共查询到20条相似文献，搜索用时 31 毫秒
1.
The ability of several ab initio models to predict experimental 29Si-NMR chemical shift is examined. The shielding values of trimethylsilyl chloride (A), t-butyldimethylsilyl chloride (B)
and allytrimethylsilane (C) are calculated by GIAO, CSGT and IGAIM methods, using HF/6–31G*, B3LYP/6-31G*, HF/6–311+G**, B3LYP/6–311+G** and MPW1PW91/6–311+G** models respectively. The 29Si chemical shifts calculated by GIAO method using HF/6–311+G** model are highly in agreement with those obtained experimentally. All of the models above reproduce the trends of chemical
shifts in all cases studied, suggesting that the models are of practical value. 相似文献
2.
N-(2-hydroxy-1-naphthaldene)-4-aminoantipyrine has been synthesized. The structure is determined by X-ray diffraction method and elemental analysis. The crystal system belongs to orthorhombic space group P(2)2(1)2(1). The geometry has been ob-tained from the density functional theory (DFT) method and the B3LYP method employing the 6-31G* basis sets. The calculated results propose that the latter is close to the experimental data. The structural parameters from the theory are close to those of the crystal and the calculated total energy of coordination is -31677.172 eV. The energy of HOMO and LUMO and the energy gap are 5.179 eV, -1.603 eV and 3.577 eV, respectively. 相似文献
3.
N-(2-hydroxy-1-naphthaldene)-4-aminoantipyrine has been synthesized. The structure is determined by X-ray diffraction method and elemental analysis. The crystal system belongs to orthorhombic space group P(2)2(1)2(1). The geometry has been ob-tained from the density functional theory (DFT) method and the B3LYP method employing the 6-31G* basis sets. The calculated results propose that the latter is close to the experimental data. The structural parameters from the theory are close to those of the crystal and the calculated total energy of coordination is -31677.172 eV. The energy of HOMO and LUMO and the energy gap are 5.179 eV, -1.603 eV and 3.577 eV, respectively. 相似文献
4.
LIUManhong GAOTianxiang ZHANGXiumei CHENSiqing 《中国海洋大学学报(英文版)》2005,4(1):43-48
To investigate the tissue-specificities of isozymes and the genetic structure of wild spotted halibut ( Verasper variegatus) population, horizontal starch gel electrophoresis was performed on 45 individuals collected in part of the Yellow Sea. The performances of 17 isozymes in 8 kinds of tissues or organs were screened preliminarily in a TC-7.0 buffer system. The results showed that the screened isozymes displayed remarkable tissue-specificities. Finally, 14 enzymes (AAT, ADH, EST, GPI, G3PDH, IDHP, LAP, LDH, MDH, MPI, PGDH, PGM, SDH and SOD) and 4 kinds of tissues (eye, skeleton muscle, liver and heart) were selected for genetic analysis. Fourteen isozymes are encoded by 20 loci, and 9 of them are poly-morphic. The polymorphic loci are AAT-1*, GPI-2*, G3PDH*, IDHP-1*, LDH*, MPI*, PGM-1*, PGM-2* and SDH*, and the proportion of polymorphic loci is 0.450 0 (P0.99). The mean values of observed and expected heterozygosities are 0.027 8 and 0.026 5, respectively and the average effective number of alleles is 1.067 5. 相似文献
5.
Landsat5图像的增益、偏置取值及其对行星反射率计算分析 总被引：12，自引：1，他引：11
在对比不同时相的数据或建立遥感反演模型时,往往需要将图像的灰度值转换为反射率。增益和偏置是计算反射率时使用的两个基本参数。如果这两个参数发生偏差,反射率的计算结果就有问题,大气校正和其他相关工作的结果也是不可靠的。根据USGS文档和1995年以来的Landsat5遥感图像,对图像头文件中的增益和偏置参数的取值进行了分析,并按照标准单位将增益和偏置进行了转换。为了分析不同增益和偏置取值对反射率计算结果的影响,对比计算了植被和水体的行星反射率值。对2004年7月26日的太湖地区的TM图像。取值分为4种方案: (1)使用遥感软件ENV14．0计算;(2)使用图像头文件中的参数;(3)使用USGS提供的同期参数;(4)使用USGS提供的2003年前的参数。结果表明,不同增益和偏置取值导致计算结果变化较大。如果以方案3的USGS参数计算的结果为标准,那么,其他方案的相对误差值可从0．2％到20％以上。从各个波段的误差分布看,以第3波段的相对误差最小。从工作成果的可比性角度出发,建议统一使用USGS的增益和偏置参数计算Landsat5图像的反射率。 相似文献
6.
