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1The first offshore natural gas hydrate production test in South China Sea显示文摘Natural gas hydrates (NGH)is one of key future clean energy resources.Its industrialized development will help remit the huge demand of global natural gas,relieve the increasing pressure of the environment, and play a vital role in the green sustainable growth of human societies.Based on nearly two decades' studying on the reservoir characteristics in the South China Sea (SCS)and the knowledge of reservoir system,the China Geological Survey (CGS)conducted the first production test on an optimal target selected in Shenhu area SCS in 2017.Guided by the 'three-phase control'exploitation theory which focused on formation stabilization,technologies such as formation fluid extraction,well drilling and completing, reservoir stimulating,sand controlling,environmental monitoring,monitoring and preventing of secondary formation of hydrates were applied.The test lasted for 60 days from May 10^th when starting to pump, drop pressure and ignite to well killing on July 9^th,with gas production of 3.09×10^5 m^3 in total,which is a world record with the longest continuous duration of gas production and maximal gas yield.This successful test brings a significant breakthrough on safety control of NGH production.Jin-fa Li Jian-liang Ye Xu-wen Qin Hai-jun Qiu Neng-you Wu Hai-long Lu Wen-wei Xie Jing-an Lu Fei Peng Zhen-qiang Xu Cheng Lu Zeng-gui Kuang Jian-gong Wei Qian-yong Liang Hong-feng Lu Bei-bei Kou 2018China Geology2018,1,1:117
2Egger’s test与Begg’s test的功效差异比较与原因分析显示文摘目的比较Meta分析中Egger’s test、Begg’s test方法在检测发表偏倚时的功效(检验效能)差异并探讨其原因。方法收集28篇相关文献建立数据库,采用倾向性缺失手段产生11份新的Meta分析资料样本,然后行Egger’stest、Begg’s test检验其发表偏倚,比较结果的差异,并同时做纳入研究的异质性和样本含量的正态性检验,寻找影响发表偏倚检验功效的因素。结果①11个倾向性缺失样本中,Begg’s test有5项的P值小于0.05,而Egger’s test的P值都大于0.27;②异质性检验P值全部小于0.05,正态性检验有9项P值小于0.05。结论①倾向性缺失导致发表偏倚,此时Begg’s test较Egger’s test更容易检出发表偏倚的真实情况,而Egger’s test的检验效能此时并不高;②导致Egger’s test对发表偏倚的检验效能下降的可能因素有样本含量非正态和异质性等。石修权 王增珍 2009华中科技大学学报(医学版)2009,38,1:33
3在SPSS中利用均数和标准差做两独立样本t检验显示文摘[目的]在SPSS中利用两样本均数、标准差和样本含量做两独立样本t检验。[方法]通过SPSS软件编写程序,实现两独立样本t检验。[结果]实例验证证明,程序运行的结果正确。[结论]在没有原始数据的情况下利用统计量做两独立样本t检验在SPSS软件中是完全可以实现的。申希平 丁建生 李娟生 刘小宁 李江红 米友军 2007现代预防医学2007,34,21:29
4高温对仁用杏光合特性及PSⅡ光化学活性的影响显示文摘为探讨高温胁迫下仁用杏叶片的光合适应机制,以科尔沁沙地生长的4年生‘超仁’仁用杏为试材,设置环境温度为25℃、30℃、40℃和50℃处理,利用气体交换技术和快速叶绿素荧光诱导动力学曲线分析技术(JIP-test),研究了仁用杏叶片光合特性和PSⅡ光化学活性.结果表明:在一定温度范围内,随着温度升高,仁用杏通过提高光合色素含量和比例来维持光能的吸收、传递和转换能力,从而保证光合机构正常运转;当高温超过叶片自身生理调节限度后,叶绿素发生分解、净光合速率(Pn)明显下降、胞间CO2浓度(Ci)上升,说明光合作用的下降是由叶肉因素造成的.温度40℃导致单位面积有活性反应中心数量(RC/CSo)显著下降;而50℃高温下荧光诱导曲线中K点(Wk)和J点(Vj)明显增加,高温对仁用杏叶片放氧复合体(OEC)、受体侧和PSⅡ反应中心造成了伤害.此外,50℃高温还导致初始荧光(Fo)显著升高,为对照的2.26倍,PSⅡ最大光化学效率(Fv/Fm)和光化学性能指数(PIABS)分别下降为对照的37.9%和10.3%.高温损害了PSⅡ供体侧和受体侧的功能,造成光合效率下降,这是高温胁迫对仁用杏叶片光合机构伤害的主要机制之一.杜国栋 吕德国 赵玲 王素素 蔡倩 2011应用生态学报2011,22,3:30
