高分求高手翻譯，不要機(jī)械翻譯
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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
全部評論(2條)
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- 木塵宇 2009-04-06 00:00:00
- 雙金屬樹狀包覆納米粒子（洞穴）是重要的材料，因為他們已經(jīng)證明的性能提升相比，單洞穴在許多系統(tǒng)當(dāng)他們被用作catalysts.This教程審查的ZD是Z近的研究進(jìn)展雙金屬洞穴就其合成，表征和應(yīng)用catalysts.Bimetallic洞穴，可主要通過三個途徑：合作絡(luò)合，順序 載入中，部分displacement.The研究雙金屬洞穴已大大促進(jìn)提高表征instruments.The表演的雙金屬洞穴為均勻和多相催化劑在有機(jī)合成中已與這兩個單洞穴和他們的身體mixtures.It結(jié)束電子的協(xié)同效應(yīng)的雙金屬納米粒子增強(qiáng)其催化活性。
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- zdinnmjx32851 2009-03-25 00:00:00
- 兩種金屬的dendrimer被濃縮的nanoparticles (小室)是重要材料，因為他們展示了在表現(xiàn)的改善與許多系統(tǒng)的單金屬小室比較，當(dāng)他們使用作為催化劑時。在Z近研究的本指南回顧焦點在兩種金屬的小室推進(jìn)關(guān)于他們的綜合、描述特性和應(yīng)用作為催化劑。兩種金屬的小室可以主要通過三條路線被做：co絡(luò)合，連續(xù) 裝載和部份位移。研究在兩種金屬的小室由描述特性儀器的推進(jìn)顯著促進(jìn)了。兩種金屬的小室表現(xiàn)作為同類和異種催化劑的在有機(jī)綜合與兩單金屬小室和他們的物理混合物比較。結(jié)束在兩種金屬的nanoparticles的協(xié)同作用的電子作用提高他們的催化作用。 有的不會
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- 高分求高手翻譯，不要機(jī)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
366
2
- 求翻譯，不要機(jī)器翻
- All cell lines were grown in RPMI-1640 medium (GIBCO) supplemented with 10% heat-inactivated bovine serum， 2 nM L-glutamine， 105 IU/liter penicillin G， 100 mg/liter streptomycin and 10 mM HEPES， pH 7.4. Cells were kept at 37°C in a humidif... All cell lines were grown in RPMI-1640 medium (GIBCO) supplemented with 10% heat-inactivated bovine serum， 2 nM L-glutamine， 105 IU/liter penicillin G， 100 mg/liter streptomycin and 10 mM HEPES， pH 7.4. Cells were kept at 37°C in a humidified 5% CO2 incubator. 展開
2012-07-23 12:44:48
380
1
- 機(jī)械翻譯!!
- 13.本系列儀器采用電流、電壓雙組取樣并經(jīng)單片處理后顯示，其讀數(shù)直觀、準(zhǔn)確。由于儀器采用了負(fù)載四線制取樣，從面消除了負(fù)載導(dǎo)線電阻對電顯示的影響。電路的電壓限幅，使得實驗更加安全，可靠。 16.采用古埃法（gu-ai method）研究分子結(jié)構(gòu)，測量順磁和逆... 13.本系列儀器采用電流、電壓雙組取樣并經(jīng)單片處理后顯示，其讀數(shù)直觀、準(zhǔn)確。由于儀器采用了負(fù)載四線制取樣，從面消除了負(fù)載導(dǎo)線電阻對電顯示的影響。電路的電壓限幅，使得實驗更加安全，可靠。 16.采用古埃法（gu-ai method）研究分子結(jié)構(gòu)，測量順磁和逆磁磁化率。主要結(jié)構(gòu)有：電磁鐵和恒流電源、數(shù)字式高斯計（霍爾效應(yīng)）、安培計和伏特計、配有照明系統(tǒng)的控制盤。系統(tǒng)采用了PID電子調(diào)節(jié)，全數(shù)字電源（0~10A無級調(diào)節(jié)），無需水冷卻，使得儀器動礦層運行更加穩(wěn)定可靠，防止因操作不當(dāng)而造成儀器損壞。 34. 本儀器由光學(xué)系統(tǒng)和信號處理系統(tǒng)兩部分組成，它根據(jù)光拍頻原理設(shè)計，通過光電轉(zhuǎn)換檢測，在普通示波器上同時觀察和比較兩束光的波形和相位，測量光程差和位相差，求得光速。 采用新的分頻、觸發(fā)措施，能在示波器上觀察到精確、清晰的波形。 35.本裝置用霍爾效應(yīng)的原理測量螺線管軸向磁場強(qiáng)度分布。能判斷半導(dǎo)體載流子的符號，移開螺線管，可做共軛線圈實驗。 此裝置由測定儀和專用電源兩部分組成，實驗儀上裝有螺線管、霍爾元件、二維移動標(biāo)尺及IM，IH，VH轉(zhuǎn)換開關(guān)。專用電源提供霍爾元件工作電流IH，螺線管勵磁電流IM以及對霍爾電壓VH的測量。電流和電壓的測量均采用3 1/2位數(shù)顯表，測量精度高。 翻出來后我再給分!一定會追加分!Z少50分!! 展開
2007-03-25 21:10:45
533
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- 高分請高手幫忙翻譯英文文獻(xiàn)資料（4）
- Whenliquidisheateditevaporates.Theevaporationprocessisdependentonpressure，temperatureandcompositionoftheliquidandgas.Gascanalsocondense.Inadditionthereisaconvectiveheattr... When liquid is heated it evaporates. The evaporation process is dependent on pressure， temperature and composition of the liquid and gas. Gas can also condense. In addition there is a convective heat transfer between the liquid and gas zone that must be considered. The surfaces in the gas zone also radiates from the shell to the liquid. During the blowdown process mass is usually evacuated from the gas zone， but also liquid might be released. The rate of release is dependent on density and pressure as well as the