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在校大学生创业现状调查及其对策研究

江苏科技信息 2024年第6期41卷 126-130页

作者：李美善魏登梁燕吕红英吉林农业科技学院食品工程学院吉林吉林132101

文章通过调查吉林省本科高校在校大学生创业现状,分析其存在的问题和成因,并提出针对性的对策建议。研究发现,在校大学生创业类型呈多元化趋势,失败率高,创业类型常规,创业能力不足,创业规模小;其形成原因受到社会、学校、家庭和个人等... 详细信息

文章通过调查吉林省本科高校在校大学生创业现状,分析其存在的问题和成因,并提出针对性的对策建议。研究发现,在校大学生创业类型呈多元化趋势,失败率高,创业类型常规,创业能力不足,创业规模小;其形成原因受到社会、学校、家庭和个人等综合因素影响。因此,高校应加强在校大学生的创业教育训练,提高大学生创业的成功率;为学生创业提供制度保障,兼顾学业与创业平衡;引进校外多元主体参与到学生创业过程中,提高在校大学生的创业质量。

关键词：大学生创业现状调查成因分析对策研究

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Facile Synthesis of Multi-Branched Gold Nanostructures through a TBAB-Assisted Route in Aqueous Solution and Their SERS Property

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Chinese Journal of Chemistry 2011年第1期29卷 185-190页

作者： Wang, Luyan Wu, Xinzhou Pei, meishan Wu, Zhiyan Li, Xiaonan Tao, Xutang School of Chemistry and Chemical Engineering University ofJinan Shandong Provincial Key Laboratory of Fluorine Chemistry and Chemical Materials Jinan Shandong 250022 China State Key Laboratory of Crystal Materials (Shandong University) Jinan Shandong 250100 China

Facile synthesis of multi-branched gold nanostructures by using the tetrabutyl ammonium bromide （TBAB） as a capping agent is described. The reaction is carried out in a one-step process at mild temperature. Gold nanostructures with more than six sharp branches ranging from 70 to 130 nm in length are synthesized in high yield. It is proposed that the relative weak adsorption capacity of TBAB leads to the incompletely covered gold surface and the growth of nanoparticles occurs on the uncovered gold surface, and therefore short branches appear consequently. Then positively charged TBAB layers on the gold surfaces prevent the branches from aggregating with each other which stimulates the branch growth. The prepared branched gold nanoparticles show efficient surface-enhanced Raman scattering （SERS） properties. Low temperature （4 ℃） is unfavorable to the formation of multi-branched gold nanostructures, and only thin small irregular plate-like nanoparticles are produced. The addition of SDS in TBAB aqueous solution results in forming SDS micelles at much lower concentration of SDS （0.4 mmol/L） as compared to that in pure water, and short branched gold nanoparticles are obtained in the SDS-TBAB system.

关键词： gold multi-branched nanostructures tetrabutyl ammonium bromide surface-enhanced Ramanscattering

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基于响应面法的单元发动机喷注器优化设计

上海航天（中英文） 2024年第2期41卷 130-136,153页

作者：邱鑫白梅杉陆文杰姚天亮刘俊上海空间推进研究所上海201112 上海空间发动机工程技术研究中心上海201112

针对某新研单元发动机喷注器热阻优化的问题,采用仿真计算分析研究支架结构参数对支架热阻与结构强度的影响,并基于响应面法(RSM)对喷注器支架进行结构优化设计。计算结果表明:在计算范围内,对支架隔热性能影响最大的是支架高度,其次是... 详细信息

针对某新研单元发动机喷注器热阻优化的问题,采用仿真计算分析研究支架结构参数对支架热阻与结构强度的影响,并基于响应面法(RSM)对喷注器支架进行结构优化设计。计算结果表明:在计算范围内,对支架隔热性能影响最大的是支架高度,其次是支架厚度,最后是支架孔直径。随着支架高度的增加,支架热阻逐渐增大,而支架热阻则随着支架厚度与孔直径的增加而降低。对支架结构等效应力影响最大的是支架孔直径,其次是支架高度,最后是支架厚度,并且随着支架孔直径的增加,支架结构等效应力逐渐增大,而支架最大等效应力随着支架高度和厚度的增加而减小。通过采用响应面法改进后的支架在结构强度满足发动机力学环境的条件下,喷注器热阻得到明显提高。

