期刊文献+
共找到91篇文章
< 1 2 5 >
每页显示 20 50 100
Study of Swine Leukocyte Antigen Class I-3 (SLA-3) Gene for Inbreeding Wuzhishan Pig 被引量:1
1
作者 SUN Jun-li MU Wu-lian +2 位作者 LIU Xiao-lin FENG Shu-tang WANG Su-rong 《Agricultural Sciences in China》 CAS CSCD 2007年第12期1502-1510,共9页
To elucidate the structure of SLA-3 alleles on inbred line of Wuzhishan pig (WZSP) population, we examined the partial exon 1, completed exon 2, and partial exon 3 of SLA-3 loci using the reverse transcription-polym... To elucidate the structure of SLA-3 alleles on inbred line of Wuzhishan pig (WZSP) population, we examined the partial exon 1, completed exon 2, and partial exon 3 of SLA-3 loci using the reverse transcription-polymerase chain reaction (RT- PCR) and the sequencing-based method in 32 WZSPs. According to pedigree and amplification results, PCR products of 8 WZSPs were selected to clone and sequence. Nine different nucleotide sequences were obtained. After comparing the DNA and protein sequences of the WZSPs SLA-3 alleles with the published GenBank SLA sequences, it was found that the SLA-3 alleles in WZSPs were all novel, but there were very few variations among them. Comparision of SLA-3 and HLA-A protein sequences indicated that there was more sequence homology. Meanwhile, the construction of a phylogenetic tree using the nucleotide sequences of 23 SLA-3 alleles and 1 HLA-A allele represented that the WZSP population owns its unique genetics resource. In this study, the alleles of SLA-3 on WZSP group were successfully detected and analyzed, which provided the firm basis on the genotype of SLA-3 for breeding specific haplotypes WZSPs. 展开更多
关键词 inbreeding Wuzhishan pig leucocyte antigen SLA classical class 1-3 gene RT-PCR
在线阅读 下载PDF
The Shift of Discourse Right in College English Classroom
2
作者 周敏 《商情》 2011年第8期36-36,共1页
关键词 英语 语法 语言学 教材
在线阅读 下载PDF
一种高性能Class D音频放大器PWM控制的设计
3
作者 李强 杨旭 +2 位作者 李涅 周泽坤 张波 《电子元器件应用》 2012年第7期17-21,共5页
文中设计了一种应用于ClassD音频放大器中高性能PWM控制。该控制能够在较宽的电源电压范围内,使调制锯齿波的输入电平及音频输入信号经过前置放大后的共模电平跟随电源电压的变化而变化。共模电平经过PWM比较器得到占空比随输入信号变... 文中设计了一种应用于ClassD音频放大器中高性能PWM控制。该控制能够在较宽的电源电压范围内,使调制锯齿波的输入电平及音频输入信号经过前置放大后的共模电平跟随电源电压的变化而变化。共模电平经过PWM比较器得到占空比随输入信号变化的控制信号,从而提高系统的输出功率。仿真结果显示,当电源电压在2.4~5V范围变化时,音频信号和调制锯齿波的共模电平偏差在2mV以内,同时锯齿波的幅度也随着电源电压的升高而升高,显示了良好的线性跟随性。 展开更多
关键词 自适应 电平位移 class D
在线阅读 下载PDF
Culm characteristics and volume-weight relationship of a forest bamboo(Melocanna baccifera(Roxb.) Kurz) from northeast India 被引量:2
4
作者 Pator Singnar Arun Jyoti Nath Ashesh Kumar Das 《Journal of Forestry Research》 SCIE CAS CSCD 2015年第4期841-849,共9页
Culm characteristics of Melocanna baccifera, locally 'muli', culms at five different culm ages of 11 girth classes (5-6 to 15-16 cm) were studied from Cachar Dis- trict of southern Assam, northeast India. We recor... Culm characteristics of Melocanna baccifera, locally 'muli', culms at five different culm ages of 11 girth classes (5-6 to 15-16 cm) were studied from Cachar Dis- trict of southern Assam, northeast India. We recorded internode length, internode diameter, number of internodes per culm, total culm height, total culm green weight and total culm volume of all five culm age classes. Data were gathered on 165 culms, each culm age class containing 33 culms with 3 culms per girth class. Culm height ranged from 3.2 to 15.3 m with highest mean of 9.15 m (in threeyear old culms) and maximum culm height was recorded in four-year old culms. Highest mean and maximum internode length (27.45 and 54.2 cm, respectively), internode diameter (3.12 and 4.75 cm, respectively) and total culm green weight (5.42 and 12.87 kg/culm, respectively) were recorded in three-year old culms and lowest in current-year culms. Best fitted regression models for all parameters were developed. Significant linear relationships between culm green weight and culm solid volume were documented for all five culm age classes. Their corresponding best-fit regression models were also developed. 展开更多