release area. As pressure and temperature change， the properties of all materials change. This has to be considered in a prediction of a blowdown process. The main purpose of a blowdown process is as earlier stated to maintain integrity of the equipment. The strength properties of the shell are the key factor on that matter. The strength is dependent on the inside pressure as well as the support forces. If the exposing forces produce stress that exceeds the ultimate tensile stress (UTS) in some regions， the integrity of the equipment is no longer maintained. In the design phase of a process plant， these aspects are crucial and must be included as a dimensional factor. For that reason prediction of the blowdown process is essential. Lately some new standards has been introduced to the industry on this matter [3] and [4]. VessFire [1] and [2] is a multi physics system designed for calculation of this kind of problems. It has been applied for some time in the oil and process industry on many projects. The system satisfies the requirements for predictions outlined in [3] and [4]. It includes all aspects described above including integrity of the shell. As part of the verification process some experiments where performed. Some of the experiments are presented here. EXPERIMENTAL STUDY The purpose of the experiments was to investigate the evaporation process and the heat transfer to the liquid and vapour. In a complex system it is important to reduce unknown parameters as far as possible. Exposure from a flame is difficult to control. Flux measurements are point values and not necessarily representative for the average exposure. In order to control the heat exposure it was decided to apply an electric heating system. The system and the verification of the system is described in [5]， [6] and [8]. The furnace was built inside a supporting tube. Figure 2 shows a general arrangement of the experimental outfit. A 0.05 mm stainless steel foil formed as a tube， 300 mm in diameter， generated the heat. The power supply was based on a 3-phase alternating current system giving 48 Volt output as maximum. The top exposure had a limit of 300 kW. The foil had a surface of about 1 m2， giving a heat flux up to 300 kW/m2. The power input could be continuously regulated from zero to maximum load. Each experiment was started from zero and brought up to the required load within a few seconds. After that the surface temperature of the heating foil was kept constant during the exposure period. Experiments with both dry objects as well as water filled object were performed. In this paper only water filled experiments are presented Figure 2 General arrangements drawing of the experimental furnace including the specimen and its support Figure 3 Illustration of the heating unit. The black part is copper conductors for the foil. The grey part is the heating foil exposing the specimen. The foil is equipped with thermo-elements all marked H， except H5 which is the temperature in a copper ring and H6 which is the temperature between the insulation and the supporting tube. 展開
2009-03-12 04:13:30
537
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- 翻譯翻譯，請高手幫我翻譯一下這個說明
