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Fluke 9640A RF Reference Source combines level precision,dynamic range,frequency capability in a single instrument
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作者 Stream lines workload enables automationof calibration procedures with MET/CAL(Plus Calibration Measurement Software 《国外电子测量技术》 2007年第1期81-81,共1页
关键词 Source RF Fluke 9640A RF Reference Source combines level precision dynamic range frequency capability in a single instrument
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Coherent Features of Resonance-Mediated Two-Photon Absorption Enhancement by Varying the Energy Level Structure,Laser Spectrum Bandwidth and Central Frequency
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作者 程文静 梁果 +3 位作者 吴萍 贾天卿 孙真荣 张诗按 《Chinese Physics Letters》 SCIE CAS CSCD 2017年第8期41-45,共5页
The femtosecond pulse shaping technique has been shown to be an effective method to control the multi-photon absorption by the light–matter interaction. Previous studies mainly focused on the quantum coherent control... The femtosecond pulse shaping technique has been shown to be an effective method to control the multi-photon absorption by the light–matter interaction. Previous studies mainly focused on the quantum coherent control of the multi-photon absorption by the phase, amplitude and polarization modulation, but the coherent features of the multi-photon absorption depending on the energy level structure, the laser spectrum bandwidth and laser central frequency still lack in-depth systematic research. In this work, we further explore the coherent features of the resonance-mediated two-photon absorption in a rubidium atom by varying the energy level structure, spectrum bandwidth and central frequency of the femtosecond laser field. The theoretical results show that the change of the intermediate state detuning can effectively influence the enhancement of the near-resonant part, which further affects the transform-limited (TL)-normalized final state population maximum. Moreover, as the laser spectrum bandwidth increases, the TL-normalized final state population maximum can be effectively enhanced due to the increase of the enhancement in the near-resonant part, but the TL-normalized final state population maximum is constant by varying the laser central frequency. These studies can provide a clear physical picture for understanding the coherent features of the resonance-mediated two-photon absorption, and can also provide a theoretical guidance for the future applications. 展开更多
关键词 TL Coherent Features of Resonance-Mediated Two-Photon Absorption Enhancement by Varying the Energy level Structure Laser Spectrum Bandwidth and Central frequency
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Dynamic analysis of water level in the Wanquan Well and the precursory anomalies of earthquakes
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作者 曹新来 张素欣 《Acta Seismologica Sinica(English Edition)》 EI CSCD 1999年第3期357-364,共8页
According to the characteristics of frequent water level step-variation in the Wanquan Well, the step-variation frequency change on the time axis can be regarded as a sequence of step-variation. A study of the relati... According to the characteristics of frequent water level step-variation in the Wanquan Well, the step-variation frequency change on the time axis can be regarded as a sequence of step-variation. A study of the relationship between the process of development and evolution of the sequential step-variation and the regional seismicity indicated that the sequential step-variation anomalies are rather better in coincidence with the time, magnitude and frequency of regional seismic activities, which may predict the seismicity trend in months. Furthermore, on this basis, if the water level changes in a characteristic manner, the seismic regime during the time period from several days to 20 days or more may be evaluated. By using the method presented in this paper we had a prediction about the Baotou ML=6.6 earthquake on May 3, 1996. This event occurred within the predicted time span but with a less magnitude and a little location deviation. 展开更多
关键词 Wanquan Well water level frequency step-variation sequence
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HIGH FREQUENCY ELECTROACUPUNCTURE INDUCED CHANGES OF IP_3 LEVEL IN RAT BRAIN AND SPINAL CORD 被引量:3
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作者 陈素珍 韩济生 《Chinese Medical Journal》 SCIE CAS CSCD 1994年第6期42-45,共4页
In the present study, the radioreceptor binding method was used to determine the changes of IP3 content in rat brain and dorsal spinal cord of high frequency (100 Hz) electroacupuncture (EA) analgesia and EA tolerance... In the present study, the radioreceptor binding method was used to determine the changes of IP3 content in rat brain and dorsal spinal cord of high frequency (100 Hz) electroacupuncture (EA) analgesia and EA tolerance rat. The control levels of IP3 in rat brain (less cerebellum and cortex) and dorsal spinal cord were 6.3± 0.78 pmol / mg protein and 3.4± 0.60 pmol / mg protein, respectively. The results showed that IP, in brain increased gradually within 45 min after stimulation in EA analgesia rat. Meanwhile, the dorsal spinal cord IP, content decreased significantly 15 min, 30 min after EA stimulation and recovered to control level 45 min after EA stimulation. In EA tolerance rat, IP3 contents markedly increased in brain. And IP3 content in the spinal cord also increased dramatically within 30 min, but decreased rapidly to control level 45 min after EA stimulation. The IP3 level in EA tolerance rat brain and spinal cord was much higher than that in EA analgesia rat (P<0.01). The studies first reported that high frequency (100 Hz) EA may be linked to PI system in its signal transduction pathways. 展开更多
关键词 IP PI pH In HCI HIGH frequency ELECTROACUPUNCTURE INDUCED CHANGES OF IP3 level IN RAT BRAIN AND SPINAL CORD
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β-fibrinogen gene -455A/G polymorphism and plasma fibrinogen level in Chinese stroke patients 被引量:1
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作者 柳扬 潘家绮 +2 位作者 王书杰 李秀荣 黄一宁 《Chinese Medical Journal》 SCIE CAS CSCD 2002年第2期54-56,151,共4页
Abstract Objectives To investigate the relationship between the β-fibrinogen gene -455A/G polymorphism and plasma fibrinogen level and to determine the influence of the mutation on ischemic stroke. Methods Ninety-o... Abstract Objectives To investigate the relationship between the β-fibrinogen gene -455A/G polymorphism and plasma fibrinogen level and to determine the influence of the mutation on ischemic stroke. Methods Ninety-one patients (63.5±10.1 years) with ischemic stroke and 74 elderly control subjects (60.6±10.8 years) without any thromboembolic events and 98 healthy blood donators as young control (37.5±13.3 years) were enrolled in this trial. The β-fibrinogen gene -455A/G polymorphism was analyzed for all subjects by PCR-RFLP with the restrictive enzyme Hae Ⅲ, while plasma fibrinogen levels were obtained from the prothrombin time (PT) assay. For statistical analysis, the parameters were compared between any two different groups by the unpaired Student’s t test and the Chi-square test. Before analysis, log transformations for concentrations of fibrinogen were carried out.Results H2 allele frequency was higher in male ischemic stroke patients than in the elderly control (22.7% vs 7.1%, χ 2=5.56, P【0.02). There was no significant difference between the female groups. In those patients without any thromboembolic events (both elderly and young control groups), the frequency of H2 decreased with age (≤40, 21.3%; 41-59, 15.4%; and ≥60, 10.2%). In the male elderly and young control groups, the level of plasma fibrinogen was lower in the H1H1 genotype (287±96*!mg/dl and 234±58*!mg/dl) than in H1H2 and H2H2 (331±44*!mg/dl and 307±55*!mg/dl; t=2.53 and 9.67, P【0.05). In the female elderly groups, this tendency was not found.Conclusion Plasma fibrinogen expression is affected by the β-fibrinogen gene -455A/G polymorphism, and the H2 allele may be a risk factor for ischemic stroke in Chinese males. 展开更多
关键词 cerebral infarction · fibrinogen · gene frequency · H2 allel · risk factor · plasma level
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