化工專業(yè)英語求翻譯
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Hollow polymeric spheres have been attracting increasing interest because of their potential applications， which range from targeted drug delivery to advanced functional materi- als.[1，2] Because of their hollow core structure， such poly... Hollow polymeric spheres have been attracting increasing interest because of their potential applications， which range from targeted drug delivery to advanced functional materi- als.[1，2] Because of their hollow core structure， such polymeric spheres can encapsulate large quantities of guest moleculesD especially those spheres with functionalities within the empty coreDand release them at a later stage in a controlled man- ner. Although hollow polymeric spheres with dimensions in the micrometer and submicrometer regions are readily con- structedDby layer-by-layer deposition of polyelectrolytes onto a template core，[3±6] polymerizing monomers in lipid vesi- cles，[7，8] emulsion polymerization，[9，10] pH-induced micelliza- tion of a grafted copolymer，[11] and by the assembly of posi- tively charged polyelectrolytes and negatively charged nanoparticles[12]Dthe synthesis of hollow spheres 100 nm or less in size has only recently become the subject of research activity. Several different routes， such as the self-assembly of block copolymers in a selective solvent，[13，14] the deposition of polyelectrolytes on a decomplexable or soluble core，[15，16] and microemulsion (as well as miniemulsion) polymerization，[17，18] have been developed to form hollow polymeric nanospheres. Although some of these methods have been quite successful， these strategies require the core templates to be removed in order to create a hollow interior， or need large quantities of surfactants to form nanosized micelles. Furthermore， although the majority of the proposed applications of hollow nano- spheres or nanocapsules are concentrated in the biomedical field， most of the hollow polymeric spheres described to date are ill-suited for such purposes. Therefore， materials (in par- ticular for the surfaces of the hollow nanospheres) that are biocompatible， non-toxic， and sometimes also biodegradable， are highly desirable. Herein， we demonstrate a simple and di- rect method for fabricating hollow polymeric nanospheres with biocompatible and biodegradable macromolecules. In this approach， hollow polymeric nanospheres were formed in a completely aqueous system without the aid of surfactants， 展開
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- 久伴派大星pM7 2013-11-14 00:00:00
- 因其在從靶向給藥到先進的功能材料領(lǐng)域的潛在應(yīng)用，聚合物空心球受到越來越多的關(guān)注。由于它們的中空結(jié)構(gòu)，聚合物球能包覆大量的客體分子，尤其是那些具有內(nèi)空心功能的聚合物球，能在之后的階段以受控的方式釋放它們。雖然尺寸在微米和亞微米區(qū)域的空心聚合物球體很容易被一層層沉積在模板的核心聚合電解質(zhì)構(gòu)造而成，但是聚合單體在脂質(zhì)囊泡，乳液聚合，pH誘導(dǎo)膠束化的接枝共聚物，和由帶正電荷的聚電解質(zhì)的組裝和帶負電的納米粒子的空心微球的合成100nm或更小的大小，只是在Z近才成為研究活動的主題。幾個不同的路線，比如嵌段共聚物在選擇性溶劑的自組裝，聚合電解質(zhì)在不可復(fù)合的或可溶的核心的沉積，微乳液(以及實驗)聚合，已經(jīng)發(fā)展形成空心聚合物納米團簇。盡管其中的一些方法已經(jīng)相當(dāng)成功，這些策略需要核心模板被刪除以創(chuàng)建一個中空的內(nèi)部，或者需要大量的表面活性劑形成納米膠束。此外，雖然大多數(shù)的提出應(yīng)用空心簇或所研發(fā)的納米囊都集中在生物醫(yī)學(xué)領(lǐng)域，大多數(shù)的空心聚合物領(lǐng)域描述到目前為止已經(jīng)不適合這種用途。因此，材料(特別是對于表面的空心納米團簇)是生物相容的，無毒的，有時也可生物降解性，是非?？扇〉?。在這里，我們展示了一個簡單直接的方法制造空心聚合物納米球的生物相容性和生物降解的大分子。在這種方法中，在一個完全的含水系統(tǒng)形成了空心聚合物納米球而不借助表面活性劑。
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- 化工專業(yè)英語求翻譯
