期刊文献+
共找到95,033篇文章
< 1 2 250 >
每页显示 20 50 100
A-Level考试成绩在牛津大学本科招生中的作用--以专业与科目的匹配为中心 预览
1
作者 吴根洲 肖怡 《宁波大学学报:教育科学版》 2020年第1期53-60,共8页
牛津大学本科招生是对申请者A-Level成绩、AS成绩、GCSE成绩、个人陈述、推荐信、书面作品、入学考试、面试等因素的综合评价。作为衡量申请者学术能力的重要依据,牛津大学在招生过程中对A-Level考试成绩格外重视。牛津大学不同专业对A-... 牛津大学本科招生是对申请者A-Level成绩、AS成绩、GCSE成绩、个人陈述、推荐信、书面作品、入学考试、面试等因素的综合评价。作为衡量申请者学术能力的重要依据,牛津大学在招生过程中对A-Level考试成绩格外重视。牛津大学不同专业对A-Level考试科目及成绩提出了明确的等级要求,根据专业与科目的相关性设置了必选科目、建议科目、辅助科目三种科目类型,部分专业还对考试科目设定了模块要求。牛津大学本科招生极其注重A-Level考试科目与专业的匹配性,体现了科目设定详细、主次关系明显、专业与科目关联性强三个特点。 展开更多
关键词 牛津大学 专业 A-LEVEL 科目要求
在线阅读 免费下载
A distribution prior model for airplane segmentation without exact template 预览
2
作者 DAI Ming ZHOU Zhiheng GUO Yongfan 《系统工程与电子技术:英文版》 SCIE EI CSCD 2020年第1期56-63,共8页
In many practical applications of image segmentation problems,employing prior information can greatly improve segmentation results.This paper continues to study one kind of prior information,called prior distribution.... In many practical applications of image segmentation problems,employing prior information can greatly improve segmentation results.This paper continues to study one kind of prior information,called prior distribution.Within this research,there is no exact template of the object;instead only several samples are given.The proposed method,called the parametric distribution prior model,extends our previous model by adding the training procedure to learn the prior distribution of the objects.Then this paper establishes the energy function of the active contour model(ACM)with consideration of this parametric form of prior distribution.Therefore,during the process of segmenting,the template can update itself while the contour evolves.Experiments are performed on the airplane data set.Experimental results demonstrate the potential of the proposed method that with the information of prior distribution,the segmentation effect and speed can be both improved efficaciously. 展开更多
关键词 image segmentation active contour model(ACM) prior distribution level set method
在线阅读 下载PDF
机械制造企业智能制造能力成熟度评价研究 预览
3
作者 任俊飞 吴立辉 +2 位作者 鱼鹏飞 张博晖 张中伟 《科技创新与应用》 2020年第2期55-56,58,共3页
智能制造已经成为中国制造业的主攻方向。面向机械制造企业提出五级智能制造能力成熟度模型,从基础资源能力、业务活动集成能力、信息融合使用能力以及持续改进能力四个方面构建了智能制造能力成熟度评价指标体系,并采用基于层次分析法... 智能制造已经成为中国制造业的主攻方向。面向机械制造企业提出五级智能制造能力成熟度模型,从基础资源能力、业务活动集成能力、信息融合使用能力以及持续改进能力四个方面构建了智能制造能力成熟度评价指标体系,并采用基于层次分析法的二级模糊综合评判法进行企业智能制造实施能力的量化测评,从而为企业客观诊断自身实施智能制造的能力提供理论和方法支持。 展开更多
关键词 智能制造 能力成熟度 等级 评价指标 模糊综合评判
在线阅读 下载PDF
Response of benthic algae to environmental conditions in an urban lake recovered from eutrophication, China 预览
4
作者 WANG Tao WANG Qing +2 位作者 XIA Shuang YAN Chunlan PEI Guofeng 《海洋湖沼学报(英文)》 SCIE CAS CSCD 2020年第1期93-101,共9页
Benthic algae communities dominate the primary production in littoral zone of shallow lake.To tmderstand the long-term effect of alteration in the composition of benthic algae community assemblage in such as a lake in... Benthic algae communities dominate the primary production in littoral zone of shallow lake.To tmderstand the long-term effect of alteration in the composition of benthic algae community assemblage in such as a lake in China,we analyzed the benthic algae developments and indicators in the Donghu Lake in Wuhan,central China in 2004 and 2014.We compared the benthic algae biomass,compositions,and species richness of aquatic macrophytes and the changes of primary physicochemical parameters.The results show that in the 10-year period,chl a and conductivity declined significantly but nutrient level of the whole lake remained largely stable.The benthic algae biomass doubled and the relative proportion of green algae increased,whereas the benthic diatom ratio decreased.The benthic diatom assemblages and taxa differed in a number of ways,showing more epiphytic diatom species,and the relative abundance and species richness changed markedly.The number of aquatic macrophyte species increased from 3 in 2004 to 15 in 2014,presenting a remarkable recovery from previous eutrophication conditions.The changes of water level,chl a,and conductivity played a crucial role in governing aquatic macrophytes re-colonization in the littoral zones in the period.The ecological characteristics of littoral benthic diatoms reflect habitat coupling as indicated by redundancy analysis.Therefore,the close link between benthic algae and macrophyte recovery demonstrates that the benthic algae metrics are much more useful than nutrient levels to quantify the process of restoration in the lake. 展开更多
