简介：不管是在应试英语还是在实用英语中，比较性文章的写作都是很常见的，有时要强调两种事物的共同点、有时要强调不同点、有时对两者都需要强调。中国人的比较往往只是零散地罗列。使文章显得无组织无层次，那么怎样才能写出英语地道、结构紧凑的比较性文章呢？

简介：语言习得是指一个人习得语言的过程。儿童与成人之间的区别导致第一语言和第二语言习得的差异。本文从语言认知和情感因素两方面做深入分析，对第一语言和第二语言习得的差异进行比较和对照。

简介：AbstractPurpose:To evaluate the outcomes with and without aid of a computer-assisted surgical navigation system (CASNS) for treatment of unilateral orbital wall fracture (OWF).Methods:Patients who came to our hospital for repairing unilateral traumatic OWF from 2014 to 2017 were included in this study. The patients were divided into the navigation group who accepted orbital wall reconstruction aided by CASNS and the conventional group. We evaluated the surgical precision in the navigation group by analyzing the difference between actual postoperative computed tomography data and preoperative virtual surgical plan through color order ratios. We also compared the duration of surgery, enophthalmos correction, restoration of orbital volumes, and improvement of clinical symptoms in both groups systemically. Quantitative data were presented as mean ± SD. Significance was determined by the two-sample t-test using SPSS Version 19.0 A p < 0.05 was considered statistically significant.Results:Seventy patients with unilateral OWF were included in the study cohort. The mean difference between preoperative virtual planning and actual reconstruction outcome was (0.869 ± 0.472) mm, which means the reconstruction result could match the navigation planning accurately. The mean duration of surgery in the navigation group was shorter than it is in the control group, but not significantly. Discrepancies between the reconstructed and unaffected orbital-cavity volume and eyeball projection in the navigation group were significantly less than that in the conventional group. One patient had remnant diplopia and two patients had enophthalmos after surgery in the navigation group; two patients had postoperative diplopia and four patients had postoperative enophthalmos in the conventional group.Conclusion:Compare with the conventional treatment for OWF, the use of CASNS can provide a significantly better surgical precision, greater improvements in orbital-cavity volume and eyeball projection, and better clinical results, without increasing the duration of surgery.

简介：Circulargenomes,beingthelargestproportionofsequencedgenomes,playanimportantroleingenomeanalysis.However,traditional2Dcircularmaponlyprovidesanoverviewandannotationsofgenomebutdoesnotofferfeature-basedcomparison.Forremedyingtheseshortcomings,wedeveloped3DGenomeTuner,ahybridofcircularmapandcomparativemaptools.Itscapabilityofviewingcomparisonsbetweenmultiplecircularmapsina3Dspaceoffersgreatbenefitstothestudyofcomparativegenomics.Theprogramisfreelyavailable(underanLGPLlicence)athttp://sourceforge.net/projects/dgenometuner.

简介：AbstractSince severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first identified during late 2019, the sustained spread of this pathogen within the human population has caused worldwide disruption with staggering infection rates and death tolls. Due to the accumulation of mutations in SARS-CoV-2, the virus has evolved into many variants, five of which have been listed as variants of concern VOCs by the World Health Organization (WHO). Multiple animal models of SARS-CoV-2 have been developed to evaluate vaccines and drugs and to assess the pathogenicity, transmissibility and antiviral measures of these VOCs. Here, we review the cutting-edge research based on mouse, hamster, ferret and non-human primate models for evaluating SARS-CoV-2 with a focus on the Omicron variant, and highlight the importance of updating vaccines in a timely manner in order to mitigate the negative effects of SARS-CoV-2 infections in the human population.

简介：Amodellingstudyisperformedtocomparetheplasmaflowandheattransfercharacteristicsoflow-powerarc-heatedthrusters(arcjets)forthreedifferentpropellants:hydrogen,nitrogenandargon.Theall-speedSIMPLEalgorithmisemployedtosolvethegoverningequations,whichtakeintoaccounttheeffectsofcompressibility,LorentzforceandJouleheating,aswellasthetemperature-andpressure-dependenceofthegasproperties.Thetemperature,velocityandMachnumberdistributionscalculatedwithinthethrusternozzleobtainedwithdifferentpropellantgasesarecomparedforthesamethrusterstructure,dimensions,inlet-gasstagnantpressureandarccurrents.Thetemperaturedistributionsinthesolidregionoftheanode-nozzlewallarealsogiven.Itisfoundthattheflowandenergyconversionprocessesinthethrusternozzleshowmanysimilarfeaturesforallthreepropellants.Forexample,thepropellantisheatedmainlyinthenear-cathodeandconstrictorregion,withthehighestplasmatemperatureappearingnearthecathodetip;theflowtransitionfromthesubsonictosupersonicregimeoccurswithintheconstrictorregion;thehighestaxialvelocityappearsinsidethenozzle;andmostoftheinputpropellantflowstowardsthethrusterexitthroughthecoolergasregionneartheanode-nozzlewall.However,sincethepropertiesofhydrogen,nitrogenandargon,especiallytheirmolecularweights,specificenthalpiesandthermalconductivities,aredifferent,thereareappreciabledifferencesinarcjetperformance.Forexample,comparedtotheothertwopropellants,thehydrogenarcjetthrustershowsahigherplasmatemperatureinthearcregion,andhigheraxialvelocitybutlowertemperatureatthethrusterexit.Correspondingly,thehydrogenarcjetthrusterhasthehighestspecificimpulseandarcvoltageforthesameinletstagnantpressureandarccurrent.Thepredictionsofthemodellingarecomparedfavourablywithavailableexperimentalresults.