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便携式电源的工程学设计

电子技术应用 2010年第3期36卷 4-5页

作者： Richard f.Zarr 美国国家半导体公司

功率转换效率一直以来都是便携式电源设计的驱动力量。然而,当今的移动设计已经不仅仅满足于具备尽可能高的功率转换效率,除此之外还需要应对来自工程方面的诸多挑战,从系统的多个角度增添了额外的限制因素。本文将研究如何重新设计系... 详细信息

功率转换效率一直以来都是便携式电源设计的驱动力量。然而,当今的移动设计已经不仅仅满足于具备尽可能高的功率转换效率,除此之外还需要应对来自工程方面的诸多挑战,从系统的多个角度增添了额外的限制因素。本文将研究如何重新设计系统架构,从而突破目前开关功率转换器中极其有限的效率提高。

关键词：功率转换便携式电源功率增益

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Structural and Magnetic Properties of Mechanically Alloyed Nd_(15)fe_(70)T_(15)N_δ(T=V,Mo) Magnets

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Journal of Materials Science & Technology 1995年第1期11卷 1-4页

作者： Xinguo ZHAO Zhidong ZHANG Wei LIU Qun WAN and Xaokai SUN(Institute of Metal Research, Chinese Academy f Sciences, Shenyang, 110015, China) CHINESE ACAD SCI INST MET RESSHENYANG 110015PEOPLES R CHINA

Structural and magnetic properties of Nd15fe70T15Nδ(T=V, Mo) alloys, made by mechanical alloying (MA) followed by heat-treatment and nitriding, have been investigated *** of annealing temperature on the structure and magnetic properties of the materials were studied by means of X-ray diffraction, AC susceptibility and high field magnetization measurements. Under pure argon atmosphere, the optimum temperatures for the heat treatment are found to be 75 and 850℃ for Nd15fe7015Nδ and Nd15fe70Mo15Nδ respectively. Correspondingly, the following magnetic properties are achieved : (1) Nd15fe70V15Nδ:Br=0.63 T,,HC=8.01kA/cm (10.1 kOe), (BH )max=50.3 kJ/m3 (6 32 MGOe), (2) Nd15fe70Mo15Nδ :Br=0.42 T. iHc=5.6 kA/cm (7.4 kOe), (BH )max=26.6 kJ/m3 (3.34 MGOe)

关键词： fe T=V,Mo T Magnets Structural and Magnetic Properties of Mechanically Alloyed Nd

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Heating and Cooling Performance of Earth-Tube Heat Exchanger in a Mechanical Ventilated farrowing House

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Journal of Agricultural Science and Technology(A) 2011年第2X期1卷 187-193页

作者： E. f. Hessel C. Zurhake H. f. Van den Weghe Department Animal Sciences Georg-August-University Goettingen Division: Process Engineering Universitaetsstr. 7 Vechta D-49377 Germany

Earth tempering of stable air has attracted great attention as a sustainable air conditioning method in pig houses. At summer time air cooling of income air strongly reduces heat stress and required ventilation rate. At winter time heating costs can be reduced. The effect of air condition using geothermal energy was investigated in a farrowing house. Underneath the foundation of the farrowing house 88 non perforated ribbed tubes （diameter： 20 cm） were piped in a depth of 1.6-2.0 m. Over a period of 12 month following data were recorded at hourly intervals and analyzed： outside air temperature, as well as air temperature in the air supply duct and in the compartments. Incoming air （supply duct） was heated up to 20 ℃ during winter time and in summer time cooled by up to 15 ℃ compared to the outside air temperature. In contrast to the outside air diurnal variation, temperature fluctuations of the incoming air were reduced by 90%. Due to cooling of the incoming air at summer time the stable inside temperature could be limited to maximal 29 ℃（maximum outside temperature was 35℃）. Earth-tube heat exchangers with non perforated ribbed tubes were very efficient for air conditioning in farrowing houses. They were a cost effective supplement for sustainable cooling and heating of farrowing houses.

关键词： Earth heat exchanger heat stress reduction farrowing house air conditioning.

