Ltd.     

Stabilization of bzip peptides through incorporation of fluorinated aliphatic residues

Two fluorinated amino acids, 5,5,5-trifluoroisoleucine (5TFI) and (2S,3R)-4,4,4-trifluorovaline (4TFV), which have been shown to serve as isoleucine surrogates in protein synthesis in Escherichia coli, have been incorporated in vivo into basic leucine zipper (bzip) peptides derived from GCN4. The extents of residue-specific incorporation of 5TFI and 4TFV were 90 and 88 %, respectively, of the encoded isoleucine residues, as evidenced by MALDI mass spectrometry and amino acid analysis. Both circular dichroism and equilibrium sedimentation studies of the fluorinated bzip peptides indicated preservation of secondary and higher-order protein structure. Thermal-denaturation experiments showed an increase of 27 degrees C in melting temperature when isoleucine was replaced by 5TFI. However, the T(m) of the peptide containing 4TFV was increased by only 4 degrees C over that of the peptide containing valine. Similar trends were observed in chemical denaturation studies in which DeltaDeltaG(unfold) in water was determined to be 2.1 or 0.3 kcal mol(-1) upon incorporation of 5TFI or 4TFV, respectively. When the fluorinated peptides were tested for DNA binding, both their affinity and specificity were similar to those of the respective hydrogenated peptides. These results suggest that fluorinated amino acids, even when introduced into the same positions, can have markedly different effects on the physical properties of proteins, while having little impact on secondary and higher-order structure.