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求助,英文文献翻译~

妖精吾 2011-05-16 04:20:15 440  浏览
  • PMMA has good compatibility with PVC due to specific interaction of a hydrogen bonding type between carbonyl groups (C=O) of PMMA and hydrogen from (CHCl) groups of PVC (Belhaneche-Bensemra et al., 2002; Ramesh et al., 2002). Zhou et al... PMMA has good compatibility with PVC due to specific interaction of a hydrogen bonding type between carbonyl groups (C=O) of PMMA and hydrogen from (CHCl) groups of PVC (Belhaneche-Bensemra et al., 2002; Ramesh et al., 2002). Zhou et al. (2001) studied the relationship between the coating thickness of PMMA on the surface of talc and mechanical properties of PMMA-g-talc/PVC composites, and found that there existed a critical thickness. Xie (2001) found that the PMMA coating on talc improved the dispersion of talc in the PVC matrix and enhanced the interfacial adhesion between talc and PVC. There appears to be a critical coating thickness of PMMA on the talc surface for optimum toughening. Quan et al. (2002) reported improved toughness and intension of the PVC composites filled with CaCO3/ACR core-shell complex particles prepared by in-situ emulsion polymerization of acrylic ester. In the present work, PMMA coated on the surface of CaCO3 nanoparticles by in-situ emulsion polymerization was characterized by FT-IR and 1H-NMR. The effects of PMMA thickness and particle fraction on the mechanical properties of PMMA-coated CaCO3 /PVC nanocomposites were also investigated. 展开

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  • sunnyyaokongqi 2011-05-24 00:00:00
    二楼翻译机连回车都懒得去么囧

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  • ttnn123456 2011-05-24 00:00:00
    PMMA具有良好的兼容性与PVC由于特定 羰基之间的相互作用氢键类型 组(C = O等)的聚甲基丙烯酸甲酯和氢()组 聚氯乙烯(Belhaneche - Bensemra等,2002;。。拉梅什等人, 2002年)。周等人。 (2001年)之间的关系研究 对滑石粉和表面涂层厚度的PMMA 复合材料力学性能的PMMA-g-talc/PVC, 发现存在一个临界厚度。谢(2001) 发现对滑石涂层改善了分散聚甲基丙烯酸甲酯 滑石粉在PVC基体,提高了界面 滑石粉和PVC之间的粘附。似乎有一 PMMA的关键涂层厚度对滑石粉表面 Z佳增韧。泉等。 (2002年)报告改善 充满韧性和强度的PVC复合材料 CaCO3/ACR核壳复合粒子的制备 原位聚合丙烯酸酯乳液。 在目前的工作,聚甲基丙烯酸甲酯的表面涂覆 原位乳液聚合纳米碳酸钙 利用FT - IR和核磁共振。的影响 有机玻璃厚度和粒子分数对力学 性能的聚甲基丙烯酸甲酯包覆碳酸钙/聚氯乙烯纳米复合材料 进行了研究。

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  • wo007yili 2011-05-17 00:00:00
    由于PMMA(聚甲基丙烯酸甲酯)的羰基与PVC(聚氯乙烯)中CHCl基团上的H可以形成氢键这种特殊的交互作用,因此,聚甲基丙烯酸甲酯与聚氯乙烯有很好的兼容性(Belhaneche-Bensemra等人,2002;Ramesh等人,2002)。周等人(2001)研究了在云母表面上PMMA的涂膜厚度与PMMA-g-talc/PVC这种复合材料的机械性能之间的关系,并且发现存在一个临界厚度。谢(2001)发现在云母上的PMMA膜,可以提升在PVC基质中云母的分散性,并且提高了云母与PVC之间的界面吸附。在云母表面,似乎存在一个临界PMMA膜厚度,使得材料有Z佳的增韧效果。Quan等人(2002)记录了用丙烯酸酯原位乳液聚合作用制备的CaCO3/ACR核壳复合颗粒填充而改良了韧性和强度的PVC复合材料。Z近研究工作中,把由原位乳液聚合作用得到的CaCO3纳米颗粒表面的PMMA膜用傅里叶变换红外光谱和核磁共振仪图谱进行了表征。同时,也研究了PMMA厚度和颗粒多少对PMMA-膜 CaCO3 /PVC纳米复合材料机械性能的影响。 "talc"我翻译为“云母”,不知对吗?