Horizontal starch gel electrophoresis was used to investigate the biochemical genetic structure of Chinese mittencrab Eriocheir sinensis and Hepu mitten crab E. hepuensis. Sixteen putative enzyme-coding loci were examined for forty-nineChinese mitten crabs and thirty-eight Hepu mitten crabs. Nine loci, AAT-1 *, AAT-2 *, G3PDH*, GPI*, IDHP-1 *, IDHP-2 *,MDH-1 *, MDH-2 * and PGM * , are polymorphic in Chinese mitten crab, and seven, AAT-1 *, AAT-2 *, GPI *, IDHP-1 *,MDH-1 *, MDH-2 * and PGM * , are polymorphic in Hepu mitten crab. The proportion of polymorphic loci and the expectedheterozygosity are 0.562 5 and 0.080 3 for Chinese mitten crab, and 0.437 5 and 0.075 4 for Hepu mitten crab. The Nei' s ge-netic distance between two species is 0.002 4. 相似文献
7.
To investigate the tissue-specificities of isozymes and the genetic structure of wild spotted halibut (Verasper variegates) population, horizontal starch gel electrophoresis was performed on 45 individuals collected in part of the Yellow Sea. The
performances of 17 isozymes in 8 kinds of tissues or organs were screened preliminarily in a TC-7.0 buffer system. The results
showed that the screened isozymes displayed remarkable tissue-specificities. Finally, 14 enzymes (AAT, ADH, EST, GPI, G3PDH,
IDHP, LAP, LDH, MDH, MPI, PGDH, PGM, SDH and SOD) and 4 kinds of tissues (eye, skeleton muscle, liver and heart) were selected
for genetic analysis. Fourteen isozymes are encoded by 20 loci, and 9 of them are polymorphic. The polymorphic loci are AAT-1*.
GPI-2* G3PDH*, IDHP-1*, LDH*, MPI*, PGM-1*. PGM-2* and SDH*, and the proportion of polymorphic loci is 0.4500 (P0.99). The mean values of observed and expected heterozygosities are 0.027 8 and 0.026 5, respectively and the average effective
number of alleles is 1.067 5. 相似文献
8.
Correlation and path analysis of morphological and weight traits in marine gastropod Glossaulax reiniana 总被引：1，自引：0，他引：1
Using correlation and path analysis, the genetic correlation between weight traits and morphological traits was determined in the marine gastropod Glossaulax reiniana. A total of 100 G. reiniana individuals from a wild population were used. Shell width （X1）, shell height （X2）, umbo-callus height （X3）, body width （X4）, operculum length （X5）, operculum width （X6）, body weight （Y1） and soft-tissue weight （Y2） were measured, and the correlation coefficient matrix calculated. Morphological traits were used as independent variables and weight traits as dependent variables for path coefficient analysis. Path coefficients, correlation indices and determination coefficients were also determined. Results indicate that the correlation coefficients associated with each morphological and weight trait were all highly significant （P〈0.01）. After deleting redundant independent variables, the following optimum multiple regression equations were obtained using stepwise multiple regression analysis： Y1=-29.317＋0.362X2＋0.349X4＋ 1.190）（5 for body weight; and Y2=-17.292＋0.166X1＋0.171X2＋0.703X5, for soft-tissue weight. Operculum height had the highest positive direct correlation with both body weight and soft-tissue weight, which was in accordance with the test results obtained from determinate coefficient analysis. The indication of high genetic correlations between weight traits and morphological traits will provide valuable information for G. reiniana breeding programs. 相似文献
9.
