干旱地区陆面过程耦合模式及应用

主要论述干旱地区陆面过程在改善人类生存环境与研究区域经济中的重要地位与研究现状, 强调了采用耦合模式的必要性, 详细描述了该模式的特点, 并将它应用于我国西北腾格里沙漠南缘植物固沙区的水热循环研究, 揭示干旱区陆面过程的主要特征, 并同现场测试进行了比较.

On The Thermally Induced Cracking Of A Segmented Coating Deposited On The Outer Surface Of A Hollow Cylinder

In this work, the thermally induced cracking behavior of a segmented coating has been investigated. The geometry under consideration is a hollow cylinder with a segmented coating deposited onto its outer surface. The segmentation cracks are modeled as a periodic array of axial edge cracks. The finite element method is utilized to obtain the solution of the multiple crack problem and the Thermal Stress Intensity Factors (TSIFs) are calculated. Based on dimensional analysis, the main parameters affecting TSIFs are identified. It has been found that the TSIF is a monotonically increasing function of segmentation crack spacing. This result confirms that a segmented coating exhibits much higher thermal shock resistance than an intact counterpart, if only the segmentation crack spacing is narrow enough. The dependence of TSIF on some other parameters, such as normalized time, segmentation crack depth, convection severity as well as material constants, has also been discussed. (C) 2008 Elsevier B.V. All rights reserved.

Asymmetry of the photoionization rate of H atoms by a sequence of one-cycle laser pulses

Using an unperturbed scattering theory, the characteristics of H atom photoionization are studied respectively by a linearly- and by a circularly- polarized one-cycle laser pulse sequence. The asymmetry for photoelectrons in two directions opposite to each other is investigated. It is found that the asymmetry degree varies with the carrier-envelope (CE) phase, laser intensity, as well as the kinetic energy of photoelectrons. For the linear polarization, the maximal ionization rate varies with the CE phase, and the asymmetry degree varies with the CE phase in a sine-like pattern. For the circular polarization, the maximal ionization rate keeps constant for various CE phases, but the variation of asymmetry degree is still in a sine-like pattern.

激光辐照引起Ge2Sb2Te5非晶态薄膜的电/光性质变化

研究了激光辐照引起Ge2Sb2Te5非晶态薄膜的电/光性质变化,当激光功率为580mW时薄膜的方块电阻有四个数量级（10^7～10^3Ω/□）的突变;对电阻发生突变前、中、后的三个样品进行了XRD测试,结果表明,随着激光功率的增大,薄膜由非晶态向晶态转变,用椭偏仪测试了结构转变前、中、后三个样品的光学常数,在可见光范围内薄膜的光学常数在波长相同情况下有：n（非晶态）〉n（中间态）〉n（晶态）,k（晶态）〉k（中间态）〉k（非晶态）,α（晶态）〉α（中间态）〉α（非晶态）,结合电阻变化曲线和XRD图谱讨论了激光辐照Ge2Sb2Te5非晶态薄膜的电/光性质变化同激光功率和结构转变之间的关系.

A four-passed ytterbium-doped fiber amplifier

In this paper, a four-passed ytterbium-doped fiber amplifier (YDFA) is discussed. The gain and the pump and the signal light propagation characteristics of the four-passed YDFA are described. It is found that, while using a shorter length of the fiber, a four-passed fiber amplifier can realize the same output power as a single-pass fiber amplifier, and, for the same fiber lengths, a four-passed fiber amplifier offers a significantly higher power than its single-pass counterpart. (C) 2006 Elsevier Ltd. All rights reserved.

