oalib

OALib Journal期刊

ISSN: 2333-9721

费用:99美元

投稿

时间不限

2018 ( 42 )

2017 ( 48 )

2016 ( 59 )

2015 ( 884 )

自定义范围…

匹配条件: “ Feng Gui” ,找到相关结果约36416条。
列表显示的所有文章,均可免费获取
第1页/共36416条
每页显示
Numerical simulations of nutrient transport changes in Honghu Lake Basin, Jianghan Plain
Feng Gui,Ge Yu
Chinese Science Bulletin , 2008, DOI: 10.1007/s11434-008-0315-4
Abstract: Nutrients transported from catchments are one of the most important sources for lake eutrophication. In this study, the Honghu Lake Basin, located at the middle reaches of the Yangtze River, was chosen as the study area, and the watershed hydrological distribution model SWAT (Soil Water Assessment Tool) was applied to evaluate the trajectory of watershed nutrient transportation over time. Based on the analysis of driving factors, three experiments corresponding to natural, traditional and modern agriculture processes respectively were designed to evaluate the changes of nutrient inputs from catchments under the three environments. The simulation results showed that there were variations in nutrient production and changes in the range and rate. For three periods of the experiments, TN concentrations have changed as 0.12→0.31→1.15 mg/L, and production as 420→1650→6522 T/a; while TP concentrations changed as 0.018→0.057→0.117 mg/L, and production as 78→303→665 T/a. The nutrient transportation experienced slowly long-term increases during 1840–1950, then showed a relatively rapid increase during the period of 1950–1980s and the period from 1980 to early 1990s, with increasing rate of 1.4% and 2.4% respectively. And from the later 1990s to now, an obviously increasing trend with 15% increasing rate occurred. The effect from human activities on the watershed nutrient transportation increased rapidly, and had become a dominant factor in changes of the nutrient transportation.
Succession of dominant phytoplankton species in spring 2002 at Dapeng''Ao Cove, Daya Bay
大亚湾大鹏澳水域春季浮游植物优势种的演替

