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Search Results: 1 - 10 of 284828 matches for " <br>于雪 "
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Influences of error distributions of net ecosystem exchange on parameter estimation of a process-based terrestrial model

LUO Yiqi,<br>张黎,贵瑞,LUO Yiqi,顾峰,张雷明
生态学报 , 2008,
Abstract: Accuracy of model predictions can be improved by parameter estimation from measurements. It was assumed that measurement errors of net ecosystem exchange of CO2 (NEE) by the eddy covariance technique follow a normal distribution. However, recent studies have showed that errors in eddy covariance measurements closely follow a double exponential rather than a normal distribution. In this paper, we compared effects of different distributions of measurement errors of NEE data on estimation of parameters and carbon fluxes components. Daily NEE measurements from 2003 to 2005 at the Changbaishan forest site were assimilated into a process-based terrestrial ecosystem model. The Markov Chain Monte Carlo method was used to derive the probability density functions of estimated parameters. Our results showed the modeled annual total gross primary production (GPP) and ecosystem respiration (Re) using the normal error distribution were higher than those using the double exponential distribution by 61-86 g C m-2 a-1 and 107-116 g C m-2 a-1, respectively. As a result, modeled annual sum of NEE under an assumption of the normal error distribution was lower by 29-47 g C m-2 a-1 than that under the double exponential error distribution. Especially, the modeled daily NEE based on the normal distribution underestimated the strong carbon sink in Changbaishan forest during the growing seasons. We concluded that types of measurement error distributions and corresponding cost functions can substantially influence parameter estimation and estimated carbon fluxes with data assimilation.
Production of Monoclonal Antibodies to Tomato Mosaic Virus and Application in Virus Detection

Yu Cui Wu Jianxiang,Zhou Xueping,<br>,吴建祥,
微生物学报 , 2002,
Abstract: Four hybridoma cell lines secreting monoclonal antibodies(MAbs) against Tomato mosaic virus(ToMV) were produced by fusing mouse myeloma cells(SP2/0) with spleen cells from BAL B/c immunized by the ToMV particle. The four MAbs could specifically react with ToMV, and the MAbs from two cell lines can react with ToMV and TMV simultaneously. The titres of ascitic fluids of four MAbs ranged from 1:32,000 to 1:1,024,000 with ELISA, and the sensitivity for detection virus from the plant sap reached over 1:2000 dilution. The MAbs didn't crossreact with other plant viruses. The result of Western-blot showed that two MAbs can react with the 17.6 kD ToMV coat protein submit specifically, while the other two MAbs can not react with it, they are supposed to against conformational determinants of ToMV CP.

YAN Xue YU Dan,LI Yong-Ke,<br>严,,李永科
植物生态学报 , 2003,
Abstract: 研究在不同CO_2浓度下水生克隆植物刺苦草(Vallisneria spinulosa)整个生活周期中生长的动态变化及对营养元素积累情况。在不损伤植物体的前提下,采用刺苦草形态学指标组合史估计了植株生物量的动态变化。结果表明:刺苦草鳞茎的萌发不受CO_2浓度变化的影响。在高浓度CO_2即(1000±50)μmol·mol~(-1)下,刺苦草源株地上部分生长速率在整个生长前期和中期都远远高于低浓度CO_2即(400±20)μmol·mol~(-1),而在后期则出现相反的现象,其中一个原因是因为高浓度CO_2下后期光合物质向地下大量转移形成鳞茎引起地上部分生长减慢。但高浓度CO_2下克隆株中的初级和次级分株生长速率均高于低浓度CO_2。在两种CO_2浓度下相同克隆植株构件中的总碳含量没有明显差异;除鳞茎外,根、叶、匍匐茎中的总磷含量随CO_2浓度升高显著增加;由于各构件生物量增加有明显差异,导致叶和鳞茎因为生物稀释作用而使其含氮量降低了12%~14%,但根和茎中含量基本保持不变。在高浓度CO_2中植株总生物量显著升高,所以总碳、总氮和总磷吸收量均显著大于在低浓度CO_2中的吸收量。研究结果揭示,大气CO_2浓度升高对沉水克隆植物生长的促进,有利于提高水生克隆植物在群落中的竞争能力;水生植物克隆生长将增加水生生态系统中碳的沉积;水环境中N
Determination of binding domains of paeonol on immobilized human serum albumin by high-performance affinity chromatography

YU Xue,ZHANG Juncai,WEI Yinmao,<br>,张君才,卫引茂
色谱 , 2010,
Abstract: 利用亲和色谱,在模拟人体生理环境下(37 ℃、pH 7.4),采用竞争置换法研究了丹皮酚(PAE)与固定化人血清白蛋白(HSA)的相互作用。通过对PAE的自我竞争分析及PAE与HSA上结合位点的标记物间的竞争置换分析,得到了PAE和HSA间的结合常数、结合位点数和结合域。结果表明: PAE在HSA分子中仅存在一类结合位点,结合常数为4.84×103 L/mol,该结合位点为HSA上的Sudlow siteII;通过对PAE与HSA相互作用的热力学研究,推断出二者间的作用力类型为氢键或范德华力。
Experimental Study of RIP to Resist Virus in vitro