关键词 BENTHIC ALGAE BENTHIC DIATOM lake restoration AQUATIC MACROPHYTE water level
在线阅读 下载PDF
Case analysis of water exchange between the Bohai and Yellow Seas in response to high winds in winter 预览
5
作者 JU Xia MA Chao +1 位作者 YAO Zhigang BAO Xianwen 《海洋湖沼学报(英文)》 SCIE CAS CSCD 2020年第1期30-41,共12页
Based on the data from a special project titled China's Offshore Marine Integrated Investigation and Evaluation as well as Regional Ocean Modeling Systems(ROMS)diagnostic numerical model,we studied the influence o... Based on the data from a special project titled China's Offshore Marine Integrated Investigation and Evaluation as well as Regional Ocean Modeling Systems(ROMS)diagnostic numerical model,we studied the influence of high wind processes on the circulation and water exchange between the Bohai and Yellow Seas(BYS)in winter.The results show that the vertical structure of the Yellow Sea Warm Current(YSWC)is relatively uniform under condition of high winds,showing obvious barotropic features.However,this flow is not a stable mean flow,showing strong paroxysmal and reciprocating characteristics.A comparison of the changes in sea level suggests that the intensity of the northwards upwind flow is consistent with the abnormal fluctuations in the sea level.It indicates that the upwind flow is closely related to the water exchange between the BYS.The impact of high wind processes on the water exchange between the BYS is enormous.It can make the flux through the Bohai Strait,as well as that through the mouth of each constituent bay(i.e.,Liaodong Bay,Bohai Bay,and Laizhou Bay)far greater than usual,resulting in a significant increase in the water exchange rate.The exchange capacity,which is about 8%of the total volume of the Bohai Sea,can be completed in a few days.Therefore,the water exchange of the Bohai Sea may be completed by only a few occasional high wind processes in winter. 展开更多
关键词 HIGH wind Yellow SEA WARM Current (YSWC) SEA level RISE or DROP water exchange
在线阅读 下载PDF
An Analysis of Colloquial Style in Dai Wangshu’s Poetry 预览
6
作者 叶晓燕 《海外英语》 2019年第7期180-182,共3页
Dai Wangshu was best known for the beautiful rhythm in his poetry. But the publication of his poem My Memory was regarded as a sign of meter abandonment and the beginning of his modern poetry. His poetry started to sh... Dai Wangshu was best known for the beautiful rhythm in his poetry. But the publication of his poem My Memory was regarded as a sign of meter abandonment and the beginning of his modern poetry. His poetry started to show a tendency towards Colloquialism. The differences between colloquialism and vernacular will be distinguished first. And then the colloquial style will be discussed in three levels: lexicon, sentence and discourse, each level will be analyzed with several poems of Dai Wangshu. He has formed his unique writing style of poetry and became the research focus of many scholars. His attempt of using colloquialism in poetry was great contributing to the development of modern poetry and made the poetry more popularization and access to ordinary people. 展开更多
关键词 colloquialism VERNACULAR LEXICAL LEVEL SENTENCE LEVEL DISCOURSE LEVEL
在线阅读 免费下载
New Concept of Digital Structuring Landscape of the Island Systems of the Vladivostok City District 预览
7
作者 Valeriy Titovich Starozhilov 《地球科学和环境保护期刊(英文)》 2019年第2期114-121,共8页
