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Anisotropic Transport on Monolayer and Multilayer Phosphorene in the Presence of an Electric Field 下载免费PDF全文
We demonstrate theoretically the anisotropic quantum transport of electrons through an electric field on monolayer and multilayer phosphorene. Using the long-wavelength Hamiltonian with continuum approximation, we find that the transmission probability for transport through an electric field is an oscillating function of incident angle, electric field intensity, as well as the incident energy of electrons. By tuning the electric field intensity and incident angle, the channels can be transited from opaque to transparent. The conductance through the quantum waveguides depends sensitively on the transport direction because of the anisotropic effective mass, and the anisotropy of the conductance can be tuned by the electric field intensity and the number of layers. These behaviors provide us an efficient way to control the transport of phosphorene-based microstructures. 相似文献
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海南主要地域生咖啡豆挥发性化学成分对比研究 总被引:2,自引:0,他引:2
采用固相微萃取-气相色谱-质谱法(SPME-GC-MS)分析海南万宁地区咖啡豆和澄迈地区咖啡豆中挥发性化学组分,通过谱库检索、保留指数对化合物定性,比较两种咖啡豆之间差异。实验结果表明:万宁地区咖啡检出化合物种类91种,澄迈地区咖啡检出106种化合物,有66种相同的化合物,相同组分为75.52%。相同化合物中万宁地区咖啡占总含量的89.86%,澄迈地区咖啡占总含量的85.70%。 相似文献
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Domain structures in mineral crystals could be categorized into three groups and several subgroups within each group, based on characteristics of domain structures and mechanisms causing domain structures: (ⅰ) domain structures constituted by domains with the same (or identical) crystal structure and chemical composition, including anti-phase domain structures, twinning domain structures, inversion domain structures, and translationtwinning domain structures; (ⅱ) domain structures constituted by two or more than two kinds of domains with the same chemical composition but different crystal structures; and (ⅲ) domain structures constituted by two kinds of compositional and structural different domains, including exsolution-induced and polysomatic reaction-induced domain structures. Different types of domain structures may display different phenomena in their TEM images and SAED patterns, due to different crystallographic characteristics of different domain structures. The domain structures in minerals 相似文献
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固相萃取-超高效液相色谱-三重四极杆质谱联用同时测定水中菊酯类农药多残留 总被引:1,自引:0,他引:1
应用固相萃取-超高效液相色谱-三重四极杆质谱(UPLC-MS/MS)联用技术,建立了水中20种菊酯类农药多残留的分析方法。通过对固相萃取柱、淋洗液、流动相等条件的优化,确定以Oasis HLB为固相萃取柱、正己烷-丙酮(9∶1,V/V)为淋洗液、0.1%乙酸水溶液-乙腈(7∶3,V/V)为流动相做水样预处理。在最优实验条件下,目标物的回收率为73.4%~124.5%,相对标准偏差(RSD)在5.7%~9.1%之间,线性范围均在1~2 000μg/L,各目标物标准品在UPLC-MS/MS系统中有效的线性相关(R2)为0.999以上。该方法具有检测限低、回收率高等优点,经实际样品测试,可适用于水中20种菊酯类农药多残留的同时检测。 相似文献
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采用固相萃取,用超高效液相色谱-串联质谱法(UPLC-MS/MS)建立了水中27种磺酰脲类除草剂的分析方法。通过对固相萃取柱、淋洗液、流动相等的优化,确定以Oasis HLB固相萃取柱、乙腈为淋洗液、0.1%乙酸-甲醇(7∶3,V/V)为流动相做水样预处理。在最优条件下,目标物回收率均为79.8%~124.5%,相对标准偏差(RSDs)为6.9%~9.6%,线性范围均为1~2 000μg/L,线性相关系数(R2)在0.999以上。该方法具有检测限低、回收率高等优点,经实际样品测试,可适用于水中27种磺酰脲类除草剂残留的同时检测。 相似文献
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应用超高效液相色谱-三重四极杆质谱联用仪(UPLC-MS/MS)建立了环境水体中22种典型药品及个人护理用品(pharmaceuticals and personal care products, PPCPs)的分析方法。通过对固相萃取柱、淋洗液、色谱流动相等的优化,确定以Oasis HLB小柱为固相萃取柱、甲醇为淋洗液、水(0.1%甲酸)-甲醇(7:3, v/v)为流动相进行水样预处理和色谱分离。在最优条件下,目标物在水中的回收率为73%~125%,相对标准偏差(RSDs)为8.8%~17.5%。各目标物的线性范围均为2~2000 μg/L,线性相关系数(R2)不小于0.997。该方法具有检出限低、回收率高等优点,经实际样品测试,适用于环境水体中22种典型PPCPs的同时检测,可为微量有机物引起的水环境风险评价和控制的相关研究提供支持。 相似文献
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气相色谱-串联质谱法同时快速检测环境水样中11种合成麝香 总被引:1,自引:0,他引:1
应用气相色谱-串联质谱法(GC-MS/MS)建立了环境水样中佳乐、吐纳、特拉斯、开许梅龙、萨利、粉檀、二甲苯、麝香酮、伞花、葵子、西藏11种典型的合成麝香(Synthetic Musks)的同时快速检测方法。采用Oasis HLB固相萃取柱、乙酸乙酯为洗脱液对水样进行预处理。在最优条件下,目标物线性范围均为0.05~10ng/L(R2为0.995~0.999),回收率为83.9%~112.7%,相对标准偏差(RSD)为3.5%~9.9%。该方法具有检测限低、回收率高等优点,经实际样品测试,可适用于环境水样中上述11种典型合成麝香的同时检测。 相似文献