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近十余年先天愚型儿出生频率及其产前诊断效率探讨 被引量:7
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作者 金帆 陈玉兰 +1 位作者 吴莉莉 王晓华 《中国优生与遗传杂志》 1996年第4期24-25,共2页
通过近十余年出生的103名先天愚型儿、481名健康儿以及50-70年代出生的2596名健康人出生时母亲年龄比较发现,虽然高龄(≥35岁)妇女与先天愚型儿出生之间的联系依然存在,但因"一个家庭,一个孩子"政策的实施,高... 通过近十余年出生的103名先天愚型儿、481名健康儿以及50-70年代出生的2596名健康人出生时母亲年龄比较发现,虽然高龄(≥35岁)妇女与先天愚型儿出生之间的联系依然存在,但因"一个家庭,一个孩子"政策的实施,高龄孕产妇占孕产妇总数的比例已明显下降,这既有助于降低先天愚型儿总的出生频率,又使依赖母龄的产前诊断先天愚型胎儿的难度加大。 展开更多
关键词 先天愚型 出生频率 产前诊断 儿童
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Output Characteristics of n-Buried-pSOI Sandwiched RF Power LDMOS
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作者 李泽宏 吴丽娟 +1 位作者 张波 李肇基 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2008年第11期2153-2157,共5页
A novel n-buried-pSOI sandwiched structure for an RF power LDMOS is proposed. The output characteristics of the RF power LDMOS are greatly affected by the drain-substrate parasitic capacitance. The output characterist... A novel n-buried-pSOI sandwiched structure for an RF power LDMOS is proposed. The output characteristics of the RF power LDMOS are greatly affected by the drain-substrate parasitic capacitance. The output characteristics become better as the drain-substrate parasitic capacitance decreases. Results show that the drain-substrate capacitance of the n- buried-pSOI sandwiched LDMOS is 46.6% less than that of the normal LDMOS,and 11.5% less than that of the n-buried- pSOI LDMOS,respectively. At l dB compression point,its output power is 188% higher than that of the normal LDMOS, and 10.6% higher than that of the n-buried-pSOI LDMOS, respectively. The power-added efficiency of the proposed structure is 38.3%. The breakdown voltage of the proposed structure is 11% more than that of the normal LDMOS. 展开更多
关键词 n-buried-pSOI sandwiched parasitic capacitance output characteristics RF power LDMOS
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RF system of HIRFL-CSRe
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作者 XU Zhe WANG ChunXiao +7 位作者 YI XiaoPing CONG Yan WEN LiangHua MEI LiRong JIN Peng XIA JiaWen ZHAO HongWei BIAN ZhiBin 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2012年第1期44-47,共4页
The operational frequency range of RF system at HIRFL-CSRe (cooling storage experimental ring) is 0.5-2 MHz, and it works in fundamental and second harmonic. It includes five sections: ferrite ring loaded RF cavity, R... The operational frequency range of RF system at HIRFL-CSRe (cooling storage experimental ring) is 0.5-2 MHz, and it works in fundamental and second harmonic. It includes five sections: ferrite ring loaded RF cavity, RF generator, low-level system, computer system and cavity cooling. The cavity is based on the coaxial resonator type which is short at the terminal with one gap and loaded with domestic ferrite rings. The RF generator is designed in a push-pull mode. The low-level control system is based on PID, DSP, FPGA and DDS9854+USB interface and has three feedback loops. This RF system is designed independently and manufactured domestically. For the first time, it realized the pulse modulation, variable harmonic and CW operational modes. The maximum output power is up to 70 kW and the 10 kV RF voltage is used to capture the irradiative beam and decelerate the beam from 400 to 30 MeV/u. 展开更多
关键词 CSRe RF second harmonic pulse modulation CAPTURE
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