YU Hai,WANG Xue-Peng,CHANG Wei-Shan,<br>,,常维山
微生物学通报 , 2005,
Abstract: Ribosome inactivating protein(RIP) is a kind of toxin plant pr ot ein in which extensively lives in the body of higher plants and controls ribosom e's function. Beside it can control protein's combination,it has lots of biolog ical reactivity as resisting giving birth and tumor and controlling HIV. At fir st, RIP is isolated from seeds of bitter melon.The result of SDS-PAGE indicate s that there are lots of RIP in the abstraction liquid.Then we study the antivi ral action of RIP through the cell of CEF and SPF chicken embryos.The results s how that RIP can resist NDVF_48E_8,MDVCVI_988 and FPV-SD4 to so me extent.
Studies of Effects of Lipid on Rat Fetal Neural Stem Cells

John RMorrison,<br>李,扈廷茂,扎拉嘎胡,海泉,John R.Morrison
遗传 , 2002,
Abstract: Rat fetal neural stem cells (rFNSCs) was separated from embryo about 14.5-16.5 days, and cultured in DMEM/F12 media with additives and epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF). Effects of lipid on growth and proliferation of rFNSCs was examined by counting the number of neurospheres and incorporation of 3H. The data show that chemical defined lipid improved rFNSCs' growth and cell division. Lipid will be another neural stem cell's culture media's additive.
Determination of atmospheric CO and CH4 by GC-FID equipped with a low-pressure injector

WU Liling,ZENG Limin,YU Xuena,SHAO Min,<br>吴丽玲,曾立民,,邵敏
环境科学学报 , 2010,
Abstract: An improved GC-FID equipped with a self-designed low-pressure injector was developed for the determination of low-pressure COand CH4 from the SUMMAcanister.The self-designed injector can increase the sample pressure from lower to 30kPa in the canister to 100kPa effectively.The improved system could successfully separate O2,COand CH4 with a combination of three 6-port valves,two columns(5 and TDX-01) and back-flushing techniques.The 5 packed column used as pre-column can remove impurities effectively,keep the baseline smooth and enhance analytical efficiency.The detection limit of the improved GC-FIDmethod can reach 9.2 × 10-9 for COand 5.5 × 10-9 for CH4.International inter-comparison between the laboratories of Peking University and University of California Irvine was conducted and the relative errors between the two laboratories for COand CH4 were below 3% and 1%,respectively.
Online monitoring system for volatile organic compounds in the atmosphere

LIU Xinglong,ZENG Limin,LU Sihua,YU Xuena,<br>刘兴隆,曾立民,陆思华,
环境科学学报 , 2009,
Abstract: 一种新型的监测大气中挥发性有机物(包括含氧挥发性有机物)的在线监测系统被研制,即将超低温冷阱捕集-热解析装置与气相色谱-质谱仪联用.其分析方法是大气样品经除水、除O3后以60 mL·min-1的流速通过温度为-150℃的超低温冷阱捕集5min,然后样品在110℃下解析后进入GC-FID/MS系统进行分析,时间分辨率为1h.系统使用混和标气进行标定.目标化合物定量曲线的R2值为0.9137~0.9998,相对标准偏差(RSD)均小于10%.将系统与相关商业化的VOC在线监测仪器进行比对,对于相同目标化合物进行分析,其相关系数r在0.7412~0.9620之间.
Expressions of PDCD4 and survivin in condyloma acuminatum, Bowenoid papulosis, Bowen disease and squamous cell carcinoma

淑萍,, 王丹, 王玉坤<br>YU Shuping, LI Xuefei, WANG Dan, WANG Yukun
- , 2015, DOI: 10.6040/j.issn.1671-7554.0.2014.864
Color image selective segmentation under geometrical constraints

,李树荣,,王家岩<br>WANG Xueqin, LI Shurong, YU Yu, WANG Jiayan
- , 2018, DOI: 10.6040/j.issn.1672-3961.0.2017.067
Abstract: 摘要: 为了解决彩色图像分割任务中有选择性的定位感兴趣区域的具体需求,基于Lavdie-Chen的灰度图像单水平集选择性分割方法,提出带几何约束的彩色图像选择性分割方法。该试验方法将彩色图像作为一个整体,求其梯度及边缘检测函数,借助边缘检测函数、目标物体约束点确定的距离函数以及形成的多边形内外面积,共同决定曲线演化进程中的方向与速度。区域信息的加入克服了边缘函数依赖单一图像梯度的缺点;正则化优化算法的引入克服了凹陷处分割效果不理想的缺点;加法分裂算子算法可以快速求解模型的Euler-Lagrange方程。试验结果表明,本研究提出的彩色图像选择性分割方法具有有效性强和正确性高的特点。
Abstract: In order to solve the specific requirements of selectivity during the course of color image segmentation, an active contour-based color image segmentation method under geometrical constraints was proposed based on the gray image selective segmentation using one level set by Lavdie-Chen. A color image was treated as a whole for the gradient and the edge detection function. The velocity and direction of the curve evolution were determined by the edge detection function, the distance function defined about a set of points near the boundary of the interested region and the inner and outer polygon areas of the given points. Region information could help to overcome the drawbacks of edge functions relying on a single image gradient; the regularization algorithm was introduced to overcome the shortcomings of the poor segmentation effect in the depression;the Euler-Lagrange equation was quickly solved by the additive operator splitting method. Experimental results showed that the proposed color image segmentation method had the characteristics of high validity and high accuracy to selectively segment the wanted region
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