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求助,英文文献翻译~
PMMA has good compatibility with PVC due to specific interaction of a hydrogen bonding type between carbonyl groups (C=O) of PMMA and hydrogen from (CHCl) groups of PVC (Belhaneche-Bensemra et al., 2002; Ramesh et al., 2002). Zhou et al... PMMA has good compatibility with PVC due to specific interaction of a hydrogen bonding type between carbonyl groups (C=O) of PMMA and hydrogen from (CHCl) groups of PVC (Belhaneche-Bensemra et al., 2002; Ramesh et al., 2002). Zhou et al. (2001) studied the relationship between the coating thickness of PMMA on the surface of talc and mechanical properties of PMMA-g-talc/PVC composites, and found that there existed a critical thickness. Xie (2001) found that the PMMA coating on talc improved the dispersion of talc in the PVC matrix and enhanced the interfacial adhesion between talc and PVC. There appears to be a critical coating thickness of PMMA on the talc surface for optimum toughening. Quan et al. (2002) reported improved toughness and intension of the PVC composites filled with CaCO3/ACR core-shell complex particles prepared by in-situ emulsion polymerization of acrylic ester. In the present work, PMMA coated on the surface of CaCO3 nanoparticles by in-situ emulsion polymerization was characterized by FT-IR and 1H-NMR. The effects of PMMA thickness and particle fraction on the mechanical properties of PMMA-coated CaCO3 /PVC nanocomposites were also investigated. 展开
2011-05-16 04:20:15 440 4
求助,英文文献翻译!
2. Experimental 2.1 Materials Nano-CaCO3 particles (D50: 30−70 nm by TEM (Fig. 1) and BET: ca.17m2·g-1) were supplied by Shanghai Zhuoyue Nanotech Corporation. Methyl methacrylate (MMA, Shanghai Lingfeng Chemicals) was purified ... 2. Experimental 2.1 Materials Nano-CaCO3 particles (D50: 30−70 nm by TEM (Fig. 1) and BET: ca.17m2·g-1) were supplied by Shanghai Zhuoyue Nanotech Corporation. Methyl methacrylate (MMA, Shanghai Lingfeng Chemicals) was purified by distillation under reduced pressure; potassium persulphate (K2S2O8, initiator, Shanghai Lingfeng Chemicals) was of chemical grade. Silane coupling agent A174 (γ-methacryloxypropyltrimethoxysilane) was purchased from Shanghai Yaohua Factory. Polyvinylchloride (PVC, WS-1000S) was supplied by Shanghai Chlor-Alkali Chemical Co., Ltd. Fig. 1 Morphology of untreated CaCO3 nanoparticles. Fig. 2 Morphology of PMMA-coated CaCO3 nanoparticles. 2.2 PMMA emulsion polymerization on CaCO3 nanoparticles 2.2.1 Surface silanation of nano-CaCO3 particles The nano-CaCO3 particles were homogeneously dispersed in ethanol (solid content 20%) by a sonication dispersion equipment. The slurry was then heated to 80°C with stirring, and the silane coupling agent A174 (5%, calculated based on the weight of nano-CaCO3 particles) was added into the slurry. After the slurry was stirred for 120 min at 80°C, it was filtered and the filter cake was then dried at 120°C in low vacuum for 120 min to obtain silanated CaCO3 powders. 展开
2011-05-16 00:26:36 386 4
求翻译英文文献
2.2. Material Characterizations. A field emission scanning electron microscope (SEM, JEOL 6701F) was used to investigate the morphologies, particle sizes of the samples. Transmission electron microscopy and elemental compositions of the ... 2.2. Material Characterizations. A field emission scanning electron microscope (SEM, JEOL 6701F) was used to investigate the morphologies, particle sizes of the samples. Transmission electron microscopy and elemental compositions of the samples were determined by JEM-2100F (JEOL) coupled with an energy-dispersive X-ray spectroscopy (EDX, Phoenix) system. Wide-angle and low-angle X-ray powder diffraction (XRD) of the as-obtained samples were recorded on a Rigaku D/max-2500 with Cu Kα radiation (λ = 1.540 56 Å) operated at 40 kV and 200 mA. Raman measurements were performed using a DXR from Thermo Scientific with a laser wavelength of 532 nm. To calculate the pore size distribution and pore volumes, the nitrogen absorption and