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港口发展对海洋经济增长与区域收敛性的影响——基于动态面板与β-收敛模型的实证分析 被引量:2
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作者 谢冠艺 谢童伟 《调研世界》 北大核心 2015年第11期57-59,共3页
本文依据我国11个沿海省份的动态面板模型分析得到,如果港口吞吐量增加1%,那么将带动海洋产业产值增长上升0.23%;β-收敛模型的分析得到结果说明11个沿海省份大力发展港口确实可以促进海洋经济差距收敛。
关键词 港口 海洋经济 动态面板 β-收敛模型
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药代动力学药效学结合模型的研究进展 被引量:11
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作者 罗建平 张银娣 《中国临床药理学杂志》 CAS CSCD 北大核心 2000年第4期309-314,共6页
关键词 药代动力学 药效学 研究进展 线性模型 最大效应模型 SigmoidEmax模型 β-函数模型 药物效应滞后 药代动力学药效学结合模型
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Ref-1在阿尔茨海默病大鼠海马CA1区表达的研究 被引量:1
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作者 吴海琴 姚丽 +4 位作者 杜赟 张桂莲 张茹 刘璟洁 卜宁 《浙江大学学报(医学版)》 CAS CSCD 2008年第6期629-633,共5页
目的:探讨Ref-1在阿尔茨海默病(AD)大鼠发病中的变化及其可能机制。方法:采用Aβ25-35单次侧脑室注射诱导AD大鼠模型,Y迷宫测定大鼠行为学变化,免疫组化法检测建模后4d、7d和14d时痴呆组、对照组大鼠海马CA1区Ref-1的表达。结果:1Aβ注... 目的:探讨Ref-1在阿尔茨海默病(AD)大鼠发病中的变化及其可能机制。方法:采用Aβ25-35单次侧脑室注射诱导AD大鼠模型,Y迷宫测定大鼠行为学变化,免疫组化法检测建模后4d、7d和14d时痴呆组、对照组大鼠海马CA1区Ref-1的表达。结果:1Aβ注射7d、14d后,痴呆组大鼠达到学习标准的训练次数、错误次数和全天总反应时间较对照组均明显增加(P<0.05)。2痴呆组Aβ注射4d起,海马CA1区Ref-1表达开始增高(P<0.01),随着观察时点的延长,这种表达进一步增高(P<0.01)。结论:大鼠侧脑室注射Aβ7d可成功诱导AD大鼠模型;Ref-1的上调早于大鼠记忆障碍的发生,Ref-1可能参与了AD的发生发展。 展开更多
关键词 阿尔茨海默病 淀粉样Β蛋白 疾病模型 动物 β-淀粉样蛋白/模型 Ref-1/海马
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Decomposition of a β-O-4 lignin model compound over solid Cs-substituted polyoxometalates in anhydrous ethanol: acidity or redox property dependence? 被引量:1
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作者 吴学众 焦文千 +4 位作者 李秉正 黎演明 张亚红 王全瑞 唐颐 《Chinese Journal of Catalysis》 CSCD 北大核心 2017年第7期1216-1228,共13页
Production o f aromatics from lignin has attracted much attention. Because of the coexistence of C-O and C-C bonds and their complex combinations in the lignin macromolecular network, a plausible roadmap for de... Production o f aromatics from lignin has attracted much attention. Because of the coexistence of C-O and C-C bonds and their complex combinations in the lignin macromolecular network, a plausible roadmap for developing a lignin catalytic decomposition process could be developed by exploring the transformation mechanisms of various model compounds. Herein, decomposition of a lignin model compound, 2-phenoxyacetophenone (2-PAP), was investigated over several ce-sium-exchanged polyoxometalate (Cs-POM) catalysts. Decomposition of 2-PAP can follow two dif-ferent mechanisms: an active hydrogen transfer mechanism or an oxonium cation mechanism. The mechanism for most reactions depends on the competition between the acidity and redox proper-ties of the catalysts. The catalysts of POMs perform the following functions: promoting active hy-drogen liberated from ethanol and causing formation of and then temporarily stabilizing oxonium cations from 2-PAP. The use of Cs-PMo, which with strong redox ability, enhances hydrogen libera-tion and promotes liberated hydrogen transfer to the reaction intermediates. As a consequence, complete conversion of 2-PAP (〉99%) with excellent selectivities to the desired products (98.6% for phenol and 91.1% for acetophenone) can be achieved. 展开更多
关键词 Lignin model compound β-O-4 ether bond POLYOXOMETALATE Hydrogen transfer mechanism Oxonium cation mechanism Anhydrous ethanol
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ROLE OF TRANSFORMING GROWTH FACTOR β(TGF-β)IN REPAIRING OF BONE DEFECTS 被引量:4
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作者 孙玉鹏 张皖清 +3 位作者 陆裕朴 胡蕴玉 马富成 陈万禄 《Chinese Medical Sciences Journal》 CAS CSCD 1996年第4期209-214,共6页