A new concept of digital vector-layer structuring of landscape space at the local level (on a scale of 1:25,000) is considered on the example of Russian island and adjacent island systems of the Vladivostok urban dist... A new concept of digital vector-layer structuring of landscape space at the local level (on a scale of 1:25,000) is considered on the example of Russian island and adjacent island systems of the Vladivostok urban district. Synthesis, analysis and evaluation of the internal and external content of landscape systems are carried out and altitude complexes of tracts are identified, in each of which altitudes are distinguished. It is noted that one of the main criteria for identifying high-altitude complexes and levels is the high-altitude criterion and the quantitative and qualitative changes in their internal content, taking into account the state of erosion-denudation lowland and mountain landscape systems formed under the influence of the Earth’s real material-energy flows and first of all gravitational energy. According to these criteria, landscape areas are classified and vertex, saddle, upper slope, middle slope and other altitude complexes of tracts are distinguished in each of which altitude levels are distinguished. Structuring and classification proposed to the reader are presented for further study of structures as objects of industry-specific indication and possibilities of using high-landscape complexes as development areas. Noted, as well as the fact that the study was conducted for the first time and is aimed at the practical implementation of the landscape approach in the development of landscape systems, defines the relevance of the work performed. 展开更多
关键词 Concept DIGITAL STRUCTURING LANDSCAPE TRACT Complex Level RELIEF Development
在线阅读 免费下载
Distribution and Susceptibility Assessment of Collapses and Landslides in the Riparian Zone of the Xiaowan Reservoir 预览
8
作者 ZHONG Ronghua HE Daming +3 位作者 HU Jinming DUAN Xingwu HUANG Jiangcheng CHENG Xupeng 《中国地理科学:英文版》 SCIE CSCD 2019年第1期70-85,共16页
The southwest alpine gorge region is the major state base of hydropower energy development in China and hence planned many cascading hydropower stations. After the reservoir impoundment, the intense water level fluctu... The southwest alpine gorge region is the major state base of hydropower energy development in China and hence planned many cascading hydropower stations. After the reservoir impoundment, the intense water level fluctuations under the interaction of cascade dams operating and the mountainous flooding, usually cause bank collapse, landslide and debris flow hazards. The Xiaowan reservoir(XWR), for example, as the ‘dragon head’ meg reservoir located in the middle mainstream of Lancang River, have resulted in a series of geohazards during its building and operating. In this study, we investigated the number and surface area of collapses and landslides(CLs) occurred in the water level fluctuations zone(WLFZ) of XWR using remote sensing images of Gaofen-1 and Google Earth;evaluated the CLs susceptibility using information value method. The results presented that the total WLFZ area of 87.03 km2 and 804 CLs masses with a total area of 1.98 km2 were identified in the riparian zone of XWR. CLs mainly occurred at an elevation of 1190–1240 m, and the CLs density increased with an increase in altitude. The WLFZ with a slope gradient of 25°– 45° is the main CLs distribution area that accounts for more than half of the total CLs area. The susceptibility assessment revealed that high and very high susceptibility zones are generally distributed along zones with an elevation of 1210–1240 m, a slope degree of 25°–45° and a slope aspect perpendicular to the direction of Lancang River. Furthermore, these susceptible zones are close in distance to the dam site and tend to be in the riparian zones with the formation lithology of Silurian strata. These results provide a valuable contribution to prevent and control geohazards in the XWR area. Moreover, this study offers a constructive sample of geohazards assessment in the riparian zone of large reservoirs throughout the mountains of southwest China. 展开更多
关键词 SUSCEPTIBILITY assessment collapses and LANDSLIDES water level FLUCTUATIONS Xiaowan RESERVOIR Lancang-Mekong River
在线阅读 下载PDF
Why would sea-level rise for global warming and polar ice-melt? 预览
9
作者 Aftab Alam Khan 《地学前缘:英文版》 CAS CSCD 2019年第2期481-494,共14页
