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The vertical heat transport of internal solitary waves over the continental slope in the northern South China Sea 预览
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作者 Changrong Liang Xiaodong Shang Guiying Chen 《海洋学报:英文版》 SCIE CAS CSCD 2019年第3期36-44,共9页
An integrated analysis of internal solitary wave(ISW) observations obtained from two moorings over the continental slope in the northern South China Sea(SCS) leads to an assessment of the vertical heat transport of th... An integrated analysis of internal solitary wave(ISW) observations obtained from two moorings over the continental slope in the northern South China Sea(SCS) leads to an assessment of the vertical heat transport of the ISWs. The clusters of ISW packets are phase-locked to the fortnightly cycle of the semidiurnal tide. The ISWs appear during large semidiurnal tides, and there is a period of 5–6 d when no ISWs are observed. The effect of the ISWs on the continental slope heat budget is observed. The ISWs can modify a local temperature field in which the temperature in the upper layer can be changed by O(100) °C after the ISWs passed the mooring. Both ISWinduced diffusion and ISW-induced advection contribute to the temperature variation. The estimates imply an average vertical heat flux of 0.01 to 0.1 MW/m~2 in the ISWs in the upper 500 m of the water column. The vertical heat transport ranges from 0.56 to 2.83 GJ/m~2 with a mean value of 1.63 GJ/m~2. The observations suggest that the vertical heat transport is proportional to the maximum vertical displacement. 展开更多
关键词 internal SOLITARY wave VERTICAL HEAT transport temperature variation DIFFUSION advection VERTICAL HEAT FLUX
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Different vertical distribution of zooplankton community between North Pacific Subtropical Gyre and Western Pacific Warm Pool: its implication to carbon flux 预览
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作者 Dong Sun Dongsheng Zhang +1 位作者 Ruiyan Zhang Chunsheng Wang 《海洋学报:英文版》 SCIE CAS CSCD 2019年第6期32-45,共14页
The mesozooplankton in both epipelagic and mesopelagic zones is essentially important for the study of ecosystem and biological carbon pump. Previous studies showed that the diel vertical migration (DVM) pattern of me... The mesozooplankton in both epipelagic and mesopelagic zones is essentially important for the study of ecosystem and biological carbon pump. Previous studies showed that the diel vertical migration (DVM) pattern of mesozooplankton varied among ecosystems. However, that pattern was largely unknown in the Western Pacific Warm Pool (WPWP). The vertical distribution, DVM and community structure of mesozooplankton from the surface to 1 000 m were compared at Stas JL7K (WPWP) and MA (North Pacific Subtropical Gyre, NPSG). Two sites showed similarly low biomass in both epipelagic and mesopelagic zones, which were in accordance with oligotrophic conditions of these two ecosystems. Stronger DVM (night/day ratio) was found at JL7K (1.31) than that at MA (1.09) on surface 0–100 m, and an obvious night increase of mesopelagic biomass was observed at JL7K, which was probably due to migrators from bathypelagic zone. Active carbon flux by DVM of zooplankton was estimated to be 0.23 mmol/(m2·d) at JL7K and 0.16 mmol/(m2·d) at MA. The community structure analysis showed that calanoid copepods, cnidarians and appendicularians were the main contributors to DVM of mesozooplankton at both sites. We also compared the present result with previous studies of the two ecosystems, and suggested that the DVM of mesozooplankton was more homogeneous within the WPWP and more variable within the NPSG, though both ecosystems showed typically extremely oligotrophic conditions. The different diel vertical migration strength of mesozooplankton between NPSG and WPWP implied different efficiency of carbon pump in these two ecosystems. 展开更多