TGF-β is a multifunctional cytokine that regulates many aspects of cellular function, including periosteal mesenchymal cell proliferation, differentiation. This experiment is to study its effects on bone defect repai... TGF-β is a multifunctional cytokine that regulates many aspects of cellular function, including periosteal mesenchymal cell proliferation, differentiation. This experiment is to study its effects on bone defect repair. A rabbit radial bone defect model was used to evaluate the effect of TGF-β, which was extracted and purified from bovine blood platelets, on the healing of a large segmental osteoperiosteal defect. A 1. 5-centimeter segmental defect was created in the mid-upper part of the radial shaft of adult rabbits. The defect was filled with implant containing TGF-β that consisted of carrier and bovine TGF-β. Limbs served as controls received carrier alone. The defectswere examined radiographically and histologically at 4, 8,12 , 16 and 20 weeks after implantation. The results showed that in TGF-β implant group . the defect areas at 12 weeks post operation were bridged by uniform new bone and the cut ends of cortex could not be seen;while in control group, the defects remained clear. Only a small amount of new bone formed as a cap on the cut bone ends. In the experimental group, new lamellar and woven bone formed in continuity with the cut ends of the cortex. An early medullar canal appears to be forming and contained normal-appearancing marrow elements; while the control group displayed entirely fibrous tissue within the defect site. Remnants of the cancellous bone carrier were observed in the control specimen. These data demonstrate that exogenous TGF-β initiate osteogenesis and stimulate the bone defects repair in animal model. 展开更多
关键词 transforming growth factor beta bone defects bone repair
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A possible hydrolysis mechanism of β-naphthyl acetate catalyzed by antibodies
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作者 YUAN YU REN ZONG XIANG XIA +3 位作者 CUI HONG YANG BING HUI YANG MING YEH(Shanghai Institute of Cell Biology, Chinese Academy of Sciences, China)(Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, China) 《Cell Research》 SCIE CAS CSCD 1998年第3期219-230,共12页
The mechanism of ester hydrolysis has been extensively studied; however, the precise function of active-site residues in promoting catalysis is nuclear. We describe here the structural models for the complex of a cata... The mechanism of ester hydrolysis has been extensively studied; however, the precise function of active-site residues in promoting catalysis is nuclear. We describe here the structural models for the complex of a catalytic sntibody Fv fragment with a phosphonate transition -state analogue, constructed by using gene cloning, sequencing and molecular modeling, mainly based on a known X-ray structure of a catalytic atibody. Hydrophobic and electrostatic analyses of the Fv/analog and Fv/substrate interaction suggest the hydrolysis mechanism: In L91 and Tyr H97 play important roles to stabilize the β-naphthyl group of hapten through r-stack; His H35 donates a pair of free electrons at the atom NEZ to an active water and let it to be a partial hydroxide, which attacks the carbon atom of the carbonyl group of the substrate. Both His H35 and Arg L96 can form hydrogen bonds and stabilize the Anoinc tetrahedral intermediate formed during turnover. This mechanism emphasizes that an active water bridge may be formed during hydrolysis process. 展开更多
关键词 Catalytic antibody gene cloning cDNA sequence molecular modeling ester hydrolysis mechanism
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基于Schweizer-Sklar算子的模糊推理模型的连续性 被引量:4
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作者 谷敏强 刘智斌 《应用数学学报》 CSCD 北大核心 2010年第3期532-546,共15页
本文将Schweizer-Sklar算子引入模糊系统,引入了模糊推理模型连续性的新定义,给出了两种典型的模糊推理模型为连续模型的充要条件.讨论了几种常用的模糊推理模型的连续性,给出其改进形式.