Two major causes of global sea level rise such as thermal expansion of the oceans and the loss of landbased ice for increased melting have been claimed by some researchers and recognized by the IPCC.However, other cli... Two major causes of global sea level rise such as thermal expansion of the oceans and the loss of landbased ice for increased melting have been claimed by some researchers and recognized by the IPCC.However, other climate threat investigators revealed that atmosphere-ocean modeling is an imperfect representation, paleo-data consist of proxy climate information with ambiguities, and modern observations are limited in scope and accuracy. It is revealed that global warming and polar ice-melt although a reality would not contribute to any sea level rise. Floating-ice of the polar region on melting would reoccupy same displaced volume by floating ice-sheets. Land-ice cover in the polar region on melting can reduce load from the crust to activate elastic rebound that would raise land for its isostatic equilibrium.Such characteristics would not contribute to sea level rise. Equatorial bulge, polar flattening, elevation difference of the spheroidal surface between equator and pole with lower in the pole, strong gravity attraction of the polar region and week gravity attraction of the equatorial region, all these phenomena would play dominant role in preventing sea level rise. Palaeo-sea level rise and fall in macro-scale(10-100 m or so) were related to marine transgression and regression in addition to other geologic events like converging and diverging plate tectonics, orogenic uplift of the collision margin, basin subsidence of the extensional crust, volcanic activities in the oceanic region, prograding delta buildup, ocean floor height change and sub-marine mass avalanche. This study also reveals that geophysical shape, gravity attraction and the centrifugal force of spinning and rotation of the earth would continue acting against sea level rise. 展开更多
关键词 Global warming POLAR ice-melt EQUATORIAL BULGE POLAR FLATTENING GEOLOGIC events Sea level rise
在线阅读 下载PDF
Estimating trends of the Mediterranean Sea level changes from tide gauge and satellite altimetry data (1993-2015) 预览
10
作者 TAIBI Hebib HADDAD Mahdi 《海洋湖沼学报(英文)》 SCIE CAS CSCD 2019年第4期1176-1185,共10页
The impact of climate change on sea level has received a great deal of attention by scientists worldwide. In this context, the problem of sea levels on global and regional scales have been analyzed in a number of stud... The impact of climate change on sea level has received a great deal of attention by scientists worldwide. In this context, the problem of sea levels on global and regional scales have been analyzed in a number of studies based on tide gauges observations and satellite altimetry measurements. This study focuses on trend estimates from 18 high-quality tide gauge stations along the Mediterranean Sea coast. The seasonal Mann-Kendall test was run at a 5% significance level for each of the 18 stations for the period of 1993-2015 (satellite altimetry era). The results of this test indicate that the trends for 17 stations were statistically significant and showed an increase (no significant trend was observed only at one station). The rates of sea level change for the 17 stations that exhibit significant trends, estimated using seasonal Sen's approach, range after correction for Vertical Land Motion (VLM) from 1.48 to 8.72 mm/a for the period 1993-2015. Furthermore, the magnitude of change at the location of each tide gauge station was estimated using the satellite altimetry measurements. Thus, the results obtained agree with those from the tide-gauge data analysis. 展开更多
关键词 sea level TIDAL HEIGHT SATELLITE ALTIMETRY trend analysis MANN-KENDALL test Sen's slope ESTIMATES
在线阅读 下载PDF
Bayesian analysis of two methods MALDI-TOF-MS system and culture test in otomycosis infection
11
作者 Sibanarayan Rath Saumya Ranjan Das Rabindra Nath Padhy 《世界耳鼻咽喉头颈外科杂志(英文)》 2019年第1期6-13,共8页
