关于Mordell方程y^2=x^3＋k

设l,l1,l2,…,ls为任意整数,n为正整数,n1,n2,…,ns为任意非负整数．用初等数论方法证明了：如果k满足k=（4l＋2）^3-Пi=1^s（4li＋1）^2ni或k=（4l＋3）^3-2^2nПi=1^s（4li＋1）^2ni,则Mordell方程y^2=x^3＋k无整数解．     

Enabling Mg metal anodes rechargeable in conventional electrolytes by fast ionic transport interphase

Rechargeable magnesium batteries have received extensive attention as the Mg anodes possess twice the volumetric capacity of their lithium counterparts and are dendrite-free. However, Mg anodes suffer from surface passivation film in most glyme-based conventional electrolytes, leading to irreversible plating/stripping behavior of Mg. Here we report a facile and safe method to obtain a modified Mg metal anode with a Sn-based artificial layer via ion-exchange and alloying reactions. In the artificial coating layer, Mg₂Sn alloy composites offer a channel for fast ion transport and insulating MgCl₂/SnCl₂ bestows the necessary potential gradient to prevent deposition on the surface. Significant improved ion conductivity of the solid electrolyte interfaces and decreased overpotential of Mg symmetric cells in Mg(TFSI)₂/DME electrolyte are obtained. The coated Mg anodes can sustain a stable plating/stripping process over 4000 cycles at a high current density of 6 mA cm⁻². This finding provides an avenue to facilitate fast ion diffusion kinetics of Mg metal anodes in conventional electrolytes.     

发展中国电子商务的几点思考

“电子商务”这个名词在我国已经不在是陌生的名词了,它已经在中国越来越被人们所认可.什么是电子商务?所谓电子商务(ElectronicCommerce)是利用计算机技术、网络技术和远程通信技术,实现整个商务(买卖)过程中的电子化、数字化和网络化。人们不再是面对面的、看着实实在在的货物、靠纸介质单据(包括现金)进行买卖交易。而是通过网络,通过网上琳琅满目的商品信息、完善的物流配送系统和方便安全的资金结算系统进行交易(买卖)。     

Genomic diversity and post-admixture adaptation in the Uyghurs

Population admixture results in genome-wide combinations of genetic variants derived from different ancestral populations of distinct ancestry, thus providing a unique opportunity for understanding the genetic determinants of phenotypic variation in humans. Here, we used whole-genome sequencing of 92 individuals with high coverage (30–60×) to systematically investigate genomic diversity in the Uyghurs living in Xinjiang, China (XJU), an admixed population of both European-like and East-Asian-like ancestry. The XJU population shows greater genetic diversity, especially a higher proportion of rare variants, compared with their ancestral source populations, corresponding to greater phenotypic diversity of XJU. Admixture-induced functional variants in EDAR were associated with the diversity of facial morphology in XJU. Interestingly, the interaction of functional variants between SLC24A5 and OCA2 likely influences the diversity of skin pigmentation. Notably, selection has seemingly been relaxed or canceled in several genes with significantly biased ancestry, such as HERC2–OCA2. Moreover, signatures of post-admixture adaptation in XJU were identified, including genes related to metabolism (e.g. CYP2D6), digestion (e.g. COL11A1), olfactory perception (e.g. ANO2) and immunity (e.g. HLA). Our results demonstrated population admixture as a driving force, locally or globally, in shaping human genetic and phenotypic diversity as well as in adaptive evolution.     

Replication,pathogenicity, and transmission of SARS-CoV-2 in minks

Minks are raised in many countries and have transmitted severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to humans. However, the biologic properties of SARS-CoV-2 in minks are largely unknown. Here, we investigated and found that SARS-CoV-2 replicates efficiently in both the upper and lower respiratory tracts, and transmits efficiently in minks via respiratory droplets; pulmonary lesions caused by SARS-CoV-2 in minks are similar to those seen in humans with COVID-19. We further found that a spike protein-based subunit vaccine largely prevented SARS-CoV-2 replication and lung damage caused by SARS-CoV-2 infection in minks. Our study indicates that minks are a useful animal model for evaluating the efficacy of drugs or vaccines against COVID-19 and that vaccination is a potential strategy to prevent minks from transmitting SARS-CoV-2.     

认证机构服务质量对关系质量影响实证研究

摘要：本文在认证行业领域,研究了认证机构服务质量对关系质量的影响。在认证机构服务质量4维度结构（即过程服务能力、过程交互质量、潜在服务能力和结果质量）及关系质量3维度结构（即合作性、适应性和关系氛围）的基础上,构建了认证机构服务质量对关系质量的影响模型。对721家企业的实证研究表明,过程服务能力、结果质量两个维度对认证机构和顾客之间的关系质量有显著影响,而过程交互质量、潜在服务能力两个维度对两者关系质量的影响不显著。最后对认证机构如何提高其服务质量,维持良好的顾客关系提出了建议。         

Static analysis of synchronism deployable antenna

INTRODUCTION Large antennas for space applications have some differences as compared to their counterparts de-signed and manufactured for ground usage. For a larger space antenna, the applied loads in space can be several orders of magnitude less than the gravity loading it is subjected to when being fabricated and assembled on the ground. Since the effect of gravity cannot be removed from any experimental verifica-tion performed on the ground, we must rely on the use of efficient and hig…     

汉英表量结构中隐喻的分类及认知解读

以＂合成空间理论＂为理论背景,研究汉英表量结构中隐喻的分类与认知解读问题。根据输入空间的不同,从认知角度将汉英表量结构中的隐喻分为两类：显性隐喻和隐性隐喻。显性隐喻是通过＂量词＂和＂名词＂两个输入空间之间的概念整合进行建构的,而隐性隐喻是通过量词所描述的＂原型名词＂和表量结构中的＂名词＂两个输入空间之间的概念整合进行建构的。     

论社会弱势群体的成因及其扶助措施

弱势群体问题关系着社会稳定的大局,已成为时下中国社会关注的热点问题。本文客观剖析了弱势群体产生的原因,提出了扶助社会弱势群体的具体措施。     

小粒子Mie散射理论及应用（Ⅰ）

本详细综述了近几年小粒子Mie散射的理论基础及其发展。