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排序方式: 共有116条查询结果,搜索用时 15 毫秒
61.
Zhang C  Li W  Bao X  Chen L  Du M 《Optics letters》2007,32(17):2565-2567
The strain dependence of Brillouin gain spectrum in two novel carbon/polyimide coated fibers (CPCFs) is studied, for what we believe to be the first time, by numerical simulation and experiment. The strain dependence of the Brillouin frequency shift for the two CPCFs maintained linear relation with the elongation up to 4.26% and 4.0%, respectively. The effects of strain on the elastic modulus, the core refractive index, and density are determined, which have been used to simulate the strain dependence of the frequency shift, linewidth, and gain coefficient for the two CPCFs. The simulated and measured results are well matched.  相似文献   
62.
Pt-Ga/HZSM-5催化剂上丙烷芳构化   总被引:4,自引:0,他引:4  
考察了Pt/HZSM-5,Ga/HZSM-5和Pt-Ga/HZSM-5上的丙烷芳构化反应,其中Pt-Ga/HZSM-5双组份催化剂上有较高的丙烷反应活性和芳烃选择性,用程序升温还原(TPR)和H2化学吸附法表征催化剂,发现Pt与Ga的协同相互作用促进了Ga^3+的还原,使其峰温向低温移动的70℃,且双组分催化剂中Pt的H2吸附性能大大降低,使催化剂表成乙烯加氢能力降低,从而提高了产物芳烃的选择性,  相似文献   
63.
3333lp/mm X射线透射光栅的研制   总被引:2,自引:1,他引:1  
针对X射线透射光栅摄谱仪中的高线密度光栅,研究了采用电子束曝光和X射线曝光技术结合制作高线密度X射线透射光栅的工艺技术.首先利用电子束曝光和微电镀技术在镂空的薄膜上制备母光栅X射线掩模版,然后利用X射线曝光和微电镀技术小批量复制光栅.在国内首次完成了3333lp/mm X射线透射光栅的研制,栅线宽度为150nm,周期为300nm,金吸收体厚度为500nm.衍射效率标定的结果表明,该光栅的占空比合理、侧壁陡直,具有良好的色散特性,能够满足空间探测、同步辐射和变等离子诊断等多个领域的应用.  相似文献   
64.
采用发酵力测定和短时面包制作法研究了面团中各添加组分对酵母活性和面包品质的影响。结果表明,JXF—1面包改良剂改善了面团的加工性能和面包瓤结构,此改良剂大大缩发短酵时间,增加面包体积50%,面包瓤的弹性和光泽也比对照好。  相似文献   
65.
环糊精由于其特殊结构可与众多物质(客体分子)形成包结物,这种包结物在化学理论研究、化工工业、农业及医药等领域有广阔的应用前景[1、2],因而受到人们极大的关注.人们用电导法、核磁技术、表面张力法等研究了环糊精与阴离子表面活性剂的相互作用,但这些方法得出的结果很...  相似文献   
66.
Noble metal nanoparticles (NPs) with 1–5 nm diameter obtained from NaHB4 reduction possess high catalytic activity. However, they are rarely used directly. This work presents a facile, versatile, and efficient aerosol‐spray approach to deliver noble‐metal NPs into metal oxide supports, while maintaining the size of the NPs and the ability to easily adjust the loading amount. In comparison with the conventional spray approach, the size of the loaded noble‐metal nanoparticles can be significantly decreased. An investigation of the 4‐nitrophenol hydrogenation reaction catalyzed by these materials suggests that the NPs/oxides catalysts have high activity and good endurance. For 1 % Au/CeO2 and Pd/Al2O3 catalysts, the rate constants reach 2.03 and 1.46 min?1, which is much higher than many other reports with the same noble‐metal loading scale. Besides, the thermal stability of catalysts can be significantly enhanced by modifying the supports. Therefore, this work contributes an efficient method as well as some guidance on how to produce highly active and stable supported noble‐metal catalysts.  相似文献   
67.