desorption isotherms were measured at 77.3 K with an Autosorb-1 specific surface area analyzer from Quantachrome. The content of N in N-doped porous carbon was determined by NHC elemental analysis using Flash EA 1112. Thermogravimetric (TG) analysis of S/C composite was performed on TG/DTA 6300 in an N2 flow to obtain the S content in the composite. A four-contact method was applied to measure the powder electronic conductivity of porous carbons. The powder sample was pressed to disk at 4 MPa with two stainless-steel plungers, whose resistance was measured by a Keithley 2400 digital multimeter in fourwire mode. The conductivity of the sample was calculated according to the resistance and the size of the disk. Information of the surface elements was obtained by X-ray photoelectron spectroscopy (XPS) performed on the Thermo Scientific ESCALab 250Xi using 200 W monochromatic Al Kα radiation. The 500 μm X-ray spot was used for XPS analysis. The base pressure in the analysis chamber was about 3 × 10−10 mbar. All reported data of XPS binding energy are calibrated based on the hydrocarbon C 1s line at 284.8 eV from adventitious carbon. Spectra were fitted with Lorentzian−Gaussian functions and smart background using Thermo Avantage software. 展开
2014-12-28 15:14:51 493 1
纳米材料英文文献加翻译
 
2013-06-26 12:47:02 387 1
通信方面的英文文献翻译!!
以下是文献的一部分,愿意帮忙的高手留下邮箱,我把文件发给你,若能完成,加分:SpatialCompressiveSensingApproachForFieldDirectionalityEstimation.I.INTRODUCTIONVarietyoft... 以下是文献的一部分,愿意帮忙的高手留下邮箱,我把文件发给你,若能完成,加分: Spatial Compressive Sensing Approach For Field Directionality Estimation. I. INTRODUCTION Variety of techniques for field directionality estimation were studied in literature [1]-[5]. Thus, a theoretical analysis of the relationship between the hydrophone array output and the noise field was conducted in [1]-[5]. The developed techniques were based on the array beamformer output or the crossspectral matrix between outputs of array elements [4]-[5]. The problem of a field directionality estimation in ocean, using horizontal line towed array was also addressed in literature [5]- [8]. Recently, problems of direction of arrival and field directionality estimation for moving sensors arrays have attracted renewed interest [9]-[12]. It was shown that an array motion can improve an array performance assuming temporal coherence of successive samples [10]-[11]. In [12], the wavefield sampling method that exploits the linear relationship between the noise field and the collection of beamformer outputs over various array orientations was proposed. It was shown that the wavefield sampling (WS) method outperforms other tested methods. This algorithm was implemented via the recursive estimation method and its convergence to the unique solution was promised for a specific set of array orientations and beamformer look directions. However, a method for a proper array orientation and beamformer look direction sequence selection remains an open question. The quality of the field directionality estimation is determined by the angular resolution. The higher angular resolution is, the more accurate estimation of the far field sources, and better detection performance can be achieved. One of fundamental relations in the array signal processing is that the angular resolution is directly proportional to the number of the array elements [13]. This relation motivates the desire for longer arrays that can achieve higher resolution. Unfortunately, the requirement contradicts the implementation and installation limitations that motivate shorter arrays. Moreover, implementation of longer arrays for maneuvering platforms such as unmanned underwater vehicles (UUV) can even be impossible [14]. These contradictions motivate the quest for alternative array signal processing methods. Usually, the field directionality is modeled as a finite set of strong far-field narrow-band sources and an isotropic lowpower noise [1]. In this work, the model of the field directionality is adopted in the following way. First, the bearing angle space is uniformly sampled into a large number of discrete angles. Next, it is assumed that ether the high energy that corresponds to the far-field strong sources or the low-energy that corresponds to the isotropic noise is received at the sensor array from every of these discrete azimuth angles. 展开