关键词 Regression model - Volume equation Ageclass Girth class Yield determination
在线阅读 下载PDF
Nanoscale mass sensing based on vibration of single-layered graphene sheet in thermal environments 被引量:3
5
作者 S.Ahmad Fazelzadeh Esmaeal Ghavanloo 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2014年第1期84-91,共8页
Based on vibration analysis, single-layered graphene sheet (SLGS) with multiple attached nanoparticles is developed as nanoscale mass sensor in thermal environments. Graphene sensors are assumed to be in simplysuppo... Based on vibration analysis, single-layered graphene sheet (SLGS) with multiple attached nanoparticles is developed as nanoscale mass sensor in thermal environments. Graphene sensors are assumed to be in simplysupported configuration. Based on the nonlocal plate the- ory which incorporates size effects into the classical theory, closed-form expressions lot the frequencies and relative fre- quency shills of SLGS-based mass sensor are derived using the Galerkin method. The suggested model is justified by a good agreement between the results given by the present model and available data in literature. The effects of tem- perature difference, nonlocal parameter, the location of the nanoparticle and the number of nanoparticles on the relative frequency shift of the mass sensor are also elucidated. The obtained results show that the sensitivity of the SLGS- based mass sensor increases with increasing temperature difference. 展开更多
关键词 Vibration - Single-layered graphene sheet. Ther- mal environment - Nonlocal elasticity theory Relative frequency shift
在线阅读 下载PDF
基于神经网络区分器的SIMON-like算法参数安全性评估
6
作者 侯泽洲 任炯炯 陈少真 《网络与信息安全学报》 2023年第2期154-163,共10页
神经网络区分器作为一种新的可被应用于密码算法安全性分析的工具,一经提出便被应用于多种密码算法的安全性分析。对于SIMON-like算法,其循环移位参数的选择有多种。利用神经网络区分器对分组长度为32 bit的SIMON-like算法的循环移位参... 神经网络区分器作为一种新的可被应用于密码算法安全性分析的工具,一经提出便被应用于多种密码算法的安全性分析。对于SIMON-like算法,其循环移位参数的选择有多种。利用神经网络区分器对分组长度为32 bit的SIMON-like算法的循环移位参数(a,b,c)的安全性进行了研究,并给出了好的循环移位参数选择。利用Kölbl等在CRYPTO2015中提出的SIMON-like算法仿射等价类思想,将分组长度为32 bit的SIMON-like算法的循环移位参数划分至509个等价类,并选择其中使gcd(a-b,2)=1成立的240个等价类进行研究。针对240个等价类的代表元构建了自动化搜索差分路径的SAT/SMT模型,并利用SAT/SMT求解器搜索了不同代表元的多轮最佳差分路径。利用搜索得到的最佳差分路径的输入差分训练了神经网络区分器,选择其中准确率最高的神经网络区分器作为代表元的神经网络区分器,统计了不同代表元的神经网络区分器准确率。发现Kölbl等给出的20个最佳循环参数并不能使神经网络区分器的准确率最低,而且其中4个循环移位参数对应的神经网络区分器的准确率超过了80%,这意味着这4个循环移位参数抗神经网络区分器的能力是差的。综合考虑Kölbl等的选择和不同代表元的神经网络区分器准确率,给出了3个好的循环移位参数选择,即(6,11,1)、(1,8,3)和(6,7,5)。 展开更多
关键词 SIMON-like 仿射等价类 神经网络区分器 循环移位参数
在线阅读 下载PDF
DFT Studies on Thermal Stabilities,Electronic Structures,and ^(13)C Chemical Shifts of C_(24)O_2 Based on Fullerene C_(24)(D_6) 被引量:2
7
作者 王振 张静 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 2011年第5期666-671,共6页
