排序方式: 共有88条查询结果,搜索用时 15 毫秒
71.
BoYU JianHUANG XiaoFengCAI XiaoYongLIU CuiQingMA FuLiLI PingXU 《中国化学快报》2005,16(7):935-938
A simple recombinant PCR method was used to delete the dszB gene responsible for the slowest step of the Dsz pathway and allow the accumulation of hydroxyphenyl benzene sulfinate (HPBS) in the recombinant E. coll. Using GC/MS, HPBS accumulation was confirmed. The recombinant E.coli could also desulfurize Cx-DBT to corresponding Cx-HPBS. The result gave a new insight to BDS process and explored a new method to obtain valuable surfactants from cheap raw materials. 相似文献
72.
73.
74.
氢化物原子荧光光谱法测定水中微量砷和硒 总被引:5,自引:0,他引:5
俞海霞 《广东微量元素科学》2004,11(2):59-62
研究了氢化物发生-原子荧光光度法测定水中微量砷和硒的方法。结果表明,检出限:砷为0.0518μg/L,硒为0.0524μg/L;11次测定的相对标准偏差为0.36%~0.62%;标准回收率:砷为96.8%~100.9%;硒为95.9%~103.7%。方法简便、快速、灵敏,适于生活饮用水、地表水和水源水中微量砷、硒的同时测定。 相似文献
75.
X荧光光谱法分析LF-VD精炼炉炉渣 总被引:4,自引:0,他引:4
采用X荧光光谱仪分析LF-VD精炼炉炉渣中TFe,CaO,MgO,Al2O3,SiO2,TiO2,MnO,P2O5等8个组分。因精炼炉渣中氧化钙含量高,我们选用了12个国家级、部级炉渣标准样品,再添加光谱纯试剂配制了数点合成标样,适应氧化钙、三氧化二铝、二氧化硅含量范围跨度较大的样品分析,同时使得分析曲线点分布均匀。用四硼酸锂作熔剂,高温熔融制样。进行了脱模剂、熔融温度及稀释比等制样条件的选择试验。采用PH模式、理论α系数校正基体的吸收增强效应,进行了方法的精密度及准确度试验。与化学法对照,各组份的定量分析结果令人满意。方法准确、快速、简便。 相似文献
76.
In order to keep subscribers up‐to‐date with the latest developments in their field, John Wiley & Sons are providing a current awareness service in each issue of the journal. The bibliography contains newly published material in the field of mass spectrometry. Each bibliography is divided into 11 sections: 1 Reviews; 2 Instrumental Techniques & Methods; 3 Gas Phase Ion Chemistry; 4 Biology/Biochemistry: Amino Acids, Peptides & Proteins; Carbohydrates; Lipids; Nucleic Acids; 5 Pharmacology/Toxicology; 6 Natural Products; 7 Analysis of Organic Compounds; 8 Analysis of Inorganics/Organometallics; 9 Surface Analysis; 10 Environmental Analysis; 11 Elemental Analysis. Within each section, articles are listed in alphabetical order with respect to author 相似文献
77.
梯度淋洗/离子色谱法对烟草及烟草制品中7种无机阴离子的快速测定 总被引:3,自引:0,他引:3
建立了同时测定烟草及其制品中7种无机阴离子的梯度淋洗/离子色谱法,通过正交实验优化了萃取条件,并对方法进行了验证及评价。在优化条件下,7种阴离子的定量下限为0.003~0.254 mg.L-1,RSD为0.09%~3.8%(n=6)。F-、Cl-、NO3-、SO42-和H2PO4-的线性范围为0.5~100.0 mg.L-1,相关系数为0.999 7~0.999 9;NO2-和Br-的线性范围为0.1~20.0 mg.L-1,相关系数为0.999 9。将该方法用于原料烟叶、成品烟丝、造纸法再造烟叶及烟梗等样品的检测,样品中7种阴离子的加标回收率为90%~106%,RSD(n=6)为0.3%~4.4%。方法适用于烟草及烟草制品中7种阴离子的快速批量检测。 相似文献
78.
采用Nb/Cu复合管作为外包套材料,通过原位法粉末装管工艺(PIT)制备了C掺杂MgB2/Nb/Cu线材.在高纯流动氩气保护条件下、650~950℃温度区间内烧结2h.微观结构分析显示,通过该工艺制备的MgB2/NbZr/Cu线材具有良好的晶粒连结性和较高的致密度.X射线衍射(XRD)分析表明在750℃左右可以生成纯度较高的MgB2相,在低温和高温下烧结后均有杂相峰出现,并且高温烧结后所生成的相结构较为复杂.采用四引线法超导临界电流的测试结果表明,低温烧结后的线材具有超导电流传输性能,而当热处理温度超过750℃时,样品中的电流传输状态表现为正常电阻态.实验结果证实采用Nb作为原位法MgB2超导线材的包套阻隔层时,成相热处理一般应该在低于750℃的温度下进行. 相似文献
79.
<正>In diode pumped Nd:YAG lasers,the quantum defect is the most important parameter determining the thermal load of the laser crystal,which can be dramatically reduced by pumping directly into the upper laser level.A compact folded three-mirror cavity with a length of 105 mm is optimized to obtain a highly efficient 473-nm laser.When the absorbed pump power(with 15.8-W incident pump power) at 885 nm into Nd:YAG is 10 W,a continuous-wave 473-nm blue laser as high as 2.34 W is achieved by LBO intra-cavity frequency doubled.The optical-to-optical conversion efficiency is 14.8%.To the best of our knowledge, this is the highest efficiency at 473 nm by an intra-cavity doubled frequency Nd:YAG laser. 相似文献
80.
In order to improve the characteristics of the general broad-waveguide 808-nm semiconductor laser diode (LD),we design a new type quantum well LD with an asymmetric cladding structure.The structure is grown by metal organic chemical vapor deposition (MOCVD).For the devices with 100-μm-wide stripe and 1000-μm-long cavity under continuous-wave (CW) operation condition,the typical threshold current is 190 mA,the slope efficiency is 1.31 W/A,the wall-plug efficiency reaches 63%,and the maximum output power reac... 相似文献