Objective:Identification of otomycotic fungi using matrix-assisted laser desorption ionization (MALDI) time of flight (TOF) mass spectroscopy (MS) and to quantify pervasive errors with Bayes rule;values of sensitivity... Objective:Identification of otomycotic fungi using matrix-assisted laser desorption ionization (MALDI) time of flight (TOF) mass spectroscopy (MS) and to quantify pervasive errors with Bayes rule;values of sensitivity and specificity of culture test and MALDI-TOF-MS method are quantified.Method:Fungi cultured ear discharge samples were identified with culture test and MALDITOF-MS system.Minimum inhibitory concentration (MIC) or MEC (minimum effective concentration) for 6 antifungals were determined by antifungal susceptibility testing in vitro.With Bayes rule,sensitivity and specificity of both MALDI-TOF MS and culture test methods were computed.Results:Cultures yielded 42 fungal isolates which were confirmed as species (specified against each species) belonging to 8 genera,A.niger 22,Candida sp.7,A.fumigatus 3,A.flavus 3,mixed Aspergillus sp.3,Mucor sp.2,Rhizopus sp.1,and Scopulariopsis sp.1;and MALDITOF-MS system also confirmed those isolates.In vitro antifungal susceptibility testing with terms of MIC 50 and MIC 90,isolates fungi were highly susceptible to 6 antifungals;and caspofungin was the most active antifungal.The high value of specificity 84.6%,suggested a limited loss of confidence on the culture test at the absence of an infection,in comparison to MALDI-TOF-MS.Sensitivity of the culture test was 87.5%;this high figure strongly approves the culture test to be the dependable method for the otomycosis diagnosis,when the infection is stable.Conclusion:Based on sensitivity and specificity together the culture test could be done in face of the gold-standardMALDI-TOF-MS system the estimating both methods. 展开更多
关键词 Otomycosis MALDI-TOF-MS system Identification at SPECIES LEVEL Sensitivity SPECIFICITY
Different Flooding Behaviors Due to Varied Urbanization Levels within River Basin: A Case Study from the Xiang River Basin,China
12
作者 Juan Du Linlin Cheng +2 位作者 Qiang Zhang Yumeng Yang Wei Xu 《国际灾害风险科学学报:英文版》 CSCD 2019年第1期89-102,共14页
Booming urbanization due to a fast-growing population results in more impervious areas, less infiltration,and hence greater flood peak and runoff. Clear understanding of flood responses in regions with different level... Booming urbanization due to a fast-growing population results in more impervious areas, less infiltration,and hence greater flood peak and runoff. Clear understanding of flood responses in regions with different levels and expansions of urbanization is of great importance for regional urban planning. In this study, comparison of flooding responses to urbanization processes in terms of flood peak and runoff volume in the upper, middle,and lower Xiang River Basin(XRB), China, was carried out using the Hydrologic Engineering Center-Hydrologic Modeling System(HEC-HMS) model. From 2005 to 2015, urbanization level and intensity were higher in the lower XRB compared to the upper and middle XRB, and the overall expansion rate of urban areas was 112.8%.Modeling results by the HEC-HMS model indicate elevated flood peak discharges and volumes due to fast urbanization in the XRB from the 1980 s to 2015. This rapid increase is particularly the case in the lower XRB. The study also revealed different hydrological responses of flood regimes—urbanization tends to have larger impacts on peak flood flow rather than on flood volume in the lowerXRB, which further corroborated urbanization-induced intensifying flood processes in terms of peak flood flow.Urbanization has increasing impacts on flood volume from the upper to the lower XRB, which can be attributed to accumulated runoff down the river system. This study provides a reference for basin-wide land use and urban planning as well as flood hazard mitigation. 展开更多
关键词 FLOOD volume FLOODING processes HECHMS PEAK FLOOD flow URBANIZATION level Xiang River Basin China
Co-seismic change in ocean bottom topography:Implication to absolute global mean sea level change
13
作者 Jiangcun Zhou Heping Sun +2 位作者 Jianqiao Xu Xiaodong Chen Xiaoming Cui 《大地测量与地球动力学:英文版》 2019年第3期179-186,共8页