5Irritable bowel syndrome and small intestinal bacterial overgrowth:Meaningful association or unnecessary hype显示文摘Irritable bowel syndrome(IBS)is a common condition characterized by abdominal pain or discomfort,bloating,and altered stool form and passage.Small intestinal bacterial overgrowth(SIBO)is a condition in which there is overgrowth of bacteria in small bowel in excess of 105colony forming units per milliliter on culture of the upper gut aspirate.Frequency of SIBO varied from 4%-78%among patients with IBS and from 1%-40%among controls.Higher frequency in some studies might be due to fallacious criteria[postlactulose breath-hydrogen rise 20 PPM above basal within 90 min(early-peak)].Glucose hydrogen breath test(GHBT)has a low sensitivity to diagnose SIBO.Hence,studies based on GHBT might have under-estimated frequency of SIBO.Therefore,it is important to analyze these studies carefully to evaluate whether the reported association between IBS and SIBO is over or under-projected.This review evaluates studies on association between SIBO and IBS,discordance between different studies,their strength and weakness including methodological issues and evidence on therapeutic manipulation of gut flora on symptoms of IBS.Uday C Ghoshal Deepakshi Srivastava 2014World Journal of Gastroenterology2014,20,10:29
6348-YEAR PRECIPITATION RECONSTRUCTION FROM TREE-RINGS FOR THE NORTH SLOPE OF THE MIDDLE TIANSHAN MOUNTAINS显示文摘Correlation census shows that the correlation between the tree-ring chronologies in the Urumqi River Basin and precipitation during July in the last year to February in the concurrent year is significant, and the best single correlation coefficient is 0.74, with significance level of 0. 0001.Using two residual chronologies collected from west Baiyanggou and Boerqingou, precipitation for 348 years can be reconstructed in the North Slope of middle Tianshan Mountains, its explained variance is 62%. According to much verification from independent precipitation data, historical climate records, glacier and other data, it shows that the reconstructed precipitation series of 348 years is reliable. Analysis of precipitation features indicates that there were three wet periods occurring during 1671 (?) -1692, 1716-1794 and 1825-1866 and three dry periods during 1693 - 1715, 1795- 1824 and 1867- 1969. Two wet periods, during 1716- 1794 and 1825 - 1866,correspond to the times of the second and the third glacial terminal moraine formation, which is in front of No. 1 glacier in Urumqi River source. According to computation, corresponding annual precipitation amounts are 59 mm and 30 mm more than now. The reconstructed precipitation series has a significant drying trend from 1716 to 1969, and has better representativeness to the precipitation of Urumqi and Changji Prefecture on the North Slope of Tianshan Mountains.袁玉江 李江风 张家宝 2001Acta meteorologica Sinica2001,15,1:27
7TCT技术在胸腹水恶性肿瘤诊断中应用显示文摘张培谊 邹赛英 王玉兰 黄海涛 曹钢 2005临床与实验病理学杂志2005,21,3:28
8A new scoring system for assessment of liver function after successful hepatectomy in patients with hepatocellular carcinoma显示文摘BACKGROUND:Whether a major liver resection is safe has been judged mainly from the patient's hepatic reserve.However,a safe limit for liver resection does not exist yet.This study aimed to construct a new scoring system as a guide to determine a safe limit for liver resection and avoid liver dysfunction after hepatectomy.METHODS:Eighty-six patients with hepatocellular carcinoma who had undergone hepatectomy in West China Hospital from March 2007 to June 2010 were reviewed.The patients were classified according to the levels of total bilirubin after hepatectomy and the parameters in the perioperative period were compared.Receiver operating characteristic (ROC) analysis was made to assess the liver function compensatory (LFC) value to predict liver dysfunction of the patients after hepatectomy.LFC value is defined as the preoperative KICG value×22.487+standard remnant liver volume (SRLV)×0.020.RESULTS:Patients were classified into group Ⅰ (normal group,n=69) and group Ⅱ (with total bilirubin >85.5 μmol/L for 7 days after hepatectomy,n=17) based on the levels of total bilirubin after hepatectomy.Group II was further divided into two subgroups:recovered subgroup (n=14) and fatal subgroup (n=3).There were no significant differences in preoperative data or intraoperative findings except the indocyanine green test parameters (KICG and ICG R15) and SRLV.ROC analysis showed that the sensitivity and specificity of an LFC value ≤13.01 were 94.1% and 82.6% respectively for predicting liver dysfunction of the patients after hepatectomy.CONCLUSIONS:The LFC value appears to be a good predictor of postoperative liver dysfunction in patients who undergo hepatectomy for HCC.An expected LFC value of 13.01 seems to be a safe limit for liver resection.Zheng-Gui Du,Bo Li,Yong-Gang Wei,Jie Yin,Xi Feng and Xi Chen Department of Liver and Vascular Surgery,West China Hospital,Sichuan University,Chengdu 610041,China 2011Hepatobiliary & Pancreatic Diseases International2011,10,3:23
9Psychometric hepatic encephalopathy score for diagnosis of minimal hepatic encephalopathy in China显示文摘AIM:To construct normal values for the tests of the psychometric hepatic encephalopathy score(PHES)and to evaluate its usefulness in the diagnosis of minimal hepatic encephalopathy(MHE)among Chinese individuals with cirrhosis.METHODS:The five tests of PHES,number connection test-A(NCT-A),number connection test-B,serial dotting test,line tracing test and digit symbol test(DST),were administered to all enrolled subjects in a quiet room with sufficient light.Cirrhotic subjects with overt HE were excluded by the West-Haven criteria and a detailed neurological examination.Based on the nomograms of healthy volunteers,the patients were classified as having MHE when their PHES was less than-4.RESULTS:In total,146 healthy volunteers completed all the PHES tests.Age and education years were confirmed to be predictors of all five tests.In total,53patients with liver cirrhosis completed the PHES.Of the patients with liver cirrhosis,24(45.3%),22(41.5%)and 7(13.2%)had Child-Pugh grades A,B and C,respectively.MHE was diagnosed in 26 patients(49.1%).Compared with compensated cirrhotic patients(Child A),decompensated cirrhotic patients(Child B and C)had a higher proportion of MHE(65.5%vs 29.2%).No differences in age and education years were found between the MHE and non-MHE groups.NCT-A and DST were able to diagnose MHE with a sensitivity of 76.9%and a specificity of 96.3%(AUC=0.866,K=0.735).CONCLUSION:The proportion of MHE is associated with liver function.NCT-A and DST are simple tools that can be used for the diagnosis of MHE in China.Su-Wen Li Kai Wang Yong-Qiang Yu Hai-Bao Wang Yuan-Hai Li Jian-Ming Xu 2013World Journal of Gastroenterology2013,19,46:21
10电气试验中的危害分析及预防措施显示文摘电气试验是确保变配电设备安全运行的一项重要工作,确保试验过程的安全,是做好电气试验管理工作的重要前提。需要根据HSE管理体系的要求,立足预防为主,体现以人为本,把电气安全措施贯穿到全体人员和试验工作的全过程,以消除试验过程中存在的各种不安全因素,以扎实可靠的安全管理措施保证试验的质量,发挥电气试验在保障电气系统安全运行中的重要作用。重点对35kV及以下变电所变配电设备的电气试验中的危害识别进行分析,并提出安全管理措施。王龄 2010石油化工安全环保技术2010,26,6:21