2010-01-17 08:59:13 489 5
谁能帮我翻译一下这段英文文献啊
Fig. 1 shows that diamond particles are dispersed in the copper matrix. Since the diamond particles are easy to be stripped off during mechanical polishing, small pits are left on the surface of samples. When the samples were analyzed b... Fig. 1 shows that diamond particles are dispersed in the copper matrix. Since the diamond particles are easy to be stripped off during mechanical polishing, small pits are left on the surface of samples. When the samples were analyzed by electron probe for carbon, the particles displayed high carbon peaks, as shown in Fig. 2. Fig. 3 exhibits the analyzed result for extracted product of the copper–diamond composite by X-ray diffraction (XRD) analysis. It is shown that three dif- fraction peaks exist, shown as A, B and C, respectively. The interplanar distances corresponding to the three peaks and standard ones for diamond are compared in Table 1. The measured values of the interplanar distances are in good agreement with the standard ones, demon- strating that the extracted product should be the carbon in diamond state. Fig. 4(a) gives a TEM micrograph showing distribution and morphology of diamond particles (indicated as A, B, and C) in the copper–diamond composite. The calibration of interplanar distance for diffraction rings in Fig. 4(b) was given in Table 2. Compared to Table 1, it is also demon- strated that the calibrated interplanar distances for the diffraction rings conform to the standard ones of diamond. Therefore, it is believed that the graphitization of diamond particles hardly occurs after sintering at 1150–1220 K in the copper–diamond composite. Although diamond is a metastable allotropic modifica- tion of carbon, the graphitization of diamond particles in the copper–diamond composite did not occur, or the degree of graphitization was too small to be found. It is believed that the beginning temperature of graphi- tization would be associated with the purity of diamond powders. The impurities such as some metallic elements reduce the beginning temperature of diamond graphitiza- tion. When diamond is fabricated by the static synthesis method, Fe and Ni are often used as catalysts and are present in diamond as impurities to decrease the beginning temperature of graphitization [6]. It is understandable that both for the graphitization and its reverse reactions, their activation energies can be decreased by catalytic agents. Compared with the diamond fabricated by static synthesis, the diamond powders prepared by explosion method do not contain metallic impurities, thus leading to an obvious increase in the beginning temperature of graphitization. Hence, the detonation synthetic diamond might be more resistant to graphitization and probably suitable for the electric contact materials. 展开
2011-03-22 08:43:56 358 2
求翻译文献
Anionsarecommonlyfoundintheenvironmentandbiologicalsystems.Forinstance,fluorideiswidelyusedindentalcareapplicationsandexhibitsinhibitionofcertainenzymefunctions.1Inadditi... Anions are commonly found in the environment and biological systems. For instance, fluoride is widely used in dental care applications and exhibits inhibition of certain enzyme functions.1 In addition to playing a central role in biological regulation, chloride is also a major groundwater contaminant that can corrode steel and concrete.2 Thyroid hormone synthesis largely determines iodine content.3 Acetate is a possible tracer for malignancies and has been extensively investigated in prostate cancer and its metastases.4 Phosphate ion is biologically and environmentally significant.5 Cyanide exerts adverse effects on human health as well as environment at low concentrations. Determining anions concentration is thus of primary concern in many areas, including food processing, industry, and clinic analysis.6 However, hydrophilic anions, such as F- and Cl-, form strong hydrogen bonds with protic solvents. Therefore, developing fluorescent probes based on electrostatic interactions for anions functioning in polar protic solvents is both challenging and currently infeasible. 展开