WEI Gui Feng,
韦桂峰

生态学报 , 2003,
Abstract: Dapeng'Ao, a small cove at the southwest of Daya Bay in Guangdong Province of China is an area covering about 14 km 2 at an average water depth of 5 m with well developed mariculture of fish and shellfish. From April 28 to May 27 2002, a 30 day continuous observation was carried out in the cove to investigate the succession of dominant phytoplankton species. Water samples were taken from the surface and bottom layers of 3 sites in Dapeng'Ao cove at about 9 a.m. daily. Physico chemical factors were measured in situ (e.g. water temperature, dissolved oxygen) or analyzed in the laboratory of Marine Biology Research Station at Daya Bay within an hour after sampling (e.g. pH, salinity, ammonia, nitrite, nitrate, phosphate, silicate, chlorophyll a). Phytoplankton was fixed with Lugol's solution in situ , and dominant species were identified and their cell numbers were enumerated. In this continuous observation, it found that diatoms dominated (about 98.9% of total phytoplankton cells) in the waters, Skeletonema costatum, Nitzschia delicatissima, and Chaetoceros sp. were the dominant species. Skel. costatum was the leading species from April 28 to May 22 whileas Nitz. delicatissima took the leading role after May 22, resulting in a phytoplankton succession. Using Principal Component Analysis (PCA) method, the most important five components account for 78% of data information. Multiple regression method was used to elucidate the relationship among those dominant species and their contribution to the principal components (represented by the physico chemical factors), based upon the correlation coefficients between the dominant phytoplankton species and the main principal components ( p <0 01), and to develop a succession model for the dominant phytoplankton species in Dapeng'Ao cove in spring. The model shows that Skel. costatum has competitive relationship with Nitz. delicatissima and the most important physico chemical factors that are closely related to the growth of diatom dominated phytoplankton community are temperature, dissolved oxygen, ammonia, nitrite, phosphate and silicate; salinity, nitrate, and the ratio of nitrate to phosphate also influenced the growth of Skel. costatum. During the period of investigation, the most significant environment change was rainfall, which resulted in a decrease of salinity and an increase of nitrogenous nutrients in water column, and such an environment change promotes the growth of Skel. costatum. Along with phytoplankton growth, the nutrients (N, P, and Si) were exhausted gradually and could not further maintain the population growth of Skel. costatum and its density declined, which relieved the competition pressure for Nitz. delicatissima and it grew rapidly thereafter. The environment change (rainfall) occurring during the period of phytoplankton succession illustrated clearly how dominant species changed from Skel. costatum to Nitz. delicatissima in the succession process.
A Rigorous and Completed Statement on Helmholtz Theorem
Yong Feng Gui;Wen-Bin Dou
PIER , 2007, DOI: 10.2528/PIER06123101
Abstract: There are some limitations on the statement of classic Helmholtz theorem although it has abroad application. Actually, it only applies to simply connected domain with single boundary surface and does not provide any conclusion about the domain where discontinuities of field function exist. However, discontinuity is often encountered in practice, for example, the location of surface sources or interface of two kinds of medium. Meanwhile, most existing versions of Helmholtz theorem are imprecise and imperfect to some extent. This paper not only tries to present a precise statement and rigorous proof on classic Helmholtz theorem with the accuracy of mathematical language and logical strictness, but also generalizes it to the case of multiply connected domain and obtains a generalized Helmholtz theorem in the sense of Lebesgue measure and Lebesgue integral defined on three-dimensional Euclidean space. Meanwhile, our proof and reasoning are more sufficient and perfect. As an important application of the generalized Helmholtz theorem, the concepts of irrotational and solenoidal vector function are emphasized. The generalized Helmholtz theorem and the present conclusion should have important reference value in disciplines including vector analysis such as electromagnetics.
Phenomena of Paired Echoes and Transmission Characteristics of the Pulse Signal in Dispersive Transmission Lines with Discontinuities
Yong Feng Gui;Wen-Bin Dou
PIER B , 2008, DOI: 10.2528/PIERB08022202
