基于SPOC的大学英语教学研究综述

SPOC 是Small Private Online Course 的缩写,即“小众私密在线课程”。本文通过对有关文献的研究综述,对近三年(2014-2017)基于SPOC 的大学英语教学的研究内容进行分析,探究其研究特点并进行研究反思。

战国策派的改造国民性思想

面临第二次世界大战这一严酷的国际竞争局势,战国策派学人提出了其改造国民性思想:把官僚化、文人化、乡愿化、阿Q化的“柔道的人格型”改造为具有柯伯尼宇宙观、战士式人生观、“忠为第一”、文武并重的“刚道的人格型”。战国策派还试图往文学艺术中灌注“悲剧精神”和“民族意识”来促进国民性的改造。战国策派的改造国民性思想是重庆抗战文化的一道独特风景。

三步投影方法及对变分不等式的应用

首先引入了三步投影方法,然后应用它来求H-空间中非线性变分不等式的解;推广了R.U.Verma的两步投影方法及其在变分不等式中的应用。在理论和实际应用中都具有一定的重要意义。

Synergistic integration of metallic Bi and defects on BiOI: Enhanced photocatalytic NO removal and conversion pathway

Surface plasmon resonance(SPR)of metals may provide a way to improve light absorption and utilization of semiconductors,achieving better solar light conversion and photocatalysis efficiency.This study uses the advantages of SPR in metallic Bi and artificial defects to cooperatively enhance the photocatalytic performance of BiOI.The catalysts were prepared by partial reduction of BiOI to form Bi@defective BiOI,which showed highly enhanced visible photocatalytic activity for NOx removal.The effects of reductant quantity on the photocatalytic performance of Bi@defective BiOI were investigated.The as-prepared photocatalyst(Bi/BiOI-2)using 2 mmol of reductant NaBH4 showed the most efficient visible light photocatalytic activity.This enhanced activity can be ascribed to the synergistic effects of metallic Bi and oxygen vacancies.The electrons from the valence band tend to accumulate at vacancy states;therefore,the increased charge density would cause the adsorbed oxygen to transform more easily into superoxide radicals and,further,into hydroxyl radicals.These radicals are the main active species that oxidize NO into final products.The SPR effect of elemental Bi enables the improvement of visible light absorption efficiency and the promotion of charge carrier separation,which are crucial factors in boosting photocatalysis.NO adsorption and reaction processes on Bi/BiOI-2 were dynamically monitored by in situ infrared spectroscopy(FT-IR).The Bi/BiOI photocatalysis mechanism co-mediated by elemental Bi and oxygen vacancies was proposed based on the analysis of intermediate products and DFT calculations.This present work could provide new insights into the design of high-performance photocatalysts and understanding of the photocatalysis reaction mechanism for air-purification applications.

Sustainable synthesis of supported metal nanocatalysts for electrochemical hydrogen evolution

Among the various types of heterogeneous catalysts,supported metal nanocatalysts(SMNCs)have attracted widespread interest in chemistry and materials science,due to their advantageous features,such as high efficiency,stability,and reusability for catalytic reactions.However,to obtain well-defined SMNCs and inhibit nanoparticle aggregation,traditional approaches generally involve numerous organic reagents,complex steps,and specialized equipment,thus hindering the practical and large-scale synthesis of SMNCs.In this review,we summarize green and sustainable synthetic methodologies for the assembly of SMNCs,including low temperature pyrolysis and solid-state,surfactant-and reductant-free,and ionic liquid assisted syntheses.The conventional application of SMNCs for electrochemical hydrogen evolution and the corresponding achievements are subsequently discussed.Finally,future perspectives toward the sustainable production of SMNCs are presented.

Facile synthesis of Bi_(12)O_(17)Br_2 and Bi_4O_5Br_2 nanosheets:In situ DRIFTS investigation of photocatalytic NO oxidation conversion pathway

Bi12O17Br2and Bi4O5Br2visible‐light driven photocatalysts,were respectively fabricated by hydrothermal and room‐temperature deposition methods with the use of BiBr3and NaOH as precursors.Both Bi12O17Br2and Bi4O5Br2were composed of irregular nanosheets.The Bi4O5Br2nanosheets exhibited high and stable visible‐light photocatalytic efficiency for ppb‐level NO removal.The performance of Bi4O5Br2was markedly higher than that of the Bi12O17Br2nanosheets.The hydroxyl radical(?OH)was determined to be the main reactive oxygen species for the photo‐degradation processes of both Bi12O17Br2and Bi4O5Br2.However,in situ diffuse reflectance infrared Fourier transform spectroscopy analysis revealed that Bi12O17Br2and Bi4O5Br2featured different conversion pathways for visible light driven photocatalytic NO oxidation.The excellent photocatalytic activity of Bi4O5Br2resulted from a high surface area and large pore volumes,which facilitated the transport of reactants and intermediate products,and provided more active sites for photochemical reaction.Furthermore,the Bi4O5Br2nanosheets produced more?OH and presented stronger valence band holeoxidation.In addition,the oxygen atoms of NO could insert into oxygen‐vacancies of Bi4O5Br2,whichprovided more active sites for the reaction.This work gives insight into the photocatalytic pollutant‐degradation mechanism of bismuth oxyhalide.