关键词：响应面法喷注器优化设计热阻结构强度敏感度

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大学生创业失败案例分析及救济机制研究

江苏科技信息 2024年第5期41卷 102-105,136页

作者：李美善梁燕魏登吕红英吉林农业科技学院食品科学与营养工程学院吉林吉林132101

文章通过调查收集吉林省本科高校在校大学生创业的典型案例,对大学生创业失败进行归因分析,并提出针对性的解决方案。研究结果表明:在校大学生创业失败主要受创业能力、创业初衷、管理能力和学业平衡因素的影响,同时经营状况和创业意志... 详细信息

文章通过调查收集吉林省本科高校在校大学生创业的典型案例,对大学生创业失败进行归因分析,并提出针对性的解决方案。研究结果表明:在校大学生创业失败主要受创业能力、创业初衷、管理能力和学业平衡因素的影响,同时经营状况和创业意志等因素也具有一定影响。因此,高校应从创业能力、创业观念、创业管理能力、学业平衡等方面对大学生创业失败进行救济,为进一步提高大学生创业质量、提升创业成功率提供切实保障。

关键词：大学生创业现状调查案例分析救济机制

基于集成计数器74LS161设计的六十进制计数器

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电子测试 2020年第21期31卷 18-19,54页

作者：栾爽翟艳男李晶金美善空军航空大学航空基础学院吉林长春130022

计数器在电子系统中应用非常广泛,计数器在数字系统中主要是对脉冲的个数进行计数,以实现测量、计数和控制的功能[1]。本文利用集成计数器74LS161设计六十进计数器,实现六十进制正计时和六十进制倒计时功能。

关键词： 555多谐振荡器 74LS161 60进制计数器

Musk secretion in muskrats(Ondatra zibethicus L.):association with lipid and cholesterol metabolism-related pathways

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BIOCELL 2021年第2期45卷 281-306页

作者： TIANXIANG ZHANG meishan ZHANG MINGHUI SHI WEIJIANG jin SHUMIAO ZHANG MENGYUAN FAN YIMENG LI YUPING MENG XUELIN TIAN SHUQIANG LIU DEFU HU School of Ecology and Nature Conservation Beijing Forestry UniversityBeijing100083China Beijing Milu Ecological Research Center Beijing100083China China Wildlife Conservation Association Beijing100083China jining Academy of Agricultural Sciences Jining272000China

Male muskrats(Ondatra zibethicus L.)secrete musk from their scent glands during musk secretion *** plays an important role as a communication pheromone during the breeding *** this study,gas chromatography–mass spectrometry(GC–MS)was used to analyze the main components of *** GC–MS results after methyl esterification showed that 71.55%of the musk is composed of fatty *** other components of muskrat musk include cholesterol(9.31%)and other *** comparison between musk secretion and non-secretion seasons showed significant changes in the scent glands for 53 genes involved in fatty acid and cholesterol synthesis and metabolism regulatory pathways,which include fatty acid biosynthesis,elongation,and metabolism;steroid biosynthesis;steroid hormone biosynthesis pathways.A reverse transcription–polymerase chain reaction analysis confirmed these detected ***,our results indicated that lipid synthesis and metabolism play important roles in musk compound synthesis by providing energy for musk production,and the produced musk provides a mechanism for male muskrats to communicate with females during the breeding season.

关键词： Muskrat Scent gland RNA-seq Lipid Cholesterol

Polarization of plane wave propagating inside elastic hexagonal system solids

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Science China(Physics,Mechanics & Astronomy) 2014年第2期57卷 251-262页

作者： FA Lin ZHAO meishan LIU YongChang WANG Lei WANG YanQiang SUN JiGang School of Electronics and Information Engineering Xi'an University of Posts and Telecommunications James Franck Institute and Department of Chemistry University of Chicago5735 South Ellis AvenueChicagoIL 60637USA