- Hollow polymeric spheres have been attracting increasing interest because of their potential applications， which range from targeted drug delivery to advanced functional materi- als.[1，2] Because of their hollow core structure， such poly... Hollow polymeric spheres have been attracting increasing interest because of their potential applications， which range from targeted drug delivery to advanced functional materi- als.[1，2] Because of their hollow core structure， such polymeric spheres can encapsulate large quantities of guest moleculesD especially those spheres with functionalities within the empty coreDand release them at a later stage in a controlled man- ner. Although hollow polymeric spheres with dimensions in the micrometer and submicrometer regions are readily con- structedDby layer-by-layer deposition of polyelectrolytes onto a template core，[3±6] polymerizing monomers in lipid vesi- cles，[7，8] emulsion polymerization，[9，10] pH-induced micelliza- tion of a grafted copolymer，[11] and by the assembly of posi- tively charged polyelectrolytes and negatively charged nanoparticles[12]Dthe synthesis of hollow spheres 100 nm or less in size has only recently become the subject of research activity. Several different routes， such as the self-assembly of block copolymers in a selective solvent，[13，14] the deposition of polyelectrolytes on a decomplexable or soluble core，[15，16] and microemulsion (as well as miniemulsion) polymerization，[17，18] have been developed to form hollow polymeric nanospheres. Although some of these methods have been quite successful， these strategies require the core templates to be removed in order to create a hollow interior， or need large quantities of surfactants to form nanosized micelles. Furthermore， although the majority of the proposed applications of hollow nano- spheres or nanocapsules are concentrated in the biomedical field， most of the hollow polymeric spheres described to date are ill-suited for such purposes. Therefore， materials (in par- ticular for the surfaces of the hollow nanospheres) that are biocompatible， non-toxic， and sometimes also biodegradable， are highly desirable. Herein， we demonstrate a simple and di- rect method for fabricating hollow polymeric nanospheres with biocompatible and biodegradable macromolecules. In this approach， hollow polymeric nanospheres were formed in a completely aqueous system without the aid of surfactants， 展開
2013-11-13 05:23:50
485
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- 【生物專業(yè)英語】摘要翻譯
- Abstract:Heavymetals，suchascadmium，copper，lead，chromiumandmercury，areimportantenvironmentalpollutants，particularlyinareaswithhighanthropogenicpressure.Theirpresenceinthea... Abstract: Heavy metals， such as cadmium， copper， lead， chromium and mercury， are important environmental pollutants， particularly in areas with high anthropogenic pressure. Their presence in the atmosphere， soil and water， even in traces can cause serious problems to all organisms， and heavy metal bioaccumulation in the food chain especially can be highly dangerous to human health. Heavy metals enter the human body mainly through two routes namely: inhalation and ingestion， ingestion being the main route of exposure to these elements in human population. Heavy metals intake by human populations through food chain has been reported in many countries. Soil threshold for heavy metal toxicity is an important factor affecting soil environmental capacity of heavy metal and determines heavy metal cumulative loading limits. For soil-plant system， heavy metal toxicity threshold is the highest permissible content in the soil (total or bioavailable concentration) that does not pose any phytotoxic effects or heavy metals in the edible parts of the crops does not exceed food hygiene standards. Factors affecting the thresholds of dietary toxicity of heavy metal in soil-crop system include: soil type which includes soil pH， organic matter content， clay mineral and other soil chemical and biochemical properties; and crop species or cultivars regulated by genetic basis for heavy metal transport and accumulation in plants. In addition， the interactions of soil-plant root-microbes play important roles in regulating heavy metal movement from soil to the edible parts of crops. Agronomic practices such as fertilizer and water managements as well as crop rotation system can affect bioavailability and crop accumulation of heavy metals， thus influencing the thresholds for assessing dietary toxicity of heavy metals in the food chain. This paper reviews the phytotoxic effects and bioaccumulation of heavy metals in vegetables and food crops and assesses soil heavy metal thresholds for potential dietary toxicity. 用翻譯軟件的免回，哥也有，真誠求助高手！ 展開
