检索结果-南通市图书馆

Research on Feature Extraction Method of No‐modeling System Error in Beidou Orbit Determination Residual

在线全文

学校读者我要写书评

暂无评论

Research on Feature Extraction Method of No‐modeling System...

A New Cyclohexene Oxide from Uvaria tonkinensis ***

第五届中国卫星导航学术年会

作者： CHEN lue TANG Geshi CUI Hongzheng CHEN Ming LIU Huicui WANG mei Science and Technology on Aerospace Flight Dynamics Laboratory Beijing Aerospace Control Center

ISBN: (纸本)9783642547393

Beidou navigation satellite precise orbit determination is one of the key technologies in Beidou satellite navigation system application. To analyze the no‐modeling system error in Beidou navigation satellite system, this paper proposes Ensemble Empirical Mode Decomposition （EEMD） and Hilbert spectrum method for orbit determination residual feature extraction. Firstly, the feature extraction principle of EEMD and Hilbert spectrum is analyzed, and the method model of feature extraction is established, then Pseudo‐range and carrier phase orbit determination residuals in Beidou satellite navigation system are analyzed, finally, the proposed method is applied to multi‐stations GEO receiving multiple Beidou navigation satellite signals for the orbit residuals analyzing. The results show that the proposed method can accurately extract the 86400s period feature which is closely related to the time period items with one day in the Beidou orbit residuals. It is very important for separating the no‐modeling system error in Beidou navigation satellite orbit determination residuals for improving the orbit determination precision.

关键词： Beidou navigation satellite orbit determination residual feature extraction Ensemble Empirical Mode Decomposition Hilbert spectrum.

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2003年第11期14卷 1144-1145页

作者： An LIU Zhong mei ZOU Li zhen XU Shi Lin YANG Institute of Medicinal Plant Development Chinese Academy of Medical Sciences and Peking Union Medical CollegeBeijing 100094

A new compound, subglain B, was isolated from the stems of Uvaria tonkinensis var. subglabra and its structure was identified as 1S, 2R, 3S, 6R-1-benzoyloxymethylene-1,2- dihydroxy-3-benzoyloxy-6-chlorocyclohex-4-ene ... 详细信息

关键词： Uvaria tonkinensis var subglabra subglain B cyclohexene.

Revegetation of Copper Mine Tailings with Ryegrass and Willow

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2004年第3期14卷 283-288页

作者： HAOXiu-zhen ZHOUDong-mei SIYou-Bin StateKeyLaboratoryofSoilandSustainableAgriculture InstituteofSoilScienceChineseAcademyofSciencesNanjing210008（China）

To restore vegetation on metal mine tailings is very difficult because theyoften contain high concentrations of heavy metals, low nutrient content and low water retentioncapacity. This study involved 3 experiments that evaluated the effects of 4 treatment amendments:montmorillonite, rice straw, organic manure and chemical fertilizer on the growth of ryegrass(Lolium perenne L.) and willow (Salix viminalis L.) with Cu and Zn mine tailings from two miningareas. The results showed that ryegrass was the most tolerant of 4 crops to Cu toxicity. Also whenorganic manure, which contained high concentrations of inorganic salts, was added to the minetailings, it significantly hindered ryegrass growth (P = 0.05). Meanwhile, with ryegrass organicmanure significantly increased (P = 0.05) the extractable Cu concentration in both mine *** montmorillonite was used as a mine tailings amendment with willow, the height and tress numberat the 1st cut were significantly greater (P = 0.05) than a control without montmorillonite. Howeverthere was no significant difference for height, tress number, dry weight or root dry weight at the2nd cut. So, amendment applications to reduce metal toxicity and increase nutrients retention inmine tailings were essential during revegetation of mine tailings.

关键词： amendment copper mine tailings ryegrass (lolium perenne L.) willow (salixviminalis L.) zinc mine tailings

Research on a forecasting model of tourism traffic volume in theme parks in China

在线全文

学校读者我要写书评

暂无评论

Transportation Safety and Environment 2019年第2期1卷 135-144页

作者： zhen-yu mei Hai Qiu Chi Feng Yang Cheng College of Civil Engineering and Architecture Zhejiang University.866 Yuhangtang RoadXihu DistricHangzhou310058China Department of Civil&Environmental Engineering University of Wisconsin-Madison1415 Engineering Drive MadisonWI 53706

In this study,a model based on multiple regression analysis is developed to forecast the tourism traffic volume of theme ***,the macro,meso and micro factors affecting traffic passenger volume are ***,SPSS software is used for multivariate regression analysis on data for 10 theme parks from 2014.A tourism traffic volume forecasting model is then ***,related data for 2015 is used to validate the model,with results showing a prediction error of 14.1%.All results show that the model has a high predictive ability.

