Journals
  Publication Years
  Keywords
Search within results Open Search
Please wait a minute...
For Selected: Toggle Thumbnails
Geochemical Features and Tectonic Significance of Late Archean Metavolcanic Rocks in Hengshan Area, North China Craton
GAO Shansong, LI Qiugen, HU Pengyue, Yasin Rahim, LI Hongying
Acta Scientiarum Naturalium Universitatis Pekinensis    2023, 59 (1): 143-160.   DOI: 10.13209/j.0479-8023.2022.102
Abstract287)   HTML    PDF(pc) (12920KB)(158)       Save
Petrographic, geochemical, zircon U-Pb geochronogical and Hf isotopic data are presented for the exposed metavolcanic rocks in Hengshan region to determine their eruption age, petrogenesis and geodynamic significance in the Trans-North China Orogen, North China Craton. Zircon U-Pb dating of the rocks yielded a weighted mean 207Pb/206Pb age of 2508 ± 20 Ma, indicating that their protoliths were erupted in the late Neoarchean. Geochemically, the Hengshan metavolcanic rocks are composed of basalt and basaltic andesite and marked by variable SiO2 (45.51%–62.67%), FeOt (4.43%–15.72%) and MgO (3.75%–8.14%) contents, indicative of product of derivation from a mantle source with subsequent fractional crystallization of clinopyroxene, hornblende and magnetite. These metavolcanic rocks are characterized by enrichments in light rare earth elements (LREE) and large-ion lithophile elements (LILE), as well as depletions in heavy rare earth elements (HREE) and high-field-strength elements (HFSE), with relatively high Th content and Th/Yb values, similar to those of the typical calc-alkaline arc-like volcanic rocks. Such arc-like geochemical signatures, together with some incompatible elemental ratios (e.g., Nb/Yb, Zr/Yb and (Nb/La)N), reveal their origination from a sub-arc enriched mantle wedge variably metasomatized by the slab-derived dehydration fluids. Combined with the region geological background, these Hengshan metavolcanic rocks were developed on a continental arc setting in the late Neoarchean.
Related Articles | Metrics | Comments0
Root Traits Variation in Inner Mongolia Grassland of China
MA Fang, ZENG Hui, LI Hongbo, MA Zeqing, GUO Dali
Acta Scientiarum Naturalium Universitatis Pekinensis    2019, 55 (2): 387-396.   DOI: 10.13209/j.0479-8023.2019.003
Abstract848)   HTML    PDF(pc) (2279KB)(425)       Save

The authors measured root morphological and architectural traits of 22 different dominant plant species across 16 Inner Mongolia grassland sites along soil water gradients, and analyzed the response of these root traits (diameter, length, SRL, RTD, BrIntensity and BrRatio) to four environmental factors (MAT, MAP, Soil N and Soil C). The results showed that variation of absorptive root diameter, tissue density and specific root length among different species was 7, 9, and 15 times, respectively. There was a significant positive correlation between root diameter and lateral root length, but negative correlation between root diameter and root branching intensity. Responses of both absorptive and non-absorptive roots to precipitation and soil nitrogen were species-specific. When using different combinations of root traits to describe plant adaptation strategies, different species’ root traits respond to environmental changes with different degrees and direction of variation, resulting in a diversity of plant adaptation strategies.

Related Articles | Metrics | Comments0
ODTrans: Fault Tolerant Transaction Protocols for the Cloud Data Store
CHENG Xu;LI Hongyan;WANG Tengjiao;YANG Dongqing
Acta Scientiarum Naturalium Universitatis Pekinensis    DOI: 10.13209/j.0479-8023.2015.011
Electrically-Pumped Metal-Organic-Metal Plasmonic Emitter
LI Hongqiang,WANG Chong
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract783)      PDF(pc) (1634KB)(686)       Save
A metal-organic-metal (MOM) plasmonic emitter with the p-type Si substrate and the active layer of Alq3: DCM is reported. The device structure is p-Si/Au/V2O5/NPB/Alq3:DCM/Sm/Au. The optical image of edge emission indicates that most of the light is well confined to the MOM waveguide. Light is collected with a confocal μ-Raman spectrometer. The TM mode is more intense than the TE mode by a factor of 2, which can be attributed to the contribution of surface plasmon polariton (SPP). The power dissipation spectrum is computed based on a simplified MOM structure of Au/organic/Au. By integrating the power of the SPP modes in the spectrum, the fraction of the total power coupled to SPP modes is 65%. The electric-field-intensity distribution and the loss coefficients are computed by finite-different time-domain (FDTD) method.