2009-12-15 12:42:12 362 6
文献求翻译
Since the formation of a titanacyclopropane en route to cyclopropylamines can only occur with alkylmagnesium halides that contain a b-hydrogen atom, Grignard reagents without b-hydrogens appeared to be the most promising reagents for th... Since the formation of a titanacyclopropane en route to cyclopropylamines can only occur with alkylmagnesium halides that contain a b-hydrogen atom, Grignard reagents without b-hydrogens appeared to be the most promising reagents for the synthesis of primary tert-alkylamines from nitriles (Scheme 1). Thus propionitrile (1a), phenylmagnesium bromide (2) and Ti(Oi-Pr)4 were chosen to optimize the reaction conditions. In the protocol for the synthesis of cyclopropylamines,10 Ti(Oi-Pr)4 is already present in the diethyl ether solution of a nitrile, before two equivalents of the Grignard reagent are added. As this did not appear to be optimal for the synthesis of primary tertalkylamines, the Grignard reagent was added before Ti(Oi-Pr)4. With 2 equivalents of PhMgBr, 0.1 equivalent of Ti(Oi-Pr)4, and 1 equivalent of propionitrile (1a), the primary tert-alkylamine 8a was not formed at all. With an equimolar quantity of Ti(Oi-Pr)4, the amine 8a was produced in a low yield (11%) but with 1 equivalent of Ti(Oi- Pr)4 and 3 equivalents of the Grignard reagent 2, a 60% yield of 8a was obtained. Monitoring of the reaction by workup of aliquots of the reaction mixture showed that the first addition of 2 to form the N-magnesio derivative of the corresponding imine was rapid, whereas the subsequent second addition of the Grignard reagent 2 required heating under reflux for up to 24 hours. In tetrahydrofuran instead of diethyl ether, the amine 8a was formed in a very low yield, if at all. 展开
2012-08-31 01:19:05 380 5
翻译段文献麻烦
Eventhoughfluorescentprobesforcopperionhavebeenextensivelyexploredowingtobiologicalsignificanceofthismetalion,4therearestillonlyafewexamplesof“off-on”typesensorsavailab... Even though fluorescent probes for copper ion have been extensively explored owing to biological significance of this metal ion,4 there are still only a few examples of “off-on” type sensors available in aqueous systems.5 Furthermore, only a few ratiometric fluorescent probes for Cu2+ have been found in the literature due the fluorescence quenching nature of paramagnetic Cu2+,6 and most of them were working only in pure organic solvents. Ratiometric fluorescent measurements observe changes in the ratio of the intensities of the emission at two wavelengths. Thus, ratiometric fluorescent sensors have an important feature that they can be used to evaluate the analyte concentration and provide built-in correction for environmental effects. On the other hand, rhodamine derivatives are nonfluorescent and colorless, whereas ring-opening of the corresponding spirolactam gives rise to strong fluorescence emission and a pink color. Recently, a spirolactam (nonfluorescent) to ringopened amide (fluorescent) process was utilized for the detection of metal ions.5a,b,d,e,7 We introduced rhodamine fluorophore onto the pyrene moiety, which was utilized as a selective fluorescent and colorimetric sensor for Cu2+ in aqueous solution. Among the various metal ions, the chemosensor PRC displayed highly selective ratiometric changes upon the addition of Cu2+. As expected, the pyrene moiety served successfully as a source of these ratiometric changes. As far as we are aware, PRC is the first ratiometric sensor based on rhodamine derivative. For comparison, pyrene-based compound P4 was synthesized to test the fluorescence change with Cu2+. 展开
