知识经济时代科技情报机构面临的挑战与机遇

阐述了知识经济及知识经济时代的特征,探讨了知识经济时代给科技情报机构带来的挑战和发展机遇。     

Cloning,sequencing of the HSC70 gene in Ctenopharyngodon idella

A cDNA encoding heat shock cognate protein 70(HSC70)was cloned from liver of grass carp(Ctenopharyngodon idella)(GenBank JF436930).This cDNA was found out to contain2 346 bp in length,including 1 950 bp of complete coding sequence encoding 649 amino acids(aa),plus 89 bp of 5′-UTR and 307 bp of3′-UTR.Analysis of its genomic structure revealed that its corresponding gene contained seven exons and six introns.Homology analysis indicated that it shared 99%of identity with HSC70 of breams and 86%of identity with HSP70 of Drosophila.Fluorescent RT-PCR analysis revealed that at 28℃,this gene was expressed in abdominal fat,muscle,intestines,brain,middle kidney,head kidney,gonads,swim bladder,liver,heart,spleen,gills,and fins with expression level in liver being the highest(p0.05),followed by that in the gonads;at 36℃,its mRNA expression level was increased at first but then decreased thereafter under heat shock stress,indicating that its expression can be regulated by heat shock.In conclusion,cloning and expression analysis identified a cDNA encoding a constitutive HSP70 gene that is expressed in many tissues of Ctenopharyngodon idella and its expression was down-regulated by heat shock.     

一种三转动并联机构的运动学及解耦性分析与仿真

对一种支链含等速万向节的RRR-PaRRS-RHJ型三转动并联机构的运动学及其解耦特性进行分析.首先,对机构进行运动特性分析和自由度计算.然后,通过构件间的几何关系对机构进行运动学分析,给出机构位置正、逆解析解,推导出机构在定坐标系和动坐标系下的速度雅克比矩阵,根据雅可比矩阵分析此机构在不同坐标系下表现的不同耦合性.最后,运用ADAMS软件进行运动学仿真,验证了理论分析的正确性.     

低发射率伪装绿色涂层的制备和性能分析

为了探索军用低发射率伪装材料,提出了复合结构设计的方法。选用具备可见光高透过和红外高反射特性的纳米锑掺杂氧化锡(ATO)薄膜,通过镀膜工艺对复合涂层的结构进行设计,从而达到光学与红外隐身兼容的目的。利用分光光度计、热成像仪及隔热测试装置对所制复合涂层样品的光学、红外和隔热效果进行测试,分析低发射率涂层对整体绿色涂层的光学及红外性能的影响。实验结果表明,采用复合结构设计后的绿色涂层样板的可见光透过率达到80%以上,红外反射率达到70%以上,在保证色彩饱和度的同时,发射率显著降低,达到了0.2。经过复合结构设计的绿色涂层拥有良好的红外伪装效果,能够较好地躲避红外侦察。     

Conductive and corrosion behaviors of silver-doped carbon-coated stainless steel as PEMFC bipolar plates

Ni–Cr enrichment on stainless steel SS316L resulting from chemical activation enabled the deposition of carbon by spraying a stable suspension of carbon nanoparticles; trace Ag was deposited in situ to prepare a thin continuous Ag-doped carbon film on a porous carbon-coated SS316L substrate. The corrosion resistance of this film in 0.5 mol·L-1 H₂SO₄ solution containing 5 ppm F- at 80℃ was investigated using polarization tests. The results showed that the surface treatment of the SS316L strongly affected the adhesion of the carbon coating to the stainless steel. Compared to the bare SS316L, the Ag-doped carbon-coated SS316L bipolar plate was remarkably more stable in both the anode and cathode environments of proton exchange membrane fuel cell (PEMFC) and the interface contact resistance between the specimen and Toray 060 carbon paper was reduced from 333.0 mΩ·cm2 to 21.6 mΩ·cm2 at a compaction pressure of 1.2 MPa.     