Quantum chemical calculations on some possible equilibrium geometries of C24O2 isomers derived from C24 (D6) and C24O have been performed using density functional theory (DFT) method. The geometric and electronic ... Quantum chemical calculations on some possible equilibrium geometries of C24O2 isomers derived from C24 (D6) and C24O have been performed using density functional theory (DFT) method. The geometric and electronic structures as well as the relative energies and thermal stabilities of various C24O2 isomers at the ground state have been calculated at the B3LYP/6-31G(d) level of theory. And the 1,4,2,5-C24O2 isomer was found to be the most stable geometry where two oxygen atoms were added to the longest carbon-carbon bonds in the same pentagon from a thermodynamic point of view. Based on the optimized neutral geometries, the vertical ionization potential and vertical electron affinity have been obtained. Meanwhile, the vibrational frequencies, IR spectrum, and 13C chemical shifts of various C24O2 isomers have been calculated and analyzed. 展开更多
关键词 C24O2 thermal stabilities 13C chemical shifts B3LYP/6-31G(d)
在线阅读 下载PDF
Maintained Exposure to Spring Water but Not Double Distilled Water in Darkness and Thixotropic Conditions to Weak (~1 µT) Temporally Patterned Magnetic Fields Shift Photon Spectroscopic Wavelengths: Effects of Different Shielding Materials 被引量:3
8
作者 N. J. Murugan L. M. Karbowski +1 位作者 R. M. Lafrenie M. A. Persinger 《Journal of Biophysical Chemistry》 2015年第1期14-28,共15页
Spring water but not double-distilled water was exposed, in darkness, to a temporally patterned weak magnetic field that has been shown to affect planarian behavior and slow the rate of cancer cell proliferation. Expo... Spring water but not double-distilled water was exposed, in darkness, to a temporally patterned weak magnetic field that has been shown to affect planarian behavior and slow the rate of cancer cell proliferation. Exposure to the magnetic field caused a reliable shift in the peak (longer) wave-length of ~10 nm for fluorescence emissions and a ~20% increase (~100 counts) in fluorescence intensity. Spectral analyses verified a shift of 5 and 10 nm, equivalent to ~1.5 × 10-20 J “periodicity” across the measured wavelengths, which could reflect a change in the an intrinsic energy as predicted by Del Giudice and Preparata and could correspond to two lengths of O-H bonds. Wrapping the water sample containers during exposure with copper foil, aluminum foil, or plastic altered these fluorescent profiles. The most conspicuous effect was the elimination of a ~280 nm peak in the UV-VIS emission spectra only for samples wrapped with copper foil but not aluminum or plastic. These results suggest that weak magnetic fields produce alterations in the water-ionic complexes sufficient to be reliably measured by spectrophotometry. Because the effect was most pronounced when the spring water was exposed in darkness and was not disturbed the role of thixotropic phenomena and Del Giudice entrapment of magnetic fields within coherent domains of Pollack virtual exclusion zones (EZ) may have set the conditions for subsequent release of the energy as photons. 展开更多
关键词 Water WEAK Magnetic Fields PHOTON Emissions DARKNESS Thixotropic Phenomena Copper Shielding Wavelength shift 10-20 Joules
暂未订购
Investigation on the Structure of Chute-feed and Card Auto-leveller and Their Selection of Technological Processes
9
作者 程隆棣 《Journal of China Textile University(English Edition)》 EI CAS 1998年第3期62-65,共4页
Based on the structure of chute - feed and autoleveHer, an analysis of their working principle and the verification of their practical production results have been carried out. Finally, the future investigation direet... Based on the structure of chute - feed and autoleveHer, an analysis of their working principle and the verification of their practical production results have been carried out. Finally, the future investigation direetiom of chute - feed and card autuleveller are put forward. 展开更多
关键词 CHUTE - FEED CARD AUTO - leveller IRREGULARITY among shifts.