2009-12-23 07:28:19 379 6
翻译以下英文:
The standard error of the mean (SEM) is a measure of how far your sample mean is likely to be from the true population mean. The SEM is calculated by this equation:SEM=SD/N. With large samples, the SEM is always small. By itself, the SEM i... The standard error of the mean (SEM) is a measure of how far your sample mean is likely to be from the true population mean. The SEM is calculated by this equation:SEM=SD/N. With large samples, the SEM is always small. By itself, the SEM is difficult to interpret. It is easier to interpret the 95% confidence interval, which is calculated from the SEM. 展开
2007-11-15 02:56:39 467 3
求助翻译
问题一:请问“在GF254硅胶板上,取样点板,在254nm紫外光下观察结果”这句话该如何翻译?ZD是不知道“取样点板”怎么翻译问题二:麻烦高手帮忙翻译一下2Results2.1柱色谱分离结果The... 问题一: 请问 “在GF254硅胶板上,取样点板,在254 nm紫外光下观察结果” 这句话该如何翻译? ZD是不知道“取样点板”怎么翻译 问题二:麻烦高手帮忙翻译一下 2 Results 2. 1 柱色谱分离结果 The results of separation by column chromatography 柱色谱分离过程中,氯仿∶甲醇95∶5和90∶10洗脱出来的流分经过反复的硅胶柱色谱分离纯化得到组分C3。 2. 2 薄层色谱检测结果 The results of Thin-layer chromatography. 组分C3在GF254硅胶板上展开后,可在254nm紫外灯下直观观测为单点,见图1。 2. 3 GX液相色谱分析和制备单体化合物 对组分C3 进行GX液相制备,色谱图显示有4个色谱峰(见图2) ,分离效果较好,收集4个单峰组分,得到4个化合物1~4,对以上4个化合物进行GX液相分析,均为单峰,见图3~4。 3 化合物的结构鉴定 通过制备液相收集得到4个化合物,对其中3个化合物进行结构鉴定: 化合物1, 淡黄色晶体, UV λmax nm (logε) : 248 nm。E IMS,m / z 501. 3 [M + 1 ] + ,分子量为500。化合物1氢谱显示7个甲基信号;δ1. 02, 0. 93, 0. 78 ( each 3H, s) , 0. 89 ( 3H, d, J =6. 4Hz) , 1. 23, 1. 25 ( each 3H, d, J = 5. 2Hz) , 1. 22(3H, s) ,一个连氧碳上的氢信号δ3. 23 (1H, dd, J= 10 Hz) ,符合三萜化合物的结构,可以证明化 合物1为三萜类化合物。 化合物2, UV λmax nm ( logε) : 250 nm。E IMS,m / z 515. 3 [M + 1 ] + ,分子量为514。化合物2的氢谱显示7个甲基信号δ0. 77, 0. 94, 1.01, 1. 22, 1. 23 (3H, s) , 0. 82 (3H, d, 10. 2 Hz) ,一个连氧碳上的氢信号δ3. 22 ( 1H, dd, J = 10. 5Hz) ,一个甲氧基上的氢信号δ3. 66 (3H, s) ,符合三萜化合物的结构,可以证明化合物2为三萜化合物。 化合物3, UV λmax nm ( logε) : 254 nm。EIMS,m / z 531. 2 [M + 1 ] + ,分子量为514。化合物2 的氢谱(见附录)显示7 个甲基信号δ0.78, 0. 82, 0. 87, 1. 03, 1. 24, 1. 31 ( 3H, s) , 1. 17(3H, d, 6. 6 Hz) ,一个乙酰基上的氢信号2. 10(3H, s) ,一个甲氧基团的氢信号3. 68 (3H, s) ,符合三萜化合物的结构,可以证明化合物3为三萜化合物。 化合物4结构较复杂,不能确定是三萜化合物。 二楼的辛苦了,非常感谢你的回答。不过好像没有明白我的意思,而且有google之嫌。 展开
2009-05-07 18:35:24 685 4
环境英语文献翻译 急用
Thereisagrowinginterestindeterminingmercury(Hg)levelsinthemarineenvironmentaswellasinfishforhumanconsumption.Methylmercury(MeHg)inparticularisthemosttoxicandbioaccumulati... There is a growing interest in determining mercury(Hg) levels in the marine environment as well as in fish for human consumption. Methyl mercury(Me Hg)in particular is the most toxic and bioaccumulative form of mercury in food webs and it is the predominant chemical form making up 80%-90% of the total mercury present in fish muscle tissue.Hence,fish and other organisms at the end of the food chain constitute the major source of MeHg in the human . As outcome of this risk,MeHg has been classically monitored in fish, and methodologies for mercury speciaion have increased significantly since the early 1990s. Currently, microwave-assisted extraction (MAE) has provided an efficient alternative strategy to conventional techniques for solvent extraction of a large amount of organometals compounds.The analytical techniques most frequently applied for Hg speciation analysis involve GC(GasChromatography) , GC-CICP-MS(Gas Chromatography -CInductively Coupled Plasma Mass Spectrometry) supercritical fluids chromatography (SFC),ion chromatograph(IC), HPLC-CCVAAS(High Performance Liqui Chromatography-Cold Vapor Atomic Absorption Spectrometry) or ICP-MS systems .Several authors recommended a back-extraction of mercury species from organic solvents to cysteine or sodium thiosulphate aqueous solutions .Because MeHg is the most common organomercury compound in biological materials ,here we offer a new simple and cost-effective method to determine MeHg. Basically, this method combines the microwave assisted extraction followed by clean-up with cysteine acetate solution and MeHg quantification by a direct mercury analyzer (DMA). 展开
2009-05-18 11:22:05 308 2
求达人 翻译下英文文献 关于 光系统Ⅱ和除草剂 通顺Z重要