利用MATLAB实现UNB3m、GPT2w+Hopfield、GPT2w+Saastamoinen、GPT3+Hopfield、GPT3+Saastamoinen等5种模型，分析它们在陕西地区的适用性。结果表明，5种模型结果普遍偏小。GPT2w+Saastamoinen和GPT3+Saastamoinen模型整体精度相当，且优于其他3种模型，bias为1.41 cm，RMS分别为4.68 cm和4.67 cm，且随着高程增加精度越来越高。5种策略精度均随季节变化而变化，其中UNB3m变化最为明显，夏冬2季bias差达到7.92 cm，RMS差达到7.67 cm。更高精度计算时，秋季应使用GPT3，而春夏2季时使用GPT2w效果更好。选用同样的气象参数模型时，Saastamoinen模型比Hopfield模型更适用于陕西地区，并且陕北地区精度最好。对比最新的全球气压温度模型GPT3与GPT2w发现，2种模型算得的地面气压P、地面温度T、地面水汽压e、大气加权平均温度Tm等4种气象参数均相差细微，所以在陕西地区利用GPT2w或GPT3分别算得的对流层总延迟ZTD和对流层干延迟ZHD相差很小，通过对流层湿延迟ZWD算得的PWV也几乎相当。 相似文献
10.
Research on quantitative models of suspended sediment concentration(SSC)using remote sensing technology is very important to understand the scouring and siltation variation in harbors and water channels.Based on laboratory study of the relationship between different suspended sediment concentrations and reflectance spectra measured synchronously,quantitative inversion models of SSC based on single factor,band ratio and sediment parameter were developed,which provides an effective method to retrieve the SSC from satellite images.Results show that the b1(430-500nm)and b3(670-735nm)are the optimal wavelengths for the estimation of lower SSC and the b4(780-835nm)is the optimal wavelength to estimate the higher SSC.Furthermore the band ratio B2/B3 can be used to simulate the variation of lower SSC better and the B4/B1 to estimate the higher SSC accurately.Also the inversion models developed by sediment parameters of higher and lower SSCs can get a relatively higher accuracy than the sin-gle factor and band ratio models. 相似文献
11.
The effects of body weight and temperature on the carbon budget of the juvenile bastard halibut, Paralichthys olivaceus , were studied at temperature 13.5, 18, 21.5 and 24 ℃, respectively. The carbon intake, faecal and growth carbon were measured, and the carbon respiration was calculated using the carbon budget equation(CC=GC+FC+RC). The combined relationship between different components of the carbon budget, body weight and temperature could be described by regression equations: CC =1.0206 W 0.8126 e 0.1483 T; G=0.0042 W 1.4096 (-5.11 T 3+285.90 T2-5173.72 T +30314.03); FC =0.0485 W0.7711e 0.1624 T ; UC = 1.4333 W 0.6715e 0.1487 T. Body weight had no significant ffect on the carbon absorption efficiency and the conversion efficiency. 相似文献
12.
Geochemistry and genesis on saturated hydrocarbon of crude oils in Gas Hure Oilfield in Qaidam Basin 
下载免费PDF全文
下载免费PDF全文 MO Xiaoye 《世界地质(英文版)》2011,14(1):7-14
Gas Hure Oilfield is the biggest one in the Qaidam Basin.Through intensive sampling and GC-MS analysis,the authors analyzed the geochemical characteristics of the crude oils in the Gas Hure Oilfield.The results show that the crude oils have even-odd carbon predominance for n-alkanes.In shallow reservoir,part of crude oils suffered biogenic degradation.As for normal oils,they have low Pr/Ph ratios with abundant gammacerane and C35 homohopane,which indicate that the crude oils are formed in strong reducing salt water environment.Compared deep(E13) reservoir with shallow(N1-N12) reservoir,the ancient salinity of sedimentary environment of N1--N12 crude oils is slightly higher than that of E13 crude oils;the C-21/C+22 ratios of crude oils are 1.02-1.71 with a higher abundance of C27 sterane,which shows that their mainly origin matrix are bacteria and algae;the C29 sterane 20S/(20S+20R)is generally low,the ratio in deep E13 reservoir distributes between 0.31 and 0.40,but in shallow reservoir is relatively low with 0.29-0.36.At the same time,C29 sterane αββ/(αββ+ααα)and Ts/Tm both are extremely lower.All the above show that the crude oils in Gas Hure are mainly low mature oils,although the maturity of deep reservoir crude oils is slightly higher than shallow one. 相似文献
13.
