共查询到20条相似文献，搜索用时 109 毫秒
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设函数迭代系统S（x）={S1（x）,S2（x）}的吸引子为F其中S1（x）=1/3x,S2（x）=1/3x＋1/3。所诱导的μ不变测度称为类cantor测度,记s=log2／log3,用θ°s（μ,x）表示S维上密度．本文给出了对 x∈F,θ^＊s（μ,x）的明确公式。 相似文献
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我们证明了如果f∈Lp^1（R）,f’（x）=O（（1＋｜x｜）^-1/p-δ）,δ〉0且f’在R上任何有限区间上Riemann可积,则‖f—Hσ（f）‖p（R）≤Cpσωb^-1-[f＇,1/σ]。其中Hσ（f）是f通过由其样本{f（kπ/σ）}k∈Z和｜f＇（kπ/σ｜k∈Z在Lp（R）中的指数2σ型整函数空间B2σ,p中的Hermite型的插值算子,ωk^-（f,t）t=sup｜b｜≤T‖△b^kf（x）‖p（R）为函数f的k阶光滑模。 相似文献
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采用硫熔法制备了系列Y2O2S：Eu^3＋x（0.02≤x≤0.10）红色蓄光材料基质。X射线衍射（XRD）结果表明：所制样品均属六方晶系;由于Eu^3＋离子半径比Y^3＋离子半径略大,故其晶胞参数a和c随着Eu^3＋摩尔浓度的增大而逐渐增大。在340nm激发下,随着Eu^3＋摩尔浓度的增大,I626/I539逐渐增大,而I626/I596基本保持不变。这主要是由于Eu^3＋的5D2和5D1等高激发态能级之间发生浓度淬灭引起的。 相似文献
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我们已经知道（e^x）^（n）=e^x，并且通过直接求导计算还可以归纳（e^x）^（n）=（x＋n）e^x，（x^2e^x）=[x^2＋2nx＋n（n-1）]e^x，等等，那么对于一般形式x^ke^x（k=0，1，2…1的n阶导数能否找到一个一般性公式呢？下面就给这个问题的一个肯定的回答，并举例说明它的应用。 相似文献
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本文在[1]-[4]的基础上对中值定理“中间点”的渐近性在二维空间泰勒公式及矢量函数中值定理中作进一步的推广，证明了由二元函数泰勒公式决定的θ，有limh,k→0=1/（n＋1），特别地当n=0时，limh,k→^θ=1/2，同时，在矢量函数中值定理中也有类似的结果，最后讨论及证明了由二元函数泰勒中值定理中值点的几何意义。本结果在数值取样中具有一定的应用。 相似文献
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本文将黎曼函数f（s）=∞↑∑↑n=1 1/n^s表示为无穷积分的形式，从而得到f（s）的一个上界；利用贝努利数求出f（2k）的值，k∈N^＋；给出f（s）的近似值的两种求法。 相似文献
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本文是证明排列组合的一个证明Cn2n-Cn＋12n=Cn2n/n＋1。作者把数列的排序抽象成表格中的上下问题,再把上下赋值为-1和1,建立坐标系,将数字0,1,2,……,2n作横坐标,对应数字前的所有箭头上数字之和为纵坐标,从而将升降抽象成坐标中的折线,最终证明Cn2n-Cn＋12n=Cn2n/n＋1。 相似文献
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本文给出公式：1＋1/2＋…＋1/n=1nn＋c＋εn的证明。然后通过实例证明了公式在处理数列、极限、级数、积分等的问题中能起的作用。 相似文献
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葱属粗根组5种材料的核型研究 总被引：1，自引：0，他引：1
本文分析了葱属Allium粗根组Sect．Bromatorrhiza Ekberg五群材料的核型。多星韭Allium
wallichii Kunth有两个类型：第一类型是二倍体，染色体组公式为AA，核型公式为K(2n)=2X=
14=2m(SAT)+2m+10sm，属2A型；第二类型是同源四倍体，染色体组公式为AAAA, 核型公
式为K(2n)＝4X＝28＝2m(SAT)+6m十20sm,属2A型。宽叶韭Allium hookeri Thwaites有
三个类型： 第一类型是双基数同源异源三倍体，染色体组公式为AAB1,核型公式为 K(2n)＝2X+
x'＝22＝(12sm+2t)十(1m十45m+1st+2t)， 属3A型； 第二类型也是双基数同源异源三倍
体，能配对的两个染色体组染色体大小和形态与第一类型大体相似，不能配对的一个染色体组染色体
大小和形态与第一类型有明显区别，其中至少有两条染色体发生了罗伯逊易位，出现一条很大的染色体
和一条很小的染色体，染色体组公式为AAB2，核型公式为K(2n)=2x+x'＝22=(12sm+2t)+
(3m+1sm十2st+2t)，属3A型；第三类型相当于第一类型染色体的自然加倍，是双基数同源异源
六倍体，染色体组公式为AAAAB1B1，核型公式为K(2n)=4X十2x'＝44＝(24sm+4t)十(2m+
8sm十2st+4t)，属3A型。 相似文献
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介绍了适用于环上椭圆曲线的加法公式,完善了局部环Z/pnZ上椭圆曲线密码学的基础理论,构造了环Z/pnZ上的基于角色的椭圆曲线密码系统.根据环Z/pnZ的结构特点,简化了其上椭圆曲线的加法完备系统,从而大大提高了环Z/pnZ上的椭圆曲线计算点加的效率;另外,给出了E(Z/pnZ)上密码群生成元的选取方法;证明Z/pnZ上的密码体系与有限域Fp的椭圆曲线密码体系有相同的安全程度;最后在环Z/pnZ上给出一个基于角色的椭圆曲线密码方案. 相似文献