Hierarchical coral-like FeNi(OH)_x/Ni via mild corrosion of nickel as an integrated electrode for efficient overall water splitting

Efficient,stable,and noble‐metal‐free electrocatalysts for both the oxygen evolution reaction and the hydrogen evolution reaction are highly imperative for the realization of low‐cost commercial water‐splitting electrolyzers.Herein,a cost‐effective and ecofriendly strategy is reported to fabricate coral‐like FeNi(OH)x/Ni as a bifunctional electrocatalyst for overall water splitting in alkaline media.With the assistance of mild corrosion of Ni by Fe(NO3)3,in situ generated FeNi(OH)x nanosheets are intimately attached on metallic coral‐like Ni.Integration of these nanosheets with the electrodeposited coral‐like Ni skeleton and the supermacroporous Ni foam substrate forms a binder‐free hierarchical electrode,which is beneficial for exposing catalytic active sites,accelerating mass transport,and facilitating the release of gaseous species.In 1.0 mol L^-1 KOH solution,a symmetric electrolyzer constructed with FeNi(OH)x/Ni as both the anode and the cathode exhibits an excellent activity with an applied potential difference of 1.52 V at 10 mA cm^-2,which is superior to that of an asymmetric electrolyzer constructed with the state‐of‐the‐art RuO2‐PtC couple(applied potential difference of 1.55 V at 10 mA cm^-2).This work contributes a facile and reliable strategy for manufacturing affordable,practical,and promising water‐splitting devices.

Comparison of corrosion resistance of MgAl-LDH and ZnAl-LDH films intercalated with organic anions ASP on AZ31 Mg alloys

The aspartic acid(ASP),an environment-friendly corrosion inhibitor,was explored to intercalate into the ZnAl-layered double hydroxide(ZnAl-LDH)and MgAl-LDH coatings on AZ31 magnesium alloys by a facile one-step hydrothermal method.The morphology,composition,structure and corrosion resistance of the prepared coatings were comparatively investigated.It is found that the uniform and dense layered nanosheet(NS)vertically grows on the substrate,and the MgAl−ASP-LDH films exhibit a three-dimensional(3D)rose-like sheet structure with high ratio of pore coverage.The MgAl−ASP-LDH coating exhibits better corrosion resistance and durability of longtime immersion than ZnAl−ASP-LDH coating.The corrosion current density of two coatings is two or three orders of magnitude lower than that of bare Mg alloy,indicating that ZnAl/MgAl-LDH films intercalated with organic ASP anions can significantly improve the corrosion resistance of Mg alloy.

Self-assembly synthesis of S-scheme g-C_(3)N_(4)/Bi_(8)(CrO_(4))O_(11) for photocatalytic degradation of norfloxacin and bisphenol A

To realize the high-efficiency photodegradation of antibiotics,a novel S-scheme heterojunction photocatalyst g-C_(3)N_(4)/Bi_(8)(CrO_(4))O_(11) was proposed and successfully prepared in this work.The 10%g-C_(3)N_(4)/Bi_(8)(CrO_(4))O_(11) heterojunction exhibits the highest degradation rate of norfloxacin(NOR)and bisphenol A(BPA).The degradation rate of NOR on 10%g-C_(3)N_(4)/Bi_(8)(CrO_(4))O_(11) is about 1.38 and 2.33 times higher than that of pure Bi_(8)(CrO_(4))O_(11) and g-C_(3)N_(4),respectively.Further,the degradation rate of BPA over 10%g-C_(3)N_(4)/Bi_(8)(CrO_(4))O_(11) heterojunction is bout 1.35 and 9.11 times higher than that of pure Bi_(8)(CrO_(4))O_(11) and g-C_(3)N_(4),respectively.The formation of S-scheme heterojunction facilitates the separation of photogenerated electron-hole pairs and reduces the recombination of charge carriers,which was confirmed by photocurrent,electrochemical impedance spectroscopy,steady-state and time-resolved transient photoluminescence spectrum,etc.The in-situ X-ray photoelectron spectroscopy,radical trapping experiments and electron paramagnetic resonance results demonstrate that the charge transfer is in accord with S-scheme mechanism.