风暴之后的风平浪静:智利的收入分配与社会福利

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国外社会科学 2001年第1期 108-109页

作者： f.H.G.费雷拉

Consequences of unilateral cryptorchidism on semen and sperm characteristics in West African Dwarf Goats

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Asian pacific Journal of Reproduction 2018年第4期7卷 172-177页

作者： Chike f.Oguejiofor Izuchukwu S.Ochiogu Okechi L.Okoro Vitalis U.Ogbu Department of Veterinary Obstetrics and Reproductive Diseases Faculty of Veterinary MedicineUniversity of NigeriaNsukka 410001Nigeria

Objective: To evaluate the influence of unilateral cryptorchidism on semen and sperm characteristics in West African Dwarf (WAD) bucks. Methods: Semen was collected using electroejaculator from five unilaterally cryptorchid (UC) and five normal (non-cryptorchid) WAD bucks and analyzed for gross, microscopic and biochemical characteristics. Results:Gross semen evaluation showed no differences between the groups in semen color, viscosity and pH, whereas the normal bucks yielded semen with significantly higher specific gravity (P=0.0436) and volume (P=0.0388) than the UC group. following semen microscopic evaluation, the percentage of sperm vitality (live sperm) was not significantly different between both groups. However, UC bucks yielded semen with significantly lower sperm motility (P=0.0387), sperm concentration per mL (P=0.0020) and total sperm count per ejaculate (P=0.0074). The percentage total sperm abnormality was also higher (Pf UC goats. Abnormalities observed included sperm with cytoplasmic droplets, looped tails, coiled tails and tailless heads. Sperm morphometry showed no differences in the sperm head length and head width between the groups. Biochemical semen evaluation did not reveal any differences between the groups in the concentration of seminal plasma total protein, catalase activity and lipid peroxidation level. Conclusions: Unilateral cryptorchidism significantly affected the quantity and quality of semen and spermatozoa in affected WAD bucks. Due to the hereditary attribute of the condition, it is recommended that animals with this condition should not be used in breeding to forestall increasing prevalence of cryptorchidism in goats.

关键词： Cryptorchidism Goat Semen Spermatozoa

BifeO_(3) codoping with Ba,La and Ti:Magnetic and structural studies

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Journal of Advanced Dielectrics 2015年第4期5卷 53-60页

作者： O.García-Zaldívar S.Díaz-Castañón f.J.Espinoza-Beltran M.A.Hernández-Landaverde G.López J.faloh-Gandarilla f.Calderón-Piñar facultad de física-Instituto de Ciencia y Tecnología de Materiales Universidad de La Habana San Láazaro y L VedadoLa Habana 10400Cuba CINVESTAV-Unidad Querétaro Libramiento Norponiente No.2000 Real de JuriquillaQuerétaroQro.76230México Instituto Latino-Americanode Ciênciasda Vidaeda Natureza Universidade federalda Integração Latino-Americana (ILCVN-UNILA)Avenida Tancredo NevesPTIBloco 6 CEP:85866-000-Foz do Iguaçu-ParanaBrazil División Materiales Avanzados Instituto Potosinode Investigación Científica Tecnológica San Luis Potosí CP78216Méexico

Conventional solid state reaction method,from oxides and carbonates,was employed to prepare bismuth(Bi)-based multiferroic *** undoped BifeO_(3)(BfO)and the codoped system with Ba,La and Ti(Bi_(1-x)Ba_(x)fe_(1-y)Ti_(y)O_(3),Bi_(1-x-z)Ba_(x)Lazfe_(1-y)TiyO_(3))with x,y,z=0.1 were prepared stoichiometrically and sintered at two different *** structural and magnetic properties were investigated at room *** measurements confirm the obtaining of the rhombohedral perovskite structure of the BfO family *** the undoped system,some reflections of undesired phases are present for two different sintering temperatures,while for the doped system only one phase is present for both *** magnetic characterization at room temperature revealed remarkable differences between the ceramic *** results show that for undoped BfO system,spontaneous magnetization is not observed at room ***,in doped one,a well-defined ferromagnetic behavior is observed at room temperature,possible,due to the suppression of the spatially modulated spin structure of BfO promoted by the reduction of the rhombohedral distortion and the weakening of the Bi-O *** XPS results confirm the presence of oxygen vacancies and the coexistence of fe^(3+)and fe^(2+) in all the studied *** measurements reveal that the dopant incorporation has not a direct effect in Neel temperature but possibly yes in ferroelectric-paraelectric transition.

