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Search Results: 1 - 10 of 78228 matches for " Jiejun Chen "
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Effect of cultivating croplands and grazing in arid grassland habitats on the conservation of melitaeine butterflies in a mountainous area in Northern China
YiFei Wang,JieJun Chen,WenHua Liu,RuMei Xu
Science China Life Sciences , 2007, DOI: 10.1007/s11427-007-0015-3
Abstract: In the study area (Yanjiaping Village, Hebei Province, China), grazing extensity varies at different locations, small and discontinuous croplands are imbedded in some arid grassland, which are habitats for the melitaeine butterflies, Euphydryas aurinia and Melitaea phoebe. These two species of butterfilies coexist in this area, in which grazing and cultivation are the main disturbances. Grazing and cultivation have a reciprocal effect on E. aurinia, rather than M. phoebe. We observed that E. aurinia preferred to occupy patches with moderate grazing and imbedded with small and discontinuous croplands, where E. aurinia also has high population density. The percentage of E. aurinia larval groups in the ribbings was significantly higher than that of M. phoebe, whereas larvae of both species tended to increase in recent years. Our data also showed that the population density and the patch occupancy rate of both E. aurinia and M. phoebe were the highest under moderate grazing. It indicates that cultivation of small and discontinuous croplands within the patch has a significant effect on the population density of both species of melitaeine butterflies. Thus, to artificially create or maintain semi-natural habitats, complemented by moderate grazing, might be an ecological strategy to conserve melitaeine butterflies effectively. Considering the distinct impacts of cultivation and grazing on the population distribution and dynamics of the two different species, human disturbance in the mountainous area might be strategically involved in proposing conservation plans for the target species in the future.
Difference in metapopulation structure and dynamics of two species of coexistent melitaeine butterflies
Yifei Wang,Jiejun Chen,Rongjiang Wang,Guangchun Lei,Rumei Xu
Chinese Science Bulletin , 2003, DOI: 10.1007/BF03183945
Abstract: According to investigation on two species of melitaeine butterflies in Yanjiaping Village, Chicheng County, Hebei Province, China, between 1998–2002, together with the use of 1–10000 contour map of the local area, some conclusions are shown by the SPSS and GIS analysis of data obained from GPS: (1) The two species of melitaeine butterflies have different metapopulation structures.M. phoebe is a source-sink metapopulation, whileE. aurinia is a classical metapopulation, supporting the analytic result from our former genetic research. (2) The two species of melitaeine butterflies exhibit different trends of population dynamics.M. phoebe source-sink metapopulation is very unsteady, and is always small, thus has a tendency to go extinct gradually. ButE. aurinia classical metapopulation is stable, and has maintained a larger population size. Therefore, it stands a better chance of long-term survival. (3) The two species of melitaeine butterflies are significantly related in both patch occupancy and local population size. (4) The effect of isolation is significant on the metapopulations of these two species of melitaeine butterflies, consistent with the classical theories, whereas the effect of patch area is not significant on the metapopulations of these two species of melitaeine butterflies, which is inconsistent with the classical theories. Therefore, other factors, such as habitat quality, should be considered for their influences on metapopulations.
Effect of cultivating croplands and grazing in arid grassland habitats on the conservation of melitaeine butterflies in a mountainous area in Northern China
WANG YiFei,CHEN JieJun,LIU WenHua,&,XU RuMei,