关键词 mesopelagic zone DIEL VERTICAL MIGRATION biological PUMP VERTICAL distribution active carbon FLUX
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No Rupture Surface Sliding Geo-Technique in Deep Excavation for Static and Especially for Seismic Thrust 预览
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作者 Ampeglio D. Garini 《土木工程与建筑:英文版》 2019年第5期305-308,共4页
In the recent literature concerning the multi-propped bottom-up technique Shanghai Metro Stations Excavations, there is evidence of the importance of the disturbance in terms of greater wall horizontal deflections and... In the recent literature concerning the multi-propped bottom-up technique Shanghai Metro Stations Excavations, there is evidence of the importance of the disturbance in terms of greater wall horizontal deflections and consequently vertical settlements in the neighbouring, caused by the late long time of open -cut excavation without propping. Here is proposed, theoretical and pragmatic at the same time, a new approach to face the problem of the wall deflections and the related vertical settlements behind the wall. The solution proposed is indeed to impede any formation of the incipient sliding in the active wedge soil rupture surface, by oblique piling crossing over the rupture surface through a longer pile penetration length in relation to the active wedge before any excavation process starts. This piled-construction will then cut to shape the excavation profiles recurring to loss of piles material. This solution is particularly fit for high seismicity prone areas, because of the minor relative loss of per unit length of pile, caused by the greater depth of the rupture surfaces to get and cross over. 展开更多
关键词 Active wedge BOTTOM-UP TECHNIQUE horizontal DEFLECTIONS VERTICAL EXCAVATION VERTICAL SETTLEMENTS metro stations flexible walls.
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大型立式强力旋压机的设计方法研究 预览
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作者 刘旭东 李初晔 +2 位作者 李志强 孙年俊 马岩 《制造技术与机床》 北大核心 2019年第6期74-79,共6页
大型立式强力旋压机具有金属数控切削机床的精度,而其旋压力远远大于切削力。其设计方案的制定在满足设计任务的同时需要兼顾生产制造工艺性、经济性、运动可靠性、操作维护的便利性等方面。为此提出了大型立式强力旋压机的一种设计方法... 大型立式强力旋压机具有金属数控切削机床的精度,而其旋压力远远大于切削力。其设计方案的制定在满足设计任务的同时需要兼顾生产制造工艺性、经济性、运动可靠性、操作维护的便利性等方面。为此提出了大型立式强力旋压机的一种设计方法,通过这种方法建立了一种大型立式强力旋压机的新结构,并提出了整机组合节点耦合的有限元分析计算验证方法。 展开更多
关键词 强力旋压 旋压机 设计 立式 分析计算 验证
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Quantifying the thermal damping effect in underground vertical shafts using the nonlinear autoregressive with external input(NARX)algorithm 预览
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作者 Pedram Roghanchi Karoly C.Kocsis 《矿业科学技术学报:英文版》 CSCD 2019年第2期255-262,共8页
As air descends the intake shaft,its infrastructure,lining and the strata will emit heat during the night when the intake air is cool and,on the contrary,will absorb heat during the day when the temperature of the air... As air descends the intake shaft,its infrastructure,lining and the strata will emit heat during the night when the intake air is cool and,on the contrary,will absorb heat during the day when the temperature of the air becomes greater than that of the strata.This cyclic phenomenon,also known as the “thermal damping effect”will continue throughout the year reducing the effect of surface air temperature variation.The objective of this paper is to quantify the thermal damping effect in vertical underground