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1.
次序期刊名称 总被引频 次1996,1997年发文数 (篇 )1996,1997年论文在 1998年被引次数影响因子即年指标基金论文数 (篇 )1武汉测绘科技大学学报 9115 7 42 0 .2 680 .0 2 3 5 02中国矿业大学学报 12 2 197 5 2 0 .2 64 0 .0 18623北京大学学报 187 2 17 5 60 .2 5 80 .0 78864青岛海洋大学学报 164 162 40 0 .2 470 .0 5 2 785华侨大学学报 99182 42 0 .2 3 10 .0 845 56清华大学学报 2 83 5 7412 80 .2 2 3 0 .0 43 2 3 87成都理工学院学报 11814 12 80 .1990 .0 3 63 58长春科技大学学报 13 8163 3 10 .190 0 .0 3 63 18哈尔滨工业大学学…  相似文献   

2.
为了促进对虾养殖业可持续发展 ,我们对养殖周期短、虾苗成活高、抗病力强的南美白对虾进行了普通池塘养殖、沙滩提水式养殖、高密度养殖、咸淡水养殖、淡化养殖等综合技术试验研究 ,经过一年多的试验研究与推广 ,获得了显著的效果。1 材料与方法1 .1 材料1 .1 .1 普通池塘养殖试验 池塘为泥质普通池塘 ,面积 0 .53 hm2的池塘试养南美白对虾 ,面积0 .67hm2 池塘养殖斑节对虾 ,水深均为 2 .0 m,1 999年 7月 2 3日投放体长 1 .0 cm南美白对虾苗1 2万尾和斑节对虾苗 1 3万尾 ,放苗密度分别为 2 2 .5万尾 /hm2 和 1 9.5万尾 /hm2 。1 .1 .2…  相似文献   

3.
The physiological responses of Nitzschia palea Kvtzing, a freshwater diatom, to elevated CO2 were investigated and compared with those of a marine diatom, Chaetoceros muelleri Lemmermann previously reported. Elevated CO2 concentration to 700 μl/L increased the dissolved inorganic carbon (D!C) and lowered the pH in the cultures of N. palea, thus enhancing the growth by 4%-20% during the whole growth period. High CO2-grown N. palea cells showed lower levels of dark respiration rates and higher Ik values. Light-saturated photosynthetic rates and photosynthetic efficiencies decreased in N. palea with the doubling CO2 concentration in airflow to the bottom of cultures, although the doubling CO2 concentration in airflow to the surface cultures had few effects on these two photosynthetic parameters. N. palea cells were found to be capable of using HCO5 in addition to gaseous CO2, and the CO2 enrichment decreased their affinity for HCO5 and CO2. Although doubled CO2 level would enhance the biomass of N. patea and C. muelleri to different extents, compared with the marine diatom, it had a significant effect on the specific growth rates of N. palea. In addition, the responses of photosynthetic parameters of IV. palea to doubled CO2 concentration were almost opposite to those of C. muelleri.  相似文献   

4.
湿地植物香蒲光合特性及其影响因素分析   总被引:1,自引:0,他引:1  
以湿地植物香蒲为材料,在水平潜流人工湿地处理单元中,采用便携式LI-6400光合作用测定仪测定其成熟叶片净光合速率(Pn)日变化,研究其光合生理生态特性。结果表明:香蒲叶片净光合速率(Pn)日变化呈双峰曲线,主峰(22.0μmol.m-2.s-1)出现在9:00左右,次峰(16.9μmol.m-2.s-1)出现在15:00,光合"午休"现象明显,且非气孔限制是产生光合"午休"的主要原因。用逐步多元回归方法得到净光合速率日变化与主要生理生态因子的回归方程为:yPn=0.7692+29.7059 xGs-0.7689xTr+0.014 2 xPAR(复相关系数0.9563,显著水平P=0.0001;叶片净光合速率Pn,μmol.m-2.s-1;气孔导度Gs,mol.m-2.s-1;蒸腾速率Tr,mmol.m-2.s-1;光合有效辐射PAR,μmol.m-2.s-1)。偏相关分析和通径分析的结果表明Gs、Tr和PAR与Pn的日变化显著相关,是影响香蒲Pn的主要因子,影响大小的顺序为:Gs>PAR>Tr。香蒲叶片Pn-PAR的响应曲线方程为yPn=-5×10-6 xPAR 2+0.0207 xPAR-1.3728(相关系数0.9935,显著水平p=0.000 1),光补偿点、光饱和点和表观量子效率分别为32.9μmol.m-2.s-1、147 6μmol.m-2.s-1、0.023 3 mol.mol-1;Pn-CO2的响应曲线方程为yPn=-2×10-5 w(CO2)2+0.054 9 w(CO2)-1.44 4(相关系数0.9694,显著水平p=0.000 1;w(CO2)单位为μmol.mol-1),CO2补偿点、CO2饱和点和羧化效率分别为23.7μmol.mol-1、621.4μmol.mol-1和0.0768 mol.m-2.s-1。  相似文献   