关键词： theme park traffic passenger volume prediction site selecting analysis multiple regression analysis traffic convenience

The Effect of Vineyard Cover Crop on Main Monomeric Phenols of Grape Berry and Wine in Vitis viniferal L. cv. Cabernet Sauvignon

在线全文

学校读者我要写书评

暂无评论

Agricultural Sciences in China 2010年第3期9卷 440-448页

作者： XI Zhu-mei ZHANG zhen-wen CHENG Yu-feng LI Hua College of Enology Northwest A＆F University/Shaanxi Engineering Research Center for Viti-Viniculture Yangling 712100 P.R.China

This study was conducted to determine the effect of cover crop inter-row in vineyard on main mono-phenol content of grape berry and wine. Three such cover crops, two perennial legumes （white clover and alfalfa） and a perennial gramineous grass （tall fescue） were sown in vineyard. The main phenolic compounds of mature grape berry and wines vinified under the same conditions were extracted with ethyl acetate and diethyl ether and analyzed by high- performance liquid chromatography （HPLC） by comparing to soil tillage. A total of ten phenolic compounds were identified and quantified in the different grape berry and wines, including nonflavonoids （hydroxybenzoic and hydroxycinnamic acids） and flavonoids （flavanols and flavonols）. The concentration of flavonoid compounds （409.43 to 538.63 mg kg^-1 and 56.16 to 81.30 mg L^-1） was higher than nonflavonoids （76.91 to 98.85 mg kg^-1 and 30.65 to 41.22 mg L^-1） for Cabernet Sauvignon grape and wine under different treatments, respectively. In the flavonoid phenolics, Catechin was the most abundant in the different grapes and wines, accounting for 74.94 to 79.70% and 48.60 to 50.62% of total nonanthocyanin phenolics quantified, respectively. Compared to soil tillage, the sward treatments showed a higher content of main mono-phenol and total nonanthocyanin phenolics in grapes and wines. There were significant differences between two cover crop treatments （tall fescue and white clover） and soil tillage for the content of benzoic acid, salicylic acid, caffeic acid, catechin, and total phenolics in the grape berry （P 〈 0.05 or P〈0.01）. The wine from tall fescue cover crop had the highest gallic acid, caffeic acid and catechin. Cover crop system increased the total nonanthocyanin phenolics of grapes and wines in order of the four treatments： tall fescue, white clover, alfalfa, and soil tillage （control）. Cover crop in vineyard increased total phenols of grape berry and wine, and thus improved the quality of wine evidently.

关键词： vineyard cover crops inter-row Cabernet Sauvignon grape berry wine monomeric phenols

Isolation and Characterization of Two New Compounds from Lysimachia Davurica

在线全文

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2005年第5期21卷 549-551页

作者： TIAN Jing-kui ZOU Zhong-mei XU Li-zhen YANG Shi-lin Department of Chinese Medicine Science and Engineering Zhefiang University Hangzhou 310027P. R. China Institute of Medicinal Plants Development Chinese Academy of Medical Scienees and Peking Union Medical College Beijing 100094 P. R. China

Two new saponins named davuricoside H and davuricoside K were isolated from the whole plant of Lysimachia davurica. The structures of davuricoside H and davuricoside K were determined by 1-D and 2-D NMR, MS techniques, and chemical methods to be 3β,16α ,28-trihydroxy-olean-12-en-30-oic acid-3-O-β-D-glucopyranosyl-（ 1→2 ）- [β-D-glucopyranosyl-（ 1 → 4 ） ] -α-L-arabinopyranoside and 3β,16or ,28-trihydroxy-olean-12-en-30-oic acid-3-O-{β-D- glucopyranosyl- （ 1 →2 ） - [β-D-glucopyranosyl- （ 1 →4 ） ] -α-L-arabinopyranosyl } -30-O-β-D-glucopyranosyl-ester.