在线阅读 下载PDF
Sandwich Complexes of the As_4~(2-) Aromatic Ring with Some Transition Metals
10
作者 李志伟 赵存元 +1 位作者 吴文胜 陈六平 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 北大核心 2008年第9期1097-1102,共6页
The equilibrium geometries, energies, harmonic vibrational frequencies, and nucleus independent chemical shifts (NICS) of the new type sandwich structures [As4MAs4]^n- (M = Fe, Co, Ni, Ru, Rh, Pd, Os, Ir and Pt; n ... The equilibrium geometries, energies, harmonic vibrational frequencies, and nucleus independent chemical shifts (NICS) of the new type sandwich structures [As4MAs4]^n- (M = Fe, Co, Ni, Ru, Rh, Pd, Os, Ir and Pt; n = 0, 1 or 2) are investigated at the B3LYP level. All the [As4MAs4]^n- species adopt staggered (D4d) conformations as their stable structures and eclipsed (D4h) conformations as their transition states, and once the sandwich complexes are formed, the As4^2- square properties remain unchanged. The NICS calculation confirms that the complexes of Fe, Co, and Ni are aromatic with negative NICS values, and those of Ru, Rh, and lx exhibit slight aromaticity, while those of Pd, Os, and Pt show slight antiaromaticity. 展开更多
关键词 As4^2- dianion AROMATICITY DFT calculation nucleus independent chemical shifts (NICS)
在线阅读 下载PDF
Computer-aided Pattern Design of Multi-bar Warp Knitted Fabrics
11
作者 李炜 《Journal of China Textile University(English Edition)》 EI CAS 2000年第1期85-87,共3页
To meet the development trend of multi-bar warp knit-ting machine towards high-speed,advanced technologyand computer control and the requirements of variousproducts with small quantity,there are many researcheson the ... To meet the development trend of multi-bar warp knit-ting machine towards high-speed,advanced technologyand computer control and the requirements of variousproducts with small quantity,there are many researcheson the computer-aided pattern design of multi-barwarp knitted fabrics.In terms of the special propertiesof the computer-aided pattern design of multi-barwarp knitted fabrics,the Object Oriented Program(OOP)programming-Object Windows class Library(OWL)programming is selected.According to thecharacters of the OWL programming,various functionsare defined.Pattern design and technical parameters canbe output,which offers a great convenience for the fac-tory. 展开更多
关键词 MULTI - bar WARP KNITTED fabric computer -aided PATTERN design PATTERN Object Windows class Library (OWL) programming.