Abstract: The performance of wideband radar system may be degraded by signal distortion occurring in anyplace of the transmission channel of the system. If the amplitude response is not flat or the signal delay is not constant in the transmission of the wideband signal, then signal distortion will occur, which can reduce the SNR and resolution. The available theory indicates that a small sinusoidal ripple variation in either amplitude-frequency or phase-frequency response of a linear system will cause signal distortion and the phenomena of paired echoes in the output signals of the time domain. In this paper, whether a dispersive transmission line with discontinuities will lead to the phenomena of paired echoes is discussed by means of finite difference time domain (FDTD) method and theoretical analysis. The results show that the technique of paired echoes is unsuited to analyze the influence of dispersive transmission line with discontinuities on time domain pulse signal. The method of Taylor series expansion shall be chosen as a more appropriate method. Meanwhile, simulations also show that a pulse signal transmitting in dispersive transmission lines with discontinuities including passive components such as filters and directional couplers will not lead to the phenomena of paired echoes.
6-Bromopyridine-2-carboxamide
Feng Xue,Shen-gui Ju
Acta Crystallographica Section E , 2009, DOI: 10.1107/s1600536809047114
Abstract: In the the title compound, C6H5BrN2O, an intramolecular N—H...N hydrogen bond generates an S(5) ring. In the crystal structure, intermolecular bifurcated N—H...(O,O) hydrogen bonds link the molecules, leading to sheets propagating in (100).
Optimization of the Technology of Wire Drawing Based on Finite Element Modeling
Gui’e Xu,Feng Fang,Zhaoxia Li
Modern Applied Science , 2009, DOI: 10.5539/mas.v3n5p193
Abstract: The initiation and propagation rule of central flaw during wire drawing was modeled with the finite element method and theory of fracture mechanics. It is shown that: J-integral value increased with the increasing of the angle of drawing die, the friction coefficient between drawing die and wire and the initial dimension of the flaw. When friction coefficient equaled 0.1, J-integral value round the crack tip with the same flaw decreased with the decreasing of the angle of the die. J-integral value changed slightly and tended to be a constant value when the angle reached to 8°. The calculated results were then applied to improve the optimization of the technology for wire drawing.
Coronin 3 promotes gastric cancer metastasis via the up-regulation of MMP-9 and cathepsin K
Ren Gui,Tian Qifei,An Yanxin,Feng Bin
Molecular Cancer , 2012, DOI: 10.1186/1476-4598-11-67
Abstract: Background Coronins are a family of highly evolutionary conserved proteins reportedly involved in the regulation of actin cytoskeletal dynamics, although only coronin 3 has been shown to be related to cancer cell migration. In glioblastoma cells, the knockdown of coronin 3 inhibits cell proliferation and invasion. Coronin 3 is also associated with the aggression and metastasis of hepatocellular carcinoma. In this paper, we analyze the migration, invasion and metastasis abilities of gastric cancer cells after up- or down-regulation of coronin 3, and explore the mechanism of coronin 3 in the process of gastric cancer metastasis. Results The expression of coronin 3 was higher in the highly metastatic sub-cell line MKN28-M, which we established in our laboratory. We also demonstrated that the expression of coronin 3 was remarkably higher in lymph lode metastases than in primary gastric cancer tissues, and over-expression of coronin 3 was correlated with the increased clinical stage and lymph lode metastasis. Recombinant lentiviral vectors encoding shRNAs were designed to down-regulate coronin 3 expression in gastric cancer cell lines. Stable knockdown of coronin 3 by this lentiviral vector could efficiently inhibit the migration and invasion of MKN45 gastric cancer cells. In contrast, up-regulation of coronin 3 significantly enhanced migration and invasion of MKN28-NM cells. In addition, knockdown of coronin 3 significantly reduced liver metastasis in mice after tail vein injection of gastric cancer cells. The Human Tumor Metastasis PCR Array was used to screen the metastasis-associated genes identified by the down-regulation of coronin 3, and the results suggested that, following the knockdown of coronin 3, the tumor cell migration and invasion were inhibited by the reduced expression of MMP-9 and cathepsin K. Conclusion Coronin 3 is highly expressed in gastric cancer metastases and can promote the metastatic behaviors of gastric cancer cells, including their migration and invasion.
Metformin vs Insulin in the Management of Gestational Diabetes: A Meta-Analysis
Juan Gui, Qing Liu, Ling Feng
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0064585