Based on the reported physical parameters for hexagonal system solids,we have calculated the effects of anisotropy on polarization of plane P-wave *** we report the results of calculations and the newly observed physical *** is found that,for a given propagation,if the polarization is parallel to the wave vector,so also to the Poynting *** such a case,the phase velocity is identical to the energy velocity;the quasi P-wave degenerates to a pure P-wave along the *** is also noted that if the polarization is parallel to the Poynting vector but not to the wave vector,the propagating wave cannot be a pure ***,the polarization in a quasi P-wave may deviate from the wave vector for more than 45°,but the deviation from the Poynting vector is always less than 45°.The energy velocity of a quasi SV-wave can be larger than that of the quasi P-wave in some propagation directions,even though the phase velocity of a quasi SV-wave may never be larger than either the phase velocity or energy velocity of the quasi ***,in case of parameters ε=0 and δ*≠0,the polarization of a quasi P-wave has an observed symmetry at a 45°phase *** anisotropy of a hexagonal system solid determines if a pure P-wave can be created and what the propagation direction is for a plane wave propagating inside such a hexagonal system solid.

关键词： anisotropy polarization pure P-wave VTI medium hexagonal crystal

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不耦合空气间隔装药结构爆破机理分析

长江技术经济 2024年第4期8卷 104-112页

作者：董源何艳飞马晨阳刘美山长江科学院水利部岩土力学与工程重点实验室武汉430010 新疆水发建设集团有限公司乌鲁木齐830000

空气间隔装药爆破广泛应用于隧道掘进开挖,其中不耦合系数是保证光面爆破效果的关键因素。QBT工程现场仅有Φ32 mm直径的药卷,为改善爆破效果,采用LS-DYNA程序对轴向不耦合系数Kl进行数值研究,分析了轴向不耦合系数Kl取2.41、3.22、4.8... 详细信息

空气间隔装药爆破广泛应用于隧道掘进开挖,其中不耦合系数是保证光面爆破效果的关键因素。QBT工程现场仅有Φ32 mm直径的药卷,为改善爆破效果,采用LS-DYNA程序对轴向不耦合系数Kl进行数值研究,分析了轴向不耦合系数Kl取2.41、3.22、4.83时炮孔壁应力场、速度场及损伤特性,与光面爆破小直径药卷(Φ25 mm)连续装药结构进行对比,揭示轴向不耦合系数对爆破效果的影响,得到最优取值。结果表明:有效应力峰值与轴向不耦合系数成反比,应力衰减程度与轴向不耦合系数成正比;质点峰值速度下降率为64%~82%,有效降低了爆破振动,轴向不耦合系数越大,控制振动水平能力越强,但由于岩石损伤程度分布发育不充分,在孔口处可能存在挂门帘现象。

关键词：光面爆破空气间隔装药不耦合系数数值模拟

Effects of electric-acoustic and acoustic-electric conversions of transducers on acoustic logging signal

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Chinese Science Bulletin 2012年第11期57卷 1246-1260页

作者： FA Lin XIE WenYan TIAN Yong ZHAO meishan MA Li DONG DaQun School of Electronics Engineering Xi'an University of Post and TelecommunicationsXi'an 710121China PetroChina Liaohe Oilfield Company Panjin 124013China The James Franck Institute and Department of Chemistry The University of ChicagoChicagoIL 60637USA Department of Digital Media andArt Xi'an University of Post and TelecommunicationsXi'an 710121China School of Marine Engineering Northwest Polytechnical UniversityXi'an 710071China

Based on an acoustic logging transmission network and the engineering pattern of a sliding wave in acoustic logging, analysis and calculations have been performed in a study of the effects of the electric-acoustic and acoustic-electric conversions of the transducers on the acoustic logging signal. The results show that acoustic-electric conversion through the transducer can cause not only a serious disturbance in the signal amplitude, but also an apparent transmission delay. For engineering applications, the amplitude variation and transmission delay must be accounted for in a practical analysis of the acoustic logging signal in rocks. The results also show that with enhanced understanding and proper justification, the error caused by the acoustic-electric conversion can be significantly reduced in evaluation of the cement bond quality of a cased well, and the accuracy of rock porosity calculated using the measured acoustic velocity can be increased.

关键词：声波测井测井信号换能器电声声电转换传输网络信号幅度传输延迟