在线阅读 下载PDF
^(13)C NMR Study of Ethylene/propylene/octene-1 Terpolymers Synthesized with TiCl_4/MgCl_2/ i -Bu_3Al as the Catalyst
12
作者 LI San xi ZHOU Zi nan +3 位作者 XIAO Yan wen JING Feng ying PANG De ren HUANG Bao tong 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 2000年第3期236-245,共10页
The theory of chemical shift effect of substituent was applied to the assignment of the 13 C NMR spectra of the ethylene/propylene and ethylene/octene 1 copolymers. Using the parameters derived above a... The theory of chemical shift effect of substituent was applied to the assignment of the 13 C NMR spectra of the ethylene/propylene and ethylene/octene 1 copolymers. Using the parameters derived above and the DEPT technique, we then entirely assigned the 13 C NMR spectra of the ethylene/propylene/octene 1 terpolymers synthesized in the presence of the same heterogeneous supported Ziegler Natta catalyst, TiCl 4/MgCl 2/ i Bu 3Al. The present paper also covers the terpolymer composition and the monomer sequence distributions of a series of ethylene/propylene/octene 1 terpolymers. 展开更多
关键词 Chemical shift effect ^(13)C NMR Ethylene/propylene/octene^(-1) terpolymer
在线阅读 下载PDF
具有宽范围负载能力双向E^(#)型WPT系统研究 被引量:2
13
作者 张信 杨奕 +2 位作者 包诗媛 张路 陈诗雨 《中国电机工程学报》 北大核心 2025年第4期1610-1622,I0032,共14页
传统双向E型无线电能传输(wireless power transfer,WPT)拓扑易进入硬开关状态,导致电能传输效率低。针对此,该文提出无线电能传输系统的改进E^(#)型拓扑及其移相控制策略。首先,构建软开关状态负载范围更宽的双向E^(#)型WPT电路拓扑数... 传统双向E型无线电能传输(wireless power transfer,WPT)拓扑易进入硬开关状态,导致电能传输效率低。针对此,该文提出无线电能传输系统的改进E^(#)型拓扑及其移相控制策略。首先,构建软开关状态负载范围更宽的双向E^(#)型WPT电路拓扑数学模型,分析并提取电路实现软开关工作状态的关键变量与约束条件,理论上证明所提拓扑的有效性。然后,推导电路中线圈互感和负载阻抗等参数的解析关系式,并基于此提出可保证系统在负载时始终处于最佳工作状态的移相控制策略。该策略通过控制开关管的门极驱动信号相位,使谐振元件内部储存的能量提前或者滞后释放,从而将开关管修正回软开关状态。最后,通过仿真和实验验证所提双向E^(#)型WPT系统的有效性。实验结果表明,所提方法可保证在5~30Ω的负载范围内电路工作在软开关状态,该范围内的电能传输效率峰值达84.3%。 展开更多