airways.A nonlinear autoregressive time series with external input(NARX)algorithm was used as a novel method to predict the dry-bulb temperature(Td)at the bottom of intake shafts as a function of surface air temperature.Analyses demonstrated that the artificial neural network(ANN)model could accurately predict the temperature at the bottom of a shaft.Furthermore,an attempt was made to quantify typical “damping coefficient”for both production and ventilation shafts through simple linear regression models.Comparisons between the collected climatic data and the regression-based predictions show that a simple linear regression model provides an acceptable accuracy when predicting the Td at the bottom of intake shafts. 展开更多
关键词 UNDERGROUND mining Vertical openings THERMAL damping effect Artificial neural network NONLINEAR AUTOREGRESSIVE with EXTERNAL input(NARX)
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绝对重力仪隔振系统发展综述
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作者 要佳敏 伍康 《导航与控制》 2019年第3期14-26,共13页
绝对重力仪是测量重力加速度的精密仪器,在计量学、地球物理、资源勘探、辅助导航等领域有着重要意义和广泛应用。目前,绝对重力仪的测量精度已经达到微伽(μGal,1μGal=1×10-8m/s2)量级,而地面振动噪声严重影响着仪器的测量精度,... 绝对重力仪是测量重力加速度的精密仪器,在计量学、地球物理、资源勘探、辅助导航等领域有着重要意义和广泛应用。目前,绝对重力仪的测量精度已经达到微伽(μGal,1μGal=1×10-8m/s2)量级,而地面振动噪声严重影响着仪器的测量精度,垂直隔振系统的性能已成为限制绝对重力仪精度的瓶颈。对绝对重力仪所应用的超低频垂直隔振系统进行了详细回顾。现有的超低频垂直隔振系统可被分为被动式隔振和主动式隔振两大类。其中,被动式隔振系统主要基于零长弹簧结构,周期一般可超过15s。主动式隔振系统可以分为一级主动式隔振系统和二级主动式隔振系统,其结构形式包含弹簧振子结构、弹簧摆杆结构等。通过测量待隔振物体的位移、速度、加速度信号等信息并进行反馈控制,可实现超低本振频率,等效周期可超过15s,最长可超过100s。国内研究机构已经开展了多年的针对超低频垂直隔振系统的研究工作,并取得了阶段性的研究成果。通过改进,有望将超低频垂直隔振系统应用于国产绝对重力仪,显著提高仪器的整体性能。 展开更多
关键词 绝对重力仪 绝对重力测量 超低频 隔振 垂直
光标定位技术在拉伸试验中的应用 预览
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作者 张春花 《天津冶金》 CAS 2019年第2期49-52,共4页
拉伸试验中,试样夹持垂直度要求高。手动夹持试样垂直度不佳,试样断裂后经常出现两段试样对接后不在一条直线上、头部夹持部位扭曲变形、断裂位置在钳口内部等问题。采用光标定位技术定位试样后,夹持垂直度提高了,上述问题得到解决,试... 拉伸试验中,试样夹持垂直度要求高。手动夹持试样垂直度不佳,试样断裂后经常出现两段试样对接后不在一条直线上、头部夹持部位扭曲变形、断裂位置在钳口内部等问题。采用光标定位技术定位试样后,夹持垂直度提高了,上述问题得到解决,试验合格率由使用前的88.87%提高到96.33%。 展开更多
关键词 光标 定位 拉伸试验 夹持 垂直 扭曲 变形 钳口 断裂
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54例高病毒载量乙型肝炎e抗原阳性孕妇抗病毒短期干预的临床安全性及阻断乙型肝炎病毒母婴传播的效果
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作者 高庆伟 高鹏 +4 位作者 丁楠 李璇 刘昕 韩光 孙艾军 《中国医师进修杂志》 2019年第7期649-653,共5页
目的探讨乙型肝炎e抗原(HBeAg)阳性高病毒载量孕妇孕中期开始给予核苷类药物替比夫定短期干预后乙型肝炎病毒(HBV)母婴传播阻断效果及安全性。方法选择2016年11月至2017年11月大连医科大学附属大连市第六人民医院门诊HBeAg阳性慢性HBV... 目的探讨乙型肝炎e抗原(HBeAg)阳性高病毒载量孕妇孕中期开始给予核苷类药物替比夫定短期干预后乙型肝炎病毒(HBV)母婴传播阻断效果及安全性。方法选择2016年11月至2017年11月大连医科大学附属大连市第六人民医院门诊HBeAg阳性慢性HBV感染孕妇54例,血清HBVDNA≥10^10U/L。孕妇在妊娠第24周开始口服替比夫定600mg,1次/d,至分娩当日停用;新生儿分娩后12h内分别注射乙肝疫苗10μg和乙型肝炎免疫球蛋白100U,出生后1和6个月再分别注射乙肝疫苗10μg。于妊娠第12、24、28、32周和产后1、7个月检测HBVDNA(行对数转换)、肌酸激酶(CK)、丙氨酸氨基转移酶(ALT)和总胆红素(TBIL)。婴儿于出生后28~30周检测乙型肝炎表面抗体(HBsAb)和乙型肝炎表面抗原(HBsAg)情况。结果54例孕妇各时间点CK、ALT和TBIL比较差异无统计学意义(P>0.05)。妊娠第28周、妊娠第32周和产后1个月HBVDNA明显低于妊娠12周(5.7±2.2、5.1±2.3和8.3±1.7比9.5±1.0),差异有统计学意义(P<0.05);产后7个月与妊娠第12周比较差异无统计学意义(P>0.05)。54例婴儿出生后28~30周检查结果显示,血清HBsAb>109U/L,血清HBsAg<30U/L。结论高病毒载量HBeAg阳性慢性HBV感染孕妇孕中期替比夫定短期干预可明显降低HBVDNA至安全线以下,干预期间孕妇未出现明显不良事件,停药后HBVDNA均有不同程度反弹,但婴儿病毒学检查结果证实,孕中期替比夫定短期干预后可实现母婴完全阻断。 展开更多
关键词 肝炎病毒 乙型 孕妇 肝炎e抗原 乙型 传染性疾病传播 垂直 替比夫定
Error correction for short-range optical interconnect using COTS transceivers
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作者 Ziyuan ZHENG Chuanchuan YANG +1 位作者 Dan ZHAO Ziyu WANG 《中国科学:信息科学(英文版)》 SCIE EI CSCD 2019年第6期72-78,共7页
