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由于资料缺乏,人们对宋代"二徐"以前《说文》的情况不甚清楚。《经典释文》引《说文》(许慎)反切达94次,这些反切不同于现今流传的唐宋注音,反映了魏晋南北朝人们为《说文》创制反切的情况。  相似文献   

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阐明了相对论中“测量”与“观察”两个不同的概念,论述了高速运动秩本的视觉现象,从而澄清了洛仑慈收缩是一种观察效应的误解。  相似文献   

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To investigate the preventive effects of Xin-Kang oral liquid on myocarditis induced by Coxsakie virus B ( CVB) > the medicine was given to mice two days prior to the challenge of mice with the CVB to induce myocarditis. The oral liquid was continuously given to mice for 20 days and quantitative histological changes at various stages of the myocarditis were observed. The pathological changes on the cardiac surface were significantly reduced in Xin-Kang treated mice compared to those in control group (P<0. 01). and the occurrence of severe myocardium damage ( massive cardiac tissue death and degradation) was less in the Xin-Kang group than the groups either challenged with CVB or treated with interferon. The group treated with 0. 015g per gram body weight per day showed significant improvement over the viral group (P<0.01). The results proved that Xin-Kang could protect the cardiac muscle from viral infection and accelerate recovery of damaged cardiac tissue.  相似文献   

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Atherosclerosis is a chronic inflammatory disease, and is the primary cause of heart disease and stroke in Western countries. Derivatives of cannabinoids such as delta-9-tetrahydrocannabinol (THC) modulate immune functions and therefore have potential for the treatment of inflammatory diseases. We investigated the effects of THC in a murine model of established atherosclerosis. Oral administration of THC (1 mg kg(-1) per day) resulted in significant inhibition of disease progression. This effective dose is lower than the dose usually associated with psychotropic effects of THC. Furthermore, we detected the CB2 receptor (the main cannabinoid receptor expressed on immune cells) in both human and mouse atherosclerotic plaques. Lymphoid cells isolated from THC-treated mice showed diminished proliferation capacity and decreased interferon-gamma secretion. Macrophage chemotaxis, which is a crucial step for the development of atherosclerosis, was also inhibited in vitro by THC. All these effects were completely blocked by a specific CB2 receptor antagonist. Our data demonstrate that oral treatment with a low dose of THC inhibits atherosclerosis progression in the apolipoprotein E knockout mouse model, through pleiotropic immunomodulatory effects on lymphoid and myeloid cells. Thus, THC or cannabinoids with activity at the CB2 receptor may be valuable targets for treating atherosclerosis.  相似文献   

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研究了有机溶剂中4,4'-二溴联苯(4,4'-DBB)的超声降解.考察了初始质量浓度、处理时间及添加氧化剂(H2O2)和盐(NaCl)后的联合作用对降解率的影响.采用超声频率20 kHz、固定声强0.16W/cm2的超声波作用一段时间,结果表明:初始质量浓度越大,降解率越低;超声时间越长,降解率越高.单独超声降解8 mg/L 4,4'-DBB溶液600 min,降解率可达16.0%.而加盐超声240 min,10 mg/L 4,4'-DBB溶液的降解率可提高到12.1%,符合一级反应规律,一级反应常数为-5.231 18×10-4 min-1.超声与过氧化氢(US/H2O2)联合作用180 min,2 mg/L 4,4'-DBB溶液的最终降解率可达到43.1%.  相似文献   

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J W Olney  O L Ho 《Nature》1970,227(5258):609-611
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Temirov R  Soubatch S  Luican A  Tautz FS 《Nature》2006,444(7117):350-353
Thin films of molecular organic semiconductors are attracting much interest for use in electronic and optoelectronic applications. The electronic properties of these materials and their interfaces are therefore worth investigating intensively, particularly the degree of electron delocalization that can be achieved. If the delocalization is appreciable, it should be accompanied by an observable electronic band dispersion. But so far only limited experimental data on the intermolecular dispersion of electronic states in molecular materials is available, and the mechanism(s) of electron delocalization in molecular materials are also not well understood. Here we report scanning tunnelling spectroscopy observations of an organic monolayer film on a silver substrate, revealing a completely delocalized two-dimensional band state that is characterized by a metal-like parabolic dispersion with an effective mass of m* = 0.47m(e), where m(e) is the bare electron mass. This dispersion is far stronger than expected for the organic film alone, and arises as a result of strong substrate-mediated coupling between the molecules within the monolayer.  相似文献   

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小鼠同种异基因皮肤移植模型的建立   总被引:7,自引:0,他引:7  
目的:为移植免疫及药物免疫机理研究建立小鼠同种异基因皮肤移植动物模型。方法:受体BALB/c分为A~E共5组,即对照组,5.0、7.5、10、20mg/kg环孢菌素A(CsA)剂量组,通过背-背法进行C57BL/6的全厚皮皮片移植,以探求通过较小剂量CsA及优化实验条件和护理方式建立供免疫机理研究的动物试验平台。结果:5.0、7.5、10mg/kg组相对于对照组皮片排斥时间无明显差别,而20mg/kg组植皮能较长时间存活。结论:20mg/kg的CsA剂量可以经济,快速地建立小鼠同种异基因移植动物模型。  相似文献   

