Beta
Beta的相关文献在1994年到2023年内共计1018篇,主要集中在自动化技术、计算机技术、肿瘤学、内科学
等领域,其中期刊论文329篇、专利文献689篇;相关期刊167种,包括硅谷、互联网天地、电脑知识与技术-经验技巧等;
Beta的相关文献由1793位作者贡献,包括凌凤香、毛裕民、谢毅等。
Beta
-研究学者
- 凌凤香
- 毛裕民
- 谢毅
- 王少军
- 张会成
- 范峰
- 杨春雁
- 舒兴田
- 陈晓刚
- 罗一斌
- 刘中民
- 田鹏
- 袁扬扬
- 杨淼
- 王林英
- 杨越
- 田辉平
- 周灵萍
- 杜艳泽
- 王永睿
- 秦波
- 于吉红
- 慕旭宏
- 闫文付
- 刘瑞田
- 张蔚琳
- 彭欣欣
- 徐龙伢
- 朱斌
- 朱玉霞
- 林民
- 欧阳颖
- 王宝荣
- 陈振宇
- 王诗瑶
- 谢鲜梅
- 陈文勇
- 刘建强
- 庄立
- 朱向学
- 杨清河
- 王凤来
- 王小平
- 田志坚
- 肖丰收
- 刘盛林
- 奚红霞
- 孙洪敏
- 张伟
- 徐如人
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盛路阳;
展俊岭;
张旭鹏;
吴邦昊;
张钰;
张吉波
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摘要:
以ZSM-5分子筛为核相,通过聚二烯丙基二甲基氯化铵(PDDA)偶连纳米Beta分子筛晶种,经动态水热合成方法制备了ZSM-5@Beta核壳二元复合分子筛。采用XRD、N吸附-脱附、SEM、TEM、ICP、NH-TPD及Py-FTIR等手段对复合分子筛的结构和物性进行了表征,考察了复合分子筛催化2-甲萘(2-MN)与甲醇烷基化合成2,6-二甲基萘(2,6-DMN)的催化性能。结果表明,采用该方法制备出粒径约为500 nm的核壳结构ZSM-5@Beta复合分子筛。与机械混合二元分子筛相比,核壳结构材料具有更高的比表面积和外表面积,并降低了酸强度和强酸中心密度。通过限域催化理念、核壳界面和多级孔道的构建,借助12元环壳相Beta分子筛提高催化活性,利用10元环核相ZSM-5的择形催化作用提高催化选择性。在2-MN与甲醇烷基化反应中提高了2-MN的转化率和2,6-DMN的选择性,产物中2,6-/2,7-DMN比达到1.35,2,6-DMN收率达到4.29%。
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钱吉;
侯鹏;
王成业;
杨瑞云;
刘超;
马文俊
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摘要:
本文对HZSM-5、HMCM-22和HBeta沸石进行了系统表征,采用固定床评价三种沸石样品在苯和甲醇烷基化的反应性能.结果表明,HBeta的十二元环孔道有利于大分子产物的生成,积碳速率快导致催化剂失活最快,而HZSM-5和HMCM-22由于十元环孔道和窗口相对较小,大分子产物不容易生成,积碳速率缓慢,具有较好的稳定性.由于H-MCM-22具有更高的甲苯和二甲苯总选择性,同时乙苯在碳八组分中的百分含量只有1.02%.所以,H-MCM-22催化剂是优异的苯和甲醇烷基化催化剂.
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钱吉;
侯鹏;
王成业;
杨瑞云;
刘超;
马文俊
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摘要:
本文对HZSM-5、HMCM-22和HBeta沸石进行了系统表征,采用固定床评价三种沸石样品在苯和甲醇烷基化的反应性能。结果表明,HBeta的十二元环孔道有利于大分子产物的生成,积碳速率快导致催化剂失活最快,而HZSM-5和HMCM-22由于十元环孔道和窗口相对较小,大分子产物不容易生成,积碳速率缓慢,具有较好的稳定性。由于H-MCM-22具有更高的甲苯和二甲苯总选择性,同时乙苯在碳八组分中的百分含量只有1.02%。所以,H-MCM-22催化剂是优异的苯和甲醇烷基化催化剂。
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Maria Mercedes Chang Villacreses;
Rudruidee Karnchanasorn;
Panadeekarn Panjawatanan;
Horng-Yih Ou;
Ken C Chiu
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摘要:
As an endocrine hormone,vitamin D plays an important role in bone health and calcium homeostasis.Over the past two decades,the non-calcemic effects of vitamin D were extensively examined.Although the effect of vitamin D on beta cell function were known for some time,the effect of vitamin D on glucose and fuel homeostasis has attracted new interest among researchers.Yet,to date,studies remain inconclusive and controversial,in part,due to a lack of understanding of the threshold effects of vitamin D.In this review,a critical examination of interventional trials of vitamin D in prevention of diabetes is provided.Like use of vitamin D for bone loss,the benefits of vitamin D supplementation in diabetes prevention were observed in vitamin D-deficient subjects with serum 25-hydroxyvitamin D75 nmol/L(30 ng/mL).Furthermore,no benefit was noted in subjects that achieved serum 25-hydroxyvitamin D>100 nmol/L(40 ng/mL).Further studies are required to confirm these observations.