- Followthesysteminstallationinstructionscarefullyandinthespecifiedorder.ThesoftwaremustbeinstalledonthecomputerbeforeconnectingtheUSBcable.2.1FacilitiesRequirementsFacilit... Follow the system installation instructions carefully and in the specified order. The software must be installed on the computer before connecting the USB cable. 2.1 Facilities Requirements Facilities requirements for the alpha-SE system are listed in Table 2-1 and the system dimensions are given in Fig. 2-1. As shown in Fig. 2-2， the alpha-SE tool requires a clear work area of 20 by 18 inches (500 by 460 mm)， excluding the operator computer. 2.2 Unpacking the Hardware Opening the Shipping Container Move the alpha-SE shipping container to the area where the tool will be installed. Open the container and remove the top and side pieces of packing foam. Carefully remove all smaller components from the shipping container， verifying that you received all components， as shown in Fig. 2-3. Finally， remove the alpha-SE ellipsometer and position it on your clear 20” by 18” (510 by 460 mm) workspace. Caution: The alpha-SE ellipsometer without sample chuck weighs approximately 37 lbs. (16 kg.). Please find an assistant to lift the alpha-SE unit out of the shipping carton and on to clear work surface. 展開
2008-06-22 06:30:36
886
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- 高手幫忙翻譯一工科英文??！高分大謝！
- Figure 2 SEM micrographs of worn seat insert surface of engine #6175 after 1474 hours of testing. The arrows and labels indicate the locations of EDX analysis. The same adhesion phenomenon occurs on the valve seat surfaces. Figure 4 show... Figure 2 SEM micrographs of worn seat insert surface of engine #6175 after 1474 hours of testing. The arrows and labels indicate the locations of EDX analysis. The same adhesion phenomenon occurs on the valve seat surfaces. Figure 4 shows SEM micrographs of the worn exhaust valve seat surface of engine #6175 after 1474 hours of testing. The valve material is Stellite 6 faced 23-8N (solution treated and aged). The arrows in Figure 4b indicate the locations of EDX analysis. Note the pits and deposits on the worn seat surface. Figures 5a shows the EDX spectrum of spot A on Figure 4b showing adhered insert material. Note molybdenum and manganese in the spectrum. Figure 5b shows the EDX spectrum of spot B in Figure 4b showing both adhered insert material and oil deposits. Note molybdenum.， phosphorous， chlorine， calcium， and zinc in the spectrum. Other valves from different engines labeled as "adhesion" in Table 2 share this typical adhesive phenomenon. The adhesive wear mode appears to predominate at valve seat interfaces with high asperity contact stresses or high combustion pressure. The surface roughness can contribute to adhesion significantly. Valves faced with Stellite alloy show less adhesive wear than unfaced valves， Table 2. The presence of high melting point phases， such as carbide or ceramic compounds in the contacting materials is believed to help prevent microwelding or adhesion related wear. Shear strain， also known as radial flow， is defined as the first derivative of the displacement， i.e.， . Figure 6 [8]. Shear strain controlled wear can characterized as a surface plastic deformation process. The wear is the result of the shear strain on the seat surface exceeding the plasticity limit of the material. The material is then detached or delaminated from the seating surface as wear particles. The typical appearance of shear strain controlled wear are ridges and/or radial flow of material on valve seats and inserts. Shear strain controlled wear sometimes is associated with adhesion. 展開
