近60年我国土壤侵蚀科学研究进展

在系统总结我国近60年土壤侵蚀科学研究取得的成就的基础上,通过分析与整合,重点介绍全国土壤侵蚀时空特征与动态变化、土壤侵蚀过程及其调控机制、黄河泥沙来源与粗泥沙集中来源区的界定、风力侵蚀机制及沙漠化防治、侵蚀环境演变与调控等5个对土壤侵蚀学科发展有重大意义的进展,提出了我国土壤侵蚀学科亟待加强的3个领域。

子午岭60年辽东栎林种子质量与森林更新

辽东栎是我国暖温带落叶阔叶林地带的优势乔木树种之一。通过26年的定位监测,对子午岭辽东栎林种子质量消减、种子萌发与环境条件、实生苗时空分布动态以及对其森林更新的影响等方面进行了初步探讨。结果表明:辽东栎林在子午岭半阳坡、半阴坡和阴坡3种类型中,平均完好种子占种子总数的26.65%;霉变种子占18.72%;动物取食虫蛀种子在阴坡远高于半阴坡和半阳坡,占到种子总数的26.32%;已发芽的种子占其总数的28.31%,且半阴坡>半阳坡>阴坡。每年均有大量种子生产,但在生境与动物的共同作用下,种子数量和质量受到很大影响,多达73.35%的种子失去生命力,直接影响实生苗的形成;地表覆盖物虽能促进种子的快速发芽,但对成苗却是一个物理障碍,影响是负作用的,主要影响因子是地表覆盖物的厚度和含水量;在辽东栎林下虽有一定的实生幼苗分布,但数量极少,平均密度仅为140~120株/hm2,且不同立地条件差异显著,严重影响森林的天然更新。

黄土高原侵蚀区长芒草对坡地土壤水分养分的影响

在黄土高原神木六道沟流域选相邻退耕坡地和裸地,均匀布点采样结合室内分析,采用SPSS处理数据,研究30龄长芒草(Stipa bungeana)对土壤水分、养分的影响。结果表明:在长芒草根系分布区土壤水分下降很快,并且形成干层,其中40~60 cm含水量均低于5.5%,最低达3.2%;同时,长芒草可使土壤养分在表层累积,而降低20~50cm土层处养分含量;全氮、全磷、有机质、硝态氮和铵态氮含量均随土层的加深而降低。

Effect of cryoprotectants on hatching rate of red seabream (Pagrus major) embryos

The objectives were to investigate the effect of cryoprotectants on the hatching rate of red seabream embryos. Heart-beat embryos were immersed in: five permeable cryoprotectants, dimethyl sulfoxide (DMSO), glycerol (Gly), methanol (MeOH), 1,2-propylene glycol (PG), and ethylene glycol (EG). in concentrations of 5-30% for 10, 30, or 60 min; and two non-permeable cryoprotectants: polyvinylpyrrolidone (PVP), and sucrose (in concentrations of 5-20% for 10 or 30 min). The embryos were then washed and incubated in filtered seawater until hatching occurred. The hatching rate of the embryos treated with permeable cryoprotectants decreased (P < 0.05) with increased concentration and duration of exposure. In addition, PG was the least toxic permeable cryoprotectant, followed by DMSO and EG, whereas Gly and MeOH were the most toxic. At a concentration of 15% and 30 min exposure, the hatching rate of the embryos immersed in PG was 93.3 +/- 7.0% (mean +/- S.D.), however. in DMSO. EG, Gly. and MeOH, it was 82.7 +/- 10.4, 22.0 +/- 5.7, 0.0 +/- 0.0, and 0.0 +/- 0.0%, respectively. Hatching rate of embryos treated with PVP decreased (P < 0.05) with the increase of concentration and exposure time, whereas for embryos treated with sucrose, there was no significant decrease in comparison with the control at the concentrations used. (C) 2008 Elsevier Inc. All rights reserved.

INVESTIGATION OF C-60 SINGLE-CRYSTAL BY X-RAY-METHODS

C-60 Single crystals grown by a single-temperature-gradient technique were characterized by synchrotron radiation white beam x-ray topography and x-ray double crystal diffraction with Cu K-alpha 1 radiation on conventional x-ray source. The results show that the crystal is rather well crystallized, The x-ray topographies give an evidence of dendritic growth mechanism of C-60 Single crystal, and x-ray double crystal diffraction rocking curve shows that there are mosaic structural defects in the sample. A phase transition st 249+/-1.5% K from a simple cubic to a face centered cubic structure is confirmed by in situ observation of synchrotron radiation white beam x-ray topography with the temperature varing from 230 to 295 K.

60%电光效率高功率激光二极管阵列

设计并制备了980 nm高量子效率和极低光损耗的激光二极管(LD)外延材料和器件。微通道封装1 cm激光二极管阵列在连续(CW)工作条件下最大电光效率达到60.0%,相应的斜率效率和输出光功率分别为1.1 W/A和38.2 W。测试得到外延材料的内损耗系数和内量子效率分别为0.58 cm~(-1)和91.6%。测试分析表明,器件电光效率的提高主要在于新型的InGaAs/GaAsP应变补偿量子阱和大光腔结构设计。

Zn-doped InGaAs Base Heterojunction Bipolar Transistors Grown by Low Pressure Metal Organic Chemical Vapor Deposition

High performance InP/InGaAs heterojunction bipolar transistors(HBTs) have been widely used in high-speed electronic devices and optoelectronic integrated circuits. InP-based HBTs were fabricated by low pressure metal organic chemical vapor deposition(MOCVD) and wet chemical etching. The sub-collector and collector were grown at 655 ℃ and other layers at 550 ℃. To suppress the Zn out-diffusion in HBT, base layer was grown with a 16-minute growth interruption. Fabricated HBTs with emitter size of 2.5×20 μm~2 showed current gain of 70~90, breakdown voltage(BV_(CE0))>2 V, cut-off frequency(f_T) of 60 GHz and the maximum relaxation frequency(f_(MAX)) of 70 GHz.

60瓦半导体激光器光纤耦合器件

应用光纤列阵耦合方式，对大功率半导体激光器线列阵输出光束的快轴方向用一根柱透镜准直，准直后的光速耦合到光纤列阵中，实现出纤功率为60瓦的大功率半导体激光二极管线列阵光纤耦合效率大于80％，光纤的数值孔径NA为0.11。

Adsorption of oxygen on KxC（60） studied by photoelectron spectroscopy

国家自然科学基金

Photoemission evidence for dilute k-doped phase KxC（60） with x<0.2

于2010-11-23批量导入

Improved digital processing method used for image motion measurement based on hybrid opto-digital joint transform correlator

Hybrid opto-digital joint transform correlator (HODJTC) is effective for image motion measurement, but it is different from the traditional joint transform correlator because it only has one optical transform and the joint power spectrum is directly input into a digital processing unit to compute the image shift. The local cross-correlation image can be directly obtained by adopting a local Fourier transform operator. After the pixel-level location of cross-correlation peak is initially obtained, the up-sampling technique is introduced to relocate the peak in even higher accuracy. With signal-to-noise ratio >= 20 dB, up-sampling factor k >= 10 and the maximum image shift <= 60 pixels, the root-mean-square error of motion measurement accuracy can be controlled below 0.05 pixels.