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电动云台是安装、固定摄像机的支撑设备,用来扩大摄像机的监视范围.传统电动云台大多效率低,体积大.本文针对上述问题,利用谐波齿轮传动,设计了电动云台.并利用虚拟仿真技术,通过CAXA实体软件,对电动云台进行了三维实体建模,最后实现了电动云台的动画模拟. 相似文献
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对中国31个省级行政区2006—2011年工程勘察设计行业投入产出面板数据,采用随机前沿分析方法测定各地区的行业生产效率及其变化,并对影响行业非技术效率的因素进行定量计算和回归分析。结果表明:产出函数的技术非效率项对产出具有显著的影响,市场化程度、执业注册人数占比和规模经济同技术非效率项之间存在负向关联,而科研投入和中高级职称人数占比则对技术非效率项具有正向影响;该行业劳动力投入产出弹性(0.672 1)远大于资本投入的产出弹性(0.440 3)。 相似文献
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Shalini Gupta Minni Verma Kamaljit Singh 《Indian journal of clinical biochemistry : IJCB》2012,27(2):127-133
Estimation of low density lipoprotein cholesterol (LDL-C) is crucial in management of coronary artery disease patients. Though a number of homogenous assays are available for estimation of LDL-C, use of calculated LDL-C by Friedewald’s formula (FF) is common in Indian laboratories for logistic reasons. Recently Anandaraja and colleagues have derived a new formula for calculating LDL-C. This formula needs to be evaluated before it is extensively applied in diagnosis. We measured LDL-C by homogenous method (D-LDL-C) in 515 fasting samples. Friedewald’s and Anandaraja’s formulas were used for calculation of LDL-C (F-LDL-C and A-LDL-C, respectively). The mean LDL-C levels were 123.3 ± 53.2, 112.4 ± 50.2 and 109.2 ± 49.8 mg/dl for D-LDL-C, F-LDL-C and A-LDL-C, respectively. There was a statistically significant difference between the results (P > 0.001) obtained by calculation formulas compared to the measured LDL-C. There was underestimation of LDL-C by 10.8 and 14 mg/dl by Friedewald’s and Anandaraja’s formulas respectively. The Pearson’s correlation between F-LDL-C and D-LDL-C was 0.931 and that between A-LDL-C and D-LDL-C was 0.930. Bland–Altman graphs showed a definite agreement between mean and differences of the calculation formulas and direct LDL-C with 95% of values lying with in ±2 SD limits. The mean percentage difference (calculated as {(Calculated LDL-C)-(D-LDL-C)}/D-LDL-C × 100) for F-LDL-C was maximum (−11.6%) at HDL-C ≥ 60 mg/dl and TG levels of 200–300 mg/dl (−10.4%) compared to D-LDL-C. A-LDL-C results gave highest mean percentage difference at total cholesterol concentrations <100 mg/dl (−37.3%) and HDL-C < 40 mg/dl (−17.1%), respectively. The results of our study showed that FF is better in agreement with D-LDL-C than Anandaraja’s formula for estimation of LDL-C by calculation though both lead to its underestimation. 相似文献
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T. A. Ajith 《Indian journal of clinical biochemistry : IJCB》2010,25(1):67-73
Iron is an essential nutrient for a number of cellular activities. However, excess cellular iron can be toxic by producing