Microstructure evolution and thixoforming behavior of 7075 aluminum alloy in the semi-solid state prepared by RAP method

The effects of isothermal treatments on the microstructural evolution and coarsening rate of semi-solid 7075 aluminum alloy produced via the recrystallization and partial remelting (RAP) process were investigated. Samples of 7075 aluminum alloy were subjected to cold extrusion, and semi-solid treatment was carried out for 5–30 min at temperatures ranging from 580 to 605°C. A backward-extrusion experiment was conducted to investigate liquid segregation during the thixoforming process. The results revealed that obvious grain coarsening and spheroidization occurred during prolonged isothermal treatments. In addition, higher soaking temperatures promoted the spheroidization and coarsening process because of the increased liquid fraction and the melting of second phases. Segregation of the liquid phase caused by the difference in fluidity between the liquid and the solid phases was observed in different regions of the thixoformed specimens.     

TMC的室内配方研究

钻井液转变成水泥的技术简称MTC技术。本文选用自制的分散剂F-2,有机缓凝剂,早强剂及激活剂进行了大量的MTC配方筛选。不同的温度条件下,在室内成功地进行了MTC转化。经辽河现场泥浆验证表明:该配方使转化后水泥石三天强度大于10MPa,流变性,稠化时间等浆体性能均满足常规注水泥要求。     

梳形聚羧酸超塑化剂在水泥颗粒表面的吸附行为

研究了吸附溶液体系温度、pH值和电解质浓度等对甲基丙烯酸-甲氧基聚乙二醇甲基丙烯酸酯(MAA-MPEGMA)梳形聚羧酸共聚物在水泥颗粒表面的吸附行为的影响。聚羧酸共聚物在水泥颗粒表面的吸附呈Langmuir等温吸附模型。吸附量随着温度的升高而降低,表明聚羧酸共聚物在水泥颗粒表面的吸附是一个放热反应。根据Clausius-Clapeyron方程计算吸附热为17.4kJ/mol。聚羧酸共聚物在水泥颗粒表面的标准吸附自由能<0,吸附是自发的。吸附量随着体系pH值的增大、电解质浓度的增大而减小。红外光谱分析表明,聚羧酸共聚物在水泥颗粒表面的吸附是通过分子结构上羧基与Ca2+间的配合作用实现的,说明这种吸附是一种化学吸附。     

Tropic1808基因重组蛋白对损伤坐骨神经脊髓细胞凋亡的影响

探讨Tropic1808基因重组蛋白对损伤坐骨神经的新生大鼠脊髓细胞凋亡影响,将新生SD大鼠一侧坐骨神经切断后,用无菌止血海绵包裹断离的神经近侧端,海绵内加入Tropic1808基因重组蛋白,阳性用神经生长因子、阴性用生理盐水作为对照;术后3、6、12h经TUNEL法染色,在光镜、电镜和图像分析系统下,了解L4－L5段脊髓细胞凋亡情况。得到生理盐水组的脊髓出现大量绸亡细胞;Tropic1808基因重组蛋白组凋亡细胞数量较生理盐水组显减少;Tropic1808基因重组蛋白组与神经生长因子组之间凋亡细胞数量的差别无显性意义。说明Tropic1808基因重组蛋白有保护受损神经组织,减少细胞凋亡的作用。     

A salmonella protein antagonizes Rac-1 and Cdc42 to mediate host-cell recovery after bacterial invasion.

An essential feature of the bacterial pathogen Salmonella spp. is its ability to enter cells that are normally non-phagocytic, such as those of the intestinal epithelium. The bacterium achieves entry by delivering effector proteins into the host-cell cytosol by means of a specialized protein-secretion system (termed type III), which causes reorganization of the cell's actin cytoskeleton and ruffling of its membrane. One of the bacterial effectors that stimulates these cellular responses is SopE, which acts as a guanyl-nucleotide-exchange factor on Rho GTPase proteins such as Cdc42 and Rac. As the actin-cytoskeleton reorganization induced by Salmonella is reversible and short-lived, infected cells regain their normal architecture after bacterial internalization. We show here that the S. Typhimurium effector protein SptP, which is delivered to the host-cell cytosol by the type-III secretion system, is directly responsible for the reversal of the actin cytoskeletal changes induced by the bacterium. SptP exerts this function by acting as a GTPase-activating protein (GAP) for Rac-1 and Cdc42.