关键词 双向无线电能传输 E^(#)型电路拓扑 零电压开关 移相控制
原文传递
从范畴转换视角探讨护理英语文本中长难句的汉译策略
14
作者 李曦 田俊英 《文化创新比较研究》 2025年第3期11-15,共5页
在护理学科全球范围内迅猛发展的背景下,国际护理知识的交流与合作得到了极大的推动。在这一进程中,护理文献的翻译工作显得尤为关键。然而,护理英语文献中频繁出现的长难句,因其结构错综复杂、信息层次繁多、专业术语密集等特性,为翻... 在护理学科全球范围内迅猛发展的背景下,国际护理知识的交流与合作得到了极大的推动。在这一进程中,护理文献的翻译工作显得尤为关键。然而,护理英语文献中频繁出现的长难句,因其结构错综复杂、信息层次繁多、专业术语密集等特性,为翻译工作带来了显著的挑战。该研究通过具体案例分析,应用范畴转换理论,从结构转换、单位转换及词类转换三个维度,对护理领域英语长难句的汉译策略进行了全面的探讨。研究结果表明,结构转换有助于译者选择恰当的语法结构,使译文更贴合目标语言的表达习惯;单位转换则使得翻译更为简洁、精练;词类转换进一步增强了译文的表现力,使其更贴合汉语的语言逻辑与表达风格。 展开更多
关键词 范畴转换 护理英语 长难句 汉译 结构转换 单位转换 词类转换
原文传递
万瓦激光加工头的透镜热致畸变及其对光束波前的影响研究
15
作者 吴烨昊 罗佩锴 +1 位作者 曹宇 刘文文 《温州大学学报(自然科学版)》 2025年第2期10-17,共8页
采用COMSOL Multiphysics多物理场仿真方法,系统分析了万瓦激光加工头的准直镜与聚焦镜热致畸变及其对光束波前的影响.当镜面温度在80℃至120℃范围内变化时,透镜在X、Y、Z三个方向产生0―10μm的热致畸变,且波前相位呈现出显著的空间... 采用COMSOL Multiphysics多物理场仿真方法,系统分析了万瓦激光加工头的准直镜与聚焦镜热致畸变及其对光束波前的影响.当镜面温度在80℃至120℃范围内变化时,透镜在X、Y、Z三个方向产生0―10μm的热致畸变,且波前相位呈现出显著的空间分布特征:准直镜的波前畸变表现为正三角分布,聚焦镜则为倒三角分布,两者的畸变程度均呈现自上而下逐渐增大的趋势.基于研究结果,建立了透镜热致畸变与波前畸变之间的定量对应关系,为有效预测万瓦激光加工头在不同工况下的畸变特征和温度分布提供了重要的理论支持. 展开更多
关键词 万瓦激光加工头 热致畸变 波前畸变 焦点偏移
在线阅读 下载PDF
英汉动词名化表达式的名化度对比分析 被引量:11
16
作者 曲英梅 杨忠 《外语学刊》 CSSCI 北大核心 2009年第3期66-69,共4页
动词名化本质上是一种跨范畴现象,即过程被重新识解为事物。不同的动词名化表达式因其所表达事物的典型程度不同而具有不同的动词名化度,名化结构的语法特征可以作为衡量动词名化度的参数。英汉动词名化度的对比分析表明:英汉转指型动... 动词名化本质上是一种跨范畴现象,即过程被重新识解为事物。不同的动词名化表达式因其所表达事物的典型程度不同而具有不同的动词名化度,名化结构的语法特征可以作为衡量动词名化度的参数。英汉动词名化度的对比分析表明:英汉转指型动词名化的名化度普遍高于自指型动词名化,但是汉语中转类型和转级型动词名化的名化度呈现出不同于英语的复杂排列趋势。这既反映了英汉语言基于认知的共性,也表现出两种语言系统之间的差异,为翻译和英语教学提供了有益的启示。 展开更多
关键词 动词名化度 转类 转级 自指 转指
原文传递
基于相移PWM调制的多电平D类功率放大器谐波分析 被引量:6
17
作者 张缨 李耀华 +1 位作者 蔡凌 孟庆德 《电工技术学报》 EI CSCD 北大核心 2007年第7期103-108,共6页
介绍了一种新颖的基于级联型多电平拓扑结构的开关型功率放大器,采用单极倍频相移PWM技术,其开关频率为单个单元开关频率的2N倍,总的输出电压波纹小。分析了级联型多电平技术的特点,重点研究了采用单极倍频相移PWM技术的多电平输出信号... 介绍了一种新颖的基于级联型多电平拓扑结构的开关型功率放大器,采用单极倍频相移PWM技术,其开关频率为单个单元开关频率的2N倍,总的输出电压波纹小。分析了级联型多电平技术的特点,重点研究了采用单极倍频相移PWM技术的多电平输出信号的谐波,最后研制了一台级联型多电平的D类功率放大器。研究结果证明了所研究的级联型多电平D类功率放大器输出电压谐波的正确性,表明该放大器具有良好的跟踪性和稳定性。 展开更多