reactive oxygen species (ROS) such as superoxide anion (O2−) and hydroxyl radical (HO·) that damage proteins, lipids and DNA. Mutagenic and genotoxic end products of lipid peroxidation can induce the decline
of mitochondrial respiration and are associated with various human ailments including aging, neurodegenerative disorders,
cancer etc. Zingiber officinale Roscoe (ginger) is a widely used spice around the world. The protective effect of aqueous
ethanol extract of Z. officinale against ROS-induced in vitro lipid peroxidation and DNA damage was evaluated in this study.
The lipid peroxidation was induced by hydroxyl radical generated from Fenton’s reaction in rat liver and brain homogenates
and mitochondrial fraction (isolated from rat liver). The DNA protection was evaluated using H2O2-induced changes in pBR-322 plasmid and Fenton reaction-induced DNA fragmentation in rat liver. The results indicated that
Z. officinale significantly (P<0.001) protected the lipid peroxidation in all the tissue homogenate/mitochondria. The extract
at 2 and 0.5 mg/ml could protect 92 % of the lipid peroxidation in brain homogenate and liver mitochondria respectively. The
percent inhibition of lipid peroxidation at 1mg/ml of Z. officinale in the liver homogenate was 94 %. However, the extract
could partially alleviate the DNA damage. The protective mechanism can be correlated to the radical scavenging property of
Z. officinale. The results of the study suggest the possible nutraceutical role of Z. officinale against the oxidative stress
induced human ailments. 相似文献
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资源富集贫困地区经济发展与生态环境协调互动作用初探——以陕西省榆林市为例 总被引：9，自引：2，他引：7
榆林市是我国最重要的能源化工基地之一,资源富集、经济贫困和生态脆弱三大特性叠加,是典型的资源富集贫困地区。对1990年～2004年榆林市人均GDP与工业三废之间关系进行分析,发现榆林工业废水排放量、工业废气排放量和工业固体废物产生量与人均GDP之间都存在较强的库兹涅茨（EKC）特性。建立环境综合污染水平指标,在对数据进行标准化处理和层次分析的基础上,得出榆林市经济发展和综合环境污染水平的EKC曲线。该曲线具有与西部地区、欠发达地区以及其他资源型城市相似的特点,在现有经济发展模式下,EKC曲线短时间内都还没有出现转折点的可能。新兴资源型城市和西部生态脆弱贫困区两大特点决定了榆林经济发展与生态环境相互作用的复杂性。在分析经济发展和生态环境互动作用一般机制基础上,提出了相关对策建议。 相似文献
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中国绞股蓝属(葫芦科)的研究 总被引：2，自引：0，他引：2
The genus Gynostemma B1. consists of 13 species and 2 varieties in the whole world,
among which 11 species and 2 varieties occur in China. They are distributed in S. Shaanxi
and the southern part of the Yangtze River (including Taiwan province) in China and also
in Korea, Japan, Sri Lanka, India and Malesia. Based on the characters and dehiscence of fruit, the genus Gynostemma B1. may be divided into two subgenera, i.e. Subgen. I. Gynostemma and Subgen. II. Trirostllum (Z. P. Wang et Q. Z. Xie) C. Y. Wu ct S. K. Chen,
comb. nov.