Abstract: Background Nowadays, there have been increasing studies comparing metformin with insulin. But the use of metformin in pregnant women is still controversial, therefore, we aim to examine the efficiency and safety of metformin by conducting a meta-analysis of randomized controlled trials (RCTs) comparing the effects of metformin with insulin on glycemic control, maternal and neonatal outcomes in gestational diabetes mellitus (GDM). Methods We used the key words “gestational diabetes” in combination with “metformin” and searched the databases including Pubmed, the Cochrane Library, Web of knowledge, and Clinical Trial Registries. A random-effects model was used to compute the summary risk estimates. Results Meta-analysis of 5 RCTs involving 1270 participants detected that average weight gains after enrollment were much lower in the metformin group (n = 1006, P = 0.003, SMD = ?0.47, 95%CI [?0.77 to ?0.16]); average gestational ages at delivery were significantly lower in the metformin group (n = 1270, P = 0.02, SMD = ?0.14, 95%CI [?0.25 to ?0.03]); incidence of preterm birth was significantly more in metformin group (n = 1110, P = 0.01, OR = 1.74, 95%CI [1.13 to 2.68]); the incidence of pregnancy induced hypertension was significantly less in the metformin group (n = 1110, P = 0.02, OR = 0.52, 95%CI [0.30 to 0.90]). The fasting blood sugar levels of OGTT were significantly lower in the metformin only group than in the supplemental insulin group (n = 478, P = 0.0006, SMD = ?0.83, 95%CI [?1.31 to ?0.36]). Conclusions Metformin is comparable with insulin in glycemic control and neonatal outcomes. It might be more suitable for women with mild GDM. This meta-analysis also provides some significant benefits and risks of the use of metformin in GDM and help to inform further development of management guidelines.
Preparation and Characterization of Novel Drug-Inserted-Montmorillonite Chitosan Carriers for Ocular Drug Delivery  [PDF]
Dongzhi Hou, Ruyi Gui, Sheng Hu, Yi Huang, Zuyong Feng, Qineng Ping
Advances in Nanoparticles (ANP) , 2015, DOI: 10.4236/anp.2015.43009
Abstract: The objective of the study was to investigate the potential of montmorillonite as a sustained carrier in the preparation of drug-loaded nanoparticles for prolonged ocular application. Nanoparticles were prepared by ionic gelation of chitosan with sodium tripolyphosphate (TPP). Betaxolol hydrochloride (BH) was applied as a model drug. TG, FT-IR, TEM, DLS and XRD have been employed in the characterization of drug-encapsulated chitosan-montmorillonite/TPP nanoparticles (CS-MMT/TPP NPs). TEM images showed that the particles were spherical in shape and had a rough surface. The size range of the nanoparticles was between 338 and 585 nm with positive zeta potential values from 24 mV to 36 mV and encapsulation efficiency values ranging from 12.27% to 50.92%. In vitro sustained drug release was observed with the BH-loaded nanoparticles in artificial tears (pH 7.4). The results of FT-IR, TG and XRD showed that the drug was coated with CSMMT/ TPP NPs. In the mucoadhesion studies, an interaction was found between drug-loaded CSMMT/ TPP NPs and mucin, which could enhance precorneal residence time and hence facilitate an effective sustained release. The optimized formulation was determined to be non-irritant and tolerable by modified Draize test. Therefore, the BH-loading CS-MMT/TPP NPs developed are a promising carrier for controlled drug delivery to the eye.
Analysis of HPV16-E6 gene mutation in Xinjiang Uygur and Han women with cervical squamous carcinoma
Jin ZHOU,Wei LIU,Jun-hao GUI,Gui-ping FENG
Medical Journal of Chinese People's Liberation Army , 2011,
Abstract: Objective The present study investigates the HPV16-E6 gene mutation in Xinjiang Uygur and Han women with cervical squamous carcinoma.Methods The viral genome DNA was extracted from the cervical biopsies of five Uygur and five Han patients from Xinjiang,and the disease was determined to be an HPV16 simplex infection through the reverse membrane hybridization test.PCR was used to amplify the HPV16-E6 genetic fragment that is to be cloned into a pUC18-T carrier for DNA sequencing.Results The HPV16-E6 gene was cloned successfully.The DNA sequencing results showed that,compared with the DNA sequence of the German strain of the HPV16-E6 gene,12 mutation types were detected in the 10 specimens.These types were 107(T→C),133(A→C),168(C→G),178(T→G),310(T→C),321(T→C),341(T→C),350(T→G),375(A→G),410(T→A),499(G→T),and 548(A→G).Among them,178(T→G) and 350(T→G) had higher mutation frequencies,which were 30%(3/10) and 30%(3/10),respectively.Furthermore,data analysis showed that 178(T→G) and 350(T→G) existed in both Uygur and Han women.However,107(T→C),133(A→C),168(C→G),310(T→C),and 499(G→T) were detected only in Han women,whereas 321(T→C),341(T→C),375(A→G),410(T→A),and 548(A→G) were identified only in Uygur women.Conclusions New HPV16-E6 gene variations were identified in Xinjiang Uygur and Han women with cervical cancer by comparing their genes with the German standard HPV16-E6 gene.Moreover,178(T→G) and 350(T→G) were found to be the hot spots of the HPV16-E6 gene mutation in these women.Therefore,the high incidence of cervical cancer in Xinjiang Uygur and Han women may be associated with the HPV16-E6 gene mutation.
第1页/共36416条
每页显示


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.