Nowadays, quantities of commercial off-the-shelf(COTS) optical transceivers are widely equipped in both exiting and abuilding data centers. As data centers are becoming larger and containing more servers, the method t... Nowadays, quantities of commercial off-the-shelf(COTS) optical transceivers are widely equipped in both exiting and abuilding data centers. As data centers are becoming larger and containing more servers, the method to ensure longer and steady transmission with COTS optical transceivers becomes one of the key issues. Meanwhile, variations in the manufacturing of COTS optical transceivers bring in fluctuation of packet error rate(PER) in communication. In this paper, we present an application layer adaptive forward error correction(AL-AFEC) coding scheme for COTS optical transceivers in optical interconnect to solve the problems mentioned above and test its performance in a 10 Gbps Ethernet(10 GbE)link using 10 GBASE-SR SFP+ modules. Experimental results show that the proposed scheme enables longer transmission distance and the instability introduced by manufactural variations is well settled. Since our scheme requires no extra hardware on optical transceivers, it is a considerable low-cost alternative to improve system reliability and achieve longer transmission distance for COTS optical transceivers. 展开更多
关键词 SHORT-RANGE OPTICAL interconnect vertical cavity surface emitting laser(VCSEL) ethernet application layer adaptive forward error correction commercial off-the-shelf OPTICAL transceiver
A Historical Sedimentary Record of Mercury in a Shallow Eutrophic Lake: Impacts of Human Activities and Climate Change 预览
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作者 Hanxiao Zhang Shouliang Huo +3 位作者 Kevin M. Yeager Beidou Xi Jingtian Zhang Fengchang Wu 《工程(英文)》 2019年第2期296-304,共9页
Mercury and its derivatives are hazardous environmental pollutants and could affect the aquatic ecosystems and human health by biomagnification. Lake sediments can provide important historical information regarding ch... Mercury and its derivatives are hazardous environmental pollutants and could affect the aquatic ecosystems and human health by biomagnification. Lake sediments can provide important historical information regarding changes in pollution levels and thus trace anthropogenic or natural influences. This research investigates the 100-year history of mercury (Hg) deposition in sediments from Chao Lake, a shallow eutrophic lake in China. The results indicate that the Hg deposition history can be separated into three stages (pre-1960s, 1960s–1980s, and post-1980s) over the last 100 years. Before the 1960s, Hg concentrations in the sediment cores varied little and had no spatial difference. Since the 1960s, the concentration of Hg began to increase gradually, and showed a higher concentration of contamination in the western half of the lake region than in the eastern half of the lake region due to all kinds of centralized human-input sources. The influences of anthropogenic factors and hydrological change are revealed by analyzing correlations between Hg and heavy metals (Fe, Co, Cr, Cu, Mn, Pb, and Zn), stable carbon and nitrogen isotopes (d13C and d15N), nutrients, particle sizes, and meteorological factors. The results show that Hg pollution intensified after the 1960s, mainly due to hydrological change, rapid regional development and urbanization, and the proliferation of anthropogenic Hg sources. Furthermore, the temperature, wind speed, and evaporation are found to interactively influence the environmental behaviors and environmental fate of Hg. 展开更多
关键词 Lake sediment MERCURY Vertical distribution ANTHROPOGENIC activities
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Numerical study of a guide-vane-augmented vertical darrieus tidal-currentturbine 预览
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作者 Zhen Liu Zhi-meng Wang +1 位作者 Hong-da Shi Heng-liang Qu 《水动力学研究与进展:英文版》 SCIE EI CSCD 2019年第3期522-530,共9页