关键词 D类功率放大器 多电平控制 相移PWM控制
在线阅读 下载PDF
“后撤并时代”寄宿制学校对农村留守儿童关爱与教育的挑战与可能——基于江西、四川两省的调研 被引量:27
18
作者 王学男 吴霓 《晓庄学院教育科学学报》 CSSCI 北大核心 2019年第1期53-60,共8页
办好农村寄宿制学校成为解决农村留守儿童关爱与教育问题的一条有力途径。经过对江西、四川两省的调研发现,在"后撤并时代"农村寄宿制学校建设取得了显著成效:一是依托乡村学校少年宫空间与课程资源,实现了农村留守儿童"... 办好农村寄宿制学校成为解决农村留守儿童关爱与教育问题的一条有力途径。经过对江西、四川两省的调研发现,在"后撤并时代"农村寄宿制学校建设取得了显著成效:一是依托乡村学校少年宫空间与课程资源,实现了农村留守儿童"选课走班";二是实现了从"基本温饱"到"心理健康"的教育观念的逐步转变;三是精准识别农村留守儿童,实施了分类分级教育与管理。但目前仍处于区域分布、供需关系不平衡和发展不充分的阶段。寄宿条件、经费、人员、编制、时间要素的有限,家庭与学校主体责任不清,共同造成农村寄宿制学校"寄而难育",无法满足家庭对寄宿的多样化需求,难以充分发挥学校的教育功能。因此,建议通过法治建设与村规民约融合、寄宿制学校标准建设和政策试点、鼓励社会托管机构合理合规进入,构建家校社联动、"寄托"并重的农村留守儿童关爱教育体系。 展开更多
关键词 后撤并时代 寄宿制学校 农村留守儿童 选课走班 托管机构 少年宫
在线阅读 下载PDF
区别词功能游移的原因 被引量:16
19
作者 齐沪扬 张素玲 《汉语学习》 CSSCI 北大核心 2008年第4期3-10,共8页
本文主要从词类地位、构词成分、语义、语用等角度探讨区别词功能游移的原因。从词类地位的角度看,区别词是名词、形容词、动词连续统的一个"中间站",由于名词、形容词、动词的空间性、程度性、时间性的消长(即弱化或突显)造... 本文主要从词类地位、构词成分、语义、语用等角度探讨区别词功能游移的原因。从词类地位的角度看,区别词是名词、形容词、动词连续统的一个"中间站",由于名词、形容词、动词的空间性、程度性、时间性的消长(即弱化或突显)造成了区别词与名词、形容词、动词间的功能游移。从构词成分的角度看,区别词构词成分的语法性质尤其是最后一个语素的语法性质在区别词功能游移时起到了一定的制约作用。从语义特征的角度看,区别词与名词、动词、形容词之间的游移,除了受其来源和构词成分的制约外,区别词本身所包含的语义也起着非常重要的作用。从语用机制的角度看,会话双方都在有意无意地遵循着会话的"经济原则"和"合作原则",从而使得一部分区别词逐渐吸收了所修饰的中心语的意思而发生了功能上的游移。 展开更多
关键词 区别词 功能游移 词类地位 词素
原文传递
采用双环控制的多电平D类功率放大器 被引量:5
20
作者 张缨 李耀华 胜小松 《电工技术学报》 EI CSCD 北大核心 2005年第11期80-83,87,共5页
介绍了一种新颖的基于级联型多电平拓扑结构的开关式功率放大器,采用相移PWM技术,其开关频率是单个单元开关频率的2N倍,通过电压电流双闭环控制保证输出信号的跟随品质,本文着重研究了双闭环控制的设计方法。试验结果表明,采用电流电压... 介绍了一种新颖的基于级联型多电平拓扑结构的开关式功率放大器,采用相移PWM技术,其开关频率是单个单元开关频率的2N倍,通过电压电流双闭环控制保证输出信号的跟随品质,本文着重研究了双闭环控制的设计方法。试验结果表明,采用电流电压双闭环控制的D类功率放大器,系统带宽较宽,具有较好的瞬时响应和输出品质。 展开更多
关键词 D类功率放大器 多电平控制 相移PWM控制 双闭环控制
在线阅读 下载PDF
上一页 1 2 5 下一页 到第
使用帮助 返回顶部