Redescription of male and female genitalia of Tipula(Emodotipula) holoteles(Diptera), with notes on the structure of the semen pump in the subgenus Emodotipula

The original description of male hypopygium of Tipula(Emodotipula) holoteles Alexander, 1924 is expanded with additional morphological characters and detailed illustrations. The additional morphological descriptions of the female ovipositor along with detailed drawings are provided. The male semen pump and the female vaginal apodeme as well as the spermatheca are also described and illustrated for the first time, representing the first report of these structures of Tipula(Emodotipula) holoteles. Additionally, the taxonomic potential of the semen pump in the subgenus Emodotipula is analyzed and discussed. The new specific name Tipula(Emodotipula) yangi nom. nov. is proposed as a replacement name for junior homonym Tipula(Emodotipula) alexanderi Men, 2017. A worldwide checklist and a key to Chinese species of the subgenus Emodotipula are provided.

Two new species in the subgenus Formotipula Matsumura(Diptera:Tipulidae:Tipula)from China

Two new species in the subgenus Formotipula Matsumura,1916,T.(Formotipula)gongshanensis sp.nov.from Yunnan and T.(F.)medogensis sp.nov.from Tibet,are described and illustrated.Males of T.(F.)spoliatrix Alexander,1941 and T.(F.)stoneana Alexander,1943 are redescribed and illustrated based on additional morphological characters.Females of T.(F.)stoneana and T.(F.)decurvans Alexander,1950 are reported for the first time.

技术进步对经济增长作用的理论与实证分析

现代经济学家比较一致地认为哈罗德——多马模型是最早的运用数学模型系

A new species of Tipulodina(Diptera: Tipulidae) from China

A new species of the genus Tipulodina Enderlein, 1912, Tipulodina simianshanensis Men sp. nov.(South China: Chongqing) is described and illustrated. A key to known species of the genus in China is provided. The new species represents the first record of Tipulodina species from Chongqing, China.

A preliminary phylogeny of Tipula and taxonomic placement of the subgenus Tipula (Sivatipula) (Diptera: Tipuloidea) based on mitochondrial COI gene

The large genus Tipula Linnaeus,1758 contributes heavily to the biodiversity of the family Tipulidae.However,the monophyly of Tipula has not yet been verified.The subgenus Sivatipula Alexander,1964 is possibly the most confusing subgeneric taxon in the genus Tipula because of its members’particularly long antenna and one-armed posterior immovable apodeme on semen pump,which makes its subgeneric position uncertain.In this research,the sequences of cytochrome oxidase I(COI)for 19 Tipula species and five taxa from other genera are analyzed.Considering the molecular evidence on genetic distance as well as phylogenetic analysis and morphological information,our results indicate that(1)the genus Tipula is not resolved as monophyletic in phylogeny based on neighbor joining(NJ)and maximum likelihood(ML)trees because the subgenus Sivatipula doesn’t form a monophyletic clade with the remaining subgenera of Tipula;and(2)Sivatipula may deserve a generic status since it forms an independent phylogenetic line.

Description of a new species in the genus Tipulodina Enderlein(Diptera:Tipulidae)from China

A new species in the genus Tipulodina Enderlein,1912,Tipulodina bispina sp.nov.(Guangxi,South China),is described and illustrated.The description,illustrations and drawings for this new species are provided.It is distinguished from related species by the shapes of the gonostylus.

基于信息分析理论的珠江河口及深圳湾悬浮泥沙时空变化分析

本文从信息分析理论出发,研究了悬浮泥沙的时空结构与时空分析模式。由于悬浮泥沙在时间变化上既具有周期性又具有随机性,在空间上存在区域差异,所以从信息分析理论角度,悬浮泥沙时间分析模式可分为基于时间跨度的时间分析模式和基于变动因素的时间分析模式,而悬浮泥沙空间分析模式可分为空间变化分析模式和空间类比分析模式。基于以上时空分析模式,本文选择珠江口及其邻近海域1995年～2000年152个时相的NOAA/AVHRR影像反演的悬浮泥沙浓度结果,及泥沙输移模型模拟的悬浮泥沙浓度,对珠江河口及深圳湾悬浮泥沙进行周期性变化分析、趋势面分析和垂向变化分析。研究表明,珠江河口悬浮泥沙具有明显的月变化、季节变化、丰枯水期变化及涨落潮变化规律,而深圳湾悬浮泥沙在垂向上则表现出由底层向上逐渐降低的变化规律。

警惕秦帝国的专制幽灵--孙皓晖隔行论史何为

不同学科学者隔行论史,共同攻关,原是好事;但也需要遵守一定的规则,保持一定的秩序,才能使讨论得以进行下去。孙皓晖为了吹捧秦始皇,不惜一再改变吹捧的形式。起初是写历史小说,想怎么写就怎么写;以后又改编为电视剧,愿怎么编就怎么编;后来竟然撞进史学的领域来了,大写史论,而且不讲任何规矩。别的史学家写文章是言必有据;他发表议论是想说就说,无所依据。对于这些无稽之谈,最好的对策就是——"稽"到底,把秦帝国的历史真相完全揭开。真相既然大白天下,则所有的谎言都将破产,无所遁形。