It is reported that the augmented vertical axis turbine (VAT) has a better operating performance. A guide-vane type augmentation is proposed in this study, with a simpler outline and a better adaptability to various d... It is reported that the augmented vertical axis turbine (VAT) has a better operating performance. A guide-vane type augmentation is proposed in this study, with a simpler outline and a better adaptability to various directions of the incident water flow, as compared to the duct-type diffuser. A 2?D numerical model based on the computational fluid dynamics software ANSYS-Fluent is established and validated by experimental data. It is found that the guide vanes could narrow the flow path together with the VAT rotor and increase the flow velocity around the blades. The fluctuation of the instantaneous torque output is significantly reduced by using the guide-vane stator. The numerical results indicate that a four blades setup is suitable for the stator and the chord length of the guide vane should be equal to that of the rotor blade. The gap between the stator and the rotor is suggested to be a quarter of the chord length of the rotor blades. The non-zero pitch angle of the guide vane is found to have negative effects on the torque and the power output. The averaged power and torque coefficients for three non-zero directional angles of the incident flow are approximately 30% lower than those for the zero-directional angle. 展开更多
关键词 Tidal current energy VERTICAL axis turbine AUGMENTED rotor GUIDE VANE numerical simulation
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Optical and scintillation properties of Bi4Si3O12:RE(RE=Eu3+, Sm3+,Ho3+, Tb3+)single crystals
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作者 Xuefeng Xiao Jiayue Xu +3 位作者 Haicheng Wei Yaoqing Chu Bobo Yang Xuefeng Zhang 《中国稀土学报:英文版》 SCIE EI CAS CSCD 2019年第3期260-264,共5页
Bi4 Si3 O12:RE(BSO:RE, RE = Eu3+, Sm3+, Ho3+, Tb3+) crystals were grown by the modified vertical Bridgeman method, and doping effects on scintillation properties were investigated. Under γ-ray irradiation, the light ... Bi4 Si3 O12:RE(BSO:RE, RE = Eu3+, Sm3+, Ho3+, Tb3+) crystals were grown by the modified vertical Bridgeman method, and doping effects on scintillation properties were investigated. Under γ-ray irradiation, the light yield of BSO doped with small doses of Eu3+ increases slightly, and the energy resolution improves significantly compared to pure BSO, therefore the ability of distinguishing between particles will be improved for BSO crystals with a small amount of Eu3+ dopant. The results show that a small amount of Eu3+ doping can sensitize the Bi3+ ions. The sensitization effect enables the reduction of intrinsic defects, and thus improves the scintillation properties. However, the relative light yield of BSO:Tb(1.0 mol%) crystal is 4.3%, which is smaller than 5.0% of pure BSO. The improved light yield and energy resolution in the BSO:Eu and BSO:Sm crystals are considered an impressive achievement in the optimization of this scintillator which is already suitable for applications such as dual-readout calorimeters and homogeneous hadron calorimeters. 展开更多
关键词 BSO crystal Vertical Bridgeman method Scintillation characteristics Relative light YIELD Rare earths
Hot Air Generator Using Natural Convection Flow in a Heated Channel 预览
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作者 Bushra AlGarawi Zeinebou Yahya 《能源与动力工程:英文版》 2019年第4期131-136,共6页