关键词： Multiferroics XPS magnetic bismuth ferrite BifeO_(3)

Studies on heart development in normal and cardiac mutant axolotls,Ambystoma Mexicanum,using cellular and molecular biology

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中国病理生理杂志 2000年第10期 84-85页

作者： L.f.Lemanski,X.Huang,R.W.Zajdel,S.L.Lemanski,C.Zhang,f.Meng,D.foster,Q.Li,N.Erginel-Unaltuna,D.K.Dube DepartmentofMedicalPhysiology!TexasA&MUniversitySystemHealthScienceCenter CollegeStation DepartmentofBiology TexasA&MUniversity CollegeStation Texas77843 DepartmentofMedicalPhysiology!TexasA&MUniversitySystemHealthScienceCenter CollegeStation T

Did maize domestication and early spread mediate the population genetics of corn leafhopper?

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Insect Science 2019年第3期26卷 569-586页

作者： Julio S. Bernal Amanda M. Davila-flores Raul f. Medina Yolanda H. Chen Kyle E. Harrison Kimberly A. Berrier Department of Entomology Texas A&M University College Station Texas USA Department of Plant and Soil Sciences University of Vermont Burlington Vermont USA

Investigating how crop domestication and early farming mediated crop attributes, distributions, and interactions with antagonists may shed light on today's agricultural pest problems. Crop domestication generally involved artificial selection for traits desirable to early farmers, for example, in creased productivity or yield, and enhanced qualities, though invariably it altered the interactions between crops and insects, and expanded the geographical ranges of crops. Thus, some studies suggest that with crop domestication and spread, insect populations on wild crop ancestors gave rise to pestiferous insect populations on crops. Here, we addressed whether the emergence of corn leafhopper (Dalbulus ma id is) as an agricultural pest may be associated with domestication and early spread of maize (Zea mays mays). We used AfLP markers and mitochondrial COI sequences to assess population genetic structuring and haplotype relationships among corn leafhopper samples from maize and its wild relative Zea diploperennis from multiple locations in Mexico and Argentina. We uncovered seven corn leafhopper haplotypes contained within two haplogroups, one haplogroup containing haplotypes associated with maize and the other containing haplotypes associated with Z. diploperennis in a mountainous habitat. Within the first haplogroup, one haplotype was predominant across Mexican locations, and another across Argentinean locations;both were considered pestiferous. We suggested that the divergence times of the maize-associated haplogroup and of the "pestiferous" haplotypes are correlated with the chronology of maize spread following its domestication. Overall, our results support a hypothesis positing that maize domestication favored corn leafhopper genotypes preadapted for exploiting maize so that they became pestiferous, and that with the geographical expansi on of maize farming, corn leafhopper colonized Z. diploperennis, a host exclusive to secluded habitats that serves as a refuge fo

关键词： Dalbulus maidis haplotype network analysis perennial teosinte population genetic structuring Zea diploperennis Zea mays mays

Current laser therapy options for endoscopic treatment of upper tract urothelial carcinoma

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Current Urology 2023年第1期17卷 62-67页

作者： Benjamin W.Zollinger Ezra J.Shoen Charles f.Gresham Michael J.Whalen George Washington School of Medicine and Health Sciences WashingtonDCUSA Department of Urology Icahn School of MedicineMount Sinai HospitalNew YorkNYUSA Department of Urology George Washington University HospitalWashingtonDCUSA

Endoscopic management via retrograde ureteroscopic laser ablation of upper tract urothelial carcinoma(UTUC)has become the preferred treatment modality for low-risk *** most popular ablative lasers over the past 15-20 years have been the holmium:yttrium-aluminum-garnet(Ho∶YAG)and neodymium(Nd∶YAG)lasers,but recently the thulium(Th∶YAG)laser has emerged as a potential *** review compares the mechanism of action,physiological properties and effects,and oncologic outcomes of Ho∶YAG/Nd∶YAG lasers versus the Th∶YAG laser for UTUC *** advantages of the Th∶YAG laser over existing technologies are outlined,followed by a discussion of emerging laser technologies in UTUC management.

关键词： Endoscopic management Holmium laser Laser ablation Thulium laser Upper tract urothelial carcinoma