关键词 Schweizer-Sklar算子 连续推理模型 α-模型 β-模型
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不同草地植被群落的结构特征研究 被引量:10
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作者 吕杰 郭君喜 +2 位作者 陈俊 张鹏莉 胡远彬 《草业科学》 CAS CSCD 北大核心 2011年第6期1059-1065,共7页
利用β-二项分布模型解析法定量探明位于陕西省神木县的3种典型草地植被的空间分布特性及其群落的物种组成、物种多样性等群落结构特征。结果表明,通过卡方检验证明黄花蒿(Artemisia annua)草地、百里香(Thymus mongolicus)草地和羊草(L... 利用β-二项分布模型解析法定量探明位于陕西省神木县的3种典型草地植被的空间分布特性及其群落的物种组成、物种多样性等群落结构特征。结果表明,通过卡方检验证明黄花蒿(Artemisia annua)草地、百里香(Thymus mongolicus)草地和羊草(Leymus chinensis)草地的主要组成植物种对β-二项分布模型具有很好的吻合性;3种草地群落的总物种数顺序为黄花蒿草地<羊草草地<百里香草地;物种多样性指数为羊草草地<黄花蒿草地<百里香草地;均匀度指数为羊草草地<百里香草地<黄花蒿草地;0.25 m2样方内的平均物种数和物种多样性指数为羊草草地<百里香草地<黄花蒿草地;群落整体的空间分布异质性指数为黄花蒿草地<羊草草地<百里香草地;0.25 m2样方内的平均生物量为百里香草地<黄花蒿草地<羊草草地。 展开更多
关键词 β-二项分布模型 物种数 物种多样性 空间异质性
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异常北折台风“洛坦”与异常西折台风“奥玛”路径的对比及预报 被引量:1
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作者 王敏 尹义星 +1 位作者 陈晓旸 赵阳 《热带海洋学报》 CAS CSCD 北大核心 2020年第1期53-65,共13页
选取在台湾岛附近发生异常北折的台风“洛坦”和异常西折的台风“奥玛”,对其环流形势进行对比分析,之后将全风场分解为气候场和瞬时扰动风场,应用扩展的β-平流模型对“洛坦”和“奥玛”的异常偏折路径进行预报尝试。结果表明:1)两个... 选取在台湾岛附近发生异常北折的台风“洛坦”和异常西折的台风“奥玛”,对其环流形势进行对比分析,之后将全风场分解为气候场和瞬时扰动风场,应用扩展的β-平流模型对“洛坦”和“奥玛”的异常偏折路径进行预报尝试。结果表明:1)两个台风的500hPa全风场分析表明,副高及槽前西南气流为“奥玛”异常北折的主要影响系统;而“洛坦”北侧的大陆高压与副高合并加强有利于其西折。2)扰动风场的分布表明,北折“洛坦”南侧的西南风逐渐增大,东侧的东南风逐渐转变为南风,在异常偏折时刻形成一条向北的“输送带”利于其北折;西折“奥玛”在其异常偏折过程中其北侧一直维持着一个反气旋性环流,向西输送分量逐渐增加,利于其西折。3)利用扩展的β-平流模型对两个台风路径进行预报,发现在综合考虑气候态和扰动场时,“洛坦”的路径预报效果最好,而考虑瞬时扰动场时“奥玛”的西折预报效果最好。 展开更多
关键词 热带气旋 异常偏折路径 大气变量分解 扩展β-平流模型
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考虑共因失效的故障树分析方法及应用 被引量:2
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作者 鲍黎涛 杨道建 《自动化与信息工程》 2018年第6期45-48,共4页
在复杂机电设备的应用中,共因失效往往是引发系统失效的重要因素。在分析β-因子共因失效模型的基础上,采用考虑共因失效的方法对地铁乘客紧急报警系统进行故障树建模和系统可靠度分析,并分别计算不考虑共因失效和考虑共因失效时系统可... 在复杂机电设备的应用中,共因失效往往是引发系统失效的重要因素。在分析β-因子共因失效模型的基础上,采用考虑共因失效的方法对地铁乘客紧急报警系统进行故障树建模和系统可靠度分析,并分别计算不考虑共因失效和考虑共因失效时系统可靠度。计算结果表明:共因失效导致系统可靠度降低,体现了考虑共因失效系统可靠度分析的必要性。 展开更多
关键词 共因失效 故障树分析 冗余系统 可靠度 β-因子模型
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Establishment and application of the screening model of the Mycobacterium tuberculosis β-lactamase BlaC inhibitors 被引量:1
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作者 刘忆霜 郑佳音 +2 位作者 黄树超 关艳 肖春玲 《Journal of Chinese Pharmaceutical Sciences》 CAS CSCD 2016年第3期189-195,共7页
With the continuous emergence and rapid spread of multidrug-resistant and extensively-drug-resistant Mycobacterium tuberculosis strains, it is imperative to develop novel therapies against this bacterium. The intrins... With the continuous emergence and rapid spread of multidrug-resistant and extensively-drug-resistant Mycobacterium tuberculosis strains, it is imperative to develop novel therapies against this bacterium. The intrinsic β-lactam resistance of M. tuberculosis is primarily due to the production of an Ambler class-A β-lactamase BlaC, which limits the application of β-lactam antibiotics in the treatment of tuberculosis. Therefore, the inhibitors of BlaC could be novel anti-tuberculosis drug synergistic agents to recover the sensibility of M. Tuberculosis to the β-lactam antibiotics. In the present study, BlaC of M. tuberculosis was expressed and purified to establish a screening model of the BlaC inhibitors. The screening conditions were determined, and the screening model was evaluated to fit for the high throughput screening. A total of 22 BlaC inhibitors were screened out from 26 400 compound samples with a positive rate of 0.083%. Taken together, our findings lay the foundation for the discovery of novel anti-tuberculosis drug synergistic agents in clinic. 展开更多