Hot air producing is one of the most important engineering applications in recent years.It is a technique used in various thermodynamic systems,such as home heating systems,food dryers.One of the main problems impedin... Hot air producing is one of the most important engineering applications in recent years.It is a technique used in various thermodynamic systems,such as home heating systems,food dryers.One of the main problems impeding the spread of hot air producing technology is the lack of homogeneity of the heat flow coming from hot air generators as well as an inadequate flow rate.The most of the existing hot air generators require to be supported by systems that can increase the low volumetric flow and the air temperature of these generators,through increasing the speed of the flow of air emitted or lifting the drawer Heat,which contributes to raising the overall cost.However,to improve the thermal and dynamic quality of the hot air flow produced by the generator,a numerical investigation of the free convection flow inside two different configurations is presented in this thesis.The primary objective of this work is to predict the behavior of the flow inside tow configurations,the first one consists of a vertical cylinder with heated walls,and the second configuration is an open-ended vertical cylinder with a hot disc placed at the entrance(configuration A,configuration B).This work characterizes through the examination of this flow,the variables that control an air emission with high flow rate and a high and homogeneous temperature to represent the appropriate criteria that should be respected to obtain a hot air generator overcoming the previously mentioned constraints.Furthermore;the results of this work show the influence the boundary conditions and Rayleigh number on the resulting flow. 展开更多
关键词 Hot air GENERATOR NATURAL CONVECTION vertical CHANNEL NAVIER-STOKES equations finite volume method
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Initiation of ice jam in front of bridge piers-An experimental study 预览
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作者 Jun Wang Jian Hua +3 位作者 Pang-pang Chen Jueyi Sui Peng Wu Todd Whitcombe 《水动力学研究与进展:英文版》 SCIE EI CSCD 2019年第1期117-123,共7页
The presence of bridge piers in natural rivers significantly changes the flow and boundary conditions.As a consequence,ice jams can often be initiated in front of bridge piers.With the changes in flow conditions,two t... The presence of bridge piers in natural rivers significantly changes the flow and boundary conditions.As a consequence,ice jams can often be initiated in front of bridge piers.With the changes in flow conditions,two types of ice jam formation may appear:surface accumulation of ice blocks (surface ice blockage) and thickened accumulation of ice blocks (vertical ice blockage).In the present study,the initiation process of ice jam was studied based on experiments.It is found that the critical ice concentration for ice jam blockage depends on the ice block dimension,channel opening and flow conditions.Under surface blockage conditions,a larger ratio of ice cube dimension to channel opening (between piers) can result in a smaller critical ice concentration for ice jam blockage,which has no obvious relation with flow conditions.Under vertical blockage conditions,the critical ice concentration for ice jam blockage increases with flow Froude number and decreases with the ratio of ice dimension to channel opening (between piers).Based on experiments conducted in laboratory,equations for determining critical ice concentration for these two types of ice jam blockage have been developed. 展开更多
关键词 Bridge PIERS surface ICE BLOCKAGE vertical ICE BLOCKAGE CRITICAL ICE CONCENTRATIONS
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Sensitivity of WRF simulated typhoon track and intensity over the South China Sea to horizontal and vertical resolutions 预览
