共查询到20条相似文献,搜索用时 15 毫秒
1.
Localization of cognitive operations in the human brain 总被引:41,自引:0,他引:41
The human brain localizes mental operations of the kind posited by cognitive theories. These local computations are integrated in the performance of cognitive tasks such as reading. To support this general hypothesis, new data from neural imaging studies of word reading are related to results of studies on normal subjects and patients with lesions. Further support comes from studies in mental imagery, timing, and memory. 相似文献
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Proton relaxation rates of water in brain and brain tumors 总被引:1,自引:0,他引:1
The distribution of relaxation rates of water in "normal" (autopsy) samples of canine and human brain shows considerable overlap with that for brain tumor samples. The following ranges of values for the spin-spin relaxation rates were observed: for normal brain gray matter, 8.6 to 11.3 sec(-1) (mean, 9.5 sec(-1)); for normal brain white matter, 13.3 to 15.7 sec(-1) (mean, 15.5 sec(-1)); for six types of malignant tumor, 4.8 to 13.4 sec(-1) (mean, 9.3 sec(-1)); for five types of benign tumor, 7.1 to 16.4 sec(-1) (mean, 11.5 sec(-1)). Spin-lattice relaxation rates showed a similar pattern. At least two nonexchanging water components with different relaxation rates were indicated by the analysis of the spin-spin relaxation measurements for the white matter samples. 相似文献
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Labeled putrescine as a probe in brain tumors 总被引:1,自引:0,他引:1
N Volkow S S Goldman E S Flamm H Cravioto A P Wolf J D Brodie 《Science (New York, N.Y.)》1983,221(4611):673-675
The polyamine metabolism of transplanted N-nitrosomethylurea-derived rat glioma was determined with radiolabeled putrescine used as a marker for malignancy. The uptake of putrescine in vivo was complete within 5 minutes and was specific for tumor tissue. The conversion of putrescine to spermine and other metabolites by the tumor was rapid, in contrast to the case for adjacent normal brain. These results suggest that putrescine labeled with carbon-11 may be used as a positron-emission tomographic tracer for the selective metabolic imaging of brain tumor and may be used in an appropriate model as a marker for tumor growth rate. 相似文献
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Human papovavirus (JC): induction of brain tumors in hamsters 总被引:40,自引:0,他引:40
D L Walker B L Padgett G M ZuRhein A E Albert R F Marsh 《Science (New York, N.Y.)》1973,181(100):674-676