关键词 Mycobacterium tuberculosis β-LACTAMASE BlaC High-through screening model Anti-tuberculosis drug synergistic agents
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Effect of acupotomy on nitric oxide synthase and beta-endorphin in third lumbar vertebrae transverse process syndrome model rats 被引量:16
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作者 Changqing Guo Naigang Liu +7 位作者 Xiaohong Li Hongmei Sun Bo Hu Jing Lu Yan Guo Chuxi Liang Hong Xu Haixia Wu 《Journal of Traditional Chinese Medicine》 SCIE CAS CSCD 2014年第2期194-198,共5页
OBJECTIVE: To explore the long-term effects and pain relief mechanism of acupotomy by observing changes in nitric oxide synthase (NOS) and beta-en- dorphin (~3-EP) in the hypothalamus, spinal cord, and peripheral... OBJECTIVE: To explore the long-term effects and pain relief mechanism of acupotomy by observing changes in nitric oxide synthase (NOS) and beta-en- dorphin (~3-EP) in the hypothalamus, spinal cord, and peripheral blood of rats with third lumbar ver- tebrae (L3) transverse process syndrome. METHODS: Twenty-eight SD rats were randomly as- signed to normal, model, electroacupuncture (EA), and acupotomy group. The last three groups were put through an operation to emulate L3 transverse process syndrome. Fourteen days after the simulation operation, EA and acupotomy treatments were applied to the respective groups. Fifty-six days afterthe simulation operation, biochemistry tests and enzyme-linked immunosorbent assay were used to measure NOS and 13-EP in the hypothalamus, spinal cord, and peripheral blood. RESULTS: Rats with the simulation operation showed significantly higher levels of NOS and II3-EP in the hypothalamus, spinal cord, and peripheral blood than those in the normal group. The EA and acupotomy groups had significantly lower levels of NOS and β-EP than those in the model group. There was no statistical difference between the EA and acupotomy groups. CONCLUSION: EA and acupotomy treatments significantly lowered NOS and β-EP levels in the hypothalamus, spinal cord, and peripheral blood and alleviated L3 transverse process syndrome. 展开更多
关键词 ACUPOTOMY Small needle knife ELECTROACUPUNCTURE L3 transverse process syndrome Nitric oxide synthase BETA-ENDORPHIN
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β-decay studies approaching the N=20 island of inversion with a new shell-model Hamiltonian
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作者 WeiGuang Jiang BaiShan Hu +2 位作者 FuRong Xu Rui Han Hui Hua 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS CSCD 2017年第8期15-20,共6页