14.
选取2018-01-23起10 d内16个iGMAS测站观测数据,对北斗三号卫星的观测数据质量及BDS单系统精密定轨精度进行评估。初步结果表明,老信号B1I、B3I北斗三号卫星的信噪比略强于二号卫星,噪声与多路径基本相当,均在0.1 m量级,新卫星不存在星内多路径偏差。新信号B1C/L1/E1频点GPS信噪比最强,Galileo和BDS卫星相当,B2a/L5/E5a和B2b/E5b各系统基本相当;噪声及多路径方面,B1C/L1/E1频点GPS优于BDS、Galileo卫星0.1 m量级,B2a/L5/E5a和B2b/E5b各系统基本相当,均在0.1 m量级,新信号中北斗三号卫星星内多路径偏差基本消失。单系统精密定轨试验中,分别进行有/无GEO卫星策略、太阳光压模型ECOM 五/九参数策略的比较,并使用卫星激光测距数据进行独立检核。初步结果表明,有GEO卫星、ECOM五参数光压模型的定轨精度最好,C19号卫星7个重叠弧段的平均定轨精度在沿迹向、法向、径向的精度分别为32 cm、16 cm、8 cm,与试验卫星的定轨精度基本相当。 相似文献
15.
A new analytical method using Back-Propagation(BP) artificial neural networks and spectrophotometry for simultaneous determination of calcium and magnesium in tap water,the Yellow River water and seawater is established.By condition experiment,the optimum analytical conditions for calcium,magnesium and Arsenazo(Ⅲ) color reactions are obtained.Levenberg-Marquart(L-M) algorithm is used for calculation in BP neural network.The topological structure of three-layer BP ANN network architecture is chosen as 11-10-2(nodes).The initial value of gradient coefficient μ is fixed at 0.001 and the increase factor and reduction factor of μ take the default values of the system.The data are processed by computers with our own programs written in MATLAB 7.0.The relative standard deviations of the calculated results for calcium and magnesium are 2.31% and 2.14%,respectively.The results of standard addition method show that the recoveries of calcium and magnesium are 103.6% and 100.8% in the tap water,103.2% and 96.6% in the Yellow River water(Lijin district of Shandong Province),and 98.8%-103.3% and 98.43%-103.4% in seawater from Jiaozhou Bay of Qingdao.It is found that 14 common cations and anions do not interfere with the determination of calcium and magnesium under the optimum experimental conditions.The comparative experiments do not show any obvious difference between the results obtained by this new method and those obtained by the classical complexometric titration method in seawater medium.This method exhibits good reproducibility and high accuracy in the determination of calcium and magnesium and can be used for the simultaneous determination of Ca2+ and Mg2+ in tap water and natural water. 相似文献
16.
??ITRF2008??????й???????5??IGS??????WUHN??BJFS??URUM??KUNM??SHAO??2012??????????????TriP?????????????????????????С??????????????????????????????????????????н?????????????????????????????????GAMIT/GLOBK????????????????????з?????????ж???????????????й??????IGS???????????д??????????????????????????????????????????????????URUM??KUNM??BJFS??SHAO?????????????????????BPPL+WN????WUHN??????N??E??U????????????????з?????????????BPPL+WN??FN+WN??PL+WN??????????BPPL+WN??????????а???????????????????????????2 mm??BPPL???????WN??????1/10???????0.28??0.89 mm????????????????С???????????????????????????????????С??????TriP?????????????????????????????????????????????????? 相似文献
17.
