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1.
As the Westernization Movement developing in the 1860 s, China began to introduce and learn western science and technology to develop modern military industry and civilian industry. In modern history, Xi’an went through the Xi ’an capital’s industrial embryonic form in the late Qing dynasty and urban industrialization construction during the period of the Republic of China so that it converted gradually from a trade city for Chinese traditional handicrafts under the background of the feudal society to a city in the industrial society where machine were used for production. 相似文献
2.
We presented a numerical examination of the effect of microtexturing negative rings’ structure on the tribological performance of parallel bearing couples’ cell. Three mcirotexturing rings, which are circle, square and ellipse, were chosen and the analysis model were established. We used the Reynolds equation coupled with finite difference method and successive over relaxation Gauss-Seidel iterative method to solve the Newtonian flow’s hydrodynamics within a bearing couple. The effect of texture density and radius ratio (thickness) of the microtexturing rings were investigated on the tribological performance under the similar operating conditions. The numerical simulation reveals that: 1) The microtexturing rings’ structure can homogenize the local pressure much uniformly within the bearing cell. 2) The tribological performance is determined mainly by the microtexturing rings’ geometry and texture density, and the thickness of the rings’ structure can help to change the quantitative values. 3) The square and circle rings’s microtexturing surface can slightly improve the frictional performance with the bearing cells’ gap, while the ellipse ring’s surface may decrease the frictional performance. 4) The ellipse rings’ microtexturing surface can achieve the minimum spacing gap but the maximum friction coefficient of the bearing couple, and then the circle and square rings’ structure take the second and third place, respectively 相似文献
3.
Background： Endothelial and smooth muscle cells were used as seeding cells and heterogeneous acellularized matrix was used as scaffold to construct the tissue-engineered graft. Methods： A 2 weeks piglet was selected as a donor of seeding cells. Two-centimetre length of common carotid artery was dissected. Endothelial cells and smooth muscle cells were harvested by trypsin and collagenase digestion respectively. The isolated cells were cultured and expanded using routine cell culture technique. An adult sheep was used as a donor of acellularized matrix. The thoracic aorta was harvested and processed by a multi-step decellularizing technique to remove the original cells and preserve the elastic and collagen fibers. The cultured smooth muscle cells and endothelial cells were then seeded to the acellularized matrix and incubated in vitro for another 2 weeks. The cell seeded graft was then transplanted to the cell-donated piglet to substitute part of the native pulmonary artery. Results： The cultured cells from piglet were characterized as endothelial cells by the presence of specific antigens vWF and CD31, and smooth muscle cells by the presence of specific antigen a-actin on the cell surface respectively with immunohistochemical technique. After decellularizing processing for the thoracic aorta from sheep, all the cellular components were extracted and elastic and collagen fibers kept their original morphology and structure. The maximal load of acellular matrix was decreased and 20% lower than that of untreated thoracic aorta, but the maximal tensions between them were not different statistically and they had similar load-tension curves. Three months after transplantation, the animal was sacrificed and the graft was removed for observation. The results showed that the inner surfaces of the graft were smooth, without thrombosis and calcification. Under microscopy, a great number of growing cells could be seen and elastic and collagen fibers were abundant. Conclusion： Cultured self-derived endothelial and smooth muscle cells could be used as seeding cells and heterogeneous acellularized matrix could be used as scaffold in constructing tissue-engineered graft. 相似文献
4.
The article focuses on some points of view in disagreement with Bley-Vroman’s. In the author’s opinion, different from the L1 learning, UG is not or partially accessible to the adult foreign language learners. Some evidence is exposed to support the author’s hypothesis. The author will illustrate this from the following aspects: the concept of UG, the relation of L2 learning and problem-solving, UG accessibility, critical period, comprehensible input and interlanguage. 相似文献
5.
FENG Zhou-yan CHEN Wei-dong YE Xue-song ZHANG Shao-min ZHENG Xiao-jing WANG Peng JIANG Jun JIN Lin XU Zhi-jian LIU Chun-qing LIU Fu-xin LUO Jian-hong ZHUANG Yue-ting ZHENG Xiao-xiang 《浙江大学学报(A卷英文版)》2007,8(2):323-330
INTRODUCTION Electrical stimulation in the animal brain is an indispensable means to investigate brain mechanisms in many experimental setups. However, the cable connections between the stimulation instruments and the animal brain always limit the animal’s freedom of movement and thereby cause entwisting and breaking of the cables, especially in freely moving animal ex-periments. In order to solve this problem, telemetry systems have been designed to deliver the stimulationsignals as sub… 相似文献
6.
