基于改进RUSLE模型的皇甫川流域土壤侵蚀产沙模拟研究

采用GIS与RS技术,以RUSLE模型为基础,增加流域输沙能力与淤地坝拦沙效率模块,并在黄土高原粗沙多沙区流域皇甫川进行验证。模型模拟结果显示:率定期1991-1999年皇甫站实测输沙量与模拟值拟合较好,纳什系数(Nash)与相关系数均超过0.7,而验证期2000-2009年的模拟结果相对较差。不同土地利用状况的土壤侵蚀模数表明:皇甫川流域土壤侵蚀模数超过15 000t/(km2·a)的区域主要发生于裸露的砒砂岩与植被覆盖较差的沙地;而土壤侵蚀模数小于2 500t/(km2·a)的区域主要分布在地势较为平坦的河滩地与植被盖度好的高原区。在相同降雨条件下,皇甫川流域不同土地利用类型土壤侵蚀模数的大小顺序为裸砒砂岩沙地耕地草地林地。根据修正RUSLE模型分析皇甫川流域淤地坝的拦沙效益发现,1991-2009年淤地坝平均年拦蓄泥沙约为0.42亿t,几乎与皇甫站(1955-2010年)年均输沙量0.41亿t相当。     

IDENTIFYING SCANVENGING EFFECTS OF ANTIOXIDANTS ON ACTIVE OXYGEN BY A NEW SYSTEM

ＩＤＥＮＴＩＦＹＩＮＧＳＣＡＮＶＥＮＧＩＮＧＥＦＦＥＣＴＳＯＦＡＮＴＩＯＸＩＤＡＮＴＳＯＮＡＣＴＩＶＥＯＸＹＧＥＮＢＹＡＮＥＷＳＹＳＴＥＭ￥ＭａＹａｏ；ＺｈａｎｇＪｉａｎｚｈｏｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＣｈｅｍｉｓｔｒｙ，ＧｒａｄｕａｔｅＳｃｈｏ...     

CFD simulation of micro-particle trapping under water tweezers

In early research, capture and manipulation of particles were mainly achieved by means of light, electricity and plasma in micro-fabficaton and micro-assembly. A new method is proposed using micro-water jet to form water tweezers to capture solid particles and implement position control of micro-particles. This paper analyzes the basic prin- ciple of water tweezers, and the discrete element method and smoothed particle hydrodynamics method are employed to establish a solid-liquid coupling model used in analyzing the trapping mechanism. A flow field model is set up to simulate dynamic characteristic of water tweezers based on computa- tional fluid dynamics （CFD）. Selection of boundary conditions, initial guess, solver control and convergence strategies of the model are discussed. Velocity and pressure of streamline are predicted and discussed under certain input conditions. Simu- lation results demonstrate that it is an efficiently theoretical method to eventually trap solid particles by water tweezers.     

乳腺癌MiR-34a启动子荧光素酶载体构建及活性测定

提取人乳腺癌细胞（MCF7）基因组DNA,应用PCR扩增miR-34a启动子序列,将其克隆连接到荧光素酶报告质粒p GL3-Basic中;瞬时转染人肾上皮细胞（293T）,检测荧光素酶活性。成功构建了p GL3-miR34a-promoter报告基因载体并对其测序验证,结果表明启动子序列正确,载体具有较高的启动子活性。     

浅谈诡道谋略在散手运动中的运用

文章通过对兵法战术的研究,使广大武术界人士从中吸取更多的营养,使散打谋略的艺术发展到更高的水平。同时也提高广大散手爱好者的技战术素养,提高其对武术精髓的更进一步的认识。     

辐照对MOS结构氧化硅薄膜可靠性的影响

研究了经γ射线辐照后MOS结构的SiO2薄膜中可动离子的能量状态和数量变化。结果表明，辐照后SiO2膜中可动离子的最可机陷阱能量下降，离子总量大大减少。利用内建场增强离子发射模型和可动离子中性化模型对实验结果进行了分析与计算，理论与实验吻合较好。     

钾对镍—钴复合氧化物催化剂表面状态及电子性能的影响

用Ｘ光电子能谱研究了镍—钴复合氧化物催化剂添加助剂Ｋ＋后的结构及表面组成,并结合电导率的测定结果与反应性能相关联,考察了它们之间的关系．研究表明：助剂Ｋ＋的掺入对镍—钴尖晶石复合氧化物的电子性能、表面状态均有影响,能使电子激活能降低,元素结合能减小,氧化反应活性增高．     

女足在对方罚球区30m区域接停球失误原因的调查研究

通过对全运会西安赛区女足预选赛的统计分析，了解到女足队员在攻入对方罚球区附近３０ｍ区域内的接停球失误的主要原因是接停球过大和接停球不到位，次要原因是接停球的方法和方向不当，同时了解到女足的失误多是在原地和非对抗状态下的，因而反映出女足队员的接停球基本技术水平较低，要想尽快提高女足的运动技术水平，冲出亚洲走向世界就必须在女足的接停球基本技术方面下功夫，扎扎实实打好技术功底，才有可能使我国的女足走向奥运．     

关于涤纶碱减量促进剂的探讨

本文运用基本有机理论,对涤纶碱减量所用的促进剂的促进原理以及促进剂的结构与促进作用的关系进行了初步的探讨,从而找出了一条基本规律。     

Conditional gene manipulation: Cre-ating a new biological era

To solve the problem of embryonic lethality in conventional gene knockouts,site-specific recombinase(SSR)systems(Cre-loxP,Flp-FRT,andΦC31)have been used for tissue-specific gene knockout.With the combination of an SSR system and inducible gene expression systems(tetracycline and tamoxifen),stage-specific knockout and transgenic expression can be achieved.The application of this"SSR+inducible"conditional tool to genomic manipulation can be extended in various ways.Alternatives to conditional gene targeting,such as conditional gene trapping,multipurpose conditional alleles,and conditional gene silencing,have been developed.SSR systems can also be used to construct precise disease models with point mutations and chromosomal abnormalities.With these exciting achievements,we are moving towards a new era in which the whole genome can be manipulated as we wish.