11盐碱胁迫对山葡萄光合特性及生长发育的影响显示文摘以棚内盆栽山葡萄品种‘双优’(抗逆性弱)和‘左山一’(抗逆性强)扦插苗为材料,利用气体交换分析和叶绿素荧光诱导动力学分析手段,研究了轻度、中度和重度盐碱胁迫对不同抗逆性山葡萄品种的光合特性及PSⅡ活性以及生长发育的影响,为山葡萄耐盐碱品种的评价提供理论依据。结果显示:(1)‘双优’各胁迫程度下的净光合速率(P_n)、气孔导度(Gs)和重度胁迫下的蒸腾速率(T_r)显著低于对照,而‘左山一’重度胁迫下的Pn和T_r、中重度胁迫下的Gs、各胁迫程度下的胞间二氧化碳浓度(Ci)显著低于对照,净光合速率下降主要归因于气孔限制和非气孔限制。(2)轻度、中度盐碱胁迫‘双优’叶片单位反应中心吸收的光能(ABS/RS)、单位面积内有活性反应中心数目(RS/CS)和吸收光能为基础的性能指数(PIABS),以及重度盐碱胁迫下‘左山一’的ABS/RS、RS/CS、用于电子传递的光能(ETo/CS)均显著低于相应对照,其余均无显著变化。(3)2品种山葡萄植株茎流率及株高、叶片数和根系生物量等生长指标在不同盐碱胁迫水平下均比对照显著降低,并以‘双优’品种降低幅度更大。研究表明,盐碱胁对山葡萄‘左山一’的叶片净光合速率、PSⅡ光能吸收和传递效率以及生长的抑制作用均小于‘双优’,‘左山一’的耐盐碱性更强。王振兴 吕海燕 秦红艳 赵滢 刘迎雪 艾军 曹建冉 杨义明 沈育杰 2017西北植物学报2017,37,2:19
12Experimental study on dynamic mechanical property of cemented tailings backfill under SHPB impact loading显示文摘Cemented tailings backfill(CTB) have increasingly been used in recent years to improve the stability of mining stopes in deep underground mines. Deep mining processes are often associated with rock bursting and high-speed dynamic loading conditions. Therefore, it is important to investigate the characteristics and dynamic mechanical behavior of CTB. This paper presents the results of dynamic tests on CTB specimens with different cement and solid contents using a split Hopkinson pressure bar(SHPB). The results showed that some CTB specimens exhibited one to two lower stress peaks after reaching dynamic peak stress before they completely failed. The greater the cement-to-tailings ratio is, the more obvious the strain reaction. This property mainly manifested as follows. First,the dynamic peak stress increased with the increase of the cement-to-tailings ratio when the impact velocity was fixed. Second, the dynamic peak stress had a quadratic relationship with the average stress rate. Third, the cement-to-tailings ratio could enhance the increase rate of dynamic peak stress with strain rate. In addition, the dynamic strength enhancement factor K increased with the increase of strain rate, and its value was larger than that of the rock samples. The failure modes of CTB specimens under low-speed impact were tensile failure and X conjugate shear failure, where were nearly the same as those under static uniaxial and triaxial compression. The CTB specimens were crushed and broken under critical strain, a failure mode similar to that of low-strength concrete. The results of the experimental research can improve the understanding of the dynamic mechanical properties of CTB and guide the strength design of deep mining backfills.Yu-ye Tan Xin Yu Davide Elmo Lin-hui Xu Wei-dong Song 2019International Journal of Minerals,Metallurgy and Materials2019,26,4:19
13Preliminary results of environmental monitoring of the natural gas hydrate production test in the South China Sea显示文摘Natural gas hydrate (NGH)is considered as one of the new clean energy sources of the 21st century with the highest potential.The environmental issues of NGH production have attracted the close attention of scientists in various countries.From May 10 to July 9,2017,the first offshore NGH production test in the South China Sea (SCS)was conducted by the China Geological Survey.In addition,environmental security has also been effectively guaranteed via a comprehensive environmental monitoring system built during the NGH production test.The monitoring system considered sea-surface atmosphere methane and carbon dioxide concentrations,dissolved methane