2009-02-19 16:10:31
425
1
- 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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- 求日文翻譯，不要翻譯器，迅速給分C1
2012-09-16 02:22:56
619
4
- 求翻譯，與生物有關(guān)，不要機(jī)翻
- AfterdissectioneachsamplewasplacedinamicrotubefilledwithNaClsolution(0.9%w/v)andwascarefullycrushedmechanicallyandasuspensionwaspreparedusingavibrationshaker.HPLC-diodear... After dissection each sample was placed in a microtube filled with NaCl solution (0.9% w/v) and was carefully crushed mechanically and a suspension was prepared using a vibration shaker. HPLC-diode array laminar flow cabinet. 展開
2014-03-12 13:25:56
538
2
- 急求英譯漢高手（詞霸翻譯不加分）翻譯好了 追加50
- http://hi.baidu.com/lyl464797826/blog/item/0c12e646eca6ee3287947334.html
2010-06-19 21:53:22
518
1
- 高手幫忙翻譯??！+100
- 虛擬儀器是一種新的測試與測控技術(shù)，近年來得到了迅速發(fā)展，基于虛擬儀器的機(jī)器視覺系統(tǒng)就是其領(lǐng)域的一個重要分支。本文圍繞基于虛擬儀器的機(jī)器視覺有關(guān)理論和其在玻璃瓶口缺陷檢測中... 虛擬儀器是一種新的測試與測控技術(shù)，近年來得到了迅速發(fā)展，基于虛擬儀器的機(jī)器視覺系統(tǒng)就是其領(lǐng)域的一個重要分支。本文圍繞基于虛擬儀器的機(jī)器視覺有關(guān)理論和其在玻璃瓶口缺陷檢測中的具體應(yīng)用進(jìn)行了研究。 針對玻璃瓶這一對象檢測的高精度、高準(zhǔn)確度、實時性的特點，本文提出了一種基于LabVIEW的數(shù)字圖像處理檢測方案，并在設(shè)計過程中解決了一系列關(guān)鍵問題：利用硬件和軟件的編程實現(xiàn)了對玻璃瓶口的缺陷監(jiān)測；使用閾值進(jìn)行圖像的二值化處理，并進(jìn)行開啟、閉合以增強(qiáng)圖像質(zhì)量；使用Vision Builder AI對有故障的圖像進(jìn)行故障特征識別； 通過理論研究與實驗，證明了本文所提出的玻璃瓶口缺陷監(jiān)測方法是有效和可行的，為其機(jī)器視覺檢測的進(jìn)一步研究和開發(fā)奠定了很好的基礎(chǔ) 請用專業(yè)術(shù)語，不要用在線翻譯。謝謝····好可以多加分 展開
2008-06-10 11:03:29
488
3
- 高分求高人翻譯植物化學(xué)英文材料，謝謝
- Review Enzymatic protein hydrolysis plays a major role in various physiological processes， including digestion， and is regulated by proteinase inhibitors. Inhibitors in foods and food ingredients can reduce the absorption of free amino aci... Review Enzymatic protein hydrolysis plays a major role in various physiological processes， including digestion， and is regulated by proteinase inhibitors. Inhibitors in foods and food ingredients can reduce the absorption of free amino acids， and can impair protein hydrolysis in industrial processes. However， inhibitors can be useful tools in pest control， in the prevention and treatment of diseases such as cancers and AIDS， and in the elimination of unwanted proteinase activity in food processes. Proteinase inhibitors are also useful biochemical tools for studying proteinase classes and specificities. This article discusses how proteinase inhibition is involved in some processes of current interest to food scientists and technologists. Enzymatic protein hydrolysis is a major concern for biological scientists. The hydrolysis of proteins is catalyzed by peptide-bond-splitting enzymes (Box 1). Proteinases and peptidases are involved in the hydrolysis of protein during digestion， and have important roles in physiology and pathology. Enzymatic protein hydrolysis is controlled in several ways， including by the use of specific inhibitors (Box 2). Proteinase inhibition is a common process in nature. Proteinase-inhibitor interactions are involved in protein digestion， various physiological processes (e.g. blood coagulation， fibrinolysis， complement activation and phagocytosis)， pathological processes (e.g. cancers and hypertension) and infection Another natural method of controlling proteinase activity is the synthesis of an inactive form of the enzyme， the zymogen. Zymogens are activated， usually by the action of another proteinase， in the digestive system and also during regulatory