Related Articles | Metrics | Comments0
Social Network Compression Based on the Importance of the Community Nodes
LI Hongbo,ZHANG Jianpei,YANG Jing,BAI Jinbo,CHU Yan,ZHANG Lejun
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract531)      PDF(pc) (1901KB)(353)       Save
In response to the inadequacies of current graph compression methods, such as higher time complexity, dependence on experiences to set parameters, too many parameters to adjust, compression loss, ignoring the community structure of network, a social network compression method is proposed based on the importance of the community nodes. The method include community discovery algorithm (GS) based on greedy strategy and social network compression algorithm (SNC). Adopting topological potential theory GS algorithm is not only capable of discovering communities but also capable of mining important nodes in the communities. SNC algorithm takes communities as targets, achieves lossless compression while maintaining the connections between communities, and keeps important nodes in communities or basic community structure if necessary. The feasibility and effectiveness of the method are verified in experiments.
Related Articles | Metrics | Comments0
Pore-Throat Structure Evaluation of Artificial Cores with Rate-Controlled Porosimetry
CHAI Zhi,SHI Yongmin,XU Changsheng,ZHANG Yuguang,LI Hong,WU Wenjuan,XU Hongbo,WANG Lei
Acta Scientiarum Naturalium Universitatis Pekinensis   
Improved 2nd-Order Multi-bit Noise-Coupled Sigma-Delta Modulator for GSM Standard
LI Hongyi,WANG Yuan,JIA Song,ZHANG Xing
Acta Scientiarum Naturalium Universitatis Pekinensis   
Cauchy Problem for the “Bad” Boussinesq-Type Equation with Damping Term
LI Qingshan,LI Hong,SONG Changming,ZHANG Yiran
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract631)            Save
The Cauchy problem for the “bad” Boussinesq-type equation with damping term uu-uxx-2kuxxt-αuxxxx=β(u<>sup>n)xx is studied Where k, α and β are real numbers, with k>0,α>0, and n≥2 is an integer It proves that for any T>0 the Cauchy problem admits a global smooth solution u∈C((0,T];H(R))∩C([0,T];H1(R))∩C1([0,T];H-1(R)) under suitable assumptions on the initial data
Related Articles | Metrics | Comments0
Anticancer Activity on Prostate Cancer of the Extracts of Prescription of TCM 921
LI Jiangbin,LI Hongyan,ZHANG Zhihong,CHEN Xiaoguang,YE Zuguang,GUO Yinglu
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract629)            Save
In order to investigate the inhibition of the extracts of prescription of 921 on prostate cancer cell proliferation in vitro and tumor growth in vivo, the authors used the methods as follows: SRB assay was applied to examine the anti-proliferation of the extracts of prescription of 921 in vitro both on human cancer cell DU-145, PC-3m, EJ and mice prostate cancer TRAMP-C2. The experimental implanted tumor mice model Hepatoma (H22), Sarcoma (S180), Prostate cancer (TRAMP-C2) and tumor nude mice model Prostate cancer (PC-3M) were used to evaluate its anti-tumor activity in vivo. Furthermore, the enhance therapeutic effect was also observed when combined with cyclophosphamide (CTX) on S180. The results were 1) the extracts of prescription of 921 showed proliferation inhibitory activities on DU-145, PC-3M, EJ and TRAMP-C2 cell lines; 2) it inhibited mice H22, S180, TRAMP-C2 and naked mice PC-3M when administered i.g. at 3.6~14.3 g/(kg?day) for 9 days. The extracts of prescription of 921 enhanced CTX's therapeutic effect and didn't enhance its toxicity. In summary, the extracts of prescription of 921 showed inhibitory activity on the growth of prostate cancer.
Related Articles | Metrics | Comments0
Retrieval of Atmospheric Total Water Vapor with MODIS Near Infrared Measurements
LI Honglin,LI Wanbiao
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract685)            Save
Retrieving atmospheric water vapor from remote sensing data is very important in such aspects as water circulation, global climatic change, weather forecast and atmosphere correction. Considering the scanning angle of the sensor, the two-band ratio method for retrieval of atmospheric total water vapor is developed by moderate-resolution imaging spectro-radiometer(MODIS) near infrared measurements. The RMS error compared to radiosonde observation is 0.29 g/cm2, and the correlation coefficient is 92%. The comparison of the monthly mean total water vapor distribution shows that the retrieval water vapor field is in good agreement with that of the MODIS product.