Earthquakes perturb both the ocean bottom topography due to displacements of sea floor and the geoid due to mass redistribution, which induces the relative sea level(RSL) change. However, the relative global mean sea ... Earthquakes perturb both the ocean bottom topography due to displacements of sea floor and the geoid due to mass redistribution, which induces the relative sea level(RSL) change. However, the relative global mean sea level(GMSL) change is zero in that sea water mass is conserved. But the absolute GMSL change is not zero because earthquakes displace total ocean mass with respect to the Earth’s center of mass(CM) which remains unchanged after an earthquake. This displacement, i.e. the absolute GMSL change, may be detectable by altimetry since the satellites are orbiting around CM. In this paper, we proposed a method to estimate co-seismic absolute GMSL change caused by earthquakes based on the point dislocation theory for a spherically symmetric, non-rotating, elastic and isotropic(SNREI) Earth.This change can be directly connected to the perturbation of ocean bottom topography. We first computed co-seismic displacements as well as the change in geo-potential and solved the sea level equation to validate the insignificance of the oceans’ feedback, i.e. the loading effect due to RSL change, to co-seismic displacements. The results imply that the loading effect due to RSL change is negligible on displacements while is considerable on geoid. We then computed the absolute GMSL change caused by co-seismic vertical and horizontal displacements by making use of the integrated Green’s function method. The numerical results show that a large earthquake may raise the absolute GMSL by magnitude of sub-millimeter and the recent three large events cause GMSL to rise about one millimeter, in which the contribution from horizontal displacement is non-negligible. 展开更多
关键词 Point DISLOCATION theory SNREI earth Sea level equation ABSOLUTE GMSL Ocean BOTTOM TOPOGRAPHY
Teacher’s Code-switching to L1 in Chinese College EFL Class 预览
14
作者 Yang Ning 《教育理论综述(英文)》 2019年第2期34-41,共8页
The paper tries to explore teachers’ code-switching to Chinese in EFL classroom. Quantitative and qualitative research methods are adopted in the study. The case study centers on showing the attitude of teachers and ... The paper tries to explore teachers’ code-switching to Chinese in EFL classroom. Quantitative and qualitative research methods are adopted in the study. The case study centers on showing the attitude of teachers and that of students towards the CS to L1. It indicated that both teachers and students had positive attitude toward CS to Chinese in EFL classroom. The results in the classroom recording showed that students’ English proficiency level influenced the frequency of teachers’ CS;teachers alternate to Chinese mainly to facilitate students’ understanding or to emphasize some key points. 展开更多
关键词 Teacher's CODE-SWITCHING ATTITUDE Frequency PROFICIENCY level
在线阅读 免费下载
Prediction and analysis of the potential risk of sudden oak death in China 预览
15
作者 Bo Xie Chunxiang Cao +1 位作者 Wei Chen Bing Yu 《林业研究:英文版》 CAS CSCD 2019年第6期2357-2366,共10页
Sudden oak death(SOD)is one of the most rapid and destructive forest pathogens,which has caused the death of many host plants in Europe and America.There are currently no cases in China where there are more host plant... Sudden oak death(SOD)is one of the most rapid and destructive forest pathogens,which has caused the death of many host plants in Europe and America.There are currently no cases in China where there are more host plants and a more suitable climate for this pathogen to survive.Therefore,it is vital to discern the potential suitable habitat,quantify the risk levels,and monitor the potential high-risk areas.In this study,we modelled the potential invasion range and risk level of this pathogen at present and in future scenarios in China,using the least correlated components of all the environmental factors based on the Genetic Algorithm for Ruleset Production niche model and GIS analysis.The results indicate that most areas in China are free from a potential SOD risk,and the majority of potential occurrence areas are concentrated in Southern China(Yunnan,Sichuan,Guizhou,Chongqing,Hunan,Fujian).The area of high and extremely high risk in 2050(RCP26,RCP45,RCP60,and RCP85)is larger than that at present.The most susceptible area is Yunnan province with 80%of the area prone to SOD at extremely high risk in present and future scenarios.The results will be important for monitoring potential high-risk areas in the currently uninfected parts of China. 展开更多