5.
养殖条件下倒刺鲃的年龄与生长   总被引:1,自引:0,他引:1  
研究了倒刺的年龄与生长规律 ,结果表明 :倒刺鳞片年轮特征主要为疏密切割型。体长与鳞长之间的直线相关L =2 .0 85 4+2 .36 2 0R和幂函数相关L =2 .85 12R0 .952 9中 ,以幂函数相关性密切 ;体重与体长呈指数函数相关W =2 .4 984× 10 - 2 L2 .9936 。 4龄以前生长较快 ,生长指标高 ,体长指标高 ,体长和体重的相对增长率大 ,其生长规律可用VonBertalanffy方程表达 :Lt=[1-e- 0 .132 5(t+ 0 .2 0 95) ],Wt=132 76 .4 0 [1-e- 0 .132 4 (t+ 0 .2 0 95) ]3。体重生长曲线的拐点位于t =8.0 9龄、W8.0 9=3933.6 1g ,即Wt=0 .2 96W∞ 处。倒刺雌性一般在 5龄性成熟 ,雄鱼 3~ 4龄时性成熟。建议江河捕捞对象应为 5 + 龄以上的个体。  相似文献   

6.
To improve the expression efficiency of exogenous genes in Chlamydomonas reinhardtii,a high efficient expression vector was constructed.Green fluorescent protein(GFP) was expressed in C.reinhardtii under the control of promoters:RBCS2 and HSP70A-RBCS2.Efficiency of transformation and expression were compared between two transgenic algae:RBCS2 mediated strain Tran-Ⅰ and HSP70A-RBCS2 mediated strain Tran-Ⅱ.Results show that HSP70A-RBCS2 could improve greatly the transformation efficiency by approximately eightfold of RBCS2,and the expression efficiency of GFP in Tran-Ⅱ was at least double of that in Tran-Ⅰ.In addition,a threefold increase of GFP in Tran-Ⅱwas induced by heat shock at 40°C.All of the results demonstrated that HSP70A-RBCS2 was more efficient than RBCS2 in expressing exogenous gene in C.reinhardtii.  相似文献   

7.
To improve the expression efficiency of exogenous genes in Chlamydomonas reinhardtii, a high efficient expression vector was constructed. Green fluorescent protein (GFP) was expressed in C. reinhardtii under the control of promoters: RBCS2 and HSP70A-RBCS2. Efficiency of transformation and expression were compared between two transgenic algae: RBCS2 mediated strain Tran-Ⅰ and HSP70A-RBCS2 mediated strain Tran-Ⅱ. Results show that HSP70A-RBCS2 could improve greatly the transformation efficiency by approximately eightfold of RBCS2, and the expression efficiency of GFP in Tran-Ⅱ was at least double of that in Tran-Ⅰ. In addition, a threefold increase of GFP in Tran-Ⅱ was induced by heat shock at 40℃. All of the results demonstrated that HSP70A-RBCS2 was more efficient than RBCS2 in expressing exogenous gene in C. reinhardtii.  相似文献   

8.
INTRODUCTIONMarinemicroalgaeacquiretheirinorganiccarbonforphotosynthesisfromseawaterwhereinorganiccarbonmaybepresentasfreeCO2 ,H2 CO3andHCO-3 andCO2 -3 .TheproportionsofdifferentDICformsareprimarilyrelatedtopH ,andtotemperatureandsalinitytoalessextent.ThetotalDICisashighas2mmol Linseawa terbutthisismainlyintheformofHCO-3 .InnormalpHrangeof7.8-8.2inseawater,HCO-3 accountsfororethan 90 %ofthetotalDIC,whilefreeCO2 islessthan1 % .TheequilibriumconcentrationoffreeCO2 isonly1 2 μm…  相似文献   