1. Subgenus Gynostemma. The fruits are baccate, globose, 3-umbonate and incorni
culate on the apical side, indehiscent when mature. The style apex in female flower is bifid.
Type of subgenus: Gynostemma pentaphyllum (Thunb.) Mak.
This subgenus contains 8 species and 2 varieties in the world, among which 6 speci-
es and 2 varieties occur in China, i.e.1.G. simplicifolium B1. (Yunnan, Hainan of Guang-
dong); 2. G. laxum (Wall.) Cogn. (S. Yunnan, Hainan of Guangdong and Guangxi); 3.
G. burmanicum King ex Chakr. (Yunnan), 3a. G. burmanicum var. molle C. Y. Wu (Yun-
nan); 4. G. pentaphyllum (Thunb.) Mak. (S. Shaanxi and the soutern area of the Yangtze
River of China), 4a. G. pentaphyllum (Thunb.) Mak. var. dasycarpum C. V. Wu (Yun-
nan); 5. G. pubescens (Gagnep.) C. Y. Wu, st. nov. (Yunnan); 6. G. longipes C. Y. Wu,
sp. nov. (endemic to China: Yunnan, Sichuan, Guizhou, Shaanxi and Guangxi).
2. Subgenus Trirostellum (Z. P. Wang et Q. Z. Xie) C. Y. Wu et S. K. Chen, comb.
nov.——Trirostellum Z. P. Wang et Q. Z. Xie in Acta Phytotaxonomia Sinica 19 (4):
483. 1981, syn. nov. The fruit are capsules, subcampanulate, 3-corniculate on the apical side, dehiscent when mature. The style apex in female flower is luniform and irregularly denticulate at margin, rarely bifid.
Type of subgenus: Gynostemma cardiospermum Cogn. ex Oliv. This subgenus comprises 5 species, which are all endemic to China. 1. G. yixingense (Z. P. Wang et Q. Z. Xie) C. Y. Wu et S. K. Chen (Jiangsu and Zhejiang); 2. G. cardio spermum Cogn. ex Oliv. (Hubei, Shaanxi and Sichuan); 3. G. microspermum C. Y. Wu et S. K. Chen (S. Yunnan); 4. G. aggregatum C. Y. Wu et S. K. Chen (NW. Yunnan); 5. G.laxiflorum C. Y. Wu et S. K. Chen (Anhui). 相似文献
20.
Dimov N Muñoz L Carot-Sans G Verhoeven ML Bula WP Kocer G Guerrero A Gardeniers HJ 《Biomicrofluidics》2011,5(3):34102-3410212
To prepare a biosynthetic module in an infochemical communication project, we designed a silicon/glass microreactor with anti-adsorption polyelectrolyte multilayer coating and immobilized alcohol acetyl transferase (atf), one of the key biosynthetic enzymes of the pheromone of Spodoptera littoralis, on agarose beads inside. The system reproduces the last step of the biosynthesis in which the precursor diene alcohol (Z,E)-9,11-tetradecadienol is transformed into the major component (Z,E)-9,11-tetradecadienyl acetate. The scope of this study was to analyze and implement a multilayer, anti-adsorption coating based on layer-by-layer deposition of polyethylenimine/dextransulfate sodium salt (PEI/DSS). The multilayers were composed of two PEI with molecular weights 750 and 1.2 kDa at pH 9.2 or 6.0. Growth, morphology, and stability of the layers were analyzed by ellipsometry and atomic force microscopy (AFM). The anti-adsorption functionality of the multilayer inside the microreactor was validated. The activity of His(6)-(atf) was measured by gas chromatography coupled to mass spectrometer (GC-MS). 相似文献