PhotosystemIIisthemulti-enzymaticchlorophyll-proteincomplex(water-plastoquinoneoxido-reductase)locatedinthethylakoidmembraneofalgae,cyanobacteriaandhigherplants.Itisanint... Photosystem II is the multi-enzymatic chlorophyll-protein complex (water-plastoquinone oxido-reductase) located in the thylakoid membrane of algae, cyanobacteria and higher plants. It is an integral part of the electron transport chain that catalyses primary charge separation. This protein complex consists of over 25 polypeptides, which make up a light-harvesting chlorophyll protein complex (LHCII), a reaction centre and the water-splitting system, also called the oxygen evolving complex (OEC). The PSII complex also contains the target site of the most widely used photosynthetic herbicides."^ The preparation of a biosensor for the detection of polluting compounds is based on the specific characteristics of PSII. Under illumination PSII drives electron transfer which is inhibited by specific chemical compounds (e.g., herbicides). Thus, the photosynthetic membrane isolated firom higher plants and photosynthetic micro-organisms, immobilised and stabilised, will serve as the biosensor biomediator. The effect of compounds that alter or inhibit photosynthetic activity, measured as oxygen evolution, electron transport or fluorescence can then be translated and monitored by amperometric or optical systems. Recent experiments that were performed by our this team resulted in amperometric, potentiometric, optical biosensors for herbicides based on isolated and immobilised PSII particles exhibiting stable biological material and a highly sensitive monitoring response (limit of detection in the nanomolar range and for diuron herbicide in the picomolar range).^'^ However, the system is specific to photosynthetic herbicides but not very selective since several classes of compounds (herbicides represented by triazines, ureas, diazines, phenols) can bind to proteins of the PSII complex, most of them to the Dl protein of the reaction centre. 展开
2010-04-30 16:23:35 350 1
帮忙翻译一段关于方酸染料合成的的英文文献 急急急
Synthesisofsquarainedyeswasreportedatleastin1966。Theyarederivedfromsquaricacidwhichundergoesanelectrophilicaromaticsubstitutionreactionwithananilineoranotherelectronrich... Synthesis of squaraine dyes was reported at least in 1966 。They are derived from squaric acid which undergoes an electrophilic aromatic substitution reaction with an aniline or another electron rich derivative to form a highly conjugated product with extensive charge distribution. For instance, squaraine dyes are also formed via reaction of squaric acid or its derivatives with so-called "methylene bases" like 2-methyl-indolenines, 2-metyl-benzthiazoles or 2-methyl-benzo-selenazoles. Indolenine-based squaraines combine good photostability including high quantum yields when bound to proteins and reactive versions of these dyes are commonly used as fluorescent probes and labels for biomedical applications . 展开
2011-05-20 09:09:32 270 2
化工类英文科技文献译中文
There is a fair body of literature concerning the electroreduction of glucose. This has been reviewed by Fedoronko. He divided his review into the polarographic work and that done on solid electrodes. The polarographic studies form a cohere... There is a fair body of literature concerning the electroreduction of glucose. This has been reviewed by Fedoronko. He divided his review into the polarographic work and that done on solid electrodes. The polarographic studies form a coherent picture, in which the experimentally observed data, which take the form of a plateau, not diffusion controlled, are explained in terms of a rate-determining step of mutarotation from the cyclic (inactive) form of the sugar to the linear (electroactive) form. The process is known to be both acid and base catalyzed, and has been reviewed by Capon. It is generally assumed that no hydrogen evolution takes place in the polaro- graphic plateau region. 翻译通顺有加分!谢谢大家!不需要机器翻译的! 展开
2009-03-05 08:04:04 287 6
波谱英文文献在哪里下载?