《英语辅导》2005,(8)
A blonde[金发女郎] walks into a bank in New York City and asks for the loan officer[信贷员].She says she’s going to Europe on business for two weeks and needs to borrow $5,000.The bank officer says the bank will need some kind of security[抵押] for the Ioan,so the blonde hands over the keys to a new Rolls Royce[劳斯莱斯]. 相似文献
7.
陈涛 《读与写:教育教学刊》2013,(3):1-2
Macbeth is the darkest of Shakespeare’s great tragedies.The personification of "Valour" fortifies Macbeth’s strength.This quality makes Macbeth,and mars him.The combination of meanings of the witches’ interpretations hints at Macbeth’s final downfall.Both Macbeth and his wife are victimized by the witches.Macbeth pretends to be friendly with Banquo.But underneath his beautiful skin there is a relentless heart.Lady Macbeth’s desires for political powers are stronger than Macbeth.What Duncan and Banquo think and say forms a sharp contrast to Macbeth’s thoughts and actions.Macbeth is marred by his destiny and by the false creation from his fevered brain. 相似文献
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Plate packages are effective and promising appa-ratus for the separation of droplets from non-homoge-neous mixed systems of liquid-liquid dispersion inchemical unit operation for their features of compactconfiguration, low equipment cost and high efficien-cy[1]. The theories of plate separators were proposedand a lot of experimental researches were carried outin 1960s. Walteret alproved that in contrast to tradi-tional gravity settlers, plate packages are successfullyused to improve the separa… 相似文献
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1IntroductionSerpentine used as inorganic material inindustry hasbeeninvestigated for many years[1-3].But there are noreports on serpentine cat’s eye owing to its rarity.During our recent field investigation in Sichuan Prov-ince,southwest of China,for the first ti me we discov-ered the rare serpentine cat’s eye with well-growntex-ture and,if properly polished,a vivid cat eye effect(see Fig.1).Weng,et al.[4]also reported the newdiscovery of nephrite cat’s eyes inthis region.Serpen-tine can… 相似文献
10.
1IntroductionSoftware reverse engineering is a process of analyz-ing a software system to identify its components andtheir interrelationships and create representations ofthe system in another form,or at a higher level ofabstraction[1].Xi Dian reverse engineering tool(XDRE)[2]previously developed in the author’s labcan partially recover the UML diagrams from C source codes[3].However,the fact that crosscuttingconcerns cannot be extracted by most software reverseengineeringtools is ani mp… 相似文献
11.
Li Mengyao Li Jie Tan Haohan Luo Ya Zhang Yong Chen Qing Wang Yan Lin Yuanxiu Zhang Yunting Wang Xiaorong Tang Haoru 《Journal of Zhejiang University. Science. B》2022,23(4):300-314
Journal of Zhejiang University-SCIENCE B - Plant metabolites are important for plant development and human health. Plants of celery (Apium graveolens L.) with different-colored petioles have been... 相似文献
12.
在青菜、芹菜、芥菜、莴苣等蔬菜种植时施用微生物肥料--益农菌,能取得一定的增产效果和一定的节肥效果,但未观察到益农菌对蔬菜病虫害的防治作用. 相似文献
13.
江贵波 《顺德职业技术学院学报》2011,11(3):19-21
试验以马缨丹为供体植物,分别以甜白菜和油菜种子为受体,采用培养皿滤纸法进行化感试验,测定马缨丹的茎叶水提液对甜白菜和油菜幼苗的根长、苗高和鲜重的影响。结果表明：马缨丹地上部分的水提液对甜白菜和油菜幼苗生长有明显的化感作用,且不同浓度水提液对不同幼苗的影响存在差异;对根的生长都有明显的抑制作用,且随着浓度的增大抑制作用明显增强;马缨丹水提液对受体植物苗高呈现出＂低促高抑＂的趋势。 相似文献
14.
为研究滴水观音对铜绿微囊藻、针杆藻的化感作用,利用根、茎、叶不同器官浸出液,测定对藻类叶绿素a含量的影响.结果表明：根浸出液对实验藻表现为低浓度促进、高浓度抑制作用;叶浸出液对实验藻均表现为化感抑制作用,叶浸出液的化感抑制能力高于根浸出液,对铜绿微囊藻的化感抑制随着浓度的增加逐渐的增强,第18d、叶片浸出液浓度为10g/L时,对微囊藻和针杆藻的抑制率分别为93％和58％;茎浸出液的化感作用对藻类表现为促进作用,且对微囊藻的化感促进效果强于针杆藻. 相似文献
15.
INTRODUCTION Environmental contamination by toxic metals isa serious problem worldwide due to their incrementalaccumulation in the food chain and continued per-sistence in the ecosystem. Conventional technologies,such as ion exchange or lime precipitation, are oftenineffective and/or expensive, particularly for the re-moval of heavy metal ions at low concentrations(below 50 mg/L). Furthermore, most of these tech-niques are based on physical displacement orchemical replacement, generating … 相似文献
16.