9.
2-haloacid dehalogenases constitute a group of dehalogenases which are capable of dehalogenating the halogenatedorganic compounds. So far, the 2-haloacid dehalogenases have been found in many bacteria, but not in Paracoccus genus. In thepresent study, one enzyme 2-haloacid dehalogenase (designated as Deh99), induced by DL-2-chloropropionate (DL-2-CPA), waspurified from the marine bacterium Paracoccus sp. DEH99, isolated from marine sponge Hymeniacidon perlevis. The enzyme ofDeh99 was purified to homogeneity by ammonium sulfate precipitation, ion exchange chromatography (Q-Sepharose HP), and Su-perdex 200 gel filtration chromatography. The molecular weight of Deh99 was estimated to be 25.0 kDa by sodium dodecyl sul-fate-polyacrylamide gel electrophoresis (SDS-PAGE), and 50.0 kDa natively by gel filtration chromatography. The enzyme of Deh99stereospecifically dehalogenated L-2-CPA to produce D-lactate, with an apparent Michaelis-Menten constant (Kin) value of0(21 mmolL-1 for L-2-CPA. The optimal pH and temperature for Deh99 activity were 10.0 and 40°C, respectively. The enzyme ofDeh99 acted on short-carbon-chain 2-haloacids, with the highest activity towards monochloroacetate. The activity of Deh99 wasslightly affected by DTT and EDTA, but strongly inhibited by Cu2+ and Zn2+. The enzyme of Deh99 shows unique substrate specific-ity and inhibitor sensitivities compared to previously characterized 2-haloacid dehalogenases and is the reported one about purified 2-haloacid dehalogenase isolated from the bacteria of Paracoccus genus.  相似文献   

10.
Because of the large number and remoteness, satellite data, including microwave data and optical imagery, have commonly been used in alpine glaciers surveys. Using remote sensing and Geographical Information System (GIS) techniques, the paper presents the results of a multitemporal satellite glacier extent mapping and glacier changes by glacier sizes in the Mt. Qomolangma region at the northern slopes of the middle Himalayas over the Tibetan Plateau. Glaciers in this region have both retreated and advanced in the past 35 years, with retreat dominating. The glacier retreat area was 3.23 km2 (or o.75 km^2 yr^-1 during 1974 and 1976, 8.68 km^2 (or 0.36 km^2 yr^-1 during 1976 and 1992, 1.44 km^2 (or 0.12 km^2 yr^-1) during 1992-2ooo. 1.14 km^2 (or 0.22 km^2 yr^-1 during 2000-2003, and 0.52 km^2 (or 0.07 km^2 yr^-1 during 2003-2008, respectively. While supra-glacier lakes on the debris-terminus of the Rongbuk Glacier were enlarged dramatically at the same time, from 0.05 km^2 in 1974 increased to 0.71 km^2 in 2008, which was more than 13 times larger in the last 35 years. In addition, glacier changes also showed spatial differences, for example, glacier retreat rate was the fastest at glacier termini between 5400 and 5700 m a.s.l than at other elevations. The result also shows that glaciers in the middle Himalayas retreat almost at a same pace with those in the western Himalayas.  相似文献   

11.
A stochastic two-dimensional Fornasini-Marchesini's Model Ⅱ (2-D FMM Ⅱ) with multiplicative noise is given,and a filtering algorithm for this model, which is optimal in the sense of linear minimum-variance, is developed. The stochastic 2-D FMM Ⅱ with multiplicative noise can be reduced to a 1-D model, and the proposed optimal filtering algorithm for the stochastic 2-D FMM Ⅱ with multiplicative noise is obtained by using the state estimation theory of 1-D systems. An example is given to illustrate the validity of this algorithm.  相似文献   

12.
高斯和滤波可利用高斯混合模型精化非高斯噪声随机模型来提高估计精度,但导航测量环境的动态性和复杂性使非高斯噪声具有时变性特征,若GMM不随之调整会导致滤波解算失真。针对该问题,本文提出一种基于位移参数自适应估计的高斯和滤波算法。首先分析GMM位移参数对非高斯噪声拟合精度的影响,然后利用位移参数自适应技术修正GMM,进而改善高斯和滤波性能。实验结果表明,当GNSS/SINS量测模型存在时变非高斯噪声时,本文算法的滤波结果较传统高斯和滤波算法的波动小,抗干扰能力强,在实际应用中可进一步改善估计精度和稳定性。  相似文献   