关键词 PHYTOPHTHORA ramorum GARP ECOLOGICAL NICHE MODELS Suitable HABITAT Risk level
在线阅读 下载PDF
不同锌源和水平对断奶仔猪生长性能及血清、粪中锌含量的影响 预览
16
作者 陈雅湘 陈思佳 +1 位作者 穆蕊 方热军 《动物营养学报》 CAS CSCD 北大核心 2019年第10期4852-4858,共7页
本试验旨在研究不同锌源和水平对断奶仔猪生长性能及血清、粪中锌含量的影响。锌源为2种新型氧化锌,分别是以包合技术制成的包合分子氧化锌和以硬脂酸包被的氧化锌。选取250头24日龄平均体重为(6.74±0.35)kg的“杜×长×... 本试验旨在研究不同锌源和水平对断奶仔猪生长性能及血清、粪中锌含量的影响。锌源为2种新型氧化锌,分别是以包合技术制成的包合分子氧化锌和以硬脂酸包被的氧化锌。选取250头24日龄平均体重为(6.74±0.35)kg的“杜×长×大”断奶仔猪,随机分为5组,每组5个重复,每个重复10头猪(公母各1/2)。5组分别为对照组(基础饲粮+2 250 mg/kg普通氧化锌,以锌计,下同)、包合分子氧化锌300组(基础饲粮+300 mg/kg包合分子氧化锌)、包合分子氧化锌600组(基础饲粮+600 mg/kg包合分子氧化锌)、包被氧化锌300组(基础饲粮+300 mg/kg包被氧化锌)、包被氧化锌600组(基础饲粮+600 mg/kg包被氧化锌)。预试期3 d,正试期14 d。结果显示:1)与对照组相比,各试验组的末重、平均日采食量、平均日增重、料重比以及腹泻率均无显著差异(P>0.05)。与包被氧化锌组相比,包合分子氧化锌组的平均日增重显著提高(P<0.05),平均日采食量有提高趋势(0.05<P<0.10)。2)与对照组相比,各试验组的血清锌含量分别降低了62.01%、39.94%、56.17%和48.70%;粪锌含量分别是对照组的0.25倍、0.41倍、0.31倍和0.32倍,均差异显著(P<0.05)。综上,300或600 mg/kg的包合分子氧化锌和包被氧化锌与高剂量(2 250 mg/kg)氧化锌在生长性能方面可达到同等效果,且粪锌排放显著降低。 展开更多
关键词 锌源 水平 断奶仔猪 生长性能 微量元素
在线阅读 下载PDF
提高医院经济管理水平的探究分析 预览
17
作者 张恺 《黑龙江科学》 2019年第1期120-121,共2页
随着我国现代医疗体系改革的不断深化,对医院经济管理水平的研究也在不断的强化,但医院经济管理现状仍存在很多不尽如人意的地方。为更好地促进医院管理水平的提高,各医院要结合自身实际情况不断进行改革。进行成本核算和完善内部控制... 随着我国现代医疗体系改革的不断深化,对医院经济管理水平的研究也在不断的强化,但医院经济管理现状仍存在很多不尽如人意的地方。为更好地促进医院管理水平的提高,各医院要结合自身实际情况不断进行改革。进行成本核算和完善内部控制体系是我国医院发展稳定的重要保证和前提,要对医院实施的具体要求和管理措施有一个全面的认识。本文分析了目前我国医院在经济管理中存在的具体问题,并提出了合理的改进措施和意见,使医院的经济管理走向正规化,从而积极应对现代医疗市场的激烈竞争。 展开更多
关键词 医院 经济管理 水平
在线阅读 下载PDF
Forecasting vulnerability of deep extraction level excavations to drawinduced cave loads 预览
18
作者 Matthew E.Pierce 《岩石力学与岩土工程学报:英文版》 CSCD 2019年第3期527-534,共8页
Block and panel caving methods are increasingly used for mining of large and strong orebodies at large depths below the ground surface (>1 km). This paper focuses on the production phase of caving when the extracti... Block and panel caving methods are increasingly used for mining of large and strong orebodies at large depths below the ground surface (>1 km). This paper focuses on the production phase of caving when the extraction level is fully developed and subjected to the weight of overlying caved material. A limit equilibrium solution for estimation of cave loads is critically reviewed and combined with existing empirical tools in order to forecast extraction level performance under cave loading. The analysis results, presented in nomogram form, suggest that the risk of severe squeezing of extraction level tunnels does not increase with cave depths below 500-1000 m due to the beneficial effects of arching. Under normal extraction ratios (ER = ~50%), severe squeezing experienced from cave loads in deep mines appears to be unlikely in all but the weakest rock masses (σcm < 5 MPa, where σcm is the rock mass global strength), even with poor draw control or low drawpoint availability. The likelihood of severe squeezing is greater when large draw areas (HR = 50-75 m, where HR is the hydraulic radius) are combined with low drawpoint availability or poor draw control and locally higher extraction ratios (ER = ~75%), even in better quality rock (σcm = 5-10 MPa). The analysis results are back-analyzed with the extraction level performance before and after a doubling production of rate and draw area at the deep ore zone (DOZ) mine in Indonesia. The extraction level conditions predicted by the nomograms correlate well with the experience at the DOZ, in which extraction level damage increases significantly over the production rampup, accompanied by a significant drop in drawpoint availability. 展开更多
关键词 Block CAVING Panel CAVING Extraction level DRAW control SQUEEZING
在线阅读 下载PDF
Coastal sea level variability in the Bohai Bay: influence of atmospheric forcing and prediction 预览
19
作者 Lü Xianqing WANG Daosheng +1 位作者 YAN Bing YANG Hua 《海洋湖沼学报(英文)》 SCIE CAS CSCD 2019年第2期486-497,共12页