in the sea water column,and the seafloor physical oceanography and marine chemistry environment.The whole process was monitored via multiple means, in multiple layers,in all domains,and in real time.After the production test,an environmental investigation was promptly conducted to evaluate the environmental impact of the NGH production test. The monitoring results showed that the dissolved methane concentration in seawater and the near-seabed environment characteristics after the test were consistent with the background values,indicating that the NGH production test did not cause environmental problems such as methane leakage.Jian-liang Ye Xu-wen Qin Hai-jun Qiu Qian-yong Liang Yi-fei Dong Jian-gong Wei Hai-long Lu Jing-an Lu Yao-hong Shi Chao Zhong Zhen Xia 2018China Geology2018,1,2:19
14Probiotic monotherapy and Helicobacter pylori eradication: A systematic review with pooled-data analysis显示文摘AIM To define probiotic monotherapy effect on Helicobacter pylori(H. pylori) status by performing a systematic review.METHODS Methods of analysis and inclusion criteria were based on PRISMA recommendations. Relevant publications were identified by searching Pub Med, MEDLINE, Science Direct, and EMBASE. The end-point was to estimate eradication rate and urea breath test delta value before and after probiotic monotherapy across all studies and, overall, with a pooled data analysis. Adverse events of probiotic therapy were evaluated. The data were expressed as proportions/percentages, and 95%CIs were calculated. For continuous variables, we evaluated the weighted mean difference. Odd ratios(ORs) were calculated according to the Peto method for the comparison of eradication rates between probiotics and placebo.RESULTS Eleven studies were selected. Probiotics eradicated H. pylori in 50 out of 403 cases. The mean weighted eradication rate was 14%(95%CI: 2%-25%, P =0.02). Lactobacilli eradicated the bacterium in 30 out of 235 patients, with a mean weighted rate of 16%(95%CI: 1%-31%). Saccharomyces boulardii achieved eradication in 6 out of 63 patients, with a pooled eradication rate of 12%(95%CI: 0%-29%). Multistrain combinations were effective in 14 out of 105 patients, with a pooled eradication rate of 14%(95%CI: 0%-43%). In the comparison of probiotics vs placebo, we found an OR of 7.91 in favor of probiotics(95%CI: 2.97-21.05, P < 0.001). Probiotics induced a mean reduction in delta values higher than placebo(8.61% with a 95%CI: 5.88-11.34, vs 0.19% for placebo, P < 0.001). Finally, no significant difference in adverse events was found between probiotics and placebo(OR = 1, 95%CI: 0.06-18.08).CONCLUSION Probiotics alone show a minimal effect on H. pylori clearance, thus suggesting a likely direct role.Giuseppe Losurdo Rossella Cubisino Michele Barone Mariabeatrice Principi Gioacchino Leandro Enzo Ierardi Alfredo Di Leo 2018World Journal of Gastroenterology2018,24,1:18
15妊娠期糖筛查时机的探讨显示文摘目的评价在不同孕周进行50 g葡萄糖负荷试验(glucose challenge test, GCT)对妊娠期糖尿病(gestational diabetes mellitus, GDM)和妊娠期糖耐量受损(gestational impaired glucose tolerance test, GIGT)的筛查效果. 方法对不同孕周的2000例孕妇进行50 g GCT,异常者再做正规糖耐量试验,确诊GDM或GIGT,并比较不同孕周妊娠期糖尿病或妊娠期糖耐量受损的诊断效果. 结果不同孕周进行50 g糖筛不影响GDM和GIGT最后诊断率,本研究GDM的发生率为4.75%(95/2000),GIGT为5.51%(103/2000).空腹进行50 g GCT阳性率和假阳性率均高于餐后1 h的50 g GCT,两组比较差异有统计学意义(P<0.01).在较早孕周初次进行GCT筛查,有助于早期发现GIGT和GDM.在GCT筛查推荐时期(孕24~28周)再进行一次50 g GCT,有助于提高GDM和GIGT的诊断率.对于GIGT血糖控制不满意者,必要时重做葡萄糖耐量试验以确诊是否发展为GDM.早期行50 g GCT组的剖宫产率和巨大儿发生率均低于孕24~28周筛查组. 结论对于GDM和GIGT的孕妇及时诊断与及时治疗,可以降低巨大儿和剖宫产率.吴霞 翟桂荣 黄醒华 2005中华围产医学杂志2005,8,5:18
16液基细胞学与传统巴氏涂片对普查人群宫颈病变筛查的比较显示文摘目的分析比较新柏氏液基细胞学(thinPrepcytologytest,TCT)及传统巴氏涂片(conventionalsmears,CS)在普查人群中对宫颈病变筛查的作用。方法回顾性分析了3581例TCT普查人群及同时期4776例CS普查人群的宫颈涂片结果。对两种方法的标本满意率及宫颈病变的阳性检出率进行了比较,并对两种方法与组织学的符合率进行了比较。结果TCT组标本满意率明显高于CS组(P<0.01);对非典型鳞状上皮细胞(atypicalsqumaouscells,ASC)及其以上病变的检出率TCT组亦明显高于CS组(P<0.05)。以阴道镜下组织学活检结果为标准,TCT组与CS组对LSLL及HSIL的诊断符合率分别为86.11%(31/36),91.7%(11/12)及66.7%(16/24),80%(4/5)。结论与CS相比,TCT技术明显提高了标本满意率及宫颈病变的阳性检出率,TCT技术是宫颈病变筛查的有效手段。张威 梅平 刘艳辉 庄恒国 曾仁海 陈国艳 2005广东医学2005,26,5:17
17THE COLONIC TRANSIT TEST IN THE ASSESSMENT OF CHRONIC CONSTIPATION显示文摘Chronicconstipationisacommoncomplaint.Itspathophysiologyispoorlyknown.Wemadecolonictransittesttoas-sesscolonicmotilityintheco...戴菲 罗金燕 龚均 1999Journal of Pharmaceutical Analysis1999,13,1:17
18Silymarin in non alcoholic fatty liver disease显示文摘AIM: This study was undertaken to evaluate the hepatic effects of silybum marianum on non alcoholic fatty liver disease (NAFLD). METHODS: In 72 patients affected by NAFLD, main metabolic, hepatic and anti-inflammatory parameters were assayed after 3 mo of a restricted diet and before silymarin treatment (twice a day orally). The brightness of liver echography texture (hepatorenal ratio brightness) was also defined at same time. These evaluations were repeated after 6 mo of treatment. RESULTS: Serum levels of some metabolic and anti-inflammatory data nonsignificantly lowered after 6 mo of silymarin. On the contrary, Steato test, alanine aminotransferase (ALT), aspartate aminotransferase (AST) and gamma-glutamyl transpeptidase were significantly (P < 0.001) reduced. Instead, the AST/ALT ratio unchanged. Finally, the hepatorenal brightness ratio, as an index of hepatic steatosis, significantly (P < 0.05) dropped. CONCLUSION: The obtained results indicate that silymarin appears to be effective to reduce the biochemical, inflammatory and ultrasonic indices of hepatic steatosis. Some parameters indicative of early stage of atherosclerosis were also lowered.Fulvio Cacciapuoti Anna Scognamiglio Rossella Palumbo Raffaele Forte Federico Cacciapuoti 2013World Journal of Hepatology2013,5,3:17
19Timing, distribution, and microbiology of infectious complications after necrotizing pancreatitis显示文摘BACKGROUND Acute pancreatitis(AP)is a common acute abdominal disease worldwide,and its incidence rate has increased annually.Approximately 20%of AP patients develop into necrotizing pancreatitis(NP),and 40%to 70%of NP patients have infectious complications,which usually indicate a worse prognosis.Infection is an important sign of complications in NP patients.AIM To investigate the difference in infection time,infection site,and infectious strain in NP patients with infectious complications.METHODS The clinical data of AP patients visiting the Department of General Surgery of Xuanwu Hospital of Capital Medical University from January 1,2014 to December 31,2018 were collected retrospectively.Enhanced computerized tomography or magnetic resonance imaging findings in patients with NP were included in the study.Statistical analysis of infectious bacteria,infection site,and infection time in NP patients with infectious complications was performed,because knowledge about pathogens and their antibiotic susceptibility patterns is essential for selecting an appropriate antibiotic.In addition,the factors that might influence the prognosis of patients were analyzed.RESULTS In this study,539 strains of pathogenic bacteria were isolated from 162 patients with NP infection,including 212 strains from pancreatic infections and 327 strains from extrapancreatic infections.Gram-negative bacteria were the main infectious species,the most common of which were Escherichia coli and Pseudomonas aeruginosa.The extrapancreatic infection time(9.1±8.8 d)was earlier than the pancreatic infection time(13.9±12.3 d).Among NP patients with early extrapancreatic infection(<14 d),bacteremia(25.12%)and respiratory tract infection(21.26%)were predominant.Among NP patients with late extrapancreatic infection(>14 d),bacteremia(15.94%),respiratory tract infection(7.74%),and urinary tract infection(7.71%)were predominant.Drug sensitivity analysis showed that P.aeruginosa was sensitive to enzymatic penicillins,thirdand fourth-generation cephalosporins,and carbapenems.Acinetobacter baumannii and Klebsiella pneumoniae were sensitive only to tigecycline;Staphylococcus epidermidis and Enterococcus faecium were highly sensitive to linezolid,tigecycline,and vancomycin.CONCLUSION In this study,we identified the timing,the common species,and site of infection in patients with NP.Jiong-Di Lu Feng Cao Yi-Xuan Ding Yu-Duo Wu Yu-Lin Guo Fei Li 2019World Journal of Gastroenterology2019,25,34:17
20Motion simulation and test on threshed grains in tapered threshing and transmission device for plot wheat breeding based on CFD-DEM显示文摘Mechanization of field experiments is the only way to improve crop breeding and seed propagation effects.In order to further clarify and improve the working performance of tapered threshing device for plot breeding,and reduce the remaining seeds in the device,the numerical simulation was carried out on the motion process of materials in the longitudinal-axial tapered cylinder threshing and transmission device of the plot wheat breeding combine harvester based on CFD-DEM method.Simulation results showed that,threshing and transmission of particles and short stalks at axial direction could be realized under the influence of air flow.Meanwhile,the material transference and distribution rule and stream field distribution rule of air flow in the threshing and transmission device were obtained,the variations of velocity and displacement of particles and short stalks with time were obtained;the motion trajectories and forms of particles in different types of retention were also studied.At rotating speed of 1300-1600 r/min for the tapered threshing cylinder in the verification test,the particle retention rate in the enclosure was 0-0.13%,while in the simulation the particle retention rate in the enclosure was 0-0.11%,only a 0.02%difference between them.The results proved a favorable feasibility to simulate the working performance of the tapered threshing and transmission device for plot breeding through gas-solid coupling method.Fei Dai Xuefeng Song Wuyun Zhao Zhengsheng Han Fengwei Zhang Shilin Zhang 2019International Journal of Agricultural and Biological Engineering2019,12,1:16
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