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• 2017-04-07 11:15發(fā)布了問答

  為什么從x射線衍射可以看出是外消旋

  　

  396人看過

• 2015-03-22 02:35發(fā)布了問答

  我要測(cè)檢測(cè)求助更新列表

  　

  390人看過

• 2014-12-28 15:14發(fā)布了問答

  求翻譯英文文獻(xiàn)

  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 ?) 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. 展開

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• 2013-10-16 02:24發(fā)布了問答

  金剛石怕火燒嗎？

  如題。 原來聽說過一個(gè)故事就是一個(gè)富人和一個(gè)窮學(xué)者打賭。這個(gè)學(xué)者是學(xué)化學(xué)的，堅(jiān)持說只要金剛石是碳的結(jié)構(gòu)，就會(huì)在高溫下燃燒。富人不信隨手讓他燒掉自己的鉆戒。后來學(xué)者用隨身帶的放大鏡聚光讓金剛石在陽光下想蒸發(fā)一樣燒掉了。 以前，我的一個(gè)化學(xué)老師... 如題。 原來聽說過一個(gè)故事就是一個(gè)富人和一個(gè)窮學(xué)者打賭。這個(gè)學(xué)者是學(xué)化學(xué)的，堅(jiān)持說只要金剛石是碳的結(jié)構(gòu)，就會(huì)在高溫下燃燒。富人不信隨手讓他燒掉自己的鉆戒。后來學(xué)者用隨身帶的放大鏡聚光讓金剛石在陽光下想蒸發(fā)一樣燒掉了。 以前，我的一個(gè)化學(xué)老師偶爾說到金剛石的結(jié)構(gòu)，她說其結(jié)構(gòu)可以讓金剛石的熔點(diǎn)超過三千攝氏度。近期我學(xué)地質(zhì)，地質(zhì)老師又提到自然形成的金剛石必須在上千度的上層地幔中受高壓百萬年才能形成。這些理論不是證明金剛石不怕火燒嗎？ 可惜我沒有可能有經(jīng)濟(jì)實(shí)力拿出一顆自然金剛石做實(shí)驗(yàn)。懂的朋友請(qǐng)踴躍回答問題，謝謝。 展開

  3307人看過

• 2012-11-03 06:47發(fā)布了問答

  一樣物質(zhì)怎樣知道構(gòu)成它的元素

  　

  403人看過

• 2011-10-23 17:25發(fā)布了問答

  XRD是什么

  　

  419人看過

• 2010-12-01 00:09發(fā)布了問答

  X射線衍射圖怎么看

  X射線衍射圖怎么看

  890人看過

• 2007-05-15 14:49發(fā)布了問答

  拍攝X射線對(duì)身體的危害

  我小腿骨折，平均每一個(gè)半月復(fù)查一次，拍攝一次X光片，這樣對(duì)身體有危害嗎?

  702人看過