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931.
Zhang Xu Liu Jia Chen ChuangYe Liu Wei Liu JingBin Li BaoHui He Ming Zhou TieGe Zhao XinJie Yan ShaoLin Fang Lan 《科学通报(英文版)》2011,56(35):3884-3887
A new circuit model for designing and manufacturing an S-band low noise amplifier(LNA) with the software,Advanced Design System(ADS),is introduced in this paper.The proposed model involves shunted impedance at the grid to achieve a stable LNA without measuring the S-parameters of transistors at low temperatures.The LNA was measured over the operation band of 2.2-2.3 GHz,which has input and output standing wave ratios below 1.2.The noise figure of the manufactured LNA was about 0.2 dB and the gain was above 22 dB,which indicated that our LNA worked well at 77 K. 相似文献
932.
Yong Wei QiuGang Zong ZuYin Pu WeiXing Wan JianJun Liu SuiYan Fu QuanQi Shi 《科学通报(英文版)》2011,56(11):1117-1122
It is believed that a southward interplanetary magnetic field (IMF) is mainly responsible for the energy input from solar
wind into the magnetosphere. This paper presents an unusual case of strong anti-sunward plasma flow (up to 2 km/s) in the
polar cap ionosphere and large cross-polar cap potential (CPCP) during a period of horizontal IMF (|B
Z
| < 2 nT) observed by both ACE (at the L1 point) and Geotail (on the dusk flank of the magnetosheath). The CPCP is even higher
than that under preceding B
Z
≈ −23 nT. Furthermore, GOES8 observed that the magnetosheath field turns northward as the anti-sunward plasma flow and CPCP
start to increase, which implies that the magnetosheath field interacting with the Earth’s magnetopause has significantly
rotated and differs from the IMF observed by ACE and Geotail. In accordance with previous theoretical work, we suggest that
the magnetic field line draping produces a southward magnetosheath field and enhances anti-sunward plasma flow and the CPCP. 相似文献
933.
Fan Yu Jun Xiao XiangYang Liang ShaoJun Liu GongJian Zhou KaiKun Luo Yun Liu Wei Hu YaPing Wang ZuoYan Zhu 《科学通报(英文版)》2011,56(16):1679-1684
Triploid carp (100%) with 150 (3n=150) chromosomes were obtained by crossing the females of improved tetraploid hybrids (♀,
4n=200) of red crucian carp (♀)×common carp (♂) with the males of diploid yellow river carp (♂, 2n=100). The crosses yielded
transgenic triploid carp (positive triploid fish, 44.2% of the progeny) and non-transgenic triploid carp (negative triploid
fish). Histological examination of the gonads of 24-month-old positive triploid fish suggested they were sterile and the fish
were not able to produce mature gametes during the breeding season. Morphologically, both the positive and negative triploid
fish were similar. They had a spindle-shaped, laterally compressed, steel grey body with two pairs of barbells. Most of the
quantifiable traits of the triploid carp were intermediate between those of the two parents. The positive and negative triploid
fish were raised in the same pond for 2 years. The mean body weight of the positive triploid fish was 2.3 times higher than
the negative triploid fish. The weight of the largest positive triploid fish was 2.91 times higher than that of the largest
negative triploid fish. Thus, we produced fast-growing transgenic triploid carp that have a reduced ecological risk because
of their inability to mate and produce progeny. 相似文献
934.
ZHOU Wei LU BinFeng KONG LingTi LI JinFu & ZHOU YaoHe State Key Laboratory of Metal Matrix Composites School of Materials Science Engineering Shanghai Jiao Tong University Shanghai China 《科学通报(英文版)》2011,(36)
The microstructures and free-volume evolutions of as-cast and pre-annealed Zr65Al7.5Ni10Cu12.5Ag5 bulk metallic glasses during rolling deformation have been investigated. No phase transformation is detected in the as-cast/rolled specimen. However,the structural stability of the glass against plastic deformation is worse after pre-annealing,indicated by nanocrystallization in preannealed/rolled specimens with large deformation degrees. Moreover,with increasing deformation degree,the free-volume content in a ... 相似文献
935.
936.
