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Search Results: 1 - 10 of 19402 matches for " 范婤 "
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沉水植物茎叶微界面及其对水体氮循环影响研究进展
王文林?,刘波?,韩睿明?,,王国祥?
生态学报 , 2014,
Abstract: 沉水植物茎叶表面常富集了水中各类物质,包括有机质、泥沙、菌胶团、藻类、微生物等,形成厚度不等的附着层,形成特殊的茎叶微界面,其具有特殊的氧化-还原异质环境,并能为氮素循环细菌提供有机质,是水中氨化、反硝化及厌氧氨氧化等脱氮行为的重要基础,因此,了解沉水植物茎叶微界面组分、微环境变化特征及其对氮循环的调控作用,对于正确认识和利用沉水植物的生态调控功能、改善水环境质量具有十分重要的意义.基于此,就沉水植物茎叶微界面物质组成、微环境特征及其对水体氮循环影响研究现状进行了归纳总结,并对今后的研究方向进行了简要展望.
外源营养盐输入后水体中营养盐浓度的时空变化
傅玲,赵凯,王国祥,欧媛,,毛丽娜,张佳,韩睿明
环境科学 , 2014,
Abstract: 在温室内的水泥沟渠中人工构建6种不同的植物镶嵌群落,通过人工添加营养盐的方式模拟外源营养盐输入,并持续测量单次营养盐添加后22d内水体表层、中层和底层可溶性总氮(DTN)、可溶性总磷(DTP)、氨氮(NH4+-N)、硝氮(NO3--N)以及亚硝氮(NO2--N)浓度变化情况,以揭示单次外源营养盐输入后水体营养盐浓度的时空变化过程.结果表明:1不同水深和测量时间下各形态营养盐浓度有显著差别,植物群落类型对不同形态营养盐浓度影响不显著;2外源营养盐进入表层水体后扩散到中层水体的过程较为缓慢,在本实验条件下需要6d;3实验过程中底层水体NO2--N以外的其它营养盐浓度均无显著变化,外源营养盐输入仅影响表层和中层水体营养盐浓度;4单次外源营养盐输入一定时间后DTP和NH4+-N浓度逐渐下降到输入前水平,本实验条件下这一过程需要22d,DTN和NO3--N浓度则下降非常缓慢;5外源营养盐输入水体后不同深度水体中NO2--N浓度均呈上升趋势,一方面说明外源营养盐输入后,水体N循环过程中的硝化作用和反硝化作用加强,另一方面也说明外源营养盐输入除危害水生生态系统健康以外更会直接危及人类自身的健康.
青藏牧场的毒药、围栏与生物多样性危机——雪域藏人与动物关系及生态行动的民族志研究
The Rat Poison, Fence and Biodiversity Crisis in Qinghai-Tibetan Pastures ——An Ethnographic Study on the Relationship among Tibetans and Animals and Ecological Actions
 [PDF]

长风
Modern Anthropology (MA) , 2014, DOI: 10.12677/MA.2014.21001
Abstract:

草原退化的根源是高原鼠兔的破坏还是人类过度干预的结果。研究表明高原鼠兔是青藏高原的“关键物种”,其存在意味着生物多样性的维系和生态系统正常生态功能的发挥,故毒杀高原鼠兔只能损害生物多样性却不能真正解决草原退化问题。在1950年代以来的青藏高原,权力话语对高原鼠兔进行了妖魔化建构和大规模毒杀活动。生态危机是草原使用方式包括科学手段的使用出了问题,也是文化危机。生态危机的解决需要文化自觉去点亮科学技术的伦理之光,把科学知识体系与藏族地方知识有机整合。保护青藏高原生物多样性的希望不是毒药加围栏,而是科学与文化的整合加上权力下沉社区。
Grassland degradation resulted from pikas’ destroying or human’s excessive interference. This study shows that pika is one kind of key species on Qinghai-Tibet Plateau, whose existence maintains biodi- versity and normal function of ecosystem. So, killing pikas will only damage biodiversity, but will not stop grassland degradation. Since 1950, power discourses which demonized pika have rationalized government’s large-scale killing-pika movements. Ecological crisis is caused by wrong exploitation of prairie including scientific misconduct, so in some sense, it is cultural crisis. To solve ecological crisis, we should integrate scientific knowledge with Tibetan local knowledge, namely, to stimulate cultural self-consciousness to ensure the ethics of science and technology. To maintain the biodiversity on the Qinghai-Tibet Plateau, we should not rely on poison and fence, but strengthen the integration of culture and science, empowering the local community as well.