β-decay properties of N=18-22,Z=10-14 nuclei are analyzed with a new shell-model Hamiltonian using the Gogny densitydependent interaction.The Gogny force which has been widely and successfully used in mean-field theo... β-decay properties of N=18-22,Z=10-14 nuclei are analyzed with a new shell-model Hamiltonian using the Gogny densitydependent interaction.The Gogny force which has been widely and successfully used in mean-field theory can provide reasonable two-body matrix elements for cross-shell calculations.The log f t values andβ-decay level schemes are systematically studied using the D1S-Gogny interaction and compared with the SDPF-M results and experimental data.It is shown that the new Hamiltonian provides reliable results forβ-decay along with subtle level schemes for this region.Shell-model calculations with Gogny interaction can lead to a successful description of nuclei in and around the N=20 island of inversion and supplements experiment where sufficient data are not available. 展开更多
关键词 island of inversion β decay shell model Gogny interaction
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Effect of Bushenyisui Formula on brain tissue apoptosis and Bcl-2 in beta-amyloid protein-induced Alzheimer's disease rat models 被引量:6
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作者 Shuke Cui Yan Sun Chengzang Liu 《Journal of Traditional Chinese Medicine》 SCIE CAS CSCD 2012年第4期646-650,共5页
OBJECTIVE: To investigate the effect of Bushenyisui Formula on cell apoptosis and positive B cell lym- phoma (Bcl-2) in the Brain of rat models of Alzheim- er's disease (AD) induced by beta-amyloid protein (All... OBJECTIVE: To investigate the effect of Bushenyisui Formula on cell apoptosis and positive B cell lym- phoma (Bcl-2) in the Brain of rat models of Alzheim- er's disease (AD) induced by beta-amyloid protein (All3) and the mechanism underlying the effect. METHODS: Total of 40 SD rats, 20 females and 20 males, were randomly assigned to 4 groups, con- trolled group (A), model group (B), conventional treatment group (C) and Bushenyisui Formula treat- ment (BYFT) group (D), 10 rats in each group. AI3 1-42 was injected into the bilateral hippocampus of the rats in group B, C and D to create the models of AD. Sham operation was performed on the rats of group A in the same way by injecting equal volume of 0.9% sodium chloride solution into their bilateral hippocampus. 5 days after operation, Bushenyisui Formula was intraperitoneally administered at a dose of 450 mg/kg to the rats of group D (QD) for 20 days. Equal volume of 0.9% sodium chloride solution was intraperitoneally injected into the rats of group B with the same procedure. C suspension (20 mg/mL) was intraperitoneally injected into the rats of group B with the same procedure. The number of apoptot- ic cells in Brain and the positive Bcl-2 were count- ed. The changes of learning and memory abilities were evaluated using Y-maze. RESULTS: Right after the establishment of the mod- els, group B, C and D compared to group A respec- tively, the outcomes of Y-maze were significantly different from that of group A, which suggested ob- vious learning and memory disorder in those groups (P〈0.01). After treatment, the times of elec- tronic shocks of group C and D were significantly less than that of group B (P〈0.05), and the numbers of apoptotic cells and positive Bcl-2 were signifi- cantly different from those of group B, apoptotic sells' number of group C and D smaller than that of group B and the number of positive Bcl-2 greater than that of group B. CONCLUSION: Bushenyisui Formula could increase the number of Bcl-2 in brain, which improved the function of nervous system pertaining to learning and memory abilities. 展开更多