2010-12-13 19:23:10
629
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- 急求幫我翻譯一段電力專業(yè)英語文章啊??！
- What's therole of the Supercapacitor? The supercapacitor resembles a regular capacitorwith the exception that it offers very high capacitance in a small package.Energy storage is by means of static charge rather than of an electro-che... What's therole of the Supercapacitor? The supercapacitor resembles a regular capacitorwith the exception that it offers very high capacitance in a small package.Energy storage is by means of static charge rather than of an electro-chemicalprocess that is inherent to the battery. Applying a voltage differential on thepositive and negative plates charges the supercapacitor. This concept issimilar to an electrical charge that builds up when walking on a carpet. Thesupercapacitor concept has been around for a number of years. Newer designsallow higher capacities in a smaller size. Whereas a regular capacitor consists ofconductive foils and a dry separator， the supercapacitor crosses into batterytechnology by using special electrodes and some electrolyte. There are threetypes of electrode materials suitable for the supercapacitor. They are: highsurface area activated carbons， metal oxide and conducting polymers. The highsurface electrode material， also called Double Layer Capacitor (DLC)， is leastcostly to manufacture and is the most common. It stores the energy in thedouble layer formed near the carbon electrode surface. 展開
2013-06-11 09:00:02
513
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- 求翻譯這段話，化工相關(guān)的，20分奉上
- ThethreelevelcontrollersareproportionalwithKC=2.ThepressurecontrollershavetheAspendefaultsettingsofKC=20and?I=12min.Thetwocompositioncontrollersaretunedsequentially... The three level controllers are proportional with K C = 2. The pressure controllers have the Aspen default settings of K C = 20 and ?I = 12 min. The two composition controllers are tuned sequentially. Since the CCxD loop is blending two streams， its dynamics are fast with the composition deadtime the only dynamic element in the loop. So the distillate composition controller CCxD is tuned with the bottoms loop on manual. Then the bottoms composition controller CCxB is tuned with the distillate loop on automatic. Deadtimes of 3 min are inserted in the loops to account for composition measurement delays. Relay-feedback testing and Tyreus-Luyben settings give controller tuning constants K C = 0.40 and _ I = 37 min for the CCxB controller and K C = 22 and _ I = 13 min for the CCxD controller. 展開
2018-11-17 07:21:42
304
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- 麻煩幫我翻譯以下文章(生物專業(yè)英語)
- The most common means of agitation of liquid media is by placing the culture vessels on a drum(for test tubes)or a disk(for flasks)slowly rotating around a near horizontal axis. This assures good aeration of the liquid cultures with little... The most common means of agitation of liquid media is by placing the culture vessels on a drum(for test tubes)or a disk(for flasks)slowly rotating around a near horizontal axis. This assures good aeration of the liquid cultures with little mechanical damage to the cells.Agitation can also be achieved by placing culture flasks on reciprocating or gyrotory platform shakers.Gyrotoy (horizontal rotary orbit)shakers are preferred over reciprocating (horizontal linear motion)ones for a variety of reasons .The performance of the gyrotory shaker is determined by the speed of agitation and angle position of the flasks，with optimal aeration occurring in flasks tilted about 45° from the vertical.A new shaker design is the "tapping" motion shaker in which the culture is agitated by a magnetic bar moving up and down.This vertical movement of the bar is less injurious to cells than rotary movement of the bar at the bottom of the flask used in some conventional culture systems. 展開