几种因子对鞍带石斑鱼精子活力的影响 总被引：3，自引：0，他引：3
研究不同梯度的盐度、pH、温度及低温保存时间对鞍带石斑鱼精子活力的影响。结果表明:鞍带石斑鱼精子活力的适宜盐度范围为27.5～35.0,最适盐度为32.5,此时精子的快速运动时间和寿命分别为13.2min和14.8min;最适pH为8.5,精子的快速运动时间及寿命最长,分别达12.7min和17.3min;温度范围为27～31℃,以29℃时快速运动时间最长,达16.6min;在0～4℃冰箱保存6h后鞍带石斑鱼精子活力未显著降低,其中保存前精子快速运动时间为18.4min,保存6h后为18.2min,保存120h后仍有活力,精子快速运动时间为2.3min,精子激活率为3.3%。以x为保存时间,快速运动时间y和寿命y′符合线性方程y=-0.8334x+19.164(R2=0.9856),y′=-1.1358x+27.8(R2=0.9573)。 相似文献
18.
利用美国德克萨斯大学空间研究中心（UTCSR）最新发布的GRACE卫星RL05月重力场模型数据,采用去相关和300 km半径的高斯平滑滤波,提取出2012年苏门答腊MW8.6地震的同震和震后形变,并利用最小二乘拟合方法计算了地震前后震中附近区域的形变率。结果表明,GRACE卫星观测到的同震形变约为-8~14 cm,震前和震后震中附近区域的形变率分别为1~4 cm/a和-1~-3 cm/a。 相似文献
19.
地形校正是崎岖山区遥感图像预处理的关键步骤。为了评估基于DEM数据的经验校正模型、山地辐射传输模型和波段组合优化计算模型在去除地形阴影效应方面的性能,并将其应用于福州市植被覆盖监测,本文采用C模型（和SCS+C模型）、6S+C模型和阴影消除植被指数（SEVI）进行评估、比较。采用1999年和2014年两期Landsat 5 TM卫星数据和相关的 30 m ASTER GDEM V2高程数据,分别计算了C校正（和SCS+C校正）和6S+C校正后的归一化植被指数（NDVI）和比值植被指数（RVI）以及基于表观反射率数据的SEVI。通过目视比较、光谱特征比较以及太阳入射角余弦值（cos i）与植被指数的线性回归分析,可以看出C模型和SCS+C模型对本影具有较好的校正效果,但对落影的校正效果欠佳。NDVI和RVI的本影与邻近无阴影阳坡的相对误差分别从71.64%、52.57%降至4.80%、6.43%（C模型）和0.50%、9.94%（SCS + C模型）,而落影与邻近无阴影阳坡的相对误差分别从62.01%、47.57%降至31.05%、24.40%（C模型）和33.42%、16.01%（SCS + C模型）。在NDVI的落影校正效果上,6S+C模型比C模型和SCS+C模型有一定的提升,本影与邻近无阴影阳坡之间的相对误差为8.63%,落影与邻近无阴影阳坡之间的相对误差为14.27%。而SEVI在消除本影和落影方面整体效果更好,本影和落影与邻近无阴影阳坡的相对误差分别为9.86%和10.53%。最后,基于SEVI对福州市1999-2014年的植被覆盖变化进行了监测。监测结果表明： ① 1999-2014年植被覆盖增加了893.61 km 2,植被增加区域主要分布在海拔250~1250 m范围内;② SEVI均值在坡度40°附近达到峰值。 相似文献
20.
The 60% ethanolic extract fromGracilaria textorii (Rhodophyta) was degraded with β-agarase, and certain charged (sulfated) and neutral oligosaccharides were separated by using
DEAE Sephadex A25 and Bio- gel P6, P2 chromatographic techniques. Some of the charged oligomers were verified to be neoagarotetraose-63-sulfate (DP2), neoagarohexaose-63, 65-disulfate (DP3) and neoagarooctaose-63, 65, 67-trisulfate (DP4) by using13C- and1H-NMR spectroscopy. One neutral oligomer was assumed to be a mixture of methylated neoagarotetraoses (DP2) by1H-NMR spectroscopy.
These oligomers assigned by their chemical shifts may be used as the model compounds for the structural investigation of the
agar-type sulfated polysaccharides using the β-agarase degradation method.
Contribution No. 1749 from the Institute of Oceanology, Academia Sinica. 相似文献