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作者 Zhiyuan Wu Changbo Jiang +2 位作者 Bin Deng Jie Chen Xiaojian Liu 《海洋学报:英文版》 SCIE CAS CSCD 2019年第7期74-83,共10页
To determine the grid resolutions of the WRF model in the typhoon simulation,some sensitivity analysis of horizontal and vertical resolutions in different conditions has been carried out.Different horizontal resolutio... To determine the grid resolutions of the WRF model in the typhoon simulation,some sensitivity analysis of horizontal and vertical resolutions in different conditions has been carried out.Different horizontal resolutions(5,10,20,30 km),nesting grids(15 and 5 km),different vertical resolutions(35-layers,28-layers,20-layers)and different top maximum pressures(1 000,2 000,3 500,5 000 Pa)had been used in the mesoscale numerical model WRF to simulate the Typhoon Kai-tak.The simulation results of typhoon track,wind speed and sea level pressure at different horizontal and vertical resolutions have been compared and analyzed.The horizontal and vertical resolutions of the model have limited effect on the simulation effect of the typhoon track.Different horizontal and vertical resolutions have obvious effects on typhoon strength(defined by wind speed)and intensity(defined by sea level pressure,SLP),especially for sea level pressure.The typhoon intensity simulated by the high-resolution model is closer to the real situation and the nesting grids can improve computational accuracy and efficiency.The simulation results affected by vertical resolution using 35-layers is better than the simulation results using 20-layers and 28-layers simulations.Through comparison and analysis,the horizontal and vertical resolutions of WRF model are finally determined as follows:the two-way nesting grid of 15 and 5 km is comprehensively determined,and the vertical layers is 35-layers,the top maximum pressure is 2 000 Pa. 展开更多
关键词 sensitivity analysis TYPHOON track and INTENSITY HORIZONTAL and vertical RESOLUTIONS TYPHOON Kai-tak WRF
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HBV感染对人工辅助生殖的影响及其防范对策 预览
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作者 朱彤 李成忠 《临床肝胆病杂志》 CAS 北大核心 2019年第7期1425-1429,共5页
我国越来越多HBV感染的不孕夫妇选择人工辅助生殖技术(ART)方式行助孕治疗。HBV感染对ART实施过程以及子代健康状况的影响尚无定论。从女性及男性生殖细胞、实验环境、妊娠结局和对子代健康等方面出发综述了HBV感染对ART的影响,并探讨HB... 我国越来越多HBV感染的不孕夫妇选择人工辅助生殖技术(ART)方式行助孕治疗。HBV感染对ART实施过程以及子代健康状况的影响尚无定论。从女性及男性生殖细胞、实验环境、妊娠结局和对子代健康等方面出发综述了HBV感染对ART的影响,并探讨HBV感染者实施ART的防范对策,为制订科学的管理制度、预防疾病的传播提供支持。 展开更多
关键词 肝炎病毒 乙型 传染性疾病传播 垂直 生殖技术 辅助
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Hydraulics and swimming behavior of schizothorax prenanti in vertical slot fishways 预览
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作者 Rui-dong An Jia Li +1 位作者 Wen-min Yi Xi Mao 《水动力学研究与进展:英文版》 SCIE EI CSCD 2019年第1期169-176,共8页
This paper presents a novel experiment for the correlation between the hydraulics and the swimming behavior of Schizothorax prenanti,a rare species of fish in southwest China,in passing a vertical slot fishway.With an... This paper presents a novel experiment for the correlation between the hydraulics and the swimming behavior of Schizothorax prenanti,a rare species of fish in southwest China,in passing a vertical slot fishway.With an acoustic Doppler velocimeter,the velocities of a physical model in the equidimension fishway in the Shaping II power station are measured.The hydraulic parameters include the hydraulic head drop,the velocity patterns and the flow rate,and the swimming behavior includes the burst-coast,the sustained swimming and the migratory path,and they are analyzed under the test conditions.The sustained