The sea level variabilities, especially the atmosphere-driven sea level variabilities, which are diff erent in studies on diverse areas and timescales, need to be further documented in the Bohai Bay. Coastal sea level... The sea level variabilities, especially the atmosphere-driven sea level variabilities, which are diff erent in studies on diverse areas and timescales, need to be further documented in the Bohai Bay. Coastal sea level data and coincident meteorological data collected hourly at two observation stations (E1 and E2) in the Bohai Bay, which is a typical semi-enclosed coastal sea in China, are analyzed for the period from 19 August 2014 to 18 November 2014. The sub-sampled low-pass (<0.8 cpd) sea levels (SLSLs) at E1 and E2 are almost the same as each other, while the winds are not. On the whole, SLSLs at E1 and E2 are dominantly influenced by the across-shore wind;in detail, the dominant wind orientation at E1 is 65° measured clockwise from north, and SLSL at E2 is significantly influenced by the sub-sampled wind (SW) at 55°. Regression of SLSL onto the corresponding SW in dominant orientation and the atmospheric pressure is used to predict SLSL, which make the frequency of occurrences when the predicted total sea level is within 0.15 m from the observed values increase to 66.03% and 58.08% at E1 and E2 from original 36.71% and 34.80% without using it, respectively. The results indicate that for the prediction of the total sea level variability in the coastal shallow waters, the SLSL influenced by the atmospheric forcing, including local wind and atmospheric pressure, can be predicted using the multivariable linear regression model. 展开更多
关键词 COASTAL sea level ATMOSPHERIC FORCING Bohai BAY PREDICTION
在线阅读 下载PDF
Concurrent optimization of structural topology and infill properties with a CBF-based level set method
20
作者 Long JIANG Yang GUO +3 位作者 Shikui CHEN Peng WEI Na LEI Xianfeng David GU 《机械工程前沿:英文版》 CSCD 2019年第2期171-189,共19页
In this paper,a parametric level-set-based topology optimization framework is proposed to concurrently optimize the structural topology at the macroscale and the effective infill properties at the micro/meso scale.The... In this paper,a parametric level-set-based topology optimization framework is proposed to concurrently optimize the structural topology at the macroscale and the effective infill properties at the micro/meso scale.The concurrent optimization is achieved by a computational framework combining a new parametric level set approach with mathematical programming.Within the proposed framework,both the structural boundary evolution and the effective infill property optimization can be driven by mathematical programming,which is more advantageous compared with the conventional partial differential equatiodriven level set approach.Moreover,the proposed approach will be more efficient in handling nonlinear problems with multiple constraints.Instead of using radial basis functions(RBF),in this paper,we propose to construct a new type of cardinal basis functions(CBF)for the level set function parameterization.The proposed CBF parameterization ensures an explicit impose of the lower and upper bounds of the design variables.This overcomes the intrinsic disadvantage of the conventional RBF-based parametric level set method,where the lower and upper bounds of the design variables oftentimes have to be set by trial and error;A variational distance regularization method is utilized in this research to regularize the level set function to be a desired distanceregularized shape.With the distance information embedded in the level set model,the wrapping boundary layer and the interior infill region can be naturally defined.The isotropic infill achieved via the mesoscale topology optimization is conformally fit into the wrapping boundary layer using the shape-preserving conformal mapping method,which leads to a hierarchical physical structure with optimized overall topology and effective infill properties.The proposed method is expected to provide a timely solution to the increasing demand for multiscale and multifunctional structure design. 展开更多
关键词 CONCURRENT TOPOLOGY OPTIMIZATION PARAMETRIC level set method cardinal basis function shell-infill structure design confonnal mapping
上一页 1 2 250 下一页 到第
使用帮助 返回顶部 意见反馈