2008-05-30 20:14:03
743
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- 請幫我翻譯一段專業(yè)英語吧。。急用。。多謝。。。
- Practical applications of colossal magnetoresistive(CMR) oxides are limited by the large magnetic fields and/or low temperature required to observe a significant change in electric resistivity[1-5]. In recent years，research on tunneling mag... Practical applications of colossal magnetoresistive(CMR) oxides are limited by the large magnetic fields and/or low temperature required to observe a significant change in electric resistivity[1-5]. In recent years，research on tunneling magnetoresistance(TMR) is a very active field because of its scientific interest and potential technological applications[6].Polycrystalline Sr2FeMoO6 perovskite is a candidate for magnetic sensors owing to its high ferromagnetic transition temperature …（Tc~420K）and the half-metallic electronic band structure predicted theoretically [7]. The conduction electrons in this compound are expected to be highly spin-polarized even at room temperature. More recently， perovskite Sr2FeMoO6 with nanometer grain size showed large magnetoresistance(~20%) at a low magnetic field of 4k Oe and at room temperature[8].Dai et al.[9]observed two different ordered structures in polycrystalline Sr2FeMoO6 perovskite: the double perovskite and the superstructure with tripled c-axis(ST).In this paper， another new layered structure of body-centered tetragonal phase (BT) is reported for the polycrystalline magnetoresistive Sr2FeMoO6 sample. Ceramic samples of Sr2FeMoO6 were prepared by standard solid state reaction. Stoichiometric materials of SrCO3，F(xiàn)e2O3 and MoO3 were mechanically mixed， and then calcined at 950℃ for 4h in air.The calcined mixture was then ball-milled and made into pellets followed by sintering at 1250℃for 4h in carbon monoxide atmosphere.Transmission electron microscopy(TEM) specimens were prepared by mechanical polishing，dimpling and ion milling.Electron diffraction patterns were taken at 120kV using a Phillips CM12 electron microscope， and high resolution TEM imaging was conducted using JEOL 2010 microscope. Energy dispersion of X-rays(EDX) was conducted by TEM attached with EDAX PV9100. 展開
2009-05-20 03:06:41
494
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- 化學(xué)專業(yè)英語·翻譯·謝\(^o^)/YES！
- Fig. 1 illustrates the microstructure and surface morphology of samples which include the bare substrate， the fluorinated with and without CeO2 thin film. Fig. 1a shows the initial surface state of the polished bare substrate. Some fine ste... Fig. 1 illustrates the microstructure and surface morphology of samples which include the bare substrate， the fluorinated with and without CeO2 thin film. Fig. 1a shows the initial surface state of the polished bare substrate. Some fine steaks resulting from the polishing progress are visible in the image. The surface is considerably rough and the activity of surface for magnesium alloy is various from sample to sample and within the same sample due to the presence of different phases [24，25]. In Fig. 1b， the micrograph was taken when the sample was fluorinated in the 20% HF for 20 h. There are a large number of pores and cracks on the surface of this sample; however， we cannot find the presence of remarked grinding scratches originated from the sample preparation on the surface in contrast with the bare substrate. It is well known that the magnesium alloy reacts with HF to form the fluoride coating via displacement reaction and the fluoride is insoluble， thus form a barrier on the surface of magnesium alloy. The pores and cracks distributed uneven also suggest that the activities on the surface of magnesium alloy are not very identical. The SEM image of the fluorinated sample with CeO2 thin film is shown in Fig. 1c. As can be seen from