广西华缨鱼属鱼类一新种记述

在整理华缨鱼属标本时发现，1993年9月在广西壮族自治区天峨县红水河水系地下河采集到的一批 标本为一个未经发表的新种，新种订名为大眼华缨鱼(＆加c瑚soc^eiz獬胧gnzDp^f^8h邯)。其下咽齿2行，可与 下咽齿3行的7种华缨鱼相区别，而与属内同样具2行下咽齿的贵州华缨鱼(s．肛妇b淝瑚括)、小口华缨鱼 (Js．m幻M幻，抛￡琳)和宽唇华缨鱼(5．z06缸t琳)亲缘关系较近。但：(1)新种胸鳍中点上方无黑斑，背鳍分枝 鳍条7，腹鳍分枝鳍条7，背鳍前鳞15—16，眼大，头长为眼径2．5—3．1倍，眼径为头宽44．7％一57．8％，吻 须后伸至前后鼻孔之间或眼前缘，口角须后伸至眼前缘至眼中之问或眼中至眼后缘之间，体长为尾柄高8．9一 lO．7倍，头长为吻长2．5—3．7倍，可与贵州华缨鱼(胸鳍中点上方有一明显黑斑，背鳍分枝鳍条8，腹鳍分枝 鳍条8，背鳍前鳞12—14，头长为眼径4．O一5．0倍，眼径为头宽16．6％一20．7％，吻须后伸不达后鼻孔后缘， 口角须后伸至眼前缘，体长为尾柄高7．2—8．2倍，头长为吻长1．9—2．2倍)相区别；(2)新种背鳍前鳞15— 16，侧线鳞39～40，侧线上鳞4．5—5．5，背鳍分枝鳍条7，鳃耙13，腹鳍末端伸达肛门，眼径为头宽44．7％一 57．8％，可与宽唇华缨鱼(背鳍前鳞22，侧线鳞42—45，侧线上鳞6．5，背鳍分枝鳍条8，鳃耙10，腹鳍末端 不达肛门，眼径为头宽23．3％一30．O％)相区别；(3)新种与同水系的小口华缨鱼在鳍条数、侧线鳞、体色、 斑纹等方面最为相似，但新种围尾柄鳞14／16，眼大，头长为眼径2．5—3．1倍，腹鳍末端伸达肛门，口角须后 伸至眼前缘至眼中之间或眼中至眼后缘之间，吻皮边缘深裂成小穗，背鳍起点距吻端较距尾鳍基为近，背鳍长 大于头长，体长为尾柄长4．8—5．9倍，头长为吻长2．5—3．7倍，尾柄长为尾柄高1．6—2．1倍，可与之(围尾 柄鳞12，眼小，头为眼径4．4—4．6倍，腹鳍末端不达肛门，口角须伸达眼下方，吻皮边缘不开裂或开裂不明 显，背鳍起点距吻端等于距尾鳍基，背鳍条约等于头长，体长为尾柄长6．1—6．4倍，头长为吻长2，1—2．4倍， 尾柄长为尾柄高1．4—1．5倍)相区别。

外源抗坏血酸对烟草细胞生长及衰老的影响

用不同浓度的外源抗坏血酸(ASA)对BY-2烟草悬浮细胞进行处理,测定了细胞中可溶性蛋白质含量、脂质过氧化产物丙二醛(MDA)含量、相对电解质渗透率、超氧化物歧化酶(SOD)活性、抗坏血酸(ASA)含量和还原型谷胱甘肽(GSH)含量等生理生化指标,从细胞脂质过氧化及抗氧化功能的角度探讨了不同浓度抗坏血酸对BY-2烟草悬浮细胞生长及衰老的影响。结果表明,当用2mmol.L-1 ASA处理时,能促进细胞分裂生长,增加可溶性蛋白产量,减少膜透性和MDA含量,维持SOD活性和ASA与GSH含量在较高水平,说明AS

HLA-DRB1等位基因多态性与食管癌遗传易感性研究

目的 :从基因水平探讨湖北地区汉族人食管癌HLA -DRB1等位基因的遗传易感性。方法 :运用序列特异性引物聚合酶链反应结合基因序列分析等技术 ,检测无亲缘关系湖北汉族健康人 136例、食管癌组 4 2例患者的HLA -DRB1等位基因。SAS统计软件数据处理。结果 :湖北地区汉族人食管癌患者与正常人比较 ,HLA -DRB1 0 90 1基因频率显著增高 (0 2 5 0 0vs 0 1397,P =0 0 2 8,OR =2 0 5 3,病因分数 =0 12 82 ) ;两者间其余HLA -DRB1等

Dependence of bimodal size distribution on temperature and optical properties of InAs quantum dots grown on vicinal GaAs (1-00) substrates by using MOCVD

Self-assembled InAs quantum dots (QDs) are grown on vicinal GaAs (100) substrates by using metal-organic chemical vapour deposition (MOCVD). An abnormal temperature dependence of bimodal size distribution of InAs quantum dots is found. As the temperature increases, the density of the small dots grows larger while the density of the large dots turns smaller, which is contrary to the evolution of QDs on exact GaAs (100) substrates. This trend is explained by taking into account the presence of multiatomic steps on the substrates. The optical properties of InAs QDs on vicinal GaAs(100) substrates are also studied by photoluminescence (PL). It is found that dots on a vicinal substrate have a longer emission wavelength, a narrower PL line width and a much larger PL intensity.

结构化P2P网络上可靠的基于内容路由协议

在结构化P2P网络上构建基于内容的发布/订阅系统,可以很好地支持大规模、高度动态的分布式应用.然而,现有的基于内容的路由协议在P2P网络上只能提供弱的可靠性保证.根据结构化P2P网络的路由协议的特点,设计了一种新型的基于内容的路由协议——基于编码区间的路由(identifierrangebasedrouting,简称IRBR)协议.IRBR协议具有良好的容错性,只要事件的发布者与订阅者之间在P2P网络中是可达的,则订阅者一定能够收到它所订阅的事件,且只收到一次.同时,该协议也比现有的协议具有更高的事件路由效率.在Pastry上开发了一个原型系统,模拟实验表明了该协议的效率和容错性.