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Jia-He Li;
Zhong-Ju Shi;
Yan Li;
Bin Pan;
Shi-Yang Yuan;
Lin-Lin Shi;
Yan Hao;
Fu-Jiang Cao;
Shi-Qing Feng
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摘要:
Zebrafish and human genomes are highly homologous;however,despite this genomic similarity,adult zebrafish can achieve neuronal proliferation,regeneration and functional restoration within 6–8 weeks after spinal cord injury,whereas humans cannot.To analyze differentially expressed zebrafish genes between axon-regenerated neurons and axon-non-regenerated neurons after spinal cord injury,and to explore the key genes and pathways of axonal regeneration after spinal cord injury,microarray GSE56842 was analyzed using the online tool,GEO2R,in the Gene Expression Omnibus database.Gene ontology and protein-protein interaction networks were used to analyze the identified differentially expressed genes.Finally,we screened for genes and pathways that may play a role in spinal cord injury repair in zebrafish and mammals.A total of 636 differentially expressed genes were obtained,including 255 up-regulated and 381 down-regulated differentially expressed genes in axon-regenerated neurons.Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment results were also obtained.A protein-protein interaction network contained 480 node genes and 1976 node connections.We also obtained the 10 hub genes with the highest correlation and the two modules with the highest score.The results showed that spectrin may promote axonal regeneration after spinal cord injury in zebrafish.Transforming growth factor beta signaling may inhibit repair after spinal cord injury in zebrafish.Focal adhesion or tight junctions may play an important role in the migration and proliferation of some cells,such as Schwann cells or neural progenitor cells,after spinal cord injury in zebrafish.Bioinformatic analysis identified key candidate genes and pathways in axonal regeneration after spinal cord injury in zebrafish,providing targets for treatment of spinal cord injury in mammals.
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Heydari MEHDI;
Aazami FATEMEH;
Faramarzi MARZBAN;
Omidipour REZA;
Bazgir MASOUD;
Pothier DAVID;
Prévosto BERNARD
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摘要:
This study aimed to investigate the interaction between regions with different climatic conditions(arid vs. semi-arid) and management(protected vs. unprotected) on the turnover and nestedness of vegetation in relation to physical, chemical and biological properties of soils in the Ilam Province of Iran. In each of the two regions, we sampled 8 sites(4 managed and 4 unmanaged sites) within each of which we established 4 circular plots(1000 m^2) that were used to investigate woody species, while two micro-plots(1 m×1 m) were established in each 1000-m^2 plot to analyze herbaceous species. In each sample unit, we also extracted three soil samples(0–20 cm depth) for measuring soil properties. The results indicated that the interaction between region and conservational management significantly affected the percent of canopy cover of Persian oak(Quercus brantii Linddl), soil respiration, substrate-induced respiration, as well as beta and gamma diversities and turnover of plant species. The percent of oak canopy cover was positively correlated with soil silt, electrical conductivity, available potassium, and alpha diversity, whereas it was negatively correlated with plant turnover. In addition, plant turnover was positively related to available phosphorus, while nestedness of species was positively related to organic carbon and total nitrogen. According to these results, we concluded that physical, chemical, and biological characteristics of limited ecological niche generally influenced plant diversity. Also, this study demonstrated the major contribution of the beta diversity on gamma diversity, especially in semi-arid region, because of the higher heterogeneity of vegetation in this area.
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Vu B. Ho
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摘要:
In this work we re-examine a model of the nucleons that involve the weak interaction which was once considered by Heisenberg;that is a neutron may have the structure of a dwarf hydrogen-like atom. We formulate a quantum dynamics for the Heisenberg model of the neutron associated with interaction that involves the beta decay in terms of a mixed Coulomb-Yukawa potential and the More General Exponential Screened Coulomb Potential (MGESCP), which has been studied and applied to various fields of physics. We show that all the components that form the MGESCP potential can be derived from a general system of linear first order partial differential equations similar to Dirac relativistic equation in quantum mechanics. There are many interesting features that emerge from the MGESCP potential, such as the MGESCP potential can be reduced to the potential that has been proposed to describe the interaction between the quarks for strong force in particle physics, and the energy spectrum of the bound states of the dwarf hydrogen-like atom is continuous with respect to distance. This result leads to an unexpected implication that a proton and an electron may also interact strongly at short distances. We also show that the Yukawa potential when restrained can generate and determine the mathematical structures of fundamental particles associated with the strong and weak fields.
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Siaka Touré
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摘要:
The Weibull distribution is a probability density function (PDF) which is widely used in the study of meteorological data. The statistical analysis of the wind speed v by using the Weibull distribution leads to the estimate of the mean wind speed , the variance of v around and the mean power density in the wind. The gamma function Γ is involved in those calculations, particularly Γ (1+1/k), Γ (1+2/k) and Γ (1+3/k). The paper reports the use of the Weibull PDF f(v) to estimate the gamma function. The study was performed by looking for the wind speeds related to the maximum values of f(v), v2 f(v) and v3 f(v). As a result, some approximate relationships were obtained for Γ (1+1/k), Γ (1+2/k) and Γ (1+3/k), that use some fitting polynomial functions. Very good agreements were found between the exact and the estimated values of Γ (1+n/k) that can be used for the estimation of the mean wind speed , the variance σ2 of the wind speed v;around the mean speed and the average wind power density.
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- 太原理工大学
- 公开公告日期:2019-01-18
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摘要:
本发明涉及分子筛、催化剂,具体为微‑介孔Beta分子筛、Ni基微介孔Beta分子筛催化剂及其制备方法,解决现有微孔Beta分子筛孔道狭窄、比表面积小和Ni基分子筛催化剂扩散限制问题,步骤:在乙腈和甲苯(1:1 v/v)中,以摩尔比为2:1的溴代十八烷和N,N,N’,N’‑四甲基‑1,6‑己二胺反应制得模板剂C
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