this image， most of the pores and cracks existed on the surface of the fluorinated sample have disappeared which is ascribed to the presence of CeO2 thin film. Moreover， the surface of CeO2 thin film is more uniform and more compact than that of the fluorinated sample， and this may explain why this kind of samples is the best corrosion resistant. XPS analysis is performed aiming at identifying the chemical composition of the film and the typical survey scan spectra are shown in Fig. 2. The main element peaks of Mg， C， O， F and Ce are shown in the spectra. A significant amount of carbon is present on the surface of the sample due to some contaminant that originates from the polishing， cleaning and heat-treatment procedure; moreover， there may be some remnant since the deficiently burning for celloidin during the heat-treatment. There are three peaks in the survey scan spectra as follows: Mg 2p3/2 at about 50 eV， Mg 2s at about 88 eV and Mg Auger peak at about 301 eV. The peak of Mg 2p around 50 eV is shown in Fig. 2 which reveals only one peak at 50.2 eV belonging to Mg 2p being the fingerprint for Mg2+ in the transitional region. Hence， it is most probable that the presence of Mg in the coating is a result of the formation of MgF2 in the course of the fluorinated process and the formation of MgO during the heat-treatment. Both the main components of O 1s peak located at 530.6 eV and the F 1s peak located at 684.7 eV give the evidence that the major states are MgO and MgF2. It is found that almost a pure Ce(IV) state in the spectrum of CeO2 and this is similar to these reported by ?koda et al. [26]. 展開
2009-03-30 12:58:40
424
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- 求翻譯。。。。。。。。。。。
- During the preparation of the nano-products， these nano-units， such as nanoparticles， nanoclusters， nanowires and nanorods， can also self-assemble into the novel structural aggregates by several routes， including electron irradiation deposi... During the preparation of the nano-products， these nano-units， such as nanoparticles， nanoclusters， nanowires and nanorods， can also self-assemble into the novel structural aggregates by several routes， including electron irradiation deposition [19]， chemical vapor deposition [20]， laser vaporization-condensation [21]， charge transferring [22]， an organic reagent-assisted method [23]， solution-liquid-solid method [24] and catalytic vapor-liquid-solid growth [25]. With these routes， various nanoscale or microscale aggregates can demonstrate novel architectures， including tree-like， web-like， spherical， nanowire-like， network and fishbone-like aggregates. As a well-known method for producing the nanocapsules， however， arc-discharge has been rarely used to synthesize the aggregates self-assembled by the nanocapsules prepared simultaneously in arc-discharge. Nevertheless， it is possible that the arc-discharge can be developed into a new way to synthesize the aggregates. In the present work， we utilized arc-discharge technique with modified strategies， involving changing the hydrogen pressure， introducing gadolinium - aluminum alloy ingot as the anode and adjusting the elements percent of the anode according to their evaporation pressure， to synthesize a new type of nanocapsules， with intermetallic compound GdAl2 as core and amorphous Al2O3 as shell， which enlarge the family of the magnetic nanocapsules. At the same time， the regularly aligned three-dimensional macro-aggregates self-assembled by the nanocapsules without any template and catalyst were simultaneously synthesized in arc-discharge process. 展開
2008-06-09 10:41:10
398
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- Determine the weight per milliliter by dividing the weight in g， 化工上的 求翻譯
- Determine the weight per milliliter by dividing the weight in g， of the quantity of liquid， which fills the pycnometer at 25°C， by the capacity expressed in ml， of the pycnometer at the same temperature.