[目的]建立一套高效、快速的体外中草药抗肺癌活性物质筛选模型。[方法]采用MTT法,对芸香草、地榆、甘草、柴胡、莪术、蜜蒙花、半边莲和旱芹等8种中草药体外抗肺癌细胞SPC-A1的活性进行检测。分析肿瘤细胞生长曲线,观察倒置显微镜下肺癌细胞在不同阶段的生长状况。[结果]在中草药活性物质作用下细胞尽管仍然贴壁,但出现萎缩及边缘清晰化,与生长状况良好的细胞形态区别明显。浓度为1.5mg/ml的莪术乙醇浸提液（ESCC）和甘草乙醇浸提液（ESCG）对体外培养的肺癌细胞SPC-A1有较强的抑制增殖作用,抑制率分别为：52.9%和51.6%,且抑制作用随着浓度的加大而加强。[结论]MTT法筛选可作为8种中草药抗肺癌细胞的一个基本筛选模型。 相似文献
17.
以铁皮石斛去根苗为试材,研究了外源精胺(Spm)对离体铁皮石斛花芽分化过程中内源游离多胺含量的影响.在添加14.5mg/L Spm的MS培养基上培养铁皮石斛去根苗的花芽分化率为15.0%,未添加激素的对照组的为0.在花芽分化过程中去根苗内源游离亚精胺(Spd)、Spm的含量及Spm/Put(腐胺)、Spd/Put的值均高于对照组,说明高水平的内源游离Spm、Spd含量及Spm/Put、Spd/Put有利于去根苗花芽的分化.在花芽分化过程中游离Put含量低于对照组,说明外源Spm促进了Put转化为Spd和Spm.实验揭示外源Spm可引起铁皮石斛内源游离多胺代谢及比值的变化,促进花芽分化. 相似文献
18.
对购买的巫山神茶进行体外抗氧化及抗突变效果评价.通过体外实验分析,研究巫山神茶的功能性效果.研究结果表明,高浓度的巫山神茶水提取物比低浓度茶具有更好的羟基自由基和DPPH自由基清除能力.1000 mg/kg浓度巫山神茶水提取物也表现出最好的抗突变效果.综合分析得出,一定浓度的巫山神茶水提取物具有较好的体外功能性效果. 相似文献
19.
Fu Y Wang SQ Liu YP Wang GP Wang JT Gong SS 《Journal of Zhejiang University. Science. B》2008,9(4):299-305
Objective: To evaluate the transduction efficiency of a recombinant adenovirus carrying the gene for green fluorescent protein (Ad-GFP) into the primary cultures of fetal neural stem cells (NSCs) by the expression of GFP. Methods: The Ad-GFP was constructed by homologous recombination in bacteria with the AdEasy system; NSCs were isolated from rat fetal hippocampus and cultured as neurosphere suspensions. After infection with the recombinant Ad-GFP, NSCs were examined with a fluorescent microscopy and a flow cytometry for their expression of GFP. Results: After the viral infection, flow cytometry analysis revealed that the percentage of GFP-positive cells was as high as 97.05%. The infected NSCs sustained the GFP expression for above 4 weeks. After differentiated into astrocytes or neurons, they continued to express GFP efficiently. Conclusion: We have successfully constructed a viral vector Ad-GFP that can efficiently infect the primary NSCs. The reporter gene was showed fully and sustained expression in the infected cells as well as their differentiated progenies. 相似文献
20.
(R)-2-hydroxy-3-phenylpropionic acid (PLA) is an ideal antimicrobial compound with broad-spectrum activity against a wide range of Gram-positive bacteria, some Gram-negative bacteria, and fungi. We studied the bioconversion of phenylpyruvate (PPA) to PLA using whole recombinant Escherichia coli cells in a series of buffer/organic solvent systems. Octane was found to be the best organic solvent. The optimum volume ratio of the water phase to the n-octane phase, conversion temperature, substrate concentration, and cell concentration were 6:4, 40 °C, 12.5 g/L, and 30 g/L wet cells, respectively. Under the optimized conditions, the average PLA productivity in the aqueous/n-octane system was 30.69% higher than that in the aqueous system, and 32.31 g/L PLA was obtained with the use of a stirred reactor (2-L scale). Taken together, our findings indicated that PLA biosynthesis was more efficient in an aqueous/n-octane biphasic system than in a monophasic aqueous system. The proposed biphasic system is an effective strategy for enhancing PLA yield and the biosynthesis of its analogues. 相似文献