Related Articles | Metrics | Comments0
Phase Solution of Modulated Fringe Carrier Using Wavelet Transform
LI Hongju ,CHEN Huijun
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract708)            Save
The relation between the carrier frequency and the maximum of the wavelet coefficient modules is given, from which the searching ranges of the maximum amplitudes in the dimension coordinate are presented. The method reduces the difficulty of phase determination from the wavelet transform coefficient maps. The computational results show the validity of the technique, and present the influence of the carrier frequency on the processing errors of the phase solution.
Related Articles | Metrics | Comments0
A Novel Unicast Based Multiplexing Scheme to Improve the Capacity of VoWLAN
WANG Dong,LIU Zhimin,ZHAO Yuping,LUO Yan,LI Honggang,LE Jilin,CAO Yang
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract720)            Save
The mergence of VoIP and WLAN created a new wireless platform for voice service delivery, VoWLAN. This paper figured out the capacity bottleneck of VoWLAN, and analyzed the problems in current solutions such as M-M. A novel unicast based multiplexing scheme (U-M, Unicast Multiplexing) to improve the capacity and performance of VoWLAN was proposed. Both theoretical and simulation results showed that this scheme improved the voice capacity to nearly 100% comparing to the traditional un-multiplexed scheme, and reduced the packet lost ratio by 10% compared with the M-M scheme. Meanwhile, the U-M scheme is a power-saving scheme in the voice-oriented application as well. Therefore the proposed U-M scheme is an effective solution to increase the voice capacity of WLAN and improve the performance of VoIP service.
Related Articles | Metrics | Comments0
A New Compact Pipeline Leak Detection and Location Monitoring System with the GPRS Wireless Communication Technology
SHI Ketian,SUN Zhili,YAN Dachun,LI Hongmei,YE Zongmei,SHANG Jiaoqing,FU Hongli,SONG Xuefeng
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract633)            Save
A new pipeline leak detection and location monitoring system is introduced. Some digital technology are applied to this system, such as pocket PC data processing system and GPRS wireless communication system. The monitoring system has the advantage of compactness, easiness of installing and fast speed of communication. The pipeline leak detection and location monitoring system can be widely applied to water pipeline, oil pipeline and gas pipeline.
Related Articles | Metrics | Comments0
Managing User Interaction Forms on Web Pages: A Template-Base Approach
XUE Ming,LI Hongyan
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract605)            Save
A metadata model called Template Model to deal with the user interaction forms on the web pages is proposed. The template model can carry the aggregation semantics of the user interaction forms and maintain it as a hierarchal structure. It is possible to reuse some of the page components to facilitate generating and maintaining large number of user interaction forms on web pages. And the template model can help to deal with the queries to these interaction forms.
Related Articles | Metrics | Comments0
Wind Tunnel Experiment on the Model of the Chinese National Grand Theatre
YAN Dachun,SUN Zhili,HUANG Sheng,DING Wuquan,CHEN Mingfu,LIN Rongsheng,QIU Panxiang,LI Hong,LIU Hanlin
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract770)            Save
The main results of the wind tunnel experiment on the 1/200 model of the Chinese National Grand Theatre were introduced. At first, the wind pressure distributions of its semi-ellipsoidal surface in an atmospheric boundary layer flow were simulated, and the effect of the surface roughness was researched. The results indicated a reasonable regularity of its wind loading in various wind directions. On the problem of the environmental influence, it demonstrated that there existed a great effect for the pressure distribution of the Great Theatre when the Grand Hall is at east.
Related Articles | Metrics | Comments0
Synthesis and Photophysical Properties of Cyano-Bridged Complexes of Ru(II)
LI Hongliang,GUO Guolin,GUI Linlin,LI Chongjia
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract597)            Save
The special property of the NO+ ligand which can be solvated by azide-assisted labilization of the nitrosyl ligand in the Ru(II) complexes was applied in the synthesis of the necomplexes: NO2-Ru(bpy)2-NC-Ru-(py)4-CN+, Cl-Ru(bpy)2-NC-Ru(py)4-CN+, NO2-Ru(bpy)2-NC-Ru(py)4-CN-Ru-(bpy)2-NO22+ and Cl-Ru(bpy)2-NC-Ru(py)4-CN-Ru(bpy)2Cl2+(bpy=2, 2'-bipyridine, py=pyridine). The UV-Visible spectra, the IR spectra and the photo-luminescence properties of these complexes were studied. It has been shown from the elemental analysis, the UV-Visible spectra and the IR spectra, that the new complexes we designed were prepared. It is very interesting that there are two different MLCT(metal-to-ligand charge transfer) process and two photo-luminescence emission bands in one molecule. These special photophysical properties were the results of the special configuration and buildups of the different blocks in the new complexes. This will present the advantage for the study of the electron transfer within those molecules.
Related Articles | Metrics | Comments0