中国科学C辑(英文版) , 2007,
Abstract: In the study area (Yanjiaping Village, Hebei Province, China), grazing extensity varies at different loca-tions, small and discontinuous croplands are imbedded in some arid grassland, which are habitats for the melitaeine butterflies, Euphydryas aurinia and Melitaea phoebe. These two species of butterflies coexist in this area, in which grazing and cultivation are the main disturbances. Grazing and cultivation have a reciprocal effect on E. aurinia, rather than M. phoebe. We observed that E. aurinia preferred to occupy patches with moderate grazing and imbedded with small and discontinuous croplands, where E. aurinia also has high population density. The percentage of E. aurinia larval groups in the ribbings was significantly higher than that of M. phoebe, whereas larvae of both species tended to increase in recent years. Our data also showed that the population density and the patch occupancy rate of both E. aurinia and M. phoebe were the highest under moderate grazing. It indicates that cultivation of small and dis-continuous croplands within the patch has a significant effect on the population density of both spe-cies of melitaeine butterflies. Thus, to artificially create or maintain semi-natural habitats, comple-mented by moderate grazing, might be an ecological strategy to conserve melitaeine butterflies effec-tively. Considering the distinct impacts of cultivation and grazing on the population distribution and dynamics of the two different species, human disturbance in the mountainous area might be strategi-cally involved in proposing conservation plans for the target species in the future.
Downregulation of metastasis suppressor 1(MTSS1) is associated with nodal metastasis and poor outcome in Chinese patients with gastric cancer
Ke Liu, Gefang Wang, Houzhong Ding, Ying Chen, Guanzhen Yu, Jiejun Wang
BMC Cancer , 2010, DOI: 10.1186/1471-2407-10-428
Abstract: Immunohistochemistry was performed using tissue microarrays containing gastric adenocarcinoma specimens from 1,072 Chinese patients with normal adjacent mucosa, primary gastric cancer and lymph node (LN) metastasis and specific antibody against MTSS1. MTSS1 mRNA and protein expression were detected by reverse transcription-polymerase chain reaction and Western blotting. The clinical follow-up was done in the 669 patients living in Shanghai that was chose from the 1072 cases.Complete loss of MTSS1 expression was observed in 751 cases (70.1%) of the 1,072 primary tumors and 103 (88%) of 117 nodal metastases; and loss of MTSS1 expression was significantly associated with poorly differentiated tumors, large tumor size, deep invasion level, the presence of nodal metastases and advanced disease stage. Moreover, multivariate analysis demonstrated that loss of MTSS1 expression correlated significantly with poor survival rates (RR = 0.194, 95% CI = 0.144-0.261, P < 0.001).MTSS1 expression decreased significantly as gastric cancer progressed and metastasized, suggesting MTSS1 may serve as a useful biomarker for the prediction of outcome of gastric cancer.Gastric carcinoma (GC), which is the second most common cause of cancer-related death in the world, deprives more than 700,000 lives per annum [1]. Its incidence varies considerably worldwide and has recently been decreasing in developed countries, but remains stably in developing countries [2-4]. Furthermore, the fact that gastric cancer is insensitive to conventional chemotherapy and is rarely amenable to radiotherapy leaves the survival durations in patients with gastric cancer unchanged in recent years. This highlights the need for the determination of prognostic factors predicting the outcome and the development of novel therapeutic strategies. Previous studies have indicated that disease stage and lymph node metastasis are the most important prognostic factors in gastric cancer. Moreover, some molecular markers have bee
Notch1 Signaling Regulates the Proliferation and Self-Renewal of Human Dental Follicle Cells by Modulating the G1/S Phase Transition and Telomerase Activity
Xuepeng Chen, Tianhou Zhang, Jiejun Shi, Ping Xu, Zexu Gu, Andrew Sandham, Lei Yang, Qingsong Ye
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0069967
Abstract: Multipotent human dental follicle cells (HDFCs) have been intensively studied in periodontal regeneration research, yet the role of Notch1 in HDFCs has not been fully understood. The aim of the current study is to explore the role of Notch1 signaling in HDFCs self-renewal and proliferation. HDFCs were obtained from the extracted wisdom teeth from adolescent patients. Regulation of Notch1 signaling in the HDFCs was achieved by overexpressing the exogenous intracellular domain of Notch1 (ICN1) or silencing Notch1 by shRNA. The regulatory effects of Notch1 on HDFC proliferation, cell cycle distribution and the expression of cell cycle regulators were investigated through various molecular technologies, including plasmid construction, retrovirus preparation and infection, qRT-PCR, western blot, RBP-Jk luciferase reporter and cell proliferation assay. Our data clearly show that constitutively activation of Notch1 stimulates the HDFCs proliferation while inhibition of the Notch1 suppresses their proliferation in vitro. In addition, the HDFCs proliferation is associated with the increased expression of cell cycle regulators, e.g. cyclin D1, cyclin D2, cyclin D3, cyclin E1, CDK2, CDK4, CDK6, and SKP2 and the decreased expression of p27 kip1. Moreover, our data show that the G1/S phase transition (indicating proliferation) and telomerase activity (indicating self-renewal) can be enhanced by overexpression of ICN1 but halted by inhibition of Notch1. Together, the current study provides evidence for the first time that Notch1 signaling regulates the proliferation and self-renewal capacity of HDFCs through modulation of the G1/S phase transition and the telomerase activity.
Volumetric Measurement of Root Resorption following Molar Mini-Screw Implant Intrusion Using Cone Beam Computed Tomography
Wen Li, Fei Chen, Feng Zhang, Wanghui Ding, Qingsong Ye, Jiejun Shi, Baiping Fu
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0060962
Abstract: Objective Molar intrusion by mini-screw implantation can cause different degrees of root resorption. However, most methods (2-D and 3-D) used for evaluating root resorption have focused on the root length without considering 3-D resorption. The purpose of this study was to volumetrically evaluate root resorption using cone beam computed tomography(CBCT) after mini-screw implant intrusion. Materials and Methods 1. The volumes of 32 teeth were measured using CBCT and laser scanning to verify the accuracy of CBCT. 2. Twelve overerupted molars from adult patients were investigated in this study. After mini-screw implants were inserted into the buccal and palatal alveolar bones, 150 g of force was applied to the mini-screw implants on each side to intrude the molars. CBCT images of all patients were taken immediately prior to intrusion and after intrusion. The volumes of the roots were calculated using the Mimics software program. The differences between the pre-intrusion and post-intrusion root volumes were statistically evaluated with a paired-samples t-test. In addition, the losses of the roots were statistically compared with each other using one-way analysis of variance at the P<0.05 level. Results No statistically significant volume differences were observed between the physical (laser scanning) and CBCT measurements (P>0.05). The overerupted molars were significantly intruded (P<0.05), and the average intrusion was 3.30±1.60 mm. The differences between the pre-intrusion and post-intrusion root volumes were statistically significant for all of the roots investigated (P<0.05). The roots were sorted by volume loss in descending order as follows: mesiobuccal, palatal, and distobuccal. Statistical significance was achieved among the three roots. The average total resorption for each tooth was 58.39±1.54 mm3. Conclusion Volume measurement using CBCT was able to effectively evaluate root resorption caused by mini-screw intrusion. The highest volume loss was observed in the mesiobuccal root among the three roots of the investigated first molar teeth.
Temporal-spatial niches of Chinese White Wax Scale insect (Ericerus pela) and its three dominant parasitoid wasps
白蜡虫及其3种优势寄生蜂的时空生态位