2011-06-18 02:54:15
432
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- 幫忙翻譯 化工文獻 在線等 拒絕使用自動翻譯
- 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 在線等 拒絕用自動翻譯 因為這個誰都會 如果有超級好用的自動在線翻譯或軟件也可以推薦 展開
2009-05-31 04:30:04
457
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- 求化學(xué)翻譯
- Graphite powder (<20m)， hydrazine， ammonia， N，Ndimethylformamide (DMF)， dopamine， 0.01M phosphate buffered saline (PBS; 0.138M NaCl， 0.0027M KCl， pH 7.4)， and ascorbic acid were purchased form Aldrich and used as received. Doubly disti... Graphite powder (<20m)， hydrazine， ammonia， N，Ndimethylformamide (DMF)， dopamine， 0.01M phosphate buffered saline (PBS; 0.138M NaCl， 0.0027M KCl， pH 7.4)， and ascorbic acid were purchased form Aldrich and used as received. Doubly distilled water was used throughout the whole experiments. The data of cyclic voltammetry (CV)， differential pulse voltammetry (DPV)， and electrochemical impedance spectra were obtained with a CHI 660 electrochemical workstation (CH instruments， Austin， TX). The electrochemical cell consisted of GCE (3mm diameter， Bioanalytical Systems， Inc.) as working electrode， Ag/AgCl (Bioanalytical Systems， Inc.) as reference electrode， and platinum wire as counter electrode. The impedance data were fitted to an appropriate equivalent circuit using ZsimpWin 3.0 software (Echem Software). The Raman spectra of graphene were obtained by micro-Raman system equipped with a homemade sample stage， a monochromator (SPEX 500 M)， and a CCD camera (Roger Scientific model 7346-001) with 514.5nm wavelength laser line. Graphene was characterized by field emission scanning electron microscope (SUPRA 55VP， Carl Zeiss) and atomic force microscope (NanostationII， Surface Imaging Systems). 展開
2012-03-12 11:00:58
425
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- 文獻求翻譯
- 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. 展開
2012-08-31 01:19:05
451
5
- 求韓語翻譯
- 3? ??然 ?? ?? ???? ? ?? ???? ??? ?? ??? ?? &... 3? ??然 ?? ?? ???? ? ?? ???? ??? ?? ??? ?? ??? ?? ??? ?? ????、 求準確翻譯 PS 3元催化劑是安裝在汽車排氣管上的 展開
2012-12-19 08:48:48
448
1
- 求翻譯文獻
- 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. 展開
2009-12-15 12:42:12
448
6
- 繼續(xù)求翻譯
- Ethylacetate(Quimis，p.a.)，methanol(Quimis，p.a.)，sec-butanol(Merck，HPLCgrade)，oleicacid(Merck，extrapure)，hydrogenperoxide(Interox，70%，w/waqueoussolution)，aluminumoxideforc... Ethyl acetate (Quimis， p.a.)， methanol (Quimis， p.a.)， sec- butanol (Merck， HPLC grade)， oleic acid (Merck， extra pure)， hydrogen peroxide (Interox， 70%， w/w aqueous solution)， aluminum oxide for chromatography (Fluka， 0.05–0.15 mm)， aluminum oxide for column chromatography (Acros Organics， activated， acidic， 0.1–0.5 mm)， aluminum tri-sec-butoxide (Aldrich， 99.99%)， oxalic acid (Synth， p.a.)， di-n-butyl ether (Fluka， >99%) and soybean oil (Cargill) were used as received. The solution of anhydrous hydrogen peroxide (24%， w/w) in ethyl acetate was prepared from aqueous H2O2 (70%， w/w) in ethyl acetate by azeotropic distillation with a Dean-Stark apparatus [14] The products were identified by gas chromatography–mass spectroscopy (GC–MS) using a Hewlett-Packard 5890 gas chromatograph equipped with a AT-Wax column and interfaced with a Hewlett-Packard 5971A mass spectrometer. Helium was used as the carrier gas. A similarly equipped Hewlett-Packard5890 gas chromatograph using nitrogen as the carrier gas and a flame ionization detector was used for product quantification， with the help of calibration curves. 展開
2009-03-18 10:12:57
457
3
- 化學(xué)專業(yè)英語