SUN Ke XIE Liang JU Yu WU XuMing HOU Jie HAN Wei WANG Xin MAN JiangWei LIU Yu YUAN HaiQing LUO ZhenAo XIONG Shang & ZHU NingHua State Key Laboratory on Integrated Optoelectronics 《科学通报(英文版)》2011,(32):3486-3492
A compact fiber-optic diode-laser sensor system for measuring relative humidity is studied. In such a system, a distributed feedback laser lasing near 1877 nm is used as light source while a high-precision Pt resistance as temperature sensor, an accuracy of 0.1% relative-humidity can be achieved. The laser sensor system is able to lock to the absorption peak and calculate the density of water vapor without any additional reference measurements. Using programs built in to the microcontroller unit, the laser system can switch functions between direct measurement at high density and second-harmonic detection at low density. The system can switch between the two modes automatically and work in a wide dynamic range. 相似文献
937.
WANG HaiPeng & WEI BingBo * Department of Applied Physics Northwestern Polytechnical University Xi’an China 《科学通报(英文版)》2011,56(32):3416-3419
Using liquid Fe 60 Cu 40 alloy as a model, the structure of liquid Fe-Cu alloy systems is investigated in the temperature range 1200 2200 K, covering a large metastable undercooled regime, to understand the phase separation of liquid Fe-Cu alloys on the atomic scale. The total pair distribution functions (PDFs) indicate that liquid Fe 60 Cu 40 alloy is ordered in the short range and disordered in the long range. If the atom types are ignored, the total atom number densities and PDFs demonstrate that the atoms are distributed homogenously in the liquid alloy. However, the segregation of Fe and Cu atoms is very obvious with decreasing temperature. The partial PDFs and coordination numbers show that the Cu and Fe atoms are not apt to get together on the atomic scale at low temperatures; this will lead to large fluctuations and phase separation in liquid Fe-Cu alloy. 相似文献
938.
A flat submerged membrane combined with a TiO 2 /UV photocatalytic reactor (FSMPR) was employed in batch mode to remove humic acid (HA). HA removal efficiency was characterized by UV 254 absorbance, UV-vis spectra, dissolved organic carbon (DOC) concentration, specific UV absorbance (SUVA), and trihalomethane formation potential (THMFP). The FSMPR process was effective in removing more than 86% of DOC and nearly 100% of UV 254 absorbance, while the THMFPs of samples were reduced to < 19 μ g/L after 150 min of treatment. In addition, changes in transmembrane pressure (TMP) with and without UV were evaluated; TiO 2 /UV was effective at controlling membrane fouling by HA. Analysis of the molecular weight (MW) distributions and three-dimensional excitation-emission matrix (EEM) fluorescence spectra of HAs revealed that the effectiveness in membrane fouling control is a result of changes in HA molecular characteristics. The TiO 2 /UV photocatalytic reactor caused the degradation of high MW, hydrophobic humic-like molecules to low MW, hydrophilic protein-like molecules, although this fraction was not completely removed during 150 min of treatment and was less responsible for membrane fouling. 相似文献
939.
TAO ChunHui LI HuaiMing HUANG Wei HAN XiQiu WU GuangHai SU Xin ZHOU Ning LIN Jian HE YongHua ZHOU JianPing 《科学通报(英文版)》2011,56(26):2828-2838
During January–May in 2007,the Chinese research cruise DY115-19 discovered an active hydrothermal field at 49°39′E/37°47′S on the ultraslow spreading Southwest Indian Ridge (SWIR).This was also the first active hydrothermal field found along an ultraslow-spreading ridge.We analyzed mineralogical,textural and geochemical compositions of the sulfide chimneys obtained from the 49°39′E field.Chimney samples show a concentric mineral zone around the fluid channel.The mineral assemblages of the interiors consist ... 相似文献
940.
The microstructures and free-volume evolutions of as-cast and pre-annealed Zr65Al7.5Ni10Cu12.5Ag5 bulk metallic glasses during rolling deformation have been investigated. No phase transformation is detected in the as-cast/rolled specimen. However,the structural stability of the glass against plastic deformation is worse after pre-annealing,indicated by nanocrystallization in preannealed/rolled specimens with large deformation degrees. Moreover,with increasing deformation degree,the free-volume content in a pre-annealed/rolled specimen increases at a lower average rate than that in an as-cast/rolled specimen. 相似文献