WANG Zili,CHEN Yong,CHEN Xiaoming,WANG Shaoyun,ZHAO Jiejun,
王自力
,陈勇,陈晓鸣,王绍云,赵杰军

生态学报 , 2011,
Abstract: The Chinese white wax scale insect, Ericerus pela (Chavannes), is an important beneficial insect in China which excretes a special wax used as raw material in the chemical industry. The cultivation and utilization of E. pela was has occurred for more than 1000 years in China. Parasitoid wasps are key factors that reduce output of white wax production by E. pela. There are more than 15 species of wasps that parasitize different stages of the life circle of E. pela. The dominant parasitoid wasps are Microterys ericeri Ishii, M. sinicus Jiang, and Metaphycus ericeri Xu et Jiang. The percentage in these wasps was 45.91%, 37.37% and 11.37% respectively. The distribution of parasite wasps is related with distribution of E. pela on host plant. Although many parasitoids (40%) occur in centre of E. pela, about 50% are distributed in the top of host plant. The flight movements of parasitoid wasps is affected by wind and sunlight; wasps in the wind cannot easy fly on top of tree because of their slim and fragile bodies, and wasps tend to like shade and do not like strong sunlight. The temporal-spatial niches (niche breadth, niche overlap and percentage similarity) of E. pela and its dominant parasitoid wasps (Microterys ericeri Ishii, M. sinicus Jiang, and Metaphycus ericeri Xu et Jiang) were analysed base on the investigation of distribution characteristics of E. pela and species of parasite wasps and their active rule. Temporal niche breadths of E. pela and its three dominant parasitoids were E. pela > Metaphycus ericeri > M. ericeri > M. sinicus and spatial niche breadths were E. pela > M. ericeri > Metaphycus ericeri > M. sinicus.The niche overlap of the three dominant parasitoids and E. pela were M. ericeri > M. sinicus > Metaphycus ericeri; the percentage similarities were M. ericeri > Metaphycus ericeri > M. sinicus. This suggests that M. ericeri and E. pela possesses the most similarity in the resources series, strong synchronism and sympatry, and the maximum resource utilization. M. ericeri is the most serious natural enemy of E. pela. M. ericeri and Metaphycus ericeri had a large overlap in temporal-spatial niches and proportion similarity. Interspecific competition for resource utilization between these species was obvious. The species and dynamics of parasitoid wasps depend on biological characteristics of host. The life cycle of E. pela is one year from April to April. E. pela is fecund and one female can reproduce 8000-10000 eggs, but itself lacks a strong capability to defend from natural enemies because its females do not have wings and population can not move after the second instar nymphae live on branches of host plant. E. pela is an abundant and stable food of many parasitoids because of its large population, has poor ability to defend itself and for longer periods, the diversity of temporal and dimensional niche of parasite wasps shows their coevolution skill.
对流层经验改正模型在中国区域的精度评估
Assessment of Tropospheric Delay Correction Models over China

王君刚, 陈俊平, 王解先, 章洁君, 宋雷
WANG Jungang
, CHEN Junping, WANG Jiexian, ZHANG Jiejun, SONG Lei