金刚石型结构晶面间距及结构因子的计算
Calculation of Interplanar Spacing and Structure-Factor of Diamond-Type Structure
 [PDF]

群成
Material Sciences (MS) , 2012, DOI: 10.12677/MS.2012.23019
Abstract: 用添加原子的“位置因子S”,得到了金刚石型结构可能的四种面间距。计算了这种结构的结构因子,并分析了晶面间距与结构因子的相关性。讨论了金刚石型结构与面心立方结构间消光条件的差异。
With the “site-factor S” of an addition atom, the possible four kinds of interplanar spacing of diamond-type structure was calculated. In addition, the structure-factor of this structure was calculated, and a correlativity between the interplanar spacing and the structure-factor was analysed. Finally, a difference in missing reflection conditions between diamond-type structure and face-centered cubic structure was discussed.
基于LEACH 无线传感网络稳定簇算法研究
A Stable Cluster Algorithms in Wireless Sensor Network Based on LEACH
 [PDF]

张博, 通让
Hans Journal of Wireless Communications (HJWC) , 2011, DOI: 10.12677/hjwc.2011.11003
Abstract: 针对LEACH 算法中随机成簇的不足和簇头选举能量消耗过大的不足进行改进,采用的方法是优化簇头的个数、不均匀成簇、最后保持已形成的簇的稳定,减少全网簇的选举消耗的能量。仿真实验表明,改进后的算法在节点死亡率的控制方面有了提高。
For the shortage of random clusters and excessive consumption of energy when the election of cluster head in LEACH, this paper improved LEACH algorithms, the method is to optimize the number of cluster head, get the unequal clustering and keeping stable of the clustering, reduce over the election of cluster energy consumption. Simulation experiments show that the improved algorithm in the control node mortality has been improved.
密排六方晶体面间距的计算
Calculation of Interplanar Spacing in Hexagonal Close-Packed Crystal
 [PDF]

群成
Material Sciences (MS) , 2012, DOI: 10.12677/ms.2012.22012
Abstract: 基于解析几何基本原理,提议用添加原子的“位置因子S”作为计算晶面间距的工具。使用“位置因子S”,算得密排六方晶体六种可能的面间距,并得到实例验证。分析了晶面间距与结构因子的相关性,并讨论了附加面与消光面的关系。
Based on a principle of analytic geometry, a “site-factor S” of an addition atom was suggested to take as a tool for calculating interplanar spacing. With the “site factor S”, the interplanar spacing of hexagonal close-packed crystal was calculated and confirmed by some examples, and the result showed that it has 6 kinds of possible interplanar spacing. The correlativity between the interplanar spacing and the structure-factor were analysed, and relation between the additional plane and the missing reflection plane was discussed.
基于贝叶斯网络的城市轨道交通应急系统可靠性分析
Research on Reliability Analysis of Urban Rail Transit Emergency System Based on Bayesian Network
 [PDF]

晓燕
Open Journal of Transportation Technologies (OJTT) , 2014, DOI: 10.12677/OJTT.2014.34015
Abstract:
通过分析城市轨道交通应急系统可靠性评价指标体系结构,建立了基于贝叶斯网络的城市轨道交通应急系统可靠性评价的贝叶斯模型。最后,以某地铁为例,建立基于贝叶斯的应急系统可靠性的模型,并利用贝叶斯推理及BayesiaLab工具进行了可靠性的计算。对计算结果进行了分析,并给出了提高该地铁应急系统可靠性的几点措施。
Urban rail transit emergency problem is very complicated, which is affected by many uncertain factors. In view of this, considering the advantages of Bayesian network in solving uncertainty problems, through the analysis of reliability of city track traffic emergency system evaluation index system, this paper has established the Bayesian model to evaluate the reliability of city rail transit emergency system. Finally, taking a subway as an example, the reliability of emergency system model is established based on Bayesian network and the calculation is carried out by using Bayesian’s reasoning and BayesiaLab tools. By analyzing the calculation results, some measures of improving reliability of the subway emergency system are given.
许昌市不同土地利用方式对土壤速效养分的影响
Characters on Available Nutrients of Soils under Different Land Use Types in Xuchang
 [PDF]