- 10、TheuseofLewis-acidcatalystsinmodernorganichasbeenstudiedextensivelyduringthelastdecade.Nowadaystheresearchisfocusonthemoreversatile，moreselective，andmorereactivecatal... 10、The use of Lewis-acid catalysts in modern organic has been studied extensively during the last decade. Nowadays the research is focus on the more versatile， more selective， and more reactive catalyst. It has been found that gold Lewis acids are effective to catalyze the formation of C-C and oxidation reactions as the heterogeneous or the homogeneous catalysts. In particular， gold-catalyzed oxidation reactions have been applied in the epoxidation， oxidation of alcohols and aldehydes， and the oxidative cleavage of C-C double bonds. Sulfides oxidation is one of the most important organic processes， because the corresponding organosulfur compounds are versatile intermediates in organic synthesis and are useful for the preparation of biologically and medically important products. To the best knowledge， two examples of gold Lewis acid reveal the catalytic property in the reaction of sulfides to sulfoxides. 11、Anhydrous ethers is generally used as the solvent in the preparation of a Grignard reagent Actually， the ether plays a more important role in the reaction than merely that of solvent. Ether molecules combine with the various components of a Grignard reagent to form complex etherates. For example， one of the components in phenyl magnesium bromide-ether solution is a complex. 展開
2008-06-10 00:23:27
364
5
- 幫忙翻譯下化工的英語。。用在線詞典翻譯部正確
- A reversed-phase ion-pairing high-performance liquid chromatography (RP-HPIPC) method for the separation of a complex mixture of heparin-derived oligosacchrides has been developed by a stepwise optimization of the mobile phase， in which the... A reversed-phase ion-pairing high-performance liquid chromatography (RP-HPIPC) method for the separation of a complex mixture of heparin-derived oligosacchrides has been developed by a stepwise optimization of the mobile phase， in which the concentration of ion-pairing reagent， mobile phase pH， and acetonitrile concentration were varied. The resolution of more than 30 oligosaccharide components was obtained， under optimized conditions， in an analysis time of less than 30 min. This represents the first RP-HPLC method that can separate a complex mixture of both small and large sulfated oligosaccharides in a single chromatographic step. The heparin-derived oligosaccharides， in this mixture， can also be separated under a second set of RP-HPIPC conditions using a volatile ion-pairing reagent， tributylammonium acetate， to aid in the recovery of individual sulfated oligosaccharides. Moreover， it was possible to replace sodium chloride gradient， required for eluting highly sulfated oligosaccharides， with a fixed， low concentration of a volatile salt， ammonium acetate， by utilizing an acetonitrile gradient. This solvent system might make it possible to directly interface this RP-HPIPC separation with mass spectral analysis. ??2003 Elsevier B.V. All rights reserved. Keywords: Ion-pairing reagents; Gradient elution; Oligosaccharides 展開
2010-06-01 05:49:52
691
4
- 高分求高手翻譯，不要機械翻譯
- Bimetallic dendrimer-encapsulated nanoparticles(DENs)are important materials，because they have demonstrated improvement in performance compared to the monometallic DENs in many systems when they are used as catalysts.This tutorial review fo... Bimetallic dendrimer-encapsulated nanoparticles(DENs)are important materials，because they have demonstrated improvement in performance compared to the monometallic DENs in many systems when they are used as catalysts.This tutorial review focuses on the recent research advances in bimetallic DENs with respect to their synthesis，characterization，and applications as catalysts.Bimetallic DENs can be made mainly via three routes:co-complexation，sequential loading，and partial displacement.The research in bimetallic DENs has been significantly promoted by the advancement of characterization instruments.The performances of bimetallic DENs as homogeneous and heterogeneous catalysts in organic synthesis have been compared with both monometallic DENs and their physical mixtures.It is concluded that the synergistic electronic effect in bimetallic nanoparticles enhances their catalytic activities. 能翻譯多少都可以的 展開
2009-03-24 13:04:22
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- 幫忙翻譯一下化工方面的單詞 英語
- 堿值測定器試劑移液管錐形瓶酸式滴定管甲基黃溴甲酚綠混合指示劑鹽酸標(biāo)準溶液摩爾/升酸式滴定管... 堿值 測定器 試劑 移液管 錐形瓶 酸式滴定管 甲基黃溴甲酚綠混合指示劑 鹽酸標(biāo)準溶液 摩爾/升 酸式滴定管 展開
2010-01-17 06:38:39
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