- , 2016, DOI: 10.13203/j.whugis20140696
Abstract: 对流层延迟是全球导航卫星系统(GNSS)计算的主要误差之一,其模型精度对测站坐标解算有较大影响,在高程方向尤为明显。因此,有必要对不同的对流层延迟改正模型的适用性进行评估。采用SHA解算了中国陆态网GNSS跟踪站的对流层天顶延迟数据,对常用的对流层改正模型EGNOS/UNB3m/GPT/GPT2的天顶延迟量在中国不同区域、不同季节的适用性进行了分析。结果显示,4种模型的RMS均为4~5 cm,各模型RMS之差小于1 cm,其中GPT2模型的RMS最小;4种模型的平均偏差(BIAS)为1 cm左右,GPT2模型的BIAS最大,为1.5 cm;时间上,各个模型在夏季精度普遍较低,这是因为夏季水汽丰富,对流层湿延迟变化较大;空间上,各模型在东南沿海精度较低,因为东南沿海气候湿润,湿延迟变化较大;各模型精度对测站高程不敏感,精度在比较高的测站并无明显降低。通过对不同模型在中国区域的精度分析,验证该改正模型可以为中国区域用户的对流层模型的选择提供一定的参考
基于有限元网格尺寸效应影响的峰值应变修正研究
Study on peak strain correction based on the impact of finite element mesh size effect

彭容新,陈爱军,贺国京,王解军
PENG Rongxin
, CHEN Aijun, HE Guojing, WANG Jiejun

- , 2018,
Abstract: 对混凝土塑性损伤模型的单轴应力-应变关系、损伤变量、屈服准则和流动法则等进行阐述。利用ABAQUS对标准立方体混凝土试块模型采用不同网格尺寸进行计算,通过回归分析得到网格尺寸与本构模型峰值应变的函数关系。随后建立矩形截面单肢墩与双肢墩的有限元模型,基于上述函数进行损伤模型的峰值应变修正。并根据2个桥墩的有限元模型,设计并进行2个试验墩的试验研究。通过对比可见,调整峰值应变可有效消除网格尺寸对混凝土结构有限元分析的影响,ABAQUS塑性损伤模型在调整峰值应变后计算所得结果与试验结果更接近。且此方法对简单结构更为有效,而对于较为复杂结构,应视具体结构的复杂情况进行详细分析。
Firstly, the uniaxial stress-strain relation, damage variable, yield criterion and flow rule of the plastic damage model of concrete were expounded. Then, ABAQUS was used to calculate the standard cubic concrete sample block model with different mesh size, the function relation between the mesh size and the peak strain of the constitutive model was obtained by regression analysis. Then the finite element model of single pier and double pier with rectangular section was established, and the peak strain of damage model was corrected based on the above function. According to the finite element model of two piers, two test piers were designed and studied. By contrast, adjusting peak strain can effectively eliminate the influence of mesh size on the finite element analysis of concrete structure, and the results obtained by ABAQUS plastic damage model in adjusting peak strain are closer to the experimental results. And this method is more effective for simple structure, but for more complex structure, it should be analyzed in detail according to the complexity of concrete structure
Difference in metapopulation structure and dynamics of two species of coexistent melitaeine butterflies
Wang Yifei,Chen Jiejun,WANG Rongjiang,LEI Guangchun,Xu Rumei,
WANG Yifei
,CHEN Jiejun,WANG Rongjiang,LEI Guangchun & XU Rumei . Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering,Beijing Normal University,Beijing,China,. College of Life Sciences,Peking University,Beijing,China Correspondence should be addressed to Xu Rumei

科学通报(英文版) , 2003,
Abstract: According to investigation on two species of melitaeine butterflies in Yanjiaping Village, Chicheng County, Hebei Province, China, between 1998-2002, together with the use of 1:10000 contour map of the local area, some conclusions are shown by the SPSS and GIS analysis of data obained from GPS: (1) The two species of melitaeine butterflies have different metapopulation structures. M. phoebe is a source-sink metapopulation, while E. aurinia is a classical metapopulation, supporting the analytic result from our former genetic research. (2) The two species of melitaeine butterflies exhibit different trends of population dynamics. M. phoebe source-sink metapopulation is very unsteady, and is always small, thus has a tendency to go extinct gradually. But E. aurinia classical metapopulation is stable, and has maintained a larger population size. Therefore, it stands a better chance of long-term survival. (3) The two species of melitaeine butterflies are significantly related in both patch occupancy and local population size. (4) The effect of isolation is significant on the metapopulations of these two species of melitaeine butterflies, consistent with the classical theories, whereas the effect of patch area is not significant on the metapopulations of these two species of melitaeine butterflies, which is inconsistent with the classical theories. Therefore, other factors, such as habitat quality, should be considered for their influences on metapopulations.
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