关键词 Alzheimer disease APOPTOSIS Genes bcl-2 Bushenyisui Formula
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Effects of Compound Danshen tablets(复方丹参片) on spatial cognition and expression of brain β-amyloid precursor protein in a rat model of alzheimer's disease 被引量:9
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作者 覃仁安 姚晓璇 黄竹英 《Journal of Traditional Chinese Medicine》 SCIE CAS CSCD 2012年第1期63-66,共4页
OBJECTIVE:To observe the effects of Compound Danshen Tablets(CDST) on spatial cognition and expression of brain b-amyloid precursor protein(β-APP) in a rat model of Alzheimer's disease.METHODS:The rat model of Al... OBJECTIVE:To observe the effects of Compound Danshen Tablets(CDST) on spatial cognition and expression of brain b-amyloid precursor protein(β-APP) in a rat model of Alzheimer's disease.METHODS:The rat model of Alzheimer's disease(AD) was established using D-galactose to cause subacute aging combined with Meynert nucleus damage.Rat behavior was monitored using the Morris water maze,and the expression of β-APP in rat brain tissue was detected via immunohistochemistry.RESULTS:CDST significantly improved spatial cognition and decreased β-APP expression in the cortex and hippocampus(P<0.05,P<0.01).CONCLUSIONS:CDST can significantly improve spatial cognition in a rat model of AD.This observation is possibly related to a reduction in β-APP ex-pression in the rat brain. 展开更多
关键词 Compound DanshenTablets(CDST) Alzheimer's disease B-amyloid precursor protein
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Effect of Qilongtoutong granule on calcitonin gene-related peptide,beta-endorphin, serotonin, dopamine, and noradrenalin in migraine model rats and mice 被引量:10
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作者 Xiaofang Wu Meikui Zhang Huai Huang 《Journal of Traditional Chinese Medicine》 SCIE CAS CSCD 2014年第2期188-193,共6页
OBJECTIVE: To study the effect of Qilongtoutong granule (QLTT) on plasma calcitonin gene-related peptide (CGRP), beta-endorphin (I[3-EP), 5-HT, dopa- mine (DA), noradrenalin (NE), and blood viscosity in mig... OBJECTIVE: To study the effect of Qilongtoutong granule (QLTT) on plasma calcitonin gene-related peptide (CGRP), beta-endorphin (I[3-EP), 5-HT, dopa- mine (DA), noradrenalin (NE), and blood viscosity in migraine model rats and mice. METHODS: Both the acute blood stasis model group and nitroglycerin-induced migraine model group included 60 Sprague-Dawley rats. The reser- pine-reduced model group had 60 Kunming mice. Rats from each test were grouped into normal con- trol group, model group, Zhengtian pill (ZTP) group, and high, moderate, or low-dose QLTT groups. In the acute blood stasis model test, after gavage for 7 days, rats were given 0.8 mL/kg adren- aline hydrochloride subcutaneously twice, and kept