Eighty-three percent of hamsters inoculated at birth with JC virus, a human papovavirus isolated from brain tissue of a case of progressive multifocal leukoencephalopathy, developed malignant gliomas within 6 months. Three brain tumors have been serially transplanted as subcutaneous tumors. JC virus was isolated from five of seven tumors tested. Cells from four tumors were cultivated in vitro. These cells contained an intranuclear antigen with the characteristics of a T antigen, and this antigen was antigenically related to SV40 T antigen. Although virus was not recovered from extracts of serially cultured tumor cells, JC virus was rescued when one tumor cell line was fused with permissive cells. 相似文献
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通过分析我国引进的土木工程软件 EaglePoint 生成的道路工程图纸与我国现行道路工程行业标准之间存在的差异,利用 AutoCAD 的开发工具 ADS 为该软件开发了外挂式模块,实现了将 EaglePoint 绘制的图纸转换为符合我国现行行业标准的功能,完成了道路工程图纸的本地化工作,为该软件应用于我国的道路工程创造了必要条件。 相似文献
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E W Pfeiffer 《Science (New York, N.Y.)》1967,158(799):397-398
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Van Middlesworth L 《Science (New York, N.Y.)》1949,110(2848):120-121
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Dramatic results with brain grafts 总被引:1,自引:0,他引:1
R Lewin 《Science (New York, N.Y.)》1987,237(4812):245-247
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Martin J Ilani S Verdene B Smet J Umansky V Mahalu D Schuh D Abstreiter G Yacoby A 《Science (New York, N.Y.)》2004,305(5686):980-983
An outstanding question pertaining to the microscopic properties of the fractional quantum Hall effect is understanding the nature of the particles that participate in the localization but that do not contribute to electronic transport. By using a scanning single electron transistor, we imaged the individual localized states in the fractional quantum Hall regime and determined the charge of the localizing particles. Highlighting the symmetry between filling factors 1/3 and 2/3, our measurements show that quasi-particles with fractional charge e* = e/3 localize in space to submicrometer dimensions, where e is the electron charge. 相似文献
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Anodal mobility of iodoinsulin on starch-gel electrophoresis increases progressively as the number of iodine atoms substituted in the molecule increases. The iodine content of iodine-131 solutions is determined by comparison of autoradiographic patterns of insulin heavily labeled with iodine-131 and of insulins lightly labeled with iodine-131 and known quantities of iodine-127. 相似文献
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POMC在不同毛色绵羊皮肤中的表达与定位 总被引:2,自引:0,他引:2
【目的】对不同毛色绵羊皮肤中的阿黑皮素原(proopiomelanocortin,POMC)进行定位和表达差异分析,确定POMC与毛色形成的关系,进一步丰富有关哺乳动物毛色形成机制的理论知识。【方法】选取年龄相近的雄性黑色和白色成年绵羊各3只,用取皮器分别在臀部采集皮肤组织3块,对其中一块制作石蜡切片后采用免疫组织化学法确定POMC在不同绵羊皮肤中的定位,另两块置于液氮中冻存后分别提取皮肤总RNA和总蛋白,总RNA经反转录成cDNA后,经NCBI分析比对后设计POMC特异性PCR引物,采用QRT-PCR方法检测POMC基因在mRNA水平的表达差异;总蛋白经SDS-PAGE凝胶电泳后,采用Western blotting方法加入POMC多克隆抗体检测POMC在蛋白水平的表达差异,得出的数据用SPSS19.0软件进行差异显著性分析,探讨POMC对毛色形成机制的调控作用。【结果】免疫组织化学结果显示POMC在黑色和白色绵羊皮肤中均有表达,且表达部位都位于毛囊根鞘周围和表皮的皮肤角质形成层细胞内;QRT-PCR结果显示POMC在黑色绵羊皮肤中mRNA的相对表达量为2.5004±0.2577**,而在白色绵羊皮肤中POMC的mRNA的相对表达量为1.0032±0.0350,黑色绵羊皮肤中POMC的mRNA的相对表达量为白色绵羊皮肤的2.5倍,二者表达差异极显著(P<0.01);Western boltting结果显示黑色绵羊皮肤POMC蛋白水平相对表达量为1.5253±0.0426*,而白色皮肤中POMC蛋白水平相对表达量为1.0005±0.0180,黑色皮肤POMC蛋白表达量是白色皮肤的1.55倍(P<0.05),两者差异显著。【结论】试验表明POMC可在黑色和白色绵羊皮肤中正常表达,且其表达位置一致,但POMC在不同毛色绵羊皮肤组织中mRNA和蛋白的表达水平存在一定的差异,表明POMC的表达量变化会在一定程度上影响毛色的生成。 相似文献