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R L O'Brien  R L Brinster  U Storb 《Nature》1987,326(6111):405-409
Initial studies of somatically acquired mutations in immunoglobulin V regions from hybridomas and myelomas that are not derived from joining aberrations, suggested a controlled and specific hypermutation process, because spontaneous mutation rates observed for other genes are extremely low. Some evidence for the idea that mutations are introduced during V-gene rearrangement came from the clustering of mutations at the joining sites, from the absence of mutations in unrearranged V genes and from the low level of mutations in only partially (D-J) rearranged nonproductive heavy-chain alleles. Another model in which mutations accumulate with each cell division, rather than being introduced all at once, was supported by the finding that immunoglobulin genes of hybridomas derived from a single mouse frequently had several mutations in common, and so might be derived from the same precursor cell whose daughters then accumulated additional mutations. But the common mutations in some cases could be due to as yet unidentified related germline genes, or could represent the effect of antigen selection for certain amino acids. To try to detect hypermutation in the absence of V-gene rearrangement, we isolated B lymphocytes with endogenous heavy-chain gene mutations from transgenic mice carrying pre-rearranged kappa-transgenes. We found that these kappa-transgenes were also somatically mutated. This and other observations indicated that: ongoing rearrangement is not required for mutation; there are signals for hypermutation in the transgenes; the mutations are found only in the variable region, so the constant region may not be a target; different transgene insertion sites are compatible with hypermutations and more than one transgene is expressed in the same cell.  相似文献   

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探讨了稀土铈掺杂纳米二氧化钛(纳米TiO2、Ce/TiO2和CeO2/TiO2)经口长期染毒对大鼠血清生化指标的影响。方法:以每只0.15 g/kg的初始剂量给大鼠灌胃染毒,每4天递增1.5倍剂量,共染毒28 d。采集测定各组大鼠第4、16、28 d血清生化指标的变化。结果:长期毒性第4和16 d TiO2、Ce/TiO2和CeO2/TiO2三组大鼠血清生化AST和LDH活力明显高于对照组(P<0.05)。长期毒性的第28 d Ce/TiO2和CeO2/TiO2三组大鼠血清生化ALT活力明显高于对照组(P<0.05),Ce/TiO2组大鼠血清的BUN活力明显高于对照组(P<0.05)。结论:纳米TiO2、Ce/TiO2和CeO2/TiO2长期染毒对大鼠血清LDH、AST、ALT活力及BUN水平有不同程度的影响,与其他两组相比,纳米TiO2组对大鼠生化指标的影响最小。  相似文献   

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通过设置室内控制实验,测定冻融过程中冰水两相的三维荧光光谱(EEMs)、SUVA254、TN、TP、DOC,并对三维荧光特征指数、SUVA254、TN、TP、DOC进行相关性分析。结果表明,冻结过程中水相的三维荧光光谱中类色氨酸峰A、类酪氨酸峰B、类腐殖酸峰C的荧光强度增强,TN、TP质量浓度增加至原水样的1.47、1.13倍。说明在冻结过程中由于冷冻浓缩效应,类色氨酸、类酪氨酸、类腐殖酸三类溶解性有机物、TN、TP由冰相向水相迁移。随着冰相体积的增加,三类溶解性有机物、TN、TP向沉积物迁移,并在溶解过程中,由沉积物向水体释放。通过测定冻融条件下冰水两相中BPA、E2、EE2的质量浓度发现,在冻结过程中BPA、E2、EE2向水相中迁移,结合相关性分析结果说明芳香族物质更易向水相中迁移。  相似文献   

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电絮凝-O3氧化法处理石化工业污水的研究   总被引:1,自引:0,他引:1  
采用电絮凝和O3氧化两步法处理石化工业污水,分别对电絮凝和O3氧化的实验条件(包括电极材料、pH值、电解质的加入量、电解电压、电解时间、通气时间和气体流速等)进行了优化。于所选的最佳实验条件下对石化工业污水进行处理,有机污染物的去除率达98.79 %。此外,文中还对电絮凝-O3氧化过程的作用机制进行了初步探讨。  相似文献   

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武夷山不同海拔土壤水溶性有机物的紫外-可见光谱特征   总被引:1,自引:0,他引:1  
水溶性有机碳(WSOC)是土壤中活跃的C库,在土壤有机质分解转化等过程中有着重要的作用.对武夷山不同海拔植被土壤水溶性有机碳的浓度和紫外-可见光谱进行研究,结果表明:在波长230~665 nm间,不同海拔植被土壤水溶性有机物的紫外可见光吸收值均随波长的增加而减小,最大吸收值在230 nm处;不同来源的吸光值E240/E420和E230/E250存在显著差异,同一海拔不同土层的水溶性有机碳浓度与E230有极显著的线性正相关关系(R为0.819~0.999,P<0.01),据此,可用E230估测武夷山土壤水溶性有机碳的浓度.  相似文献   

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