Fu H  Jin W  Xiao H  Xie C  Guo B  Zou H 《Electrophoresis》2004,25(4-5):600-606
Hydrophilic interaction capillary electrochromatography (HI-CEC) for the determination of basic pharmaceuticals spiked in human serum is described. The organic modifier content, ionic strength, and pH value of the mobile phase as well as the applied voltage are optimized for separation and elution of these drug analytes. Excellent separation was achieved for drugs using a mobile phase composition of 80% v/v acetonitrile in 100 mM triethylamine phosphate (TEAP) buffer at pH 2.8 with column efficiencies for analytes more than 200,000 plates/m. The samples of human serum spiked with basic drugs were directly injected after a simple acetonitrile treatment. The linear range and reproducibility of these basic drugs using an external and internal standard method were compared. As a result, the reproducibility could be greatly improved by using the internal standard method. Good calibration curves with regression coefficients more than 0.998 in the range of 5-160 microg/mL were observed with the internal standard method. The limits of quantitation, based on standards with acceptable relative standard deviations (RSDs), were below 5 microg/mL. The intra- and inter-day precisions, determined as RSDs, were less than 4.57%.  相似文献   
68.
An amphiphilic drug–dye conjugate ( PTX‐Pt‐BDP ) was designed and synthesized with a platinum compound as the hydrophilic head. The precursor of PTX‐Pt‐BDP was obtained under mild conditions by means of a three‐component Passerini reaction. PTX‐Pt‐BDP could self‐assemble into nanoparticles ( PTX‐Pt‐BDP NPs) in aqueous solution via a nanoprecipitation method. The obtained nanoparticles exhibited favorable structural stability in both water and physiological environment. PTX‐Pt‐BDP NPs could be endocytosed by cancer cells as revealed by confocal laser scanning microscopy and exert potent cytotoxicity. This work highlights the potential of nanomedicines from amphiphilic drug–dye conjugates for cancer cell imaging and chemotherapy.  相似文献   
69.
J Zhang  W Wang  F Yang  X Zhou  H Jin  PY Yang 《The Analyst》2012,137(18):4287-4294
The human hepatoma 3B cell line was chosen as an experimental model for in vitro test of drug screening. The drugs included chlorophyllin and its derivatives such as fluo-chlorophyllin, sodium copper chlorophyllin, and sodium iron chlorophyllin. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) method was used in this study to obtain the primary screening results. The results showed that sodium iron chlorophyllin had the best LC(50) value. Proteomic analysis was then performed for further investigation of the effect of sodium iron chlorophyllin addition to the Hep 3B cell line. The proteins identified from a total protein extract of Hep 3B before and after the drug addition were compared by two-dimensional-gel-electrophoresis. Then 32 three-fold differentially expressed proteins were successfully identified by MALDI-TOF-TOF-MS. There are 29 unique proteins among those identified proteins. These proteins include proliferating cell nuclear antigen (PCNA), T-complex protein, heterogeneous nuclear protein, nucleophosmin, heat shock protein A5 (HspA5) and peroxiredoxin. HspA5 is one of the proteins which are involved in protecting cancer cells against stress-induced apoptosis in cultured cells, protecting them against apoptosis through various mechanisms. Peroxiredoxin has anti-oxidant function and is related to cell proliferation, and signal transduction. It can protect the oxidation of other proteins. Peroxiredoxin has a close relationship with cancer and can eventually become a disease biomarker. This might help to develop a novel treatment method for carcinoma cancer.  相似文献   
70.
利用滤波荧光(FF)法建立了5~88 keV能区硬X光能谱测量系统,对闪烁探测器的灵敏度进行了精密标定,不确定度好于10%。通过研究干扰产生的原因,改善系统屏蔽,有效地排除了干扰,提高了系统的信噪比;通过更换大电流的光电倍增管,改变准直光阑的尺寸和滤片的厚度,将测量系统的线性动态范围从4提高到104。在神光Ⅲ原型物理实验中定量给出Au平面靶硬X光谱,实现硬X光能谱的精密测量。  相似文献   
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