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【目的】前期研究显示To MV外壳蛋白(coat protein,CP)可以与烟草蛋白L(CP-interacting protein-L,IP-L)相互作用,本研究旨在明确To MV CP与IP-L的共定位情况、IP-L的组织表达和在To MV侵染条件下烟草IP-L及其编码蛋白的表达变化情况,为进一步明确IP-L的功能提供依据。【方法】通过双酶切法从笔者实验室构建保存的p GBKT7-CP和p GADT7-IP-L重组载体上切下To MV CP和IP-L目的片段,构建融合蛋白植物表达载体p PZP-IP-L-N-EGFP和p PZP-CP-N-Ds Red及原核表达载体p EGX-IP-L。通过热激法将融合表达的植物表达载体转化至农杆菌EHA105,在烟草表皮细胞瞬时表达IP-L-N-EGFP和CP-N-Ds Red,共聚焦荧光显微镜下观察IP-L和To MV CP共定位情况。用实时荧光定量RT-PCR(q RT-PCR)分析IP-L在本氏烟各组织部位的表达量。原核表达载体p EGX-IP-L,转化原核表达菌BL21,优化GST-IP-L可溶性表达条件后大量表达该蛋白,用GST亲和层析法纯化获得可溶性GST-IP-L蛋白,免疫家兔制备多克隆抗体。ELISA测定抗体效价,Western印迹法明确抗体的特异性后,利用该抗体分析To MV侵染条件下番茄IP-L蛋白表达情况,用q RT-PCR检测IP-L表达变化与蛋白水平是否一致。【结果】To MV CP在本氏烟叶片表皮细胞的细胞质和细胞质膜以及叶绿体均有分布,而IP-L只在本氏烟叶片表皮细胞质膜表达,二者共定位在细胞质膜。IP-L在本氏烟叶片中特异高表达,显著高于茎、根和花中的相对表达量。在温度为30℃,IPTG诱导浓度为0.3 mmol·L-1条件下表达出大小为42.8 k D的可溶性GST-IP-L融合蛋白。纯化获得约4.2 mg可溶性蛋白,免疫家兔制备了效价为1/6400的多克隆抗体。Western印迹结果表明,该抗体可以与IP-L的原核产物特异性结合。在To MV侵染本氏烟1、3、7 d后,Western印迹分析表明IP-L在叶片内表达量随接种时间呈明显上调趋势。q RT-PCR检测结果与Western印迹结果一致,显示IP-L在To MV侵染本氏烟第7天后的叶片内表达量是健康对照的3倍多,差异达到显著水平。【结论】To MV CP和IP-L共定位于本氏烟表皮细胞质膜,IP-L在本氏烟叶片内特异高表达。制备的IP-L多克隆抗体具有良好的免疫反应活性,可以用于IP-L表达量检测;To MV侵染烟草可诱导IP-L及其编码蛋白表达量显著上调。 相似文献
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[目的]对氟磺胺草醚降解菌提取的降解酶进行定位,探讨其最适的酶促反应条件。[方法]通过采用紫外分光光度法测定酶活力来对氟磺胺草醚降解菌株F12提取的降解酶进行定位,并研究其酶学性质。[结果]氟磺胺草醚降解菌株F12降解酶属于胞外酶,最适的酶促反应时间为30 min,最佳的酶浓度为1.0 ml,最适pH为7.5,最适反应温度为35℃,最适添加药浓度为150 mg/L。[结论]试验结果为规模化生产氟磺胺草醚降解酶制剂及治理污染土壤提供了理论依据。 相似文献
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目的:总结原发小肠肿瘤的诊断及治疗方法。方法:回顾性分析63例小肠肿瘤的临床资料。结果:63例均经手术和(或)病理检查证实诊断,其中良性肿瘤16例,恶性肿瘤47例。主要表现为腹痛、腹部包块、肠梗阻及消化道出血等。术前确诊22例.其余均误诊,误诊率为65.1%。本组均行手术治疗,其中良性肿瘤行肿瘤及局部肠管切除。恶性肿瘤则行根治性切除、姑息性切除及捷径手术4例。本组无手术死亡。恶性肿瘤1、3、5a生存率分别为65.8%、42.1%、20.3%。结论:小肠肿瘤缺乏特异性体征,术前误诊率高。对有出血、腹痛、梗阻、包块等临床表现者应怀疑本病可能;对诊断不明者应综合采用各种检查,必要时剖腹探查。一经诊断.应及时手术治疗。 相似文献
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吴贝贝 《农业图书情报学刊》2017,29(9):91-95
分析了新书目框架BIBFRAME的核心类演化,指出了CNMARC模型向BIBFRAME模型转换的必要性。采用元数据映射方法,将CNMARC字段向BIBFRAME词表做映射,形成了“CNMARC书目数据与BIBFRAME词表的映射表”,从CNMARC的角度出发对映射结果进行分析,对无法一对一映射的问题提出了解决建议。 相似文献
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【目的】检测重组雌、雄捻转血矛线虫半乳糖结合凝集素(rHco-GAL-f/m)免疫山羊皱胃转录细胞因子。【方法】用rHco-GAL-f/m免疫山羊,通过原位杂交法对阴性对照组(A)、攻虫对照组(B)、免疫攻虫组(C)和免疫不攻虫组(D)山羊皱胃中白介素-1β(IL-1β)、白介素-2(IL-2)、白介素-4(IL-4)、白介素-6(IL-6)、干扰素-γ(IFN-γ)和肿瘤坏死因子-α(TNF-α)mRNA转录进行定位,并对上述细胞因子阳性反应细胞数量进行分析。【结果】A组山羊皱胃组织中没有检测到细胞因子,其它3组仅在皱胃黏膜下层中检测到了上述细胞因子。B、C和D组间IL-4和IL-6阳性反应细胞数差异显著(P0.05),其中C组明显高于其它两组;B、C和D组间IL-1?、IL-2和TNF-α阳性反应细胞数差异显著(P0.05),其中D组明显高于其它两组;IFN-γ阳性反应细胞数在B组和C组之间差异不显著(P0.05),D组与B组和C组之间差异显著(P0.05),且明显高于其它两组。【结论】重组捻转血矛线虫半乳糖结合凝集素能够诱导山羊皱胃局部免疫应答。 相似文献