physiological processes. When an enzyme is in its active form， proteinase inhibition is an exquisite means of enzyme control in physiological processes， which is achieved by highly specific inhibitors. The importance of the control of proteolytic activity by inhibitors in physiological processes is demonstrated by the fact that inhibitor molecules exceed 10% of the total protein in human plasma. The fact that the control of proteolysis by inhibitors is so specific makes it a valuable tool in medicine， agriculture and food technology. The human immune deficiency virus proteinase， the digestive systems of crop pests， and fish muscle proteases are some examples of targets for study. Most organisms produce proteinase inhibitors as a means to control proteolytic processes.Some organisms store huge amounts of inhibitors， for example legume seeds and some leaves. This seems to be an evolutionary response to predation. Inhibitors for digestive proteinases in food and feed Some food ingredients contain so-called antinutritive factors: lectins， phenols， and other factors， including certain proteins that inhibit proteinases. The presence of proteinase inhibitors in living tissues seems to be a natural regulatory process 展開
2008-06-05 11:17:05
420
2
- 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
2
- 文獻(xiàn)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(zhǔn)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(xiàn)
- 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
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- 化學(xué)專業(yè)英語翻譯 不要翻譯工具
- D，L252單取代海因是工業(yè)生產(chǎn)D2氨基酸的重要前體[1～3]。海因酶具有底物特異性，D2海因酶(EC3151212)可轉(zhuǎn)化外消旋的D，L252單取代海因中的D型消旋體成為D2N2氨甲酰氨基酸，剩余的L252單取... D ，L252單取代海因是工業(yè)生產(chǎn) D2氨基酸的重要前體[1～3 ]。海因酶具有底物特異性 ，D2海因酶(EC 3151212)可轉(zhuǎn)化外消旋的D ，L252單取代海因中的D型消旋體成為D2N2氨甲酰氨基酸 ，剩余的L252單取代海因由于完全不被 D2海因酶所作用 ，如圖 1所示 ，先進(jìn)行消旋 ，從而使得 D ，L2海因完全轉(zhuǎn)化為光學(xué)純的 D2N2氨甲酰氨基酸 ，并進(jìn)一步被轉(zhuǎn)化為D2氨基酸。因此 ，52單取代海因的自發(fā)消旋成為L2或D2N2氨甲酰氨基酸生產(chǎn)中的一個重要的步驟。若海因的自發(fā)消旋速率遠(yuǎn)低于海因水解酶的水解速率 ，則海因的消旋將成為D2N2氨甲酰氨基酸生產(chǎn)中的一個限速步驟。目前關(guān)于 52單取代海因的消旋的文獻(xiàn)非常少 ，海因消旋的細(xì)節(jié)問題也沒有被完全揭示。 1 材料與方法 111 實驗材料 L2丙氨酸(國家生化工程ZX) 、 L2苯丙氨酸(國家生化工程ZX) 、氰酸鈉(江都化工廠) ，其他試劑為國產(chǎn)分析純試劑。 112 實驗方法 11211 52取代海因衍生物的制備 采用Henze2Speer法[4～5 ]進(jìn)行52取代海因衍生物的制備: 反應(yīng)溫度為60～80 ℃。反應(yīng)6 h后 ，加入鹽酸酸化 ，繼續(xù)加熱 8 h ，冷卻后過濾得到的固體用酒精和水的混合溶液重結(jié)晶 ，得到無色晶狀目的產(chǎn)物。因使用的氨基酸不同 ，反應(yīng)條件略有變化 ，產(chǎn)率一般為40 %～80 % ，所得的52取代海因具有和底物氨基酸相同的旋光方向。 11212 海因衍生物的消旋 a.精確稱量41000 g L252甲基海因 ，溶解于蒸餾水中 ，定容至250 mL ，測定其旋光度 ，并以此值為未消旋化的起始數(shù)據(jù)。 b.用 6 mol/ L 的 NaOH溶液調(diào)整海因溶液 pH值達(dá)810 ，90 ℃水浴2 h ，于旋光儀上測定其旋光度。 c.同 b ，依次調(diào)節(jié)溶液pH值為710、 810、 910 ，分別測定其旋光度。 d.同 b ，依次于50 ℃水浴中及室溫下恒溫2 h ，分別測定其旋光度 ，并與起始數(shù)據(jù)對比 ，計算消旋比 r ( %) :r =αt/α0 ，其中αt 為 t 時間溶液的旋光度 ，α0為溶液初始旋光度。 11213 海因的堿解 精確稱量41000 g L252甲基海因 ，溶解于蒸餾水中 ，定容至 250 mL ，用 NaOH溶液和鹽酸分別調(diào)至pH = 2、 8、 12 ， 90 ℃水浴反應(yīng)4 h ，中間取樣測定其N2氨甲酰丙氨酸濃度。 11214 海因的轉(zhuǎn)化 采用012 %的海因溶液 ，按 w (底物)∶ w (菌泥)= 1∶ 5的比例 ，于pH 915 ，溫度40 ℃下進(jìn)行轉(zhuǎn)化。 取樣:取樣10 mL ，加入 5 mL 三停止反應(yīng) ，搖勻 ，放冰箱待測。 3 結(jié) 論 311 海因的消旋遵循本文所提出的碳負(fù)離子理論 ，其消旋過程為一級反應(yīng)動力學(xué)過程。由海因消旋的半衰期可看出提高溫度和pH對海因的消旋均有利 ，但pH過高的情況下海因則會發(fā)生堿解反應(yīng)從而造成損失。 312 本文采用的海因轉(zhuǎn)化酶系中所含為 D2海因酶 ，對D2海因的轉(zhuǎn)化活性非常高 ，由此可見 ，如若采用的轉(zhuǎn)化體系中沒有消旋酶的存在 ，則海因的消旋成為海因酶轉(zhuǎn)化生產(chǎn)光學(xué)活性氨基酸的一個限速步驟。 展開
2009-06-08 13:22:45
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