in ice water for 5 min. After fasting for 12 h, rats were anesthetized and blood samples were collected for detection of blood viscosity. In the nitro- glycerin-induced migraine group, after gavage for 7 days, rats were intraperitoneally injected nitro- glycerin (10 mg/kg), and 4 h later, blood samples were collected from postcava for measuring the plasma CGRP and 13-EP levels. In the reserpine-re- duced model test, except the normal control group, mice were administered reserpine (0.25 mg/ kg, i.h.) for 9 days. Mice received intragastric admin- istration from the third day to the ninth day. One hour after the last gavage, blood and brain tissue samples were obtained. Then, blood clotting time and the contents of neurotransmitters were deter- mined. RESULTS: QLTT- (3.6, 1.8, and 0.9 g/kg) and ZTP-treated rats had lower blood viscosity than that in model rats under different shear rates (P〈 0.01). QLTT- (3.6, 1.8 g/kg) and ZTP-treated rats had significantly lower plasma CGRP levels and higher plasma 13-EP levels than those in model rats (P〈 0.01). QLTT treatment at dose of 0.9 g/kg had lower plasma CGRP levels as well (P〈0.05). QLTT- (5.2, 2.6 g/kg) and ZTP-treated mice had longer blood clotting time than that in model mice (P〈0.01). QLTT- (2.6 g/kg) and ZTP-treated mice had higher plasma serotonin (5-HT) levels than those in model mice (P〈0.05). CONCLUSION: QLTT-treated animals had lower plasma CGRP level, higher plasma 13-EP, 5-HT, high- er brain tissue 5-HT, NE, DA levels, and lower blood viscosity than those in the migraine model animals. 展开更多
关键词 Migraine disorders Calcitonin gene-related peptide BETA-ENDORPHIN Medicine Chinesetraditional Qilongtoutong granule
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外商在华直接投资区域聚集非均衡性的实证研究 被引量:26
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作者 冯涛 赵会玉 杜苗苗 《经济学(季刊)》 2008年第1期565-586,共22页
本文运用空间统计学Moran I指数法和β-收敛模型分析了中国31个省级区域和八大区域的FDI聚集特征及其影响因素。结果显示:(1)中国省域FDI增长具有明显的空间依赖性,在地理空间上存在集聚现象,区域经济增长在时空上呈现出明显的空... 本文运用空间统计学Moran I指数法和β-收敛模型分析了中国31个省级区域和八大区域的FDI聚集特征及其影响因素。结果显示:(1)中国省域FDI增长具有明显的空间依赖性,在地理空间上存在集聚现象,区域经济增长在时空上呈现出明显的空间效应;(2)空间相关以及由此带来的国际国内贸易及外资等经济活动频繁程度,在很大程度上引起了31个省域区际吸引外资的空间不均衡,空间集聚使得在经济增长过程中地理区位(距离)产生的空间成本降低,但地理特征将深刻作用于区域经济增长空间集聚的中心和外围关系;(3)外商直接投资对中国区域经济增长的贡献非常重要,但它却不能轻易改变经济地理的规则,影响外商直接投资的因素在地理空间上的非均衡集聚导致了迥然不同的区域引资格局。 展开更多
关键词 外商直接投资(FDI) 区域聚集 空间统计 β-收敛模型
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基于贝叶斯网络的多状态共因失效系统可靠性分析 被引量:8
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作者 古莹奎 沈延军 +1 位作者 张全新 蔡泉 《机械设计与研究》 CSCD 北大核心 2018年第2期1-4,9,共5页
为提高多状态共因失效系统可靠性分析的准确性,降低计算的复杂性,将贝叶斯网络和β-因子模型引入到系统的可靠性分析中,提出一种基于贝叶斯网络的多状态共因失效系统可靠性分析方法。利用贝叶斯网络不确定性推理和图形化表达的特点,建... 为提高多状态共因失效系统可靠性分析的准确性,降低计算的复杂性,将贝叶斯网络和β-因子模型引入到系统的可靠性分析中,提出一种基于贝叶斯网络的多状态共因失效系统可靠性分析方法。利用贝叶斯网络不确定性推理和图形化表达的特点,建立考虑共因失效的多状态系统可靠性分析模型,通过β-因子模型对共因失效进行定量分析,充分考虑共因失效与系统部件间的逻辑关系,引入共因失效率构建考虑共因失效的可靠性评估模型。以柴油机冷却系统的共因失效分析为例进行验证,结果表明提出的方法可以对系统的共因失效问题进行清楚地表达,不需要计算最小割集,适用于复杂机械系统共因失效的研究。 展开更多
关键词 多状态系统 共因失效(CCF) 贝叶斯网络(BN) β-因子模型 柴油机冷却系统
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Biochemical and behavioral characterization of the double transgenic mouse model (APPswe/PS1dE9) of Alzheimer’s disease 被引量:4
