聚丁二炔晶体中的电场调制光吸收     

彭景翠  张高明 《湖南农业大学学报(自然科学版)》1995,22(2)

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浅海埋地双层管道过渡段长度的计算   总被引：1，自引：0，他引：1  

张对红  张进国 《油气储运》1997,16(11):12-14

过渡段是浅海采油平台立管系统的一个部分，由于管道温差和内压引起膨胀会使立管过渡段的端部产生位移，对整人立管系统产生影响。如果过渡段端部位移过大，过渡段将一平台接触，对整个立管系统和采油平台造成危害，因此，对立管系统进行分析必考虑过渡段对立管系统的影响，而考虑过渡段的影响，必须首先确定过渡段的长度。考虑到目前浅海海底管道大多采用双层结构，提出用整体等效法计算又怪管结构过渡段的长度，并根据这种方法推导  相似文献   

Effect of changing forage on the dynamic variation in rumen fermentation in sheep          下载免费PDF全文

Xiao Xie  Jia‐kun Wang  Leluo Guan  Jian‐Xin Liu 《Animal Science Journal》2018,89(1):122-131

To better understand rumen adaptation during dietary transitions between high‐ and low‐quality forages, 10 rumen‐cannulated Hu sheep were randomly allocated to two dietary treatments (five sheep each) with the same concentrate‐to‐forage ratio and concentration mixture, but different forage sequences: (i) alfalfa hay (AH) to corn stover (CS) and back to AH; and (ii) CS to AH and back to CS. A significant decrease in the rumen microbial protein concentration was observed on day 6 after dietary transition whether the transition was from AH to CS or from CS to AH, and this was accompanied by an increase in the ammonia nitrogen concentration as well as a decrease in the total volatile fatty acids concentration and pH. However, after transitioning back to the original forage, the rumen fermentation parameters returned to their initial levels within 2 weeks. Our findings suggest that abrupt substitutions of forages with large nutrient differences could influence rumen function to some extent, but recovery can occur within 2 weeks without detrimental effects. Furthermore, we speculate that the variation of fermentation in the first 6 days may indicate an important rumen transition stage that requires further study.  相似文献   

Using State and Transition Models to Determine the Opportunity Cost of Providing Ecosystem Services     

John Ritten  María E. Fernández-Giménez  James Pritchett  Emily Kachergis  Willow Bish 《Strength and Conditioning Journal》2018,71(6):737-752

A ranch-level model using state-and-transitions models for three ecological sites is used to determine the trade-offs of providing various ecosystem services. The hypothetical ranch is located in northern Colorado and is based upon area average ecological site characteristics and livestock production practices. Management decisions include stocking rate and brush control. The model includes exogenous factors such as precipitation and fire. The model solves for optimal decisions over an infinite planning horizon using stochastic dynamic programming. Results show that a ranch cannot provide all ecosystem services in tandem at their highest level, implying that land managers must decide which ecosystems service they want to provide. Also, it is much cheaper in terms of foregone profitability for a ranch to continue to provide a specific ecosystem service that is already provided by the ranch rather than try to transition the ranch to a new ecological state in order to provide a service currently not provided.  相似文献   

X-ray ionizing radiation induces epithelial-mesenchymal transition in human nasopharyngeal carcinoma CNE-2 cells     

YU Dan  LIU Xia  FAN Wan-lin  AN Xiang  LI Bing 《园艺学报》2018,34(7):1250-1255

AIM:To investigate the effect of X-ray ionizing radiation on epithelial-mesenchymal transition (EMT) in human nasopharyngeal carcinoma CNE-2 cells and its involved potential signaling pathway. METHODS:The nasopharyngeal carcinoma CNE-2 cells were irradiated with different doses (0 Gy, 2 Gy, 4 Gy and 8 Gy) of X-ray. The morphological changes of the cells were observed under inverted microscope after 24 h. The migration and invasion abilities were detected by wound healing and Transwell assays. The mRNA and protein levels of E-cadherin, N-cadherin and vimentin in nasopharyngeal carcinoma CNE-2 cells were determined by real-time PCR and Western blot, respectively. The protein levels of Akt and p-Akt were detected by Western blot. RESULTS:After X-ray irradiation, the CNE-2 cells exhibited typical ‘cobblestone’ or spindle-like shape, with extended pseudopodia and dilated intercellular space. The invasiveness and metastatic abilities of the CNE-2 cells were enhanced (P<0.01). The mRNA and protein expression levels of E-cadherin were significantly decreased (P<0.01), while the mRNA and protein expression levels of N-cadherin and vimentin were markedly increased after irradiation as compared with the control group (no irradiation) (P<0.05). The protein level of p-Akt was significantly enhanced (P<0.01), while the protein level of Akt showed little change after irradiation. CONCLUSION:X-ray ionizing radiation induces EMT in nasopharyngeal carcinoma CNE-2 cells, which may be related to the activation of PI3K/Akt signaling pathway.  相似文献   