晓红
Open Journal of Soil and Water Conservation (OJSWC) , 2015, DOI: 10.12677/OJSWC.2015.34009
Abstract:
本文选取许昌市菜地、果园、耕地、苗圃、林地和城市绿地6种土地利用类型为研究对象,通过野外采样和室内分析对不同土地利用类型表层土壤(0~10 cm)的基本理化性质和速效养分特征进行了分析。结果表明:1) 土壤容重变幅为0.9~1.82 g/cm3;城市绿地 > 林地 > 苗圃 > 菜地 > 果园 > 耕地。2) 土壤pH值变幅为7.21~8.49,均值7.93,属碱性;菜地 > 果园 > 耕地 > 苗圃 > 林地 > 城市绿地。3) 土壤速效氮变幅12.55~47.48 mg/kg,均值为26.01 mg/kg,属于土壤养分分级6级水平;耕地 > 菜地 > 果园 > 林地 > 苗圃 > 城市绿地。4) 土壤速效磷含量变幅为11.54~78.86 mg/kg,均值26.71 mg/kg,属于土壤养分分级2级水平,呈现出富磷特征;城市绿地 > 果园 > 苗圃 > 菜地 > 林地 > 耕地。5) 土壤速效钾含量变幅在129.5~295.3 mg/kg之间,均值234.59 mg/kg,属于土壤养分分级1级水平;耕地 > 苗圃 > 菜地 > 果园 > 林地 > 城市绿地。
On the basis of field sampling and laboratory experiment, the basic physicochemical properties and the available nutrients of surface soils (0 - 10 cm) were analyzed between six land use types (vegetable field, orchard, cultivated land, nursery, forest land and urban green space) in Xuchang city. The e results showed that: 1) the soil bulk density was in the range of 0.9 - 1.82 g/cm3 and followed the order of urban green land > forest land > nursery > vegetable plots > orchard > culti-vated land. 2) The value of pH was in the range of 7.21 - 8.49, with the mean of 7.93, which inda-cated the alkaline feature. The order of pH was vegetable field > orchard > cultivated land > nur-sery > forest land > urban green space. 3) The content of soil available nitrogen ranged between 12.55 to 47.48 mg/kg, with the mean of 26.01 mg/kg and the level was the sixth. The order of available nitrogen was cultivated land > vegetable field > orchard > forestland > nursery > urban green space. 4) The content of soil available phosphorus was in the range of 11.54 - 11.54 mg/kg, with the mean of 26.71 mg/kg and the level was the second, indicating a highly rich in the phos-phorus. The soil available phosphorus followed the order: urban green space > orchard > nursery > vegetable field > forestland > cultivated land. 5) The soil available potassium content ranged be-tween 129.5 to 295.3 mg/kg, with the mean of 234.59 mg/kg and the level. The order of soil avail-able potassium was cultivated land > nursery > vegetable field > orchard > woodland > urban green space.
基于改进词向量模型的深度学习文本主题分类
Deep Learning on Improved Word Embedding Model for Topic Classification
 [PDF]

周盈盈,
Computer Science and Application (CSA) , 2016, DOI: 10.12677/CSA.2016.611077
Abstract: 主题分类在内容检索和信息筛选中应用广泛,其核心问题可分为两部分: 文本表示和分类模型。近年来,基于分布式词向量对文本进行表示,使用卷积神经网络作为分类器的文本主题分类方法取得了较好的分类效果。本文研究了不同词向量对卷积神经网络分类效果的影响,提出针对中文语料的topic2vec词向量模型。本文利用该模型,对具有代表性的互联网内容生成社区“知乎”进行了实验与分析。实验结果表明,利用topic2vec词向量的卷积神经网络,在长内容文本和短标题文本的分类问题中分别取得了98.06%,93.27%的准确率,较已知词向量模型均有显著提高。
Topic classification has wide applications in content searching and information filtering. It can be divided into two core parts: text embedding and classification modeling. In recent years, methods have brought out significant results using distributed word embedding as input and convolutional neural network (CNN) as classifiers. This paper discusses the impact of different word embedding for CNN classifiers, proposes topic2vec, a new word embedding specifically suitable for Chinese corpora, and conducts an experiment on Zhihu, a representative content-oriented internet com-munity. The experiment turns out that CNN with topic2vec gains an accuracy of 98.06% for long content texts, 93.27% for short title texts and an improvement comparing with other word em-bedding models.
布伦特油价波动研究及其与BDI指数的关系研究——基于VAR-GARCH模型
Research on Brent’s Oil Price Fluctuation and Its Relationship with BDI Index—Based on VAR-GARCH Model
 [PDF]

燕君
Advances in Social Sciences (ASS) , 2016, DOI: 10.12677/ASS.2016.56116
Abstract:
本文以BDI指数和布伦特油价为基础建立时间序列模型,试图测量两者之间的关系。首先对布伦特油价数据的处理主要采取对数差分法,可以消除序列的非平稳性,并降低计算难度,因而在研究实践中具有较高的实用性。然后对布伦特油价数据进行描述性分析,再建立GARCH模型对原数据进行拟合,最后将油价与BDI数据建立VaR模型。本文使用的软件是Eviews。
In this paper, the time series model is established based on the BDI index and the Brent oil price, which attempts to measure the relationship between the two series. First, the disposal of the Brent oil price data mainly with the logarithmic difference method can eliminate non-stationary sequences, and reduce the difficulty of calculation, so it has high practicability in practice. Then the Brent oil price data were analyzed by descriptive analysis, and then established the GARCH model to fit the original data, and finally established the VaR model between oil prices and BDI data. In this paper, we used the Eviews software.
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