13.
针对现有的基于机载LiDAR数据的滤波算法未能充分利用数据提供的所有信息及其所采用的数据结构表达复杂、存在信息损失等缺陷,提出了一种灰度体素结构分割模型下的机载LiDAR 3D滤波算法。算法首先以综合利用机载LiDAR数据的高程及强度信息为目的将点云数据规则化为灰度(体素内激光点的平均强度的离散化表示)体素结构,然后基于各体素间的空间连通性和灰度相似性准则,将灰度体素结构分割并标记为若干个3D连通区域,最后依据地面与其它目标的高差特性提取与其对应的3D连通区域。算法优势在于:基于体素结构设计,为3D滤波算法;综合利用了地面目标的几何及辐射特征,对比传统滤波算法可应用于更复杂的场景;滤波结果为3D地面体素形式,可直接用于创建地面3D模型。实验采用国际摄影测量与遥感协会(International Society for Photogrammetry and Remote Sensing, ISPRS)提供的不同密度的机载LiDAR基准测试数据测试了邻域尺度参数的敏感性及提出的算法的有效性,并和其他经典滤波算法做对比。定量评价的结果表明,51邻域为最佳空间邻域尺度;点云密度为0.67点/m2的数据集1的滤波平均完整率、正确率及质量分别为0.9611、0.9248及0.8934;点云密度为4点/m2的数据集2的滤波平均完整率、正确率及质量分别为0.8490、0.8531及0.7404;对比其全经典滤波算法本文算法在高密度点云数据滤波时表现更佳。  相似文献   

14.
使用GAMIT/GLOBK软件处理四川省内23个连续GPS基准站2010~2015年数据,获取各测站的坐标时间序列,然后利用堆栈法对其进行空间滤波以剔除共模误差,通过谱指数计算和最大似然估计法(MLE)对滤波后的GPS站坐标时间序列进行噪声分析。结果表明,四川连续GPS基准站坐标时间序列N、U方向最优噪声模型为WN+FN,E方向最优噪声模型为WN+FN+RWN;空间滤波可以降低闪烁噪声,同时使一些测站显现出随机漫步噪声;根据GPS站坐标时间序列估计基准站速度时,应当顾及有色噪声的影响。  相似文献   

15.
??L P ????????£?????????λ???????????????????о?????????????3???????????????????????Bam?????????SAR??????????????????????????:Goldstein?????????Ч???????е??????????,??????????????Ч??????????????????????L 1?????????????????????????????Ч?????L 2?????????????????????????Ч?????L 0????????????????????????????????????????????????????????  相似文献   

16.
使用Bernese 5.2软件双差定位程序处理西南极区域24个GPS基准站9 a的观测资料,获得各站单日解坐标时间序列.利用主分量分析法和独立分析法对其进行空间滤波,对比分析2种方法的滤波效果,然后采用极大似然估计法分析滤波前后各站时间序列的噪声特征,建立最优噪声模型,并分析共模误差对测站速度的影响.结果表明,2种方法...  相似文献   

17.
经典Kalman滤波要求噪声是高斯白噪声,而动态GNSS定位的观测误差和状态预测误差往往是有色噪声。本文提出一种简便的有色噪声函数模型拟合滤波算法,采用前面历元的观测残差和状态残差建立有色噪声模型,削弱有色噪声对动态导航解算的影响。采用四星座GNSS接收机观测数据进行动态导航实验,结果表明,顾及有色噪声的动态导航滤波算法比未顾及有色噪声的经典Kalman滤波算法定位精度更高,三维位置精度提升9%以上。  相似文献   

18.
Demigration refers to directly applying a specific imaging technique to a migrated section. It is applied primarily to seismic data mapping. In a previous research study,a time-efficient implementation technology of demigration was expounded. In the present study,the Fast Marching Method( FMM) used for traveltime computation in the isochrone-stack demigration,is developed. Furthermore,other key techniques( such as selection of aperture and antialiasing filtering factor) are analyzed in detail. Besides,the detail implementation method and program flow are given,which is shown their good computational efficiency and high-quality demigration effect. This implementation technique is illustrated with both the V( z) model and Marmousi model. It provides a basic method for implementing demigration in the application of seismic data mapping.  相似文献   

19.
针对灰度图像中的脉冲噪声滤波的问题,提出一种具有细节保护的自适应滤波算法.算法分为两步:第一步是对图像中的噪声进行识别,第二步利用噪声点周围的相关信息,对噪声点进行修复.经实验表明算法与其他算法相比,在图像的细节保护,自适应性以及噪声的消除方面具有一定的优势.  相似文献   

20.
在滑坡的动态监测中通常存在先验几何信息和物理信息,现有的滤波算法并不能够充分利用这些信息,为控制几何观测异常对形变参数估计的影响,提出一种利用滑坡力学状态信息的约束滤波模型.同时,利用约束方程获得有益信息,精确地确定测量的等价权,给出相应的自适应约束抗差滤波算法,并通过实例说明了带有约束的滤波算法更能提高状态参数估计的...  相似文献   

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