三维应力计的工作原理及误差分析     

张宏  李顺群  张少峰  冯慧强 《保鲜与加工》2015,(5):54-59

常规应力状态由3个正应力和3个剪应力共6个分量组成,因此,确定一点的应力状态至少需要6个单向应力计。基于三维应力状态理论,以单向应力计或压力计为基本元件,设计了一种能测试受力体内部三维应力状态的装置。该测试装置由6个单向应力计组成,且应力计的轴线构成四面体的6个棱。考虑测试装置对稳定性、合理性、便利性等技术要求,该四面体的形状可以设计为正四面体和由正方体截取的正三棱锥。根据某一方向上正应力与常规应力状态表示方法中6个应力分量之间的关系,建立了三维应力计各分量与常规应力分量之间的映射关系,并进一步导出了由三维应力计计算常规应力状态的方法及产生误差的原因。  相似文献   

Progress on Electrocatalysts for Proton exchange Membrane Fuel Cell     

RAN Hong-bo  LI Lan-lan  LI Li  WEI Zhi-dong 《保鲜与加工》2005,(4):119-125

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A PREDICTION OF THE DEVELOPMENT OF COMMODITY ECONOMY BY MEANS OF MARKOVIAN DECISION PROGRAMMING     

Yang Chunwei 《保鲜与加工》1989,(1)

This paper studies the transition prdbability, transfer matrix,distribution of owning the marketplace, and the transition probapility of theflow of customers by means of the theory of Markovian Decision Programming.It gives the theory and method for scientific predietion of the main probabilityof owning the marketplace and expected revenue in commodity economy.  相似文献   

Tendency Forecast of Three Gorge Land Using by Means of Markov   总被引：1，自引：0，他引：1  

LIU Qi-cheng  XIONG Wen-qiang  HAN Gui-feng 《保鲜与加工》2005,(2):107-110

In order to grasp the trend of land-using structure transition, adjust social and economical development strategies, and optimize the land-using structure, the land structure in latest years is forecasted, based on the analysis of land using actually and the first-hand data of the year 1995~2001. The theory of Markov chain is used to construct the transition probability matrix. The character of land structure transition is analyzed. The result shows that the plough reduce rapidly,the land is not fully utilize and the traffic land increase slowly.  相似文献   

Gefitinib inhibits epithelial-mesenchymal transition by up-regulating Foxo3a expression in mice with bleomycin-induced lung fibrosis     

PENG Ting  DU Hai-jian  LI Li  LI Wei-feng  HUANG Wen-jie 《园艺学报》2014,30(3):444-448

AIM：To identify the effect of gefitinib on the expression of forkhead box protein O3a (Foxo3a), α-smooth muscle actin (α-SMA) and related signal pathway molecules in the mice with bleomycin-induced lung fibrosis and to investigate the inhibition mechanism of gefitinib on lung epithelial-mesenchymal transition. METHODS：Thirty Kunming female mice were randomly divided into 3 groups:control group (received normal saline intratracheally), bleomycin group (received bleomycin intratracheally, 3 mg/kg), and bleomycin plus gefitinib group (received bleomycin intratracheally and gefitinib orally, 20 mg/kg). All the mice were sacrificed 14 d after the treatments. Pulmonary histological changes were evaluated by hematoxylin-eosin staining and Masson trichrome staining. The mRNA levels of Foxo3a and α-SMA in the lung tissues were detected by RT-PCR. Nuclear Foxo3a, α-SMA, and phosphorylation of EGFR, Akt and Foxo3a in the lung tissues were determined by Western blotting. RESULTS：Gefitinib inhibited bleomycin-induced lung fibrosis and significantly decreased the scores of lung inflammation and fibrosis. Foxo3a mRNA expression and total Foxo3a protein expression were increased, while the phosphorylated Foxo3a was decreased. Nuclear Foxo3a was increased significantly. Meanwhile, phosphorylated EGFR and Akt were decreased. The level of α-SMA was observably increased. CONCLUSION:Gefitinib restores Foxo3a activity and reduces α-SMA expression by modulating EGFR/Akt activity, thus inhibiting bleomycin-induced lung fibrosis.  相似文献