swimming velocity is in the range from 0.65m/s to 1.09m/s.The estimated hydraulic head drop of each pool is calculated and is in the range from 0.08-0.11 m,which means that 2.6% slope is reasonable.For the same slope,the maximum velocity is further reduced from 1.24 m/s to 1.14 m/s by using an L shape baffle structure.The above findings are used as the basis to evaluate the hydraulic performance of the fishways,where the L shape baffle structure is expected to be effective tor creating a preterencial flow for the fish.For the main stream of the pool,an "Ω" shape flow pattern is more fish-friendly,which can effectively extend the energy dissipation distance and avoid the bursting through a high velocity zone.This paper provides a useful complementary tool for practical designs. 展开更多
关键词 Hydraulics SWIMMING behavior VERTICAL SLOT FISHWAYS burst-coast energy DISSIPATION
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CPⅢ点位变化对轨道线形的影响 预览
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作者 葛玉辉 《铁道勘察》 2019年第4期10-14,共5页
为了更好地解决高速铁路运营监测中重点监测段落划分及沉降监测等问题,以本次复测和竣工复测的CPⅢ实测数据为基础,通过轨道监测软件分析CPⅢ点位横向、垂向变化对轨道线形的影响,沉降量最大值为-44.0mm与工务段提供的重点沉降监测数据... 为了更好地解决高速铁路运营监测中重点监测段落划分及沉降监测等问题,以本次复测和竣工复测的CPⅢ实测数据为基础,通过轨道监测软件分析CPⅢ点位横向、垂向变化对轨道线形的影响,沉降量最大值为-44.0mm与工务段提供的重点沉降监测数据一致;经过对不同段落的对比分析,分析结果与实测数据吻合性较高,验证了方法的可靠性,较好地解决了重点段监测划分及沉降监测问题。 展开更多
关键词 CPⅢ横向 垂向 轨道线形 重点监测划分 沉降监测
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蒙古族大学生的时间空间隐喻--兼与汉族大学生的时间空间隐喻比较 预览
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作者 王婷 关宇霞 张积家 《贵阳学院学报:社会科学版》 2019年第2期47-52,共6页
采用语言线索范式和非语言排序法,通过两个实验,考察蒙古族大学生的时间空间隐喻。结果表明,蒙古族大学生同时具有水平和垂直两种时间空间隐喻。而且,在时空隐喻建构中,篇章的整体作用要大于行的局部作用。被试在阅读过程中,由于篇章整... 采用语言线索范式和非语言排序法,通过两个实验,考察蒙古族大学生的时间空间隐喻。结果表明,蒙古族大学生同时具有水平和垂直两种时间空间隐喻。而且,在时空隐喻建构中,篇章的整体作用要大于行的局部作用。被试在阅读过程中,由于篇章整体是从左到右的,所以蒙古族大学生便与过去与将来的时间概念建立了联系。文字行的从上到下对时间空间隐喻的建立影响较小。 展开更多
关键词 蒙古族 空间时间隐喻 水平 垂直
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Investigating the interlayer electron transport and its influence on the whole electric properties of black phosphorus
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作者 Bensong Wan Shaoqiang Guo +4 位作者 Jiacheng Sun Yufei Zhang Yuyan Wang Caofeng Pan Junying Zhang 《科学通报:英文版》 SCIE EI CSCD 2019年第4期254-260,共7页
Two-dimensional (2D) nanomaterials have attracted great attention in next generation electronic and optoelectronic technologies due to the unique layered structure and excellent physical and chemical properties. Howev... Two-dimensional (2D) nanomaterials have attracted great attention in next generation electronic and optoelectronic technologies due to the unique layered structure and excellent physical and chemical properties. However, the mechanism of transmission along the vertical direction of 2D semiconductor materials has not been investigated. Here, we use first-principles calculations to explore the bandgap energies along different directions, and fabricate a vertical, a lateral and a mixture-structured black phosphorus field effect transistor (BPFET) to study the electrical characteristics along different directions under variable temperatures. The variable temperature test indicates that the mixture-structured device performs more like a lateral device, while the conductanee along the vertical direction is hard to be tuned by temperature and electrical field. The unchanged conductance under electric field and variable temperatures allows the vertical device to act as a fixed resistor, promising possible application for the prospective electronic and optoelectronic devices. 展开更多
关键词 BLACK PHOSPHORUS TRANSISTOR Transmission VERTICAL VARIABLE temperature
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