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作者 Huaqi XIONG Debbie Callaghan +5 位作者 Jolanta Wodzinska Jiejing XU Maryna Premyslova Qing-Yan LIU John Con- nelly Wandong ZHANG 《Neuroscience Bulletin》 SCIE CAS CSCD 2011年第4期221-232,共12页
Objective The double transgenic mouse model (APPswe/PSldE9) of Alzheimer's disease (AD) has been widely used in experimental studies. β-Amyloid (Aβ) peptide is excessively produced in AD mouse brain, which af... Objective The double transgenic mouse model (APPswe/PSldE9) of Alzheimer's disease (AD) has been widely used in experimental studies. β-Amyloid (Aβ) peptide is excessively produced in AD mouse brain, which affects synaptic function and the development of central nervous system. However, little has been reported on characterization of this model. The present study aimed to characterize this mouse AD model and its wild-type counterparts by biochemical and functional approaches. Methods Blood samples were collected from the transgenic and the wild-type mice, and radial arm water maze behavioral test was conducted at the ages of 6 and 12 months. The mice were sacrificed at 12-month age. One hemisphere of the brain was frozen-sectioned for immunohistochemistry and the other hemisphere was dissected into 7 regions. The levels ofAβ1-40, Aβ1-42 and 8-hydroxydeoxyguanosine (8-OHdG) in blood or/and brain samples were analyzed by ELISA. Secretase activities in brain regions were analyzed by in vitro assays. Results The pre-mature death rate of transgenic mice was approximately 35% before 6-month age, and high levels of Aβ1-40 and Aβ1-42 were detected in these dead mice brains with a ratio of 1 : 1 0. The level of blood-borne Aβ at 6-month age was similar with that at 12-month age. Besides, Aβ1-40 level in the blood was significantly higher than Aβ1-42 level at the ages of 6 and 12 months (ratio 2.37:1). In contrast, the level of Aβ1-42 in the brain (160.6 ng/mg protein) was higher than that of Aβ1-40 (74 ng/mg protein) (ratio 2.17:1). In addition, the levels of Aβ1-40 and Aβ1-42 varied markedly among different brain regions. Aβ1-42 level was significantly higher than Aβ1-40 level in cerebellum, frontal and posterior cortex, and hippocampus. Secretase activity assays did not reveal major differences among different brain regions or between wild-type and transgenic mice, suggesting that the transgene PS1 did not lead to higher 7-secretase activity but was more efficient in producing Aβ1-42 peptides. 8-OHdG, the biomarker of DNA oxidative damage, showed a trend of increase in the blood of transgenic mice, but with no significant difference, as compared with the wild-type mice. Behavioral tests showed that transgenic mice had significant memory deficits at 6-month age compared to wild-type controls, and the deficits were exacerbated at 12-month age with more errors. Conclusion These results suggest that this mouse model mimics the early-onset human AD and may represent full-blown disease at as early as 6-month age for experimental studies. 展开更多
关键词 mouse model Alzheimer's disease β-amyloid peptides secretase activities DNA oxidative damage behavioral test
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