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991.
我们在研究伤寒沙门氏菌保护性抗原期间,发现了一个新的不耐热的伤寒沙门氏菌特异性抗原,暂时命名为θ抗原。这个抗原存在于各种类型的伤寒沙门氏菌中,并能从Ty2菌苗株细胞提取。以不吸收的抗θ兔血清作试管凝集时,与O90l和H901菌株的凝集效价分别为1:640和1:320。但与Ty2或9,12,Vi:d:-菌株不发生凝集,这一现象以后证实是由于Vi抗原的存在。θ抗原形成凝集较幔(31℃18~24小时),其所形成的凝集块疏松,易摇散、呈半絮状。菌体经100℃30分钟加热后与θ血清不发生凝集。玻片凝集试验显示θ血清与W和V型伤寒沙门氏菌(后者须培养在含酚培养基上)在1分钟内产生明显凝集。而与大多数D群(包括D_1和D_2)沙门氏菌和其他沙门氏菌不凝集,并与下列肠杆菌科细菌亦不凝集,包括志贺氏菌属A、B、C、D群,大肠艾希氏菌O:1~25和致病性大肠艾希氏菌12个不同的血清型,3株变形杆菌以及含有α抗原的Wakefield茵。化学分析显示,粗制θ提取物含有核酸(491μg/ml)。蛋白质(39μg/ml)和KDO(23μg/ml),但不含有O-乙酰基,表明θ抗原不同于Vi抗原。作者建议以θ血清替代现用的O:9,Vi和d因子血清作为伤寒沙门氏菌的血清学诊断。并需继续查明θ抗原的化学本质。 相似文献
992.
塑料挤出成型模具流道优化设计 总被引:3,自引:0,他引:3
本文依据流变学理论,采用优化方法进行挤出成型模具(即机头)流道设计,探讨了建立流道优化数学模型的有关问题。 相似文献
993.
Yun Huang Hai-Liang Zhang Dun-Shen Zhu Shou-Ke Yan Xiao-Fang Chen Er-Qiang Chen Qi-Feng Zhou 《Polymer》2006,47(4):1217-1225
Crystallization and melting of a poly(ethylene oxide) (PEO) diblock copolymer containing a tablet-like block of poly{2,5-bis[(4-methoxyphenyl)oxycarbonyl]styrene} (PMPCS) in ultrathin films have been studied using atomic force microscopy (AFM) coupled with a hot stage. The PEO and PMPCS block possess the number-average molecular weights (Mn) of 5300 and 2100 g/mol, respectively. The ultrathin films on the mica and glow-discharged carbon surfaces were obtained by static dilute solution casting at room temperature. Isothermal melt crystallization from ultrathin films always leads to flat-on lamellae. Selective area electron diffraction (SAED) experiments have demonstrated that the PEO blocks crystallize with a monoclinic structure identical to that of homo-PEO and the chain direction is perpendicular to the substrate. At Tc<44 °C, the monolayer crystals are dendrites. At Tc>48 °C, square-shaped crystals are formed with the (100) and (020) planes as the crystal edges. At 44 °C≤Tc≤48 °C, an intermediate monolayer morphology is observed. The monolayer thickness increases monotonically with increasing Tc. At the same Tc, the monolayer lamellae with the top and bottom amorphous layers contacting with the atmosphere and the substrate possess a significantly larger overall thickness than the long period of the crystals in bulk. For the spiral terraces induced by screw dislocation, the thickness of each terrace is close to that of the monolayer formed at the same Tc, and their melting is mainly determined by the terrace thickness. 相似文献
994.
随着唐山市经济的快速发展,高技能人才缺乏的现象已日渐明显,对唐山市的人才现状进行了调研,并分析了造成人才短缺现象的原因,提出了加快高技能人才队伍建设的建议。 相似文献
995.
996.
Jiang Bibiao Yang Yang Deng Jian Fu Shiyang Zhu Rongqi Hao Jianjun Wang Wenyun 《应用聚合物科学杂志》2002,83(10):2114-2123
A cheap acrylic AB* monomer, 2‐(2‐chloroacetyloxy)‐isopropyl acrylate (CAIPA), was prepared from 2‐hydroxyisopropyl acrylate with chloroacetyl chloride in the presence of triethylamine. The self‐condensing vinyl polymerization by atom transfer radical polymerization (ATRP), a “living”/controlled radical polymerization, has yielded hyperbranched polymers. All the polymerization products were characterized by proton nuclear magnetic resonance spectroscopy (1H NMR). CAIPA exhibited distinctive polymerization behavior that is similar to a classical step‐growth polymerization in the relationship of molecular weight to polymerization time, especially during the initial stage of the polymerization. However, a significant amount of monomer remained present throughout the polymerization, which is consistent with typical chain polymerization. Also, if a much longer polymerization time was used, the polymer became gel. As a result of the unequal reactivity of group A* and B*, the polymerization is different from an ideal self‐condensing vinyl polymerization: the branch structures of polymers prepared depend dramatically on the ratio of 2,2'‐bipyridyl to CAIPA. Hyperbranched polymers exhibit improved solubility in organic solvent, however, they have lower thermal stability than their linear analogs. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2114–2123, 2002 相似文献
997.
The research and development of catalysts, the design and operation of catalytic reactors are complicated by the phenomenon of catalyst deactivation which is affected by various factors. In this paper, the effect of internal mass transfer resistance in the second order catalytic reaction system of uniform independent deactivation on both reaction and deactivation rates of straight cylindrical pore model has been discussed. In addition, the quantitative relations between effectiveness factor and Thiele modulus in second order reaction and first order deactivation system have been correlated 相似文献
998.
Yu-zhen Zhu Xin Zhou Xiang-sheng Zang 《Journal of Automated Methods and Management in Chemistry》1989,11(3):113-118
A microcomputer-interfaced data acquisition system for chemical
kinetics (interfacing with laboratory analogue instruments) has
been developed. Analogue signals from instruments used in kinetics
experiments are amplifed by a wide-range adjustable high-gain
operational amplifier and smoothed by an op-based filter, and then
digitized at rates of up to 104 samples per channel by an ADC
0816 digitizer. The ADC data transfer and manipulation routine
was written in Assembler code and in high-level language; the
graphics package and data treatment package is in Basic. For the
various sampling speeds, all of the program can be written using
Basic-Assembler or completely in Assembler if a high sampling
rate is needed. Several numerical treatment methods for chemical
kinetics have been utilized to smooth the data from experiments.The computer-interfaced system for second-order chemical kinetic
studies was applied to the determination of the rate constant of the
saponification of ethyl acetate at 35°C. For this specific problem,
an averaging treatment was used which can be called an interval
method. The use of this method avoids the diffcully of measuring
the starting time of the reaction. Two groups of experimental data
and results were used to evaluate the systems performance. All of the
results obtained are in agreement with the reference value. 相似文献
999.
壳管式换热器在化工和食品行业中有着广泛的应用,对其分析的方法与手段也有很多。在本文中,作者尝试建立起壳管式换热器的传递函数,并利用Matlab分析软件中的Simulink模块对其分析与仿真,通过得到的动态特性仿真曲线,为提高换热器的使用效率提供一些依据。 相似文献
1000.