 
2010-12-08 02:02:14 366 3
翻译英文~专业类的
Whilegraphene,acarbon-basedtwo-dimensionalnanomaterials,hasreceivedanupsurgeofinterest,[1]self-assemblyofsmallorganicandorganometallicmoleculesinto2Dnanostructurescouldal... While graphene, a carbon-based two-dimensional nanomaterials, has received an upsurge of interest,[1] self-assembly of small organic and organometallic molecules into 2D nanostructures could also be harnessed to develop new classes of functional supramolecular nanomaterials.[2] In principle, quasi-2D lamellae or nanosheets are planar structures having a thickness less than 100 nm and lateral dimensions a few orders of magnitude greater than their thickness. Control over the bilateral intermolecular noncovalent interactions is anticipated to organize small molecules into regular 2D nanostructures, which has been a formidable challenge yet to be achieved. Recently, Shelnutt and co-workers obtained discrete porphyrin nanosheets reprecipitated from their solutions;[3] Sathish and co-workers constructed hexagonal C60 nanosheets using a liquid–liquid interfacial precipitation method;[4] the groups of Yao[5] and Hu[6] prepared singlecrystalline nanosheets of polycyclic aromatics using a surfactant- assisted reprecipitation and a physical vapor transporting method, respectively; and Zhang and co-workers suggested that molecules with intramolecular charge-transfer dipole moments could be grown into quasi-2D nanostructures.[7] Moreover, some amphiphiles and organogelators were found to self-organize into sheet-like nanostructures in contact with solvents.[8] Despite these advances, templateand surfactant-free synthesis of free-standing, crystalline, and optoelectronically active nanosheets from small molecules remains elusive. 展开
2010-03-06 01:33:12 379 6
数据采集的英文怎么翻译?
 
2010-07-05 09:53:28 341 1
帮忙翻译 化工文献 在线等 拒绝使用自动翻译
Nano-sized Beta zeolites, with a crystal size of 80–100 nm, were synthesized via surface wet method. The nano-sized Hbeta zeolites exhibit much higher activity and stability in the Friedel–Crafts acylation of anisole and toluene with acet... Nano-sized Beta zeolites, with a crystal size of 80–100 nm, were synthesized via surface wet method. The nano-sized Hbeta zeolites exhibit much higher activity and stability in the Friedel–Crafts acylation of anisole and toluene with acetic anhydride than theconventional zeolites of largeparticle size.The smallcrystalsize of nano-sized zeolitesmay bringon more accessible activesites and then enhance the catalytic activity. The exposed pore openings in nano-sized zeolites allow a fast desorption of heavy products from the catalyst and can then reduce the occupancy of active sites by the adsorption of products ,this can then alleviate the catalyst deactivation and improve the catalyst stability deactivation and improve the catalyst stability. 急用 在线等 拒绝用自动翻译 因为这个谁都会 如果有超级好用的自动在线翻译或软件也可以推荐 展开
2009-05-31 04:30:04 394 4
请问你能找到关于蛋白质纯化与分离的英文文献及翻译么
 
2015-01-04 20:46:08 485 1

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