关键词： Lysimachia davurica Triterpenoid saponin Davuficoside H Davuricoside K

Two New Sterols from Adenophora Stenanthina ***

在线全文

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 1997年第4期13卷 98-101页

作者： HOU zhen-fu SHIYan-ping mei Shuang-xi LI Yu Institute of Or ganic Chemistry State Key Laboratory of Applied Organic ChemistryLanzhou UniversityLanzhou730000

ＴｗｏＮｅｗＳｔｅｒｏｌｓｆｒｏｍＡｄｅｎｏｐｈｏｒａＳｔｅｎａｎｔｈｉｎａＳｕｂｓｐ．ＸｉｆｅｎｇｅｎｓｉｓＨＯＵＺｈｅｎ－ｆｕ，ＳＨＩＹａｎ－ｐｉｎｇ，ＭＥＩＳｈｕａｎｇ－ｘｉａｎｄＬＩＹｕ＊（Ｉｎｓｔｉｔｕｔｅ... 详细信息

ＴｗｏＮｅｗＳｔｅｒｏｌｓｆｒｏｍＡｄｅｎｏｐｈｏｒａＳｔｅｎａｎｔｈｉｎａＳｕｂｓｐ．ＸｉｆｅｎｇｅｎｓｉｓＨＯＵＺｈｅｎ－ｆｕ，ＳＨＩＹａｎ－ｐｉｎｇ，ＭＥＩＳｈｕａｎｇ－ｘｉａｎｄＬＩＹｕ＊（ＩｎｓｔｉｔｕｔｅｏｆＯｒｇａｎｉｃＣｈｅｍｉｓｔｒ...

关键词： Adenophora stenanthina subsp. Xifengensis Campanulaceae Steroids Sterols

Controllable optical activity of non-spherical Ag and Co SERS substrate with different magnetic field

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2017年第2期26卷 183-188页

作者： Chun-zhen Fan Shuang-mei Zhu Hao-Yi Xin School of Physical Science and Engineering Zhengzhou University Zhengzhou 450052 China College of Science Henan Institute of Engineering Zhengzhou 451191 China

We experimentally fabricate a non-spherical Ag and Co surface-enhanced Raman scattering（SERS） substrate, which not only retains the metallic plasmon resonant effect, but also possesses the magnetic field controllable *** detections are carried out with the test crystal violet（CV） and rhodamine 6G（R6G） molecules with the initiation of different magnitudes of external magnetic field. Experimental results indicate that our prepared substrate shows a higher SERS activity and magnetic controllability, where non-spherical Ag nanoparticles are driven to aggregate effectively by the magnetized Co and plenty of hot-spots are built around the metallic Ag nanoparticles, thereby leading to the enhancement of local electromagnetic field. Moreover, when the external magnetic field is increased, our prepared substrate demonstrates excellent SERS enhancement. With the 2500 Gs and 3500 Gs（1 Gs = 10^（-4）T） magnetic fields, SERS signal can also be obtained with the detection limit lowering down to 10^（-9）M. These results indicate that our proposed magnetic field controlled substrate enables us to freely achieve the enhanced and controllable SERS effect, which can be widely used in the optical sensing, single molecule detection and bio-medical applications.

关键词： magneto-optical materials tunable surface-enhanced Raman scattering

Chiral Diamine-catalyzed Asymmetric Aldol Reaction

在线全文

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2012年第6期28卷 1003-1010页

作者： LI Hui XU Da-zhen WU Lu-lu WANG Yong-mei State Key Laboratory of Elemento-Organic Chemistry Research Institute of Elemento-Organic Chemistry College of Chemistry Nankai University Tianjin 300071 P. R. China

A highly efficient catalytic system composed of a simple and commercially available chiral primary diamine（1R,2R）-cyclohexane-1,2-diamine（6） and trifluoroacetic acid（TFA） was employed for asymmetric Aldol reaction in i-PrOH at room temperature.A loading of 10%（molar fraction） catalyst 6 with TFA as a cocatalyst could catalyze the Aldol reactions of various ketones or aldehydes with a series of aromatic aldehydes,furnishing Aldol products in moderate to high yields（up to 99%） with enantioselectivities of up to 99% and diastereoselectivities of up to 99